GNU Automake 1 Introduction 2 An Introduction to the Autotools 2.1 Introducing the GNU Build System 2.2 Use Cases for the GNU Build System 2.2.1 Basic Installation 2.2.2 Standard 'Makefile' Targets 2.2.3 Standard Directory Variables 2.2.4 Standard Configuration Variables 2.2.5 Overriding Default Configuration Setting with 'config.site' 2.2.6 Parallel Build Trees (a.k.a. VPATH Builds) 2.2.7 Two-Part Installation 2.2.8 Cross-Compilation 2.2.9 Renaming Programs at Install Time 2.2.10 Building Binary Packages Using DESTDIR 2.2.11 Preparing Distributions 2.2.12 Automatic Dependency Tracking 2.2.13 Nested Packages 2.3 How Autotools Help 2.4 A Small Hello World 2.4.1 Creating 'amhello-1.0.tar.gz' 2.4.2 'amhello''s 'configure.ac' Setup Explained 2.4.3 'amhello''s 'Makefile.am' Setup Explained 3 General ideas 3.1 General Operation 3.2 Strictness 3.3 The Uniform Naming Scheme 3.4 Staying below the command line length limit 3.5 How derived variables are named 3.6 Variables reserved for the user 3.7 Programs automake might require 4 Some example packages 4.1 A simple example, start to finish 4.2 Building true and false 5 Creating a 'Makefile.in' 6 Scanning 'configure.ac', using 'aclocal' 6.1 Configuration requirements 6.2 Other things Automake recognizes 6.3 Auto-generating aclocal.m4 6.3.1 aclocal Options 6.3.2 Macro Search Path 6.3.3 Writing your own aclocal macros 6.3.4 Handling Local Macros 6.3.5 Serial Numbers 6.3.6 The Future of 'aclocal' 6.4 Autoconf macros supplied with Automake 6.4.1 Public Macros 6.4.2 Obsolete Macros 6.4.3 Private Macros 7 Directories 7.1 Recursing subdirectories 7.2 Conditional Subdirectories 7.2.1 'SUBDIRS' vs. 'DIST_SUBDIRS' 7.2.2 Subdirectories with 'AM_CONDITIONAL' 7.2.3 Subdirectories with 'AC_SUBST' 7.2.4 Unconfigured Subdirectories 7.3 An Alternative Approach to Subdirectories 7.4 Nesting Packages 8 Building Programs and Libraries 8.1 Building a program 8.1.1 Defining program sources 8.1.2 Linking the program 8.1.3 Conditional compilation of sources 8.1.4 Conditional compilation of programs 8.2 Building a library 8.3 Building a Shared Library 8.3.1 The Libtool Concept 8.3.2 Building Libtool Libraries 8.3.3 Building Libtool Libraries Conditionally 8.3.4 Libtool Libraries with Conditional Sources 8.3.5 Libtool Convenience Libraries 8.3.6 Libtool Modules 8.3.7 '_LIBADD', '_LDFLAGS', and '_LIBTOOLFLAGS' 8.3.8 'LTLIBOBJS' and 'LTALLOCA' 8.3.9 Common Issues Related to Libtool's Use 8.3.9.1 Error: 'required file `./ltmain.sh' not found' 8.3.9.2 Objects 'created with both libtool and without' 8.4 Program and Library Variables 8.5 Default '_SOURCES' 8.6 Special handling for 'LIBOBJS' and 'ALLOCA' 8.7 Variables used when building a program 8.8 Yacc and Lex support 8.9 C++ Support 8.10 Objective C Support 8.11 Unified Parallel C Support 8.12 Assembly Support 8.13 Fortran 77 Support 8.13.1 Preprocessing Fortran 77 8.13.2 Compiling Fortran 77 Files 8.13.3 Mixing Fortran 77 With C and C++ 8.13.3.1 How the Linker is Chosen 8.14 Fortran 9x Support 8.14.1 Compiling Fortran 9x Files 8.15 Compiling Java sources using gcj 8.16 Vala Support 8.17 Support for Other Languages 8.18 Automatic de-ANSI-fication (deprecated, soon to be removed) 8.19 Automatic dependency tracking 8.20 Support for executable extensions 9 Other Derived Objects 9.1 Executable Scripts 9.2 Header files 9.3 Architecture-independent data files 9.4 Built Sources 9.4.1 Built Sources Example 10 Other GNU Tools 10.1 Emacs Lisp 10.2 Gettext 10.3 Libtool 10.4 Java bytecode compilation (deprecated) 10.5 Python 11 Building documentation 11.1 Texinfo 11.2 Man Pages 12 What Gets Installed 12.1 Basics of Installation 12.2 The Two Parts of Install 12.3 Extending Installation 12.4 Staged Installs 12.5 Install Rules for the User 13 What Gets Cleaned 14 What Goes in a Distribution 14.1 Basics of Distribution 14.2 Fine-grained Distribution Control 14.3 The dist Hook 14.4 Checking the Distribution 14.5 The Types of Distributions 15 Support for test suites 15.1 Simple Tests 15.2 Simple Tests using 'parallel-tests' 15.3 DejaGnu Tests 15.4 Install Tests 16 Rebuilding Makefiles 17 Changing Automake's Behavior 18 Miscellaneous Rules 18.1 Interfacing to 'etags' 18.2 Handling new file extensions 18.3 Support for Multilibs (deprecated, soon to be removed). 19 Include 20 Conditionals 20.1 Usage of Conditionals 20.2 Limits of Conditionals 21 Silencing 'make' 21.1 Make is verbose by default 21.2 Standard and generic ways to silence make 21.3 How Automake can help in silencing make 22 The effect of '--gnu' and '--gnits' 23 The effect of '--cygnus' 24 When Automake Isn't Enough 24.1 Extending Automake Rules 24.2 Third-Party 'Makefile's 25 Distributing 'Makefile.in's 26 Automake API Versioning 27 Upgrading a Package to a Newer Automake Version 28 Frequently Asked Questions about Automake 28.1 CVS and generated files 28.2 'missing' and 'AM_MAINTAINER_MODE' 28.3 Why doesn't Automake support wildcards? 28.4 Limitations on File Names 28.5 Files left in build directory after distclean 28.6 Flag Variables Ordering 28.7 Why are object files sometimes renamed? 28.8 Per-Object Flags Emulation 28.9 Handling Tools that Produce Many Outputs 28.10 Installing to Hard-Coded Locations 28.11 Debugging Make Rules 28.12 Reporting Bugs 29 History of Automake 29.1 Timeline 29.2 Dependency Tracking in Automake 29.2.1 First Take on Dependency Tracking Description Bugs Historical Note 29.2.2 Dependencies As Side Effects Description Bugs 29.2.3 Dependencies for the User Description Bugs 29.2.4 Techniques for Computing Dependencies 29.2.5 Recommendations for Tool Writers 29.2.6 Future Directions for Dependencies 29.3 Release Statistics Appendix A Copying This Manual A.1 GNU Free Documentation License Appendix B Indices B.1 Macro Index B.2 Variable Index B.3 General Index GNU Automake ************ This manual is for GNU Automake (version 1.11.5, 13 April 2012), a program that creates GNU standards-compliant Makefiles from template files. Copyright (C) 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License." 1 Introduction ************** Automake is a tool for automatically generating 'Makefile.in's from files called 'Makefile.am'. Each 'Makefile.am' is basically a series of 'make' variable definitions(1), with rules being thrown in occasionally. The generated 'Makefile.in's are compliant with the GNU Makefile standards. The GNU Makefile Standards Document (*note (standards)Makefile Conventions::) is long, complicated, and subject to change. The goal of Automake is to remove the burden of Makefile maintenance from the back of the individual GNU maintainer (and put it on the back of the Automake maintainers). The typical Automake input file is simply a series of variable definitions. Each such file is processed to create a 'Makefile.in'. There should generally be one 'Makefile.am' per directory of a project. Automake does constrain a project in certain ways; for instance, it assumes that the project uses Autoconf (*note Introduction: (autoconf)Top.), and enforces certain restrictions on the 'configure.ac' contents(2). Automake requires 'perl' in order to generate the 'Makefile.in's. However, the distributions created by Automake are fully GNU standards-compliant, and do not require 'perl' in order to be built. For more information on bug reports, *Note Reporting Bugs::. ---------- Footnotes ---------- (1) These variables are also called "make macros" in Make terminology, however in this manual we reserve the term "macro" for Autoconf's macros. (2) Older Autoconf versions used 'configure.in'. Autoconf 2.50 and greater promotes 'configure.ac' over 'configure.in'. The rest of this documentation will refer to 'configure.ac', but Automake also supports 'configure.in' for backward compatibility. 2 An Introduction to the Autotools ********************************** If you are new to Automake, maybe you know that it is part of a set of tools called _The Autotools_. Maybe you've already delved into a package full of files named 'configure', 'configure.ac', 'Makefile.in', 'Makefile.am', 'aclocal.m4', ..., some of them claiming to be _generated by_ Autoconf or Automake. But the exact purpose of these files and their relations is probably fuzzy. The goal of this chapter is to introduce you to this machinery, to show you how it works and how powerful it is. If you've never installed or seen such a package, do not worry: this chapter will walk you through it. If you need some teaching material, more illustrations, or a less 'automake'-centered continuation, some slides for this introduction are available in Alexandre Duret-Lutz's Autotools Tutorial (http://www.lrde.epita.fr/~adl/autotools.html). This chapter is the written version of the first part of his tutorial. 2.1 Introducing the GNU Build System ==================================== It is a truth universally acknowledged, that as a developer in possession of a new package, you must be in want of a build system. In the Unix world, such a build system is traditionally achieved using the command 'make' (*note Overview: (make)Top.). You express the recipe to build your package in a 'Makefile'. This file is a set of rules to build the files in the package. For instance the program 'prog' may be built by running the linker on the files 'main.o', 'foo.o', and 'bar.o'; the file 'main.o' may be built by running the compiler on 'main.c'; etc. Each time 'make' is run, it reads 'Makefile', checks the existence and modification time of the files mentioned, decides what files need to be built (or rebuilt), and runs the associated commands. When a package needs to be built on a different platform than the one it was developed on, its 'Makefile' usually needs to be adjusted. For instance the compiler may have another name or require more options. In 1991, David J. MacKenzie got tired of customizing 'Makefile' for the 20 platforms he had to deal with. Instead, he handcrafted a little shell script called 'configure' to automatically adjust the 'Makefile' (*note Genesis: (autoconf)Genesis.). Compiling his package was now as simple as running './configure && make'. Today this process has been standardized in the GNU project. The GNU Coding Standards (*note The Release Process: (standards)Managing Releases.) explains how each package of the GNU project should have a 'configure' script, and the minimal interface it should have. The 'Makefile' too should follow some established conventions. The result? A unified build system that makes all packages almost indistinguishable by the installer. In its simplest scenario, all the installer has to do is to unpack the package, run './configure && make && make install', and repeat with the next package to install. We call this build system the "GNU Build System", since it was grown out of the GNU project. However it is used by a vast number of other packages: following any existing convention has its advantages. The Autotools are tools that will create a GNU Build System for your package. Autoconf mostly focuses on 'configure' and Automake on 'Makefile's. It is entirely possible to create a GNU Build System without the help of these tools. However it is rather burdensome and error-prone. We will discuss this again after some illustration of the GNU Build System in action. 2.2 Use Cases for the GNU Build System ====================================== In this section we explore several use cases for the GNU Build System. You can replay all these examples on the 'amhello-1.0.tar.gz' package distributed with Automake. If Automake is installed on your system, you should find a copy of this file in 'PREFIX/share/doc/automake/amhello-1.0.tar.gz', where PREFIX is the installation prefix specified during configuration (PREFIX defaults to '/usr/local', however if Automake was installed by some GNU/Linux distribution it most likely has been set to '/usr'). If you do not have a copy of Automake installed, you can find a copy of this file inside the 'doc/' directory of the Automake package. Some of the following use cases present features that are in fact extensions to the GNU Build System. Read: they are not specified by the GNU Coding Standards, but they are nonetheless part of the build system created by the Autotools. To keep things simple, we do not point out the difference. Our objective is to show you many of the features that the build system created by the Autotools will offer to you. 2.2.1 Basic Installation ------------------------ The most common installation procedure looks as follows. ~ % tar zxf amhello-1.0.tar.gz ~ % cd amhello-1.0 ~/amhello-1.0 % ./configure ... config.status: creating Makefile config.status: creating src/Makefile ... ~/amhello-1.0 % make ... ~/amhello-1.0 % make check ... ~/amhello-1.0 % su Password: /home/adl/amhello-1.0 # make install ... /home/adl/amhello-1.0 # exit ~/amhello-1.0 % make installcheck ... The user first unpacks the package. Here, and in the following examples, we will use the non-portable 'tar zxf' command for simplicity. On a system without GNU 'tar' installed, this command should read 'gunzip -c amhello-1.0.tar.gz | tar xf -'. The user then enters the newly created directory to run the 'configure' script. This script probes the system for various features, and finally creates the 'Makefile's. In this toy example there are only two 'Makefile's, but in real-world projects, there may be many more, usually one 'Makefile' per directory. It is now possible to run 'make'. This will construct all the programs, libraries, and scripts that need to be constructed for the package. In our example, this compiles the 'hello' program. All files are constructed in place, in the source tree; we will see later how this can be changed. 'make check' causes the package's tests to be run. This step is not mandatory, but it is often good to make sure the programs that have been built behave as they should, before you decide to install them. Our example does not contain any tests, so running 'make check' is a no-op. After everything has been built, and maybe tested, it is time to install it on the system. That means copying the programs, libraries, header files, scripts, and other data files from the source directory to their final destination on the system. The command 'make install' will do that. However, by default everything will be installed in subdirectories of '/usr/local': binaries will go into '/usr/local/bin', libraries will end up in '/usr/local/lib', etc. This destination is usually not writable by any user, so we assume that we have to become root before we can run 'make install'. In our example, running 'make install' will copy the program 'hello' into '/usr/local/bin' and 'README' into '/usr/local/share/doc/amhello'. A last and optional step is to run 'make installcheck'. This command may run tests on the installed files. 'make check' tests the files in the source tree, while 'make installcheck' tests their installed copies. The tests run by the latter can be different from those run by the former. For instance, there are tests that cannot be run in the source tree. Conversely, some packages are set up so that 'make installcheck' will run the very same tests as 'make check', only on different files (non-installed vs. installed). It can make a difference, for instance when the source tree's layout is different from that of the installation. Furthermore it may help to diagnose an incomplete installation. Presently most packages do not have any 'installcheck' tests because the existence of 'installcheck' is little known, and its usefulness is neglected. Our little toy package is no better: 'make installcheck' does nothing. 2.2.2 Standard 'Makefile' Targets --------------------------------- So far we have come across four ways to run 'make' in the GNU Build System: 'make', 'make check', 'make install', and 'make installcheck'. The words 'check', 'install', and 'installcheck', passed as arguments to 'make', are called "targets". 'make' is a shorthand for 'make all', 'all' being the default target in the GNU Build System. Here is a list of the most useful targets that the GNU Coding Standards specify. 'make all' Build programs, libraries, documentation, etc. (same as 'make'). 'make install' Install what needs to be installed, copying the files from the package's tree to system-wide directories. 'make install-strip' Same as 'make install', then strip debugging symbols. Some users like to trade space for useful bug reports... 'make uninstall' The opposite of 'make install': erase the installed files. (This needs to be run from the same build tree that was installed.) 'make clean' Erase from the build tree the files built by 'make all'. 'make distclean' Additionally erase anything './configure' created. 'make check' Run the test suite, if any. 'make installcheck' Check the installed programs or libraries, if supported. 'make dist' Recreate 'PACKAGE-VERSION.tar.gz' from all the source files. 2.2.3 Standard Directory Variables ---------------------------------- The GNU Coding Standards also specify a hierarchy of variables to denote installation directories. Some of these are: Directory variable Default value ------------------------------------------------------- 'prefix' '/usr/local' 'exec_prefix' '${prefix}' 'bindir' '${exec_prefix}/bin' 'libdir' '${exec_prefix}/lib' ... 'includedir' '${prefix}/include' 'datarootdir' '${prefix}/share' 'datadir' '${datarootdir}' 'mandir' '${datarootdir}/man' 'infodir' '${datarootdir}/info' 'docdir' '${datarootdir}/doc/${PACKAGE}' ... Each of these directories has a role which is often obvious from its name. In a package, any installable file will be installed in one of these directories. For instance in 'amhello-1.0', the program 'hello' is to be installed in BINDIR, the directory for binaries. The default value for this directory is '/usr/local/bin', but the user can supply a different value when calling 'configure'. Also the file 'README' will be installed into DOCDIR, which defaults to '/usr/local/share/doc/amhello'. As a user, if you wish to install a package on your own account, you could proceed as follows: ~/amhello-1.0 % ./configure --prefix ~/usr ... ~/amhello-1.0 % make ... ~/amhello-1.0 % make install ... This would install '~/usr/bin/hello' and '~/usr/share/doc/amhello/README'. The list of all such directory options is shown by './configure --help'. 2.2.4 Standard Configuration Variables -------------------------------------- The GNU Coding Standards also define a set of standard configuration variables used during the build. Here are some: 'CC' C compiler command 'CFLAGS' C compiler flags 'CXX' C++ compiler command 'CXXFLAGS' C++ compiler flags 'LDFLAGS' linker flags 'CPPFLAGS' C/C++ preprocessor flags ... 'configure' usually does a good job at setting appropriate values for these variables, but there are cases where you may want to override them. For instance you may have several versions of a compiler installed and would like to use another one, you may have header files installed outside the default search path of the compiler, or even libraries out of the way of the linker. Here is how one would call 'configure' to force it to use 'gcc-3' as C compiler, use header files from '~/usr/include' when compiling, and libraries from '~/usr/lib' when linking. ~/amhello-1.0 % ./configure --prefix ~/usr CC=gcc-3 \ CPPFLAGS=-I$HOME/usr/include LDFLAGS=-L$HOME/usr/lib Again, a full list of these variables appears in the output of './configure --help'. 2.2.5 Overriding Default Configuration Setting with 'config.site' ----------------------------------------------------------------- When installing several packages using the same setup, it can be convenient to create a file to capture common settings. If a file named 'PREFIX/share/config.site' exists, 'configure' will source it at the beginning of its execution. Recall the command from the previous section: ~/amhello-1.0 % ./configure --prefix ~/usr CC=gcc-3 \ CPPFLAGS=-I$HOME/usr/include LDFLAGS=-L$HOME/usr/lib Assuming we are installing many package in '~/usr', and will always want to use these definitions of 'CC', 'CPPFLAGS', and 'LDFLAGS', we can automate this by creating the following '~/usr/share/config.site' file: test -z "$CC" && CC=gcc-3 test -z "$CPPFLAGS" && CPPFLAGS=-I$HOME/usr/include test -z "$LDFLAGS" && LDFLAGS=-L$HOME/usr/lib Now, any time a 'configure' script is using the '~/usr' prefix, it will execute the above 'config.site' and define these three variables. ~/amhello-1.0 % ./configure --prefix ~/usr configure: loading site script /home/adl/usr/share/config.site ... *Note Setting Site Defaults: (autoconf)Site Defaults, for more information about this feature. 2.2.6 Parallel Build Trees (a.k.a. VPATH Builds) ------------------------------------------------ The GNU Build System distinguishes two trees: the source tree, and the build tree. The source tree is rooted in the directory containing 'configure'. It contains all the sources files (those that are distributed), and may be arranged using several subdirectories. The build tree is rooted in the directory in which 'configure' was run, and is populated with all object files, programs, libraries, and other derived files built from the sources (and hence not distributed). The build tree usually has the same subdirectory layout as the source tree; its subdirectories are created automatically by the build system. If 'configure' is executed in its own directory, the source and build trees are combined: derived files are constructed in the same directories as their sources. This was the case in our first installation example (*note Basic Installation::). A common request from users is that they want to confine all derived files to a single directory, to keep their source directories uncluttered. Here is how we could run 'configure' to build everything in a subdirectory called 'build/'. ~ % tar zxf ~/amhello-1.0.tar.gz ~ % cd amhello-1.0 ~/amhello-1.0 % mkdir build && cd build ~/amhello-1.0/build % ../configure ... ~/amhello-1.0/build % make ... These setups, where source and build trees are different, are often called "parallel builds" or "VPATH builds". The expression _parallel build_ is misleading: the word _parallel_ is a reference to the way the build tree shadows the source tree, it is not about some concurrency in the way build commands are run. For this reason we refer to such setups using the name _VPATH builds_ in the following. _VPATH_ is the name of the 'make' feature used by the 'Makefile's to allow these builds (*note 'VPATH' Search Path for All Prerequisites: (make)General Search.). VPATH builds have other interesting uses. One is to build the same sources with multiple configurations. For instance: ~ % tar zxf ~/amhello-1.0.tar.gz ~ % cd amhello-1.0 ~/amhello-1.0 % mkdir debug optim && cd debug ~/amhello-1.0/debug % ../configure CFLAGS='-g -O0' ... ~/amhello-1.0/debug % make ... ~/amhello-1.0/debug % cd ../optim ~/amhello-1.0/optim % ../configure CFLAGS='-O3 -fomit-frame-pointer' ... ~/amhello-1.0/optim % make ... With network file systems, a similar approach can be used to build the same sources on different machines. For instance, suppose that the sources are installed on a directory shared by two hosts: 'HOST1' and 'HOST2', which may be different platforms. ~ % cd /nfs/src /nfs/src % tar zxf ~/amhello-1.0.tar.gz On the first host, you could create a local build directory: [HOST1] ~ % mkdir /tmp/amh && cd /tmp/amh [HOST1] /tmp/amh % /nfs/src/amhello-1.0/configure ... [HOST1] /tmp/amh % make && sudo make install ... (Here we assume that the installer has configured 'sudo' so it can execute 'make install' with root privileges; it is more convenient than using 'su' like in *note Basic Installation::). On the second host, you would do exactly the same, possibly at the same time: [HOST2] ~ % mkdir /tmp/amh && cd /tmp/amh [HOST2] /tmp/amh % /nfs/src/amhello-1.0/configure ... [HOST2] /tmp/amh % make && sudo make install ... In this scenario, nothing forbids the '/nfs/src/amhello-1.0' directory from being read-only. In fact VPATH builds are also a means of building packages from a read-only medium such as a CD-ROM. (The FSF used to sell CD-ROM with unpacked source code, before the GNU project grew so big.) 2.2.7 Two-Part Installation --------------------------- In our last example (*note VPATH Builds::), a source tree was shared by two hosts, but compilation and installation were done separately on each host. The GNU Build System also supports networked setups where part of the installed files should be shared amongst multiple hosts. It does so by distinguishing architecture-dependent files from architecture-independent files, and providing two 'Makefile' targets to install each of these classes of files. These targets are 'install-exec' for architecture-dependent files and 'install-data' for architecture-independent files. The command we used up to now, 'make install', can be thought of as a shorthand for 'make install-exec install-data'. From the GNU Build System point of view, the distinction between architecture-dependent files and architecture-independent files is based exclusively on the directory variable used to specify their installation destination. In the list of directory variables we provided earlier (*note Standard Directory Variables::), all the variables based on EXEC-PREFIX designate architecture-dependent directories whose files will be installed by 'make install-exec'. The others designate architecture-independent directories and will serve files installed by 'make install-data'. *Note The Two Parts of Install::, for more details. Here is how we could revisit our two-host installation example, assuming that (1) we want to install the package directly in '/usr', and (2) the directory '/usr/share' is shared by the two hosts. On the first host we would run [HOST1] ~ % mkdir /tmp/amh && cd /tmp/amh [HOST1] /tmp/amh % /nfs/src/amhello-1.0/configure --prefix /usr ... [HOST1] /tmp/amh % make && sudo make install ... On the second host, however, we need only install the architecture-specific files. [HOST2] ~ % mkdir /tmp/amh && cd /tmp/amh [HOST2] /tmp/amh % /nfs/src/amhello-1.0/configure --prefix /usr ... [HOST2] /tmp/amh % make && sudo make install-exec ... In packages that have installation checks, it would make sense to run 'make installcheck' (*note Basic Installation::) to verify that the package works correctly despite the apparent partial installation. 2.2.8 Cross-Compilation ----------------------- To "cross-compile" is to build on one platform a binary that will run on another platform. When speaking of cross-compilation, it is important to distinguish between the "build platform" on which the compilation is performed, and the "host platform" on which the resulting executable is expected to run. The following 'configure' options are used to specify each of them: '--build=BUILD' The system on which the package is built. '--host=HOST' The system where built programs and libraries will run. When the '--host' is used, 'configure' will search for the cross-compiling suite for this platform. Cross-compilation tools commonly have their target architecture as prefix of their name. For instance my cross-compiler for MinGW32 has its binaries called 'i586-mingw32msvc-gcc', 'i586-mingw32msvc-ld', 'i586-mingw32msvc-as', etc. Here is how we could build 'amhello-1.0' for 'i586-mingw32msvc' on a GNU/Linux PC. ~/amhello-1.0 % ./configure --build i686-pc-linux-gnu --host i586-mingw32msvc checking for a BSD-compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking for gawk... gawk checking whether make sets $(MAKE)... yes checking for i586-mingw32msvc-strip... i586-mingw32msvc-strip checking for i586-mingw32msvc-gcc... i586-mingw32msvc-gcc checking for C compiler default output file name... a.exe checking whether the C compiler works... yes checking whether we are cross compiling... yes checking for suffix of executables... .exe checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether i586-mingw32msvc-gcc accepts -g... yes checking for i586-mingw32msvc-gcc option to accept ANSI C... ... ~/amhello-1.0 % make ... ~/amhello-1.0 % cd src; file hello.exe hello.exe: MS Windows PE 32-bit Intel 80386 console executable not relocatable The '--host' and '--build' options are usually all we need for cross-compiling. The only exception is if the package being built is itself a cross-compiler: we need a third option to specify its target architecture. '--target=TARGET' When building compiler tools: the system for which the tools will create output. For instance when installing GCC, the GNU Compiler Collection, we can use '--target=TARGET' to specify that we want to build GCC as a cross-compiler for TARGET. Mixing '--build' and '--target', we can actually cross-compile a cross-compiler; such a three-way cross-compilation is known as a "Canadian cross". *Note Specifying the System Type: (autoconf)Specifying Names, for more information about these 'configure' options. 2.2.9 Renaming Programs at Install Time --------------------------------------- The GNU Build System provides means to automatically rename executables and manpages before they are installed (*note Man Pages::). This is especially convenient when installing a GNU package on a system that already has a proprietary implementation you do not want to overwrite. For instance, you may want to install GNU 'tar' as 'gtar' so you can distinguish it from your vendor's 'tar'. This can be done using one of these three 'configure' options. '--program-prefix=PREFIX' Prepend PREFIX to installed program names. '--program-suffix=SUFFIX' Append SUFFIX to installed program names. '--program-transform-name=PROGRAM' Run 'sed PROGRAM' on installed program names. The following commands would install 'hello' as '/usr/local/bin/test-hello', for instance. ~/amhello-1.0 % ./configure --program-prefix test- ... ~/amhello-1.0 % make ... ~/amhello-1.0 % sudo make install ... 2.2.10 Building Binary Packages Using DESTDIR --------------------------------------------- The GNU Build System's 'make install' and 'make uninstall' interface does not exactly fit the needs of a system administrator who has to deploy and upgrade packages on lots of hosts. In other words, the GNU Build System does not replace a package manager. Such package managers usually need to know which files have been installed by a package, so a mere 'make install' is inappropriate. The 'DESTDIR' variable can be used to perform a staged installation. The package should be configured as if it was going to be installed in its final location (e.g., '--prefix /usr'), but when running 'make install', the 'DESTDIR' should be set to the absolute name of a directory into which the installation will be diverted. From this directory it is easy to review which files are being installed where, and finally copy them to their final location by some means. For instance here is how we could create a binary package containing a snapshot of all the files to be installed. ~/amhello-1.0 % ./configure --prefix /usr ... ~/amhello-1.0 % make ... ~/amhello-1.0 % make DESTDIR=$HOME/inst install ... ~/amhello-1.0 % cd ~/inst ~/inst % find . -type f -print > ../files.lst ~/inst % tar zcvf ~/amhello-1.0-i686.tar.gz `cat ../files.lst` ./usr/bin/hello ./usr/share/doc/amhello/README After this example, 'amhello-1.0-i686.tar.gz' is ready to be uncompressed in '/' on many hosts. (Using '`cat ../files.lst`' instead of '.' as argument for 'tar' avoids entries for each subdirectory in the archive: we would not like 'tar' to restore the modification time of '/', '/usr/', etc.) Note that when building packages for several architectures, it might be convenient to use 'make install-data' and 'make install-exec' (*note Two-Part Install::) to gather architecture-independent files in a single package. *Note Install::, for more information. 2.2.11 Preparing Distributions ------------------------------ We have already mentioned 'make dist'. This target collects all your source files and the necessary parts of the build system to create a tarball named 'PACKAGE-VERSION.tar.gz'. Another, more useful command is 'make distcheck'. The 'distcheck' target constructs 'PACKAGE-VERSION.tar.gz' just as well as 'dist', but it additionally ensures most of the use cases presented so far work: * It attempts a full compilation of the package (*note Basic Installation::), unpacking the newly constructed tarball, running 'make', 'make check', 'make install', as well as 'make installcheck', and even 'make dist', * it tests VPATH builds with read-only source tree (*note VPATH Builds::), * it makes sure 'make clean', 'make distclean', and 'make uninstall' do not omit any file (*note Standard Targets::), * and it checks that 'DESTDIR' installations work (*note DESTDIR::). All of these actions are performed in a temporary subdirectory, so that no root privileges are required. Releasing a package that fails 'make distcheck' means that one of the scenarios we presented will not work and some users will be disappointed. Therefore it is a good practice to release a package only after a successful 'make distcheck'. This of course does not imply that the package will be flawless, but at least it will prevent some of the embarrassing errors you may find in packages released by people who have never heard about 'distcheck' (like 'DESTDIR' not working because of a typo, or a distributed file being erased by 'make clean', or even 'VPATH' builds not working). *Note Creating amhello::, to recreate 'amhello-1.0.tar.gz' using 'make distcheck'. *Note Checking the Distribution::, for more information about 'distcheck'. 2.2.12 Automatic Dependency Tracking ------------------------------------ Dependency tracking is performed as a side-effect of compilation. Each time the build system compiles a source file, it computes its list of dependencies (in C these are the header files included by the source being compiled). Later, any time 'make' is run and a dependency appears to have changed, the dependent files will be rebuilt. Automake generates code for automatic dependency tracking by default, unless the developer chooses to override it; for more information, *note Dependencies::. When 'configure' is executed, you can see it probing each compiler for the dependency mechanism it supports (several mechanisms can be used): ~/amhello-1.0 % ./configure --prefix /usr ... checking dependency style of gcc... gcc3 ... Because dependencies are only computed as a side-effect of the compilation, no dependency information exists the first time a package is built. This is OK because all the files need to be built anyway: 'make' does not have to decide which files need to be rebuilt. In fact, dependency tracking is completely useless for one-time builds and there is a 'configure' option to disable this: '--disable-dependency-tracking' Speed up one-time builds. Some compilers do not offer any practical way to derive the list of dependencies as a side-effect of the compilation, requiring a separate run (maybe of another tool) to compute these dependencies. The performance penalty implied by these methods is important enough to disable them by default. The option '--enable-dependency-tracking' must be passed to 'configure' to activate them. '--enable-dependency-tracking' Do not reject slow dependency extractors. *Note Dependency Tracking Evolution::, for some discussion about the different dependency tracking schemes used by Automake over the years. 2.2.13 Nested Packages ---------------------- Although nesting packages isn't something we would recommend to someone who is discovering the Autotools, it is a nice feature worthy of mention in this small advertising tour. Autoconfiscated packages (that means packages whose build system have been created by Autoconf and friends) can be nested to arbitrary depth. A typical setup is that package A will distribute one of the libraries it needs in a subdirectory. This library B is a complete package with its own GNU Build System. The 'configure' script of A will run the 'configure' script of B as part of its execution, building and installing A will also build and install B. Generating a distribution for A will also include B. It is possible to gather several packages like this. GCC is a heavy user of this feature. This gives installers a single package to configure, build and install, while it allows developers to work on subpackages independently. When configuring nested packages, the 'configure' options given to the top-level 'configure' are passed recursively to nested 'configure's. A package that does not understand an option will ignore it, assuming it is meaningful to some other package. The command 'configure --help=recursive' can be used to display the options supported by all the included packages. *Note Subpackages::, for an example setup. 2.3 How Autotools Help ====================== There are several reasons why you may not want to implement the GNU Build System yourself (read: write a 'configure' script and 'Makefile's yourself). * As we have seen, the GNU Build System has a lot of features (*note Use Cases::). Some users may expect features you have not implemented because you did not need them. * Implementing these features portably is difficult and exhausting. Think of writing portable shell scripts, and portable 'Makefile's, for systems you may not have handy. *Note Portable Shell Programming: (autoconf)Portable Shell, to convince yourself. * You will have to upgrade your setup to follow changes to the GNU Coding Standards. The GNU Autotools take all this burden off your back and provide: * Tools to create a portable, complete, and self-contained GNU Build System, from simple instructions. _Self-contained_ meaning the resulting build system does not require the GNU Autotools. * A central place where fixes and improvements are made: a bug-fix for a portability issue will benefit every package. Yet there also exist reasons why you may want NOT to use the Autotools... For instance you may be already using (or used to) another incompatible build system. Autotools will only be useful if you do accept the concepts of the GNU Build System. People who have their own idea of how a build system should work will feel frustrated by the Autotools. 2.4 A Small Hello World ======================= In this section we recreate the 'amhello-1.0' package from scratch. The first subsection shows how to call the Autotools to instantiate the GNU Build System, while the second explains the meaning of the 'configure.ac' and 'Makefile.am' files read by the Autotools. 2.4.1 Creating 'amhello-1.0.tar.gz' ----------------------------------- Here is how we can recreate 'amhello-1.0.tar.gz' from scratch. The package is simple enough so that we will only need to write 5 files. (You may copy them from the final 'amhello-1.0.tar.gz' that is distributed with Automake if you do not want to write them.) Create the following files in an empty directory. * 'src/main.c' is the source file for the 'hello' program. We store it in the 'src/' subdirectory, because later, when the package evolves, it will ease the addition of a 'man/' directory for man pages, a 'data/' directory for data files, etc. ~/amhello % cat src/main.c #include #include int main (void) { puts ("Hello World!"); puts ("This is " PACKAGE_STRING "."); return 0; } * 'README' contains some very limited documentation for our little package. ~/amhello % cat README This is a demonstration package for GNU Automake. Type `info Automake' to read the Automake manual. * 'Makefile.am' and 'src/Makefile.am' contain Automake instructions for these two directories. ~/amhello % cat src/Makefile.am bin_PROGRAMS = hello hello_SOURCES = main.c ~/amhello % cat Makefile.am SUBDIRS = src dist_doc_DATA = README * Finally, 'configure.ac' contains Autoconf instructions to create the 'configure' script. ~/amhello % cat configure.ac AC_INIT([amhello], [1.0], [bug-automake@gnu.org]) AM_INIT_AUTOMAKE([-Wall -Werror foreign]) AC_PROG_CC AC_CONFIG_HEADERS([config.h]) AC_CONFIG_FILES([ Makefile src/Makefile ]) AC_OUTPUT Once you have these five files, it is time to run the Autotools to instantiate the build system. Do this using the 'autoreconf' command as follows: ~/amhello % autoreconf --install configure.ac: installing `./install-sh' configure.ac: installing `./missing' src/Makefile.am: installing `./depcomp' At this point the build system is complete. In addition to the three scripts mentioned in its output, you can see that 'autoreconf' created four other files: 'configure', 'config.h.in', 'Makefile.in', and 'src/Makefile.in'. The latter three files are templates that will be adapted to the system by 'configure' under the names 'config.h', 'Makefile', and 'src/Makefile'. Let's do this: ~/amhello % ./configure checking for a BSD-compatible install... /usr/bin/install -c checking whether build environment is sane... yes checking for gawk... no checking for mawk... mawk checking whether make sets $(MAKE)... yes checking for gcc... gcc checking for C compiler default output file name... a.out checking whether the C compiler works... yes checking whether we are cross compiling... no checking for suffix of executables... checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether gcc accepts -g... yes checking for gcc option to accept ISO C89... none needed checking for style of include used by make... GNU checking dependency style of gcc... gcc3 configure: creating ./config.status config.status: creating Makefile config.status: creating src/Makefile config.status: creating config.h config.status: executing depfiles commands You can see 'Makefile', 'src/Makefile', and 'config.h' being created at the end after 'configure' has probed the system. It is now possible to run all the targets we wish (*note Standard Targets::). For instance: ~/amhello % make ... ~/amhello % src/hello Hello World! This is amhello 1.0. ~/amhello % make distcheck ... ============================================= amhello-1.0 archives ready for distribution: amhello-1.0.tar.gz ============================================= Note that running 'autoreconf' is only needed initially when the GNU Build System does not exist. When you later change some instructions in a 'Makefile.am' or 'configure.ac', the relevant part of the build system will be regenerated automatically when you execute 'make'. 'autoreconf' is a script that calls 'autoconf', 'automake', and a bunch of other commands in the right order. If you are beginning with these tools, it is not important to figure out in which order all these tools should be invoked and why. However, because Autoconf and Automake have separate manuals, the important point to understand is that 'autoconf' is in charge of creating 'configure' from 'configure.ac', while 'automake' is in charge of creating 'Makefile.in's from 'Makefile.am's and 'configure.ac'. This should at least direct you to the right manual when seeking answers. 2.4.2 'amhello''s 'configure.ac' Setup Explained ------------------------------------------------ Let us begin with the contents of 'configure.ac'. AC_INIT([amhello], [1.0], [bug-automake@gnu.org]) AM_INIT_AUTOMAKE([-Wall -Werror foreign]) AC_PROG_CC AC_CONFIG_HEADERS([config.h]) AC_CONFIG_FILES([ Makefile src/Makefile ]) AC_OUTPUT This file is read by both 'autoconf' (to create 'configure') and 'automake' (to create the various 'Makefile.in's). It contains a series of M4 macros that will be expanded as shell code to finally form the 'configure' script. We will not elaborate on the syntax of this file, because the Autoconf manual has a whole section about it (*note Writing 'configure.ac': (autoconf)Writing Autoconf Input.). The macros prefixed with 'AC_' are Autoconf macros, documented in the Autoconf manual (*note Autoconf Macro Index: (autoconf)Autoconf Macro Index.). The macros that start with 'AM_' are Automake macros, documented later in this manual (*note Macro Index::). The first two lines of 'configure.ac' initialize Autoconf and Automake. 'AC_INIT' takes in as parameters the name of the package, its version number, and a contact address for bug-reports about the package (this address is output at the end of './configure --help', for instance). When adapting this setup to your own package, by all means please do not blindly copy Automake's address: use the mailing list of your package, or your own mail address. The argument to 'AM_INIT_AUTOMAKE' is a list of options for 'automake' (*note Options::). '-Wall' and '-Werror' ask 'automake' to turn on all warnings and report them as errors. We are speaking of *Automake* warnings here, such as dubious instructions in 'Makefile.am'. This has absolutely nothing to do with how the compiler will be called, even though it may support options with similar names. Using '-Wall -Werror' is a safe setting when starting to work on a package: you do not want to miss any issues. Later you may decide to relax things a bit. The 'foreign' option tells Automake that this package will not follow the GNU Standards. GNU packages should always distribute additional files such as 'ChangeLog', 'AUTHORS', etc. We do not want 'automake' to complain about these missing files in our small example. The 'AC_PROG_CC' line causes the 'configure' script to search for a C compiler and define the variable 'CC' with its name. The 'src/Makefile.in' file generated by Automake uses the variable 'CC' to build 'hello', so when 'configure' creates 'src/Makefile' from 'src/Makefile.in', it will define 'CC' with the value it has found. If Automake is asked to create a 'Makefile.in' that uses 'CC' but 'configure.ac' does not define it, it will suggest you add a call to 'AC_PROG_CC'. The 'AC_CONFIG_HEADERS([config.h])' invocation causes the 'configure' script to create a 'config.h' file gathering '#define's defined by other macros in 'configure.ac'. In our case, the 'AC_INIT' macro already defined a few of them. Here is an excerpt of 'config.h' after 'configure' has run: ... /* Define to the address where bug reports for this package should be sent. */ #define PACKAGE_BUGREPORT "bug-automake@gnu.org" /* Define to the full name and version of this package. */ #define PACKAGE_STRING "amhello 1.0" ... As you probably noticed, 'src/main.c' includes 'config.h' so it can use 'PACKAGE_STRING'. In a real-world project, 'config.h' can grow really big, with one '#define' per feature probed on the system. The 'AC_CONFIG_FILES' macro declares the list of files that 'configure' should create from their '*.in' templates. Automake also scans this list to find the 'Makefile.am' files it must process. (This is important to remember: when adding a new directory to your project, you should add its 'Makefile' to this list, otherwise Automake will never process the new 'Makefile.am' you wrote in that directory.) Finally, the 'AC_OUTPUT' line is a closing command that actually produces the part of the script in charge of creating the files registered with 'AC_CONFIG_HEADERS' and 'AC_CONFIG_FILES'. When starting a new project, we suggest you start with such a simple 'configure.ac', and gradually add the other tests it requires. The command 'autoscan' can also suggest a few of the tests your package may need (*note Using 'autoscan' to Create 'configure.ac': (autoconf)autoscan Invocation.). 2.4.3 'amhello''s 'Makefile.am' Setup Explained ----------------------------------------------- We now turn to 'src/Makefile.am'. This file contains Automake instructions to build and install 'hello'. bin_PROGRAMS = hello hello_SOURCES = main.c A 'Makefile.am' has the same syntax as an ordinary 'Makefile'. When 'automake' processes a 'Makefile.am' it copies the entire file into the output 'Makefile.in' (that will be later turned into 'Makefile' by 'configure') but will react to certain variable definitions by generating some build rules and other variables. Often 'Makefile.am's contain only a list of variable definitions as above, but they can also contain other variable and rule definitions that 'automake' will pass along without interpretation. Variables that end with '_PROGRAMS' are special variables that list programs that the resulting 'Makefile' should build. In Automake speak, this '_PROGRAMS' suffix is called a "primary"; Automake recognizes other primaries such as '_SCRIPTS', '_DATA', '_LIBRARIES', etc. corresponding to different types of files. The 'bin' part of the 'bin_PROGRAMS' tells 'automake' that the resulting programs should be installed in BINDIR. Recall that the GNU Build System uses a set of variables to denote destination directories and allow users to customize these locations (*note Standard Directory Variables::). Any such directory variable can be put in front of a primary (omitting the 'dir' suffix) to tell 'automake' where to install the listed files. Programs need to be built from source files, so for each program 'PROG' listed in a '_PROGRAMS' variable, 'automake' will look for another variable named 'PROG_SOURCES' listing its source files. There may be more than one source file: they will all be compiled and linked together. Automake also knows that source files need to be distributed when creating a tarball (unlike built programs). So a side-effect of this 'hello_SOURCES' declaration is that 'main.c' will be part of the tarball created by 'make dist'. Finally here are some explanations regarding the top-level 'Makefile.am'. SUBDIRS = src dist_doc_DATA = README 'SUBDIRS' is a special variable listing all directories that 'make' should recurse into before processing the current directory. So this line is responsible for 'make' building 'src/hello' even though we run it from the top-level. This line also causes 'make install' to install 'src/hello' before installing 'README' (not that this order matters). The line 'dist_doc_DATA = README' causes 'README' to be distributed and installed in DOCDIR. Files listed with the '_DATA' primary are not automatically part of the tarball built with 'make dist', so we add the 'dist_' prefix so they get distributed. However, for 'README' it would not have been necessary: 'automake' automatically distributes any 'README' file it encounters (the list of other files automatically distributed is presented by 'automake --help'). The only important effect of this second line is therefore to install 'README' during 'make install'. One thing not covered in this example is accessing the installation directory values (*note Standard Directory Variables::) from your program code, that is, converting them into defined macros. For this, *note (autoconf)Defining Directories::. 3 General ideas *************** The following sections cover a few basic ideas that will help you understand how Automake works. 3.1 General Operation ===================== Automake works by reading a 'Makefile.am' and generating a 'Makefile.in'. Certain variables and rules defined in the 'Makefile.am' instruct Automake to generate more specialized code; for instance, a 'bin_PROGRAMS' variable definition will cause rules for compiling and linking programs to be generated. The variable definitions and rules in the 'Makefile.am' are copied mostly verbatim into the generated file, with all variable definitions preceding all rules. This allows you to add almost arbitrary code into the generated 'Makefile.in'. For instance, the Automake distribution includes a non-standard rule for the 'git-dist' target, which the Automake maintainer uses to make distributions from the source control system. Note that most GNU make extensions are not recognized by Automake. Using such extensions in a 'Makefile.am' will lead to errors or confusing behavior. A special exception is that the GNU make append operator, '+=', is supported. This operator appends its right hand argument to the variable specified on the left. Automake will translate the operator into an ordinary '=' operator; '+=' will thus work with any make program. Automake tries to keep comments grouped with any adjoining rules or variable definitions. Generally, Automake is not particularly smart in the parsing of unusual Makefile constructs, so you're advised to avoid fancy constructs or "creative" use of whitespaces. For example, characters cannot be used between a target name and the following "':'" character, and variable assignments shouldn't be indented with characters. Also, using more complex macro in target names can cause trouble: % cat Makefile.am $(FOO:=x): bar % automake Makefile.am:1: bad characters in variable name `$(FOO' Makefile.am:1: `:='-style assignments are not portable A rule defined in 'Makefile.am' generally overrides any such rule of a similar name that would be automatically generated by 'automake'. Although this is a supported feature, it is generally best to avoid making use of it, as sometimes the generated rules are very particular. Similarly, a variable defined in 'Makefile.am' or 'AC_SUBST'ed from 'configure.ac' will override any definition of the variable that 'automake' would ordinarily create. This feature is more often useful than the ability to override a rule. Be warned that many of the variables generated by 'automake' are considered to be for internal use only, and their names might change in future releases. When examining a variable definition, Automake will recursively examine variables referenced in the definition. For example, if Automake is looking at the content of 'foo_SOURCES' in this snippet xs = a.c b.c foo_SOURCES = c.c $(xs) it would use the files 'a.c', 'b.c', and 'c.c' as the contents of 'foo_SOURCES'. Automake also allows a form of comment that is _not_ copied into the output; all lines beginning with '##' (leading spaces allowed) are completely ignored by Automake. It is customary to make the first line of 'Makefile.am' read: ## Process this file with automake to produce Makefile.in 3.2 Strictness ============== While Automake is intended to be used by maintainers of GNU packages, it does make some effort to accommodate those who wish to use it, but do not want to use all the GNU conventions. To this end, Automake supports three levels of "strictness"--the strictness indicating how stringently Automake should check standards conformance. The valid strictness levels are: 'foreign' Automake will check for only those things that are absolutely required for proper operations. For instance, whereas GNU standards dictate the existence of a 'NEWS' file, it will not be required in this mode. The name comes from the fact that Automake is intended to be used for GNU programs; these relaxed rules are not the standard mode of operation. 'gnu' Automake will check--as much as possible--for compliance to the GNU standards for packages. This is the default. 'gnits' Automake will check for compliance to the as-yet-unwritten "Gnits standards". These are based on the GNU standards, but are even more detailed. Unless you are a Gnits standards contributor, it is recommended that you avoid this option until such time as the Gnits standard is actually published (which may never happen). *Note Gnits::, for more information on the precise implications of the strictness level. Automake also has a special (and _today deprecated_) "cygnus" mode that is similar to strictness but handled differently. This mode is useful for packages that are put into a "Cygnus" style tree (e.g., older versions of the GCC and gdb trees). *Note Cygnus::, for more information on this mode. Please note that this mode is deprecated and _will be removed in the future automake versions_; you must avoid its use in new packages, and should stop using it in existing packages as well. 3.3 The Uniform Naming Scheme ============================= Automake variables generally follow a "uniform naming scheme" that makes it easy to decide how programs (and other derived objects) are built, and how they are installed. This scheme also supports 'configure' time determination of what should be built. At 'make' time, certain variables are used to determine which objects are to be built. The variable names are made of several pieces that are concatenated together. The piece that tells 'automake' what is being built is commonly called the "primary". For instance, the primary 'PROGRAMS' holds a list of programs that are to be compiled and linked. A different set of names is used to decide where the built objects should be installed. These names are prefixes to the primary, and they indicate which standard directory should be used as the installation directory. The standard directory names are given in the GNU standards (*note (standards)Directory Variables::). Automake extends this list with 'pkgdatadir', 'pkgincludedir', 'pkglibdir', and 'pkglibexecdir'; these are the same as the non-'pkg' versions, but with '$(PACKAGE)' appended. For instance, 'pkglibdir' is defined as '$(libdir)/$(PACKAGE)'. For each primary, there is one additional variable named by prepending 'EXTRA_' to the primary name. This variable is used to list objects that may or may not be built, depending on what 'configure' decides. This variable is required because Automake must statically know the entire list of objects that may be built in order to generate a 'Makefile.in' that will work in all cases. For instance, 'cpio' decides at configure time which programs should be built. Some of the programs are installed in 'bindir', and some are installed in 'sbindir': EXTRA_PROGRAMS = mt rmt bin_PROGRAMS = cpio pax sbin_PROGRAMS = $(MORE_PROGRAMS) Defining a primary without a prefix as a variable, e.g., 'PROGRAMS', is an error. Note that the common 'dir' suffix is left off when constructing the variable names; thus one writes 'bin_PROGRAMS' and not 'bindir_PROGRAMS'. Not every sort of object can be installed in every directory. Automake will flag those attempts it finds in error (but see below how to override the check if you really need to). Automake will also diagnose obvious misspellings in directory names. Sometimes the standard directories--even as augmented by Automake--are not enough. In particular it is sometimes useful, for clarity, to install objects in a subdirectory of some predefined directory. To this end, Automake allows you to extend the list of possible installation directories. A given prefix (e.g., 'zar') is valid if a variable of the same name with 'dir' appended is defined (e.g., 'zardir'). For instance, the following snippet will install 'file.xml' into '$(datadir)/xml'. xmldir = $(datadir)/xml xml_DATA = file.xml This feature can also be used to override the sanity checks Automake performs to diagnose suspicious directory/primary couples (in the unlikely case these checks are undesirable, and you really know what you're doing). For example, Automake would error out on this input: # Forbidden directory combinations, automake will error out on this. pkglib_PROGRAMS = foo doc_LIBRARIES = libquux.a but it will succeed with this: # Work around forbidden directory combinations. Do not use this # without a very good reason! my_execbindir = $(pkglibdir) my_doclibdir = $(docdir) my_execbin_PROGRAMS = foo my_doclib_LIBRARIES = libquux.a The 'exec' substring of the 'my_execbindir' variable lets the files be installed at the right time (*note The Two Parts of Install::). The special prefix 'noinst_' indicates that the objects in question should be built but not installed at all. This is usually used for objects required to build the rest of your package, for instance static libraries (*note A Library::), or helper scripts. The special prefix 'check_' indicates that the objects in question should not be built until the 'make check' command is run. Those objects are not installed either. The current primary names are 'PROGRAMS', 'LIBRARIES', 'LTLIBRARIES', 'LISP', 'PYTHON', 'JAVA', 'SCRIPTS', 'DATA', 'HEADERS', 'MANS', and 'TEXINFOS'. Some primaries also allow additional prefixes that control other aspects of 'automake''s behavior. The currently defined prefixes are 'dist_', 'nodist_', 'nobase_', and 'notrans_'. These prefixes are explained later (*note Program and Library Variables::) (*note Man Pages::). 3.4 Staying below the command line length limit =============================================== Traditionally, most unix-like systems have a length limitation for the command line arguments and environment contents when creating new processes (see for example for an overview on this issue), which of course also applies to commands spawned by 'make'. POSIX requires this limit to be at least 4096 bytes, and most modern systems have quite high limits (or are unlimited). In order to create portable Makefiles that do not trip over these limits, it is necessary to keep the length of file lists bounded. Unfortunately, it is not possible to do so fully transparently within Automake, so your help may be needed. Typically, you can split long file lists manually and use different installation directory names for each list. For example, data_DATA = file1 ... fileN fileN+1 ... file2N may also be written as data_DATA = file1 ... fileN data2dir = $(datadir) data2_DATA = fileN+1 ... file2N and will cause Automake to treat the two lists separately during 'make install'. See *note The Two Parts of Install:: for choosing directory names that will keep the ordering of the two parts of installation Note that 'make dist' may still only work on a host with a higher length limit in this example. Automake itself employs a couple of strategies to avoid long command lines. For example, when '${srcdir}/' is prepended to file names, as can happen with above '$(data_DATA)' lists, it limits the amount of arguments passed to external commands. Unfortunately, some system's 'make' commands may prepend 'VPATH' prefixes like '${srcdir}/' to file names from the source tree automatically (*note Automatic Rule Rewriting: (autoconf)Automatic Rule Rewriting.). In this case, the user may have to switch to use GNU Make, or refrain from using VPATH builds, in order to stay below the length limit. For libraries and programs built from many sources, convenience archives may be used as intermediates in order to limit the object list length (*note Libtool Convenience Libraries::). 3.5 How derived variables are named =================================== Sometimes a Makefile variable name is derived from some text the maintainer supplies. For instance, a program name listed in '_PROGRAMS' is rewritten into the name of a '_SOURCES' variable. In cases like this, Automake canonicalizes the text, so that program names and the like do not have to follow Makefile variable naming rules. All characters in the name except for letters, numbers, the strudel (@), and the underscore are turned into underscores when making variable references. For example, if your program is named 'sniff-glue', the derived variable name would be 'sniff_glue_SOURCES', not 'sniff-glue_SOURCES'. Similarly the sources for a library named 'libmumble++.a' should be listed in the 'libmumble___a_SOURCES' variable. The strudel is an addition, to make the use of Autoconf substitutions in variable names less obfuscating. 3.6 Variables reserved for the user =================================== Some 'Makefile' variables are reserved by the GNU Coding Standards for the use of the "user"--the person building the package. For instance, 'CFLAGS' is one such variable. Sometimes package developers are tempted to set user variables such as 'CFLAGS' because it appears to make their job easier. However, the package itself should never set a user variable, particularly not to include switches that are required for proper compilation of the package. Since these variables are documented as being for the package builder, that person rightfully expects to be able to override any of these variables at build time. To get around this problem, Automake introduces an automake-specific shadow variable for each user flag variable. (Shadow variables are not introduced for variables like 'CC', where they would make no sense.) The shadow variable is named by prepending 'AM_' to the user variable's name. For instance, the shadow variable for 'YFLAGS' is 'AM_YFLAGS'. The package maintainer--that is, the author(s) of the 'Makefile.am' and 'configure.ac' files--may adjust these shadow variables however necessary. *Note Flag Variables Ordering::, for more discussion about these variables and how they interact with per-target variables. 3.7 Programs automake might require =================================== Automake sometimes requires helper programs so that the generated 'Makefile' can do its work properly. There are a fairly large number of them, and we list them here. Although all of these files are distributed and installed with Automake, a couple of them are maintained separately. The Automake copies are updated before each release, but we mention the original source in case you need more recent versions. 'ar-lib' This is a wrapper primarily for the Microsoft lib archiver, to make it more POSIX-like. 'ansi2knr.c' 'ansi2knr.1' These two files are used for de-ANSI-fication support (they are deprecated now, and _will be removed_ in the next major Automake release; *note ANSI::). 'compile' This is a wrapper for compilers that do not accept options '-c' and '-o' at the same time. It is only used when absolutely required. Such compilers are rare, with the Microsoft C/C++ Compiler as the most notable exception. This wrapper also makes the following common options available for that compiler, while performing file name translation where needed: '-I', '-L', '-l', '-Wl,' and '-Xlinker'. 'config.guess' 'config.sub' These two programs compute the canonical triplets for the given build, host, or target architecture. These programs are updated regularly to support new architectures and fix probes broken by changes in new kernel versions. Each new release of Automake comes with up-to-date copies of these programs. If your copy of Automake is getting old, you are encouraged to fetch the latest versions of these files from before making a release. 'config-ml.in' This file is not a program, it is a 'configure' fragment used for multilib support (*note Multilibs::). Since the Automake multilib support has been _deprecated_ and targeted for removal, this file is going to be _removed from the Automake core_ in the next major release. The master copy of this file is maintained in the GCC tree at . 'depcomp' This program understands how to run a compiler so that it will generate not only the desired output but also dependency information that is then used by the automatic dependency tracking feature (*note Dependencies::). 'elisp-comp' This program is used to byte-compile Emacs Lisp code. 'install-sh' This is a replacement for the 'install' program that works on platforms where 'install' is unavailable or unusable. 'mdate-sh' This script is used to generate a 'version.texi' file. It examines a file and prints some date information about it. 'missing' This wraps a number of programs that are typically only required by maintainers. If the program in question doesn't exist, 'missing' prints an informative warning and attempts to fix things so that the build can continue. 'mkinstalldirs' This script used to be a wrapper around 'mkdir -p', which is not portable. Now we prefer to use 'install-sh -d' when 'configure' finds that 'mkdir -p' does not work, this makes one less script to distribute. For backward compatibility 'mkinstalldirs' is still used and distributed when 'automake' finds it in a package. But it is no longer installed automatically, and it should be safe to remove it. 'py-compile' This is used to byte-compile Python scripts. 'symlink-tree' This program duplicates a tree of directories, using symbolic links instead of copying files. Such an operation is performed when building multilibs (*note Multilibs::). Since the Automake multilib support has been _deprecated_ and targeted for removal, this file is going to be _removed from the Automake core_ in the next major release. The master copy of this file is maintained in the GCC tree at . 'texinfo.tex' Not a program, this file is required for 'make dvi', 'make ps' and 'make pdf' to work when Texinfo sources are in the package. The latest version can be downloaded from . 'ylwrap' This program wraps 'lex' and 'yacc' to rename their output files. It also ensures that, for instance, multiple 'yacc' instances can be invoked in a single directory in parallel. 4 Some example packages *********************** This section contains two small examples. The first example (*note Complete::) assumes you have an existing project already using Autoconf, with handcrafted 'Makefile's, and that you want to convert it to using Automake. If you are discovering both tools, it is probably better that you look at the Hello World example presented earlier (*note Hello World::). The second example (*note true::) shows how two programs can be built from the same file, using different compilation parameters. It contains some technical digressions that are probably best skipped on first read. 4.1 A simple example, start to finish ===================================== Let's suppose you just finished writing 'zardoz', a program to make your head float from vortex to vortex. You've been using Autoconf to provide a portability framework, but your 'Makefile.in's have been ad-hoc. You want to make them bulletproof, so you turn to Automake. The first step is to update your 'configure.ac' to include the commands that 'automake' needs. The way to do this is to add an 'AM_INIT_AUTOMAKE' call just after 'AC_INIT': AC_INIT([zardoz], [1.0]) AM_INIT_AUTOMAKE ... Since your program doesn't have any complicating factors (e.g., it doesn't use 'gettext', it doesn't want to build a shared library), you're done with this part. That was easy! Now you must regenerate 'configure'. But to do that, you'll need to tell 'autoconf' how to find the new macro you've used. The easiest way to do this is to use the 'aclocal' program to generate your 'aclocal.m4' for you. But wait... maybe you already have an 'aclocal.m4', because you had to write some hairy macros for your program. The 'aclocal' program lets you put your own macros into 'acinclude.m4', so simply rename and then run: mv aclocal.m4 acinclude.m4 aclocal autoconf Now it is time to write your 'Makefile.am' for 'zardoz'. Since 'zardoz' is a user program, you want to install it where the rest of the user programs go: 'bindir'. Additionally, 'zardoz' has some Texinfo documentation. Your 'configure.ac' script uses 'AC_REPLACE_FUNCS', so you need to link against '$(LIBOBJS)'. So here's what you'd write: bin_PROGRAMS = zardoz zardoz_SOURCES = main.c head.c float.c vortex9.c gun.c zardoz_LDADD = $(LIBOBJS) info_TEXINFOS = zardoz.texi Now you can run 'automake --add-missing' to generate your 'Makefile.in' and grab any auxiliary files you might need, and you're done! 4.2 Building true and false =========================== Here is another, trickier example. It shows how to generate two programs ('true' and 'false') from the same source file ('true.c'). The difficult part is that each compilation of 'true.c' requires different 'cpp' flags. bin_PROGRAMS = true false false_SOURCES = false_LDADD = false.o true.o: true.c $(COMPILE) -DEXIT_CODE=0 -c true.c false.o: true.c $(COMPILE) -DEXIT_CODE=1 -o false.o -c true.c Note that there is no 'true_SOURCES' definition. Automake will implicitly assume that there is a source file named 'true.c' (*note Default _SOURCES::), and define rules to compile 'true.o' and link 'true'. The 'true.o: true.c' rule supplied by the above 'Makefile.am', will override the Automake generated rule to build 'true.o'. 'false_SOURCES' is defined to be empty--that way no implicit value is substituted. Because we have not listed the source of 'false', we have to tell Automake how to link the program. This is the purpose of the 'false_LDADD' line. A 'false_DEPENDENCIES' variable, holding the dependencies of the 'false' target will be automatically generated by Automake from the content of 'false_LDADD'. The above rules won't work if your compiler doesn't accept both '-c' and '-o'. The simplest fix for this is to introduce a bogus dependency (to avoid problems with a parallel 'make'): true.o: true.c false.o $(COMPILE) -DEXIT_CODE=0 -c true.c false.o: true.c $(COMPILE) -DEXIT_CODE=1 -c true.c && mv true.o false.o As it turns out, there is also a much easier way to do this same task. Some of the above technique is useful enough that we've kept the example in the manual. However if you were to build 'true' and 'false' in real life, you would probably use per-program compilation flags, like so: bin_PROGRAMS = false true false_SOURCES = true.c false_CPPFLAGS = -DEXIT_CODE=1 true_SOURCES = true.c true_CPPFLAGS = -DEXIT_CODE=0 In this case Automake will cause 'true.c' to be compiled twice, with different flags. In this instance, the names of the object files would be chosen by automake; they would be 'false-true.o' and 'true-true.o'. (The name of the object files rarely matters.) 5 Creating a 'Makefile.in' ************************** To create all the 'Makefile.in's for a package, run the 'automake' program in the top level directory, with no arguments. 'automake' will automatically find each appropriate 'Makefile.am' (by scanning 'configure.ac'; *note configure::) and generate the corresponding 'Makefile.in'. Note that 'automake' has a rather simplistic view of what constitutes a package; it assumes that a package has only one 'configure.ac', at the top. If your package has multiple 'configure.ac's, then you must run 'automake' in each directory holding a 'configure.ac'. (Alternatively, you may rely on Autoconf's 'autoreconf', which is able to recurse your package tree and run 'automake' where appropriate.) You can optionally give 'automake' an argument; '.am' is appended to the argument and the result is used as the name of the input file. This feature is generally only used to automatically rebuild an out-of-date 'Makefile.in'. Note that 'automake' must always be run from the topmost directory of a project, even if being used to regenerate the 'Makefile.in' in some subdirectory. This is necessary because 'automake' must scan 'configure.ac', and because 'automake' uses the knowledge that a 'Makefile.in' is in a subdirectory to change its behavior in some cases. Automake will run 'autoconf' to scan 'configure.ac' and its dependencies (i.e., 'aclocal.m4' and any included file), therefore 'autoconf' must be in your 'PATH'. If there is an 'AUTOCONF' variable in your environment it will be used instead of 'autoconf', this allows you to select a particular version of Autoconf. By the way, don't misunderstand this paragraph: 'automake' runs 'autoconf' to *scan* your 'configure.ac', this won't build 'configure' and you still have to run 'autoconf' yourself for this purpose. 'automake' accepts the following options: '-a' '--add-missing' Automake requires certain common files to exist in certain situations; for instance, 'config.guess' is required if 'configure.ac' invokes 'AC_CANONICAL_HOST'. Automake is distributed with several of these files (*note Auxiliary Programs::); this option will cause the missing ones to be automatically added to the package, whenever possible. In general if Automake tells you a file is missing, try using this option. By default Automake tries to make a symbolic link pointing to its own copy of the missing file; this can be changed with '--copy'. Many of the potentially-missing files are common scripts whose location may be specified via the 'AC_CONFIG_AUX_DIR' macro. Therefore, 'AC_CONFIG_AUX_DIR''s setting affects whether a file is considered missing, and where the missing file is added (*note Optional::). In some strictness modes, additional files are installed, see *note Gnits:: for more information. '--libdir=DIR' Look for Automake data files in directory DIR instead of in the installation directory. This is typically used for debugging. '-c' '--copy' When used with '--add-missing', causes installed files to be copied. The default is to make a symbolic link. '--cygnus' Causes the generated 'Makefile.in's to follow Cygnus rules, instead of GNU or Gnits rules. For more information, see *note Cygnus::. Note that _this mode of operation is deprecated, and will be removed_ in a future Automake release. '-f' '--force-missing' When used with '--add-missing', causes standard files to be reinstalled even if they already exist in the source tree. This involves removing the file from the source tree before creating the new symlink (or, with '--copy', copying the new file). '--foreign' Set the global strictness to 'foreign'. For more information, see *note Strictness::. '--gnits' Set the global strictness to 'gnits'. For more information, see *note Gnits::. '--gnu' Set the global strictness to 'gnu'. For more information, see *note Gnits::. This is the default strictness. '--help' Print a summary of the command line options and exit. '-i' '--ignore-deps' This disables the dependency tracking feature in generated 'Makefile's; see *note Dependencies::. '--include-deps' This enables the dependency tracking feature. This feature is enabled by default. This option is provided for historical reasons only and probably should not be used. '--no-force' Ordinarily 'automake' creates all 'Makefile.in's mentioned in 'configure.ac'. This option causes it to only update those 'Makefile.in's that are out of date with respect to one of their dependents. '-o DIR' '--output-dir=DIR' Put the generated 'Makefile.in' in the directory DIR. Ordinarily each 'Makefile.in' is created in the directory of the corresponding 'Makefile.am'. This option is deprecated and will be removed in a future release. '-v' '--verbose' Cause Automake to print information about which files are being read or created. '--version' Print the version number of Automake and exit. '-W CATEGORY' '--warnings=CATEGORY' Output warnings falling in CATEGORY. CATEGORY can be one of: 'gnu' warnings related to the GNU Coding Standards (*note (standards)Top::). 'obsolete' obsolete features or constructions 'override' user redefinitions of Automake rules or variables 'portability' portability issues (e.g., use of 'make' features that are known to be not portable) 'extra-portability' extra portability issues related to obscure tools. One example of such a tool is the Microsoft 'lib' archiver. 'syntax' weird syntax, unused variables, typos 'unsupported' unsupported or incomplete features 'all' all the warnings 'none' turn off all the warnings 'error' treat warnings as errors A category can be turned off by prefixing its name with 'no-'. For instance, '-Wno-syntax' will hide the warnings about unused variables. The categories output by default are 'syntax' and 'unsupported'. Additionally, 'gnu' and 'portability' are enabled in '--gnu' and '--gnits' strictness. On the other hand, the 'silent-rules' options (*note Options::) turns off portability warnings about recursive variable expansions. Turning off 'portability' will also turn off 'extra-portability', and similarly turning on 'extra-portability' will also turn on 'portability'. However, turning on 'portability' or turning off 'extra-portability' will not affect the other category. The environment variable 'WARNINGS' can contain a comma separated list of categories to enable. It will be taken into account before the command-line switches, this way '-Wnone' will also ignore any warning category enabled by 'WARNINGS'. This variable is also used by other tools like 'autoconf'; unknown categories are ignored for this reason. If the environment variable 'AUTOMAKE_JOBS' contains a positive number, it is taken as the maximum number of Perl threads to use in 'automake' for generating multiple 'Makefile.in' files concurrently. This is an experimental feature. 6 Scanning 'configure.ac', using 'aclocal' ****************************************** Automake scans the package's 'configure.ac' to determine certain information about the package. Some 'autoconf' macros are required and some variables must be defined in 'configure.ac'. Automake will also use information from 'configure.ac' to further tailor its output. Automake also supplies some Autoconf macros to make the maintenance easier. These macros can automatically be put into your 'aclocal.m4' using the 'aclocal' program. 6.1 Configuration requirements ============================== The one real requirement of Automake is that your 'configure.ac' call 'AM_INIT_AUTOMAKE'. This macro does several things that are required for proper Automake operation (*note Macros::). Here are the other macros that Automake requires but which are not run by 'AM_INIT_AUTOMAKE': 'AC_CONFIG_FILES' 'AC_OUTPUT' These two macros are usually invoked as follows near the end of 'configure.ac'. ... AC_CONFIG_FILES([ Makefile doc/Makefile src/Makefile src/lib/Makefile ... ]) AC_OUTPUT Automake uses these to determine which files to create (*note Creating Output Files: (autoconf)Output.). A listed file is considered to be an Automake generated 'Makefile' if there exists a file with the same name and the '.am' extension appended. Typically, 'AC_CONFIG_FILES([foo/Makefile])' will cause Automake to generate 'foo/Makefile.in' if 'foo/Makefile.am' exists. When using 'AC_CONFIG_FILES' with multiple input files, as in AC_CONFIG_FILES([Makefile:top.in:Makefile.in:bot.in]) 'automake' will generate the first '.in' input file for which a '.am' file exists. If no such file exists the output file is not considered to be generated by Automake. Files created by 'AC_CONFIG_FILES', be they Automake 'Makefile's or not, are all removed by 'make distclean'. Their inputs are automatically distributed, unless they are the output of prior 'AC_CONFIG_FILES' commands. Finally, rebuild rules are generated in the Automake 'Makefile' existing in the subdirectory of the output file, if there is one, or in the top-level 'Makefile' otherwise. The above machinery (cleaning, distributing, and rebuilding) works fine if the 'AC_CONFIG_FILES' specifications contain only literals. If part of the specification uses shell variables, 'automake' will not be able to fulfill this setup, and you will have to complete the missing bits by hand. For instance, on file=input ... AC_CONFIG_FILES([output:$file],, [file=$file]) 'automake' will output rules to clean 'output', and rebuild it. However the rebuild rule will not depend on 'input', and this file will not be distributed either. (You must add 'EXTRA_DIST = input' to your 'Makefile.am' if 'input' is a source file.) Similarly file=output file2=out:in ... AC_CONFIG_FILES([$file:input],, [file=$file]) AC_CONFIG_FILES([$file2],, [file2=$file2]) will only cause 'input' to be distributed. No file will be cleaned automatically (add 'DISTCLEANFILES = output out' yourself), and no rebuild rule will be output. Obviously 'automake' cannot guess what value '$file' is going to hold later when 'configure' is run, and it cannot use the shell variable '$file' in a 'Makefile'. However, if you make reference to '$file' as '${file}' (i.e., in a way that is compatible with 'make''s syntax) and furthermore use 'AC_SUBST' to ensure that '${file}' is meaningful in a 'Makefile', then 'automake' will be able to use '${file}' to generate all these rules. For instance, here is how the Automake package itself generates versioned scripts for its test suite: AC_SUBST([APIVERSION], ...) ... AC_CONFIG_FILES( [tests/aclocal-${APIVERSION}:tests/aclocal.in], [chmod +x tests/aclocal-${APIVERSION}], [APIVERSION=$APIVERSION]) AC_CONFIG_FILES( [tests/automake-${APIVERSION}:tests/automake.in], [chmod +x tests/automake-${APIVERSION}]) Here cleaning, distributing, and rebuilding are done automatically, because '${APIVERSION}' is known at 'make'-time. Note that you should not use shell variables to declare 'Makefile' files for which 'automake' must create 'Makefile.in'. Even 'AC_SUBST' does not help here, because 'automake' needs to know the file name when it runs in order to check whether 'Makefile.am' exists. (In the very hairy case that your setup requires such use of variables, you will have to tell Automake which 'Makefile.in's to generate on the command-line.) It is possible to let 'automake' emit conditional rules for 'AC_CONFIG_FILES' with the help of 'AM_COND_IF' (*note Optional::). To summarize: * Use literals for 'Makefile's, and for other files whenever possible. * Use '$file' (or '${file}' without 'AC_SUBST([file])') for files that 'automake' should ignore. * Use '${file}' and 'AC_SUBST([file])' for files that 'automake' should not ignore. 6.2 Other things Automake recognizes ==================================== Every time Automake is run it calls Autoconf to trace 'configure.ac'. This way it can recognize the use of certain macros and tailor the generated 'Makefile.in' appropriately. Currently recognized macros and their effects are: 'AC_CANONICAL_BUILD' 'AC_CANONICAL_HOST' 'AC_CANONICAL_TARGET' Automake will ensure that 'config.guess' and 'config.sub' exist. Also, the 'Makefile' variables 'build_triplet', 'host_triplet' and 'target_triplet' are introduced. See *note Getting the Canonical System Type: (autoconf)Canonicalizing. 'AC_CONFIG_AUX_DIR' Automake will look for various helper scripts, such as 'install-sh', in the directory named in this macro invocation. (The full list of scripts is: 'ar-lib', 'config.guess', 'config.sub', 'depcomp', 'elisp-comp', 'compile', 'install-sh', 'ltmain.sh', 'mdate-sh', 'missing', 'mkinstalldirs', 'py-compile', 'texinfo.tex', and 'ylwrap'.) Not all scripts are always searched for; some scripts will only be sought if the generated 'Makefile.in' requires them. If 'AC_CONFIG_AUX_DIR' is not given, the scripts are looked for in their standard locations. For 'mdate-sh', 'texinfo.tex', and 'ylwrap', the standard location is the source directory corresponding to the current 'Makefile.am'. For the rest, the standard location is the first one of '.', '..', or '../..' (relative to the top source directory) that provides any one of the helper scripts. *Note Finding 'configure' Input: (autoconf)Input. Required files from 'AC_CONFIG_AUX_DIR' are automatically distributed, even if there is no 'Makefile.am' in this directory. 'AC_CONFIG_LIBOBJ_DIR' Automake will require the sources file declared with 'AC_LIBSOURCE' (see below) in the directory specified by this macro. 'AC_CONFIG_HEADERS' Automake will generate rules to rebuild these headers. Older versions of Automake required the use of 'AM_CONFIG_HEADER' (*note Macros::); this is no longer the case. As with 'AC_CONFIG_FILES' (*note Requirements::), parts of the specification using shell variables will be ignored as far as cleaning, distributing, and rebuilding is concerned. 'AC_CONFIG_LINKS' Automake will generate rules to remove 'configure' generated links on 'make distclean' and to distribute named source files as part of 'make dist'. As for 'AC_CONFIG_FILES' (*note Requirements::), parts of the specification using shell variables will be ignored as far as cleaning and distributing is concerned. (There are no rebuild rules for links.) 'AC_LIBOBJ' 'AC_LIBSOURCE' 'AC_LIBSOURCES' Automake will automatically distribute any file listed in 'AC_LIBSOURCE' or 'AC_LIBSOURCES'. Note that the 'AC_LIBOBJ' macro calls 'AC_LIBSOURCE'. So if an Autoconf macro is documented to call 'AC_LIBOBJ([file])', then 'file.c' will be distributed automatically by Automake. This encompasses many macros like 'AC_FUNC_ALLOCA', 'AC_FUNC_MEMCMP', 'AC_REPLACE_FUNCS', and others. By the way, direct assignments to 'LIBOBJS' are no longer supported. You should always use 'AC_LIBOBJ' for this purpose. *Note 'AC_LIBOBJ' vs. 'LIBOBJS': (autoconf)AC_LIBOBJ vs LIBOBJS. 'AC_PROG_RANLIB' This is required if any libraries are built in the package. *Note Particular Program Checks: (autoconf)Particular Programs. 'AC_PROG_CXX' This is required if any C++ source is included. *Note Particular Program Checks: (autoconf)Particular Programs. 'AC_PROG_OBJC' This is required if any Objective C source is included. *Note Particular Program Checks: (autoconf)Particular Programs. 'AC_PROG_F77' This is required if any Fortran 77 source is included. This macro is distributed with Autoconf version 2.13 and later. *Note Particular Program Checks: (autoconf)Particular Programs. 'AC_F77_LIBRARY_LDFLAGS' This is required for programs and shared libraries that are a mixture of languages that include Fortran 77 (*note Mixing Fortran 77 With C and C++::). *Note Autoconf macros supplied with Automake: Macros. 'AC_FC_SRCEXT' Automake will add the flags computed by 'AC_FC_SRCEXT' to compilation of files with the respective source extension (*note Fortran Compiler Characteristics: (autoconf)Fortran Compiler.). 'AC_PROG_FC' This is required if any Fortran 90/95 source is included. This macro is distributed with Autoconf version 2.58 and later. *Note Particular Program Checks: (autoconf)Particular Programs. 'AC_PROG_LIBTOOL' Automake will turn on processing for 'libtool' (*note Introduction: (libtool)Top.). 'AC_PROG_YACC' If a Yacc source file is seen, then you must either use this macro or define the variable 'YACC' in 'configure.ac'. The former is preferred (*note Particular Program Checks: (autoconf)Particular Programs.). 'AC_PROG_LEX' If a Lex source file is seen, then this macro must be used. *Note Particular Program Checks: (autoconf)Particular Programs. 'AC_REQUIRE_AUX_FILE' For each 'AC_REQUIRE_AUX_FILE([FILE])', 'automake' will ensure that 'FILE' exists in the aux directory, and will complain otherwise. It will also automatically distribute the file. This macro should be used by third-party Autoconf macros that require some supporting files in the aux directory specified with 'AC_CONFIG_AUX_DIR' above. *Note Finding 'configure' Input: (autoconf)Input. 'AC_SUBST' The first argument is automatically defined as a variable in each generated 'Makefile.in', unless 'AM_SUBST_NOTMAKE' is also used for this variable. *Note Setting Output Variables: (autoconf)Setting Output Variables. For every substituted variable VAR, 'automake' will add a line 'VAR = VALUE' to each 'Makefile.in' file. Many Autoconf macros invoke 'AC_SUBST' to set output variables this way, e.g., 'AC_PATH_XTRA' defines 'X_CFLAGS' and 'X_LIBS'. Thus, you can access these variables as '$(X_CFLAGS)' and '$(X_LIBS)' in any 'Makefile.am' if 'AC_PATH_XTRA' is called. 'AM_C_PROTOTYPES' This is required when using the deprecated de-ANSI-fication feature; *note ANSI::. _It will be removed_ in the next major Automake release. 'AM_CONDITIONAL' This introduces an Automake conditional (*note Conditionals::). 'AM_COND_IF' This macro allows 'automake' to detect subsequent access within 'configure.ac' to a conditional previously introduced with 'AM_CONDITIONAL', thus enabling conditional 'AC_CONFIG_FILES' (*note Usage of Conditionals::). 'AM_GNU_GETTEXT' This macro is required for packages that use GNU gettext (*note gettext::). It is distributed with gettext. If Automake sees this macro it ensures that the package meets some of gettext's requirements. 'AM_GNU_GETTEXT_INTL_SUBDIR' This macro specifies that the 'intl/' subdirectory is to be built, even if the 'AM_GNU_GETTEXT' macro was invoked with a first argument of 'external'. 'AM_MAINTAINER_MODE([DEFAULT-MODE])' This macro adds an '--enable-maintainer-mode' option to 'configure'. If this is used, 'automake' will cause "maintainer-only" rules to be turned off by default in the generated 'Makefile.in's, unless DEFAULT-MODE is 'enable'. This macro defines the 'MAINTAINER_MODE' conditional, which you can use in your own 'Makefile.am'. *Note maintainer-mode::. 'AM_SUBST_NOTMAKE(VAR)' Prevent Automake from defining a variable VAR, even if it is substituted by 'config.status'. Normally, Automake defines a 'make' variable for each 'configure' substitution, i.e., for each 'AC_SUBST([VAR])'. This macro prevents that definition from Automake. If 'AC_SUBST' has not been called for this variable, then 'AM_SUBST_NOTMAKE' has no effects. Preventing variable definitions may be useful for substitution of multi-line values, where 'VAR = @VALUE@' might yield unintended results. 'm4_include' Files included by 'configure.ac' using this macro will be detected by Automake and automatically distributed. They will also appear as dependencies in 'Makefile' rules. 'm4_include' is seldom used by 'configure.ac' authors, but can appear in 'aclocal.m4' when 'aclocal' detects that some required macros come from files local to your package (as opposed to macros installed in a system-wide directory, *note aclocal Invocation::). 6.3 Auto-generating aclocal.m4 ============================== Automake includes a number of Autoconf macros that can be used in your package (*note Macros::); some of them are actually required by Automake in certain situations. These macros must be defined in your 'aclocal.m4'; otherwise they will not be seen by 'autoconf'. The 'aclocal' program will automatically generate 'aclocal.m4' files based on the contents of 'configure.ac'. This provides a convenient way to get Automake-provided macros, without having to search around. The 'aclocal' mechanism allows other packages to supply their own macros (*note Extending aclocal::). You can also use it to maintain your own set of custom macros (*note Local Macros::). At startup, 'aclocal' scans all the '.m4' files it can find, looking for macro definitions (*note Macro Search Path::). Then it scans 'configure.ac'. Any mention of one of the macros found in the first step causes that macro, and any macros it in turn requires, to be put into 'aclocal.m4'. _Putting_ the file that contains the macro definition into 'aclocal.m4' is usually done by copying the entire text of this file, including unused macro definitions as well as both '#' and 'dnl' comments. If you want to make a comment that will be completely ignored by 'aclocal', use '##' as the comment leader. When a file selected by 'aclocal' is located in a subdirectory specified as a relative search path with 'aclocal''s '-I' argument, 'aclocal' assumes the file belongs to the package and uses 'm4_include' instead of copying it into 'aclocal.m4'. This makes the package smaller, eases dependency tracking, and cause the file to be distributed automatically. (*Note Local Macros::, for an example.) Any macro that is found in a system-wide directory, or via an absolute search path will be copied. So use '-I `pwd`/reldir' instead of '-I reldir' whenever some relative directory should be considered outside the package. The contents of 'acinclude.m4', if this file exists, are also automatically included in 'aclocal.m4'. We recommend against using 'acinclude.m4' in new packages (*note Local Macros::). While computing 'aclocal.m4', 'aclocal' runs 'autom4te' (*note Using 'Autom4te': (autoconf)Using autom4te.) in order to trace the macros that are really used, and omit from 'aclocal.m4' all macros that are mentioned but otherwise unexpanded (this can happen when a macro is called conditionally). 'autom4te' is expected to be in the 'PATH', just as 'autoconf'. Its location can be overridden using the 'AUTOM4TE' environment variable. 6.3.1 aclocal Options --------------------- 'aclocal' accepts the following options: '--automake-acdir=DIR' Look for the automake-provided macro files in DIR instead of in the installation directory. This is typically used for debugging. '--system-acdir=DIR' Look for the system-wide third-party macro files (and the special 'dirlist' file) in DIR instead of in the installation directory. This is typically used for debugging. '--acdir=DIR' _Deprecated_ shorthand for "'--automake-acdir=DIR --system-acdir=DIR'". Will be removed in future aclocal versions. '--diff[=COMMAND]' Run COMMAND on M4 file that would be installed or overwritten by '--install'. The default COMMAND is 'diff -u'. This option implies '--install' and '--dry-run'. '--dry-run' Do not actually overwrite (or create) 'aclocal.m4' and M4 files installed by '--install'. '--help' Print a summary of the command line options and exit. '-I DIR' Add the directory DIR to the list of directories searched for '.m4' files. '--install' Install system-wide third-party macros into the first directory specified with '-I DIR' instead of copying them in the output file. Note that this will happen also if DIR is an absolute path. When this option is used, and only when this option is used, 'aclocal' will also honor '#serial NUMBER' lines that appear in macros: an M4 file is ignored if there exists another M4 file with the same basename and a greater serial number in the search path (*note Serials::). '--force' Always overwrite the output file. The default is to overwrite the output file only when really needed, i.e., when its contents changes or if one of its dependencies is younger. This option forces the update of 'aclocal.m4' (or the file specified with '--output' below) and only this file, it has absolutely no influence on files that may need to be installed by '--install'. '--output=FILE' Cause the output to be put into FILE instead of 'aclocal.m4'. '--print-ac-dir' Prints the name of the directory that 'aclocal' will search to find third-party '.m4' files. When this option is given, normal processing is suppressed. This option was used _in the past_ by third-party packages to determine where to install '.m4' macro files, but _this usage is today discouraged_, since it causes '$(prefix)' not to be thoroughly honoured (which violates the GNU Coding Standards), and a similar semantics can be better obtained with the 'ACLOCAL_PATH' environment variable; *note Extending aclocal::. '--verbose' Print the names of the files it examines. '--version' Print the version number of Automake and exit. '-W CATEGORY' '--warnings=CATEGORY' Output warnings falling in CATEGORY. CATEGORY can be one of: 'syntax' dubious syntactic constructs, underquoted macros, unused macros, etc. 'unsupported' unknown macros 'all' all the warnings, this is the default 'none' turn off all the warnings 'error' treat warnings as errors All warnings are output by default. The environment variable 'WARNINGS' is honored in the same way as it is for 'automake' (*note automake Invocation::). 6.3.2 Macro Search Path ----------------------- By default, 'aclocal' searches for '.m4' files in the following directories, in this order: 'ACDIR-APIVERSION' This is where the '.m4' macros distributed with Automake itself are stored. APIVERSION depends on the Automake release used; for example, for Automake 1.11.x, APIVERSION = '1.11'. 'ACDIR' This directory is intended for third party '.m4' files, and is configured when 'automake' itself is built. This is '@datadir@/aclocal/', which typically expands to '${prefix}/share/aclocal/'. To find the compiled-in value of ACDIR, use the '--print-ac-dir' option (*note aclocal Options::). As an example, suppose that 'automake-1.11.2' was configured with '--prefix=/usr/local'. Then, the search path would be: 1. '/usr/local/share/aclocal-1.11.2/' 2. '/usr/local/share/aclocal/' The paths for the ACDIR and ACDIR-APIVERSION directories can be changed respectively through aclocal options '--system-acdir' and '--automake-acdir' (*note aclocal Options::). Note however that these options are only intended for use by the internal Automake test suite, or for debugging under highly unusual situations; they are not ordinarily needed by end-users. As explained in (*note aclocal Options::), there are several options that can be used to change or extend this search path. Modifying the Macro Search Path: '-I DIR' ......................................... Any extra directories specified using '-I' options (*note aclocal Options::) are _prepended_ to this search list. Thus, 'aclocal -I /foo -I /bar' results in the following search path: 1. '/foo' 2. '/bar' 3. ACDIR-APIVERSION 4. ACDIR Modifying the Macro Search Path: 'dirlist' .......................................... There is a third mechanism for customizing the search path. If a 'dirlist' file exists in ACDIR, then that file is assumed to contain a list of directory patterns, one per line. 'aclocal' expands these patterns to directory names, and adds them to the search list _after_ all other directories. 'dirlist' entries may use shell wildcards such as '*', '?', or '[...]'. For example, suppose 'ACDIR/dirlist' contains the following: /test1 /test2 /test3* and that 'aclocal' was called with the '-I /foo -I /bar' options. Then, the search path would be 1. '/foo' 2. '/bar' 3. ACDIR-APIVERSION 4. ACDIR 5. '/test1' 6. '/test2' and all directories with path names starting with '/test3'. If the '--system-acdir=DIR' option is used, then 'aclocal' will search for the 'dirlist' file in DIR; but remember the warnings above against the use of '--system-acdir'. 'dirlist' is useful in the following situation: suppose that 'automake' version '1.11.2' is installed with '--prefix=/usr' by the system vendor. Thus, the default search directories are 1. '/usr/share/aclocal-1.11/' 2. '/usr/share/aclocal/' However, suppose further that many packages have been manually installed on the system, with $prefix=/usr/local, as is typical. In that case, many of these "extra" '.m4' files are in '/usr/local/share/aclocal'. The only way to force '/usr/bin/aclocal' to find these "extra" '.m4' files is to always call 'aclocal -I /usr/local/share/aclocal'. This is inconvenient. With 'dirlist', one may create a file '/usr/share/aclocal/dirlist' containing only the single line /usr/local/share/aclocal Now, the "default" search path on the affected system is 1. '/usr/share/aclocal-1.11/' 2. '/usr/share/aclocal/' 3. '/usr/local/share/aclocal/' without the need for '-I' options; '-I' options can be reserved for project-specific needs ('my-source-dir/m4/'), rather than using it to work around local system-dependent tool installation directories. Similarly, 'dirlist' can be handy if you have installed a local copy of Automake in your account and want 'aclocal' to look for macros installed at other places on the system. Modifying the Macro Search Path: 'ACLOCAL_PATH' ............................................... The fourth and last mechanism to customize the macro search path is also the simplest. Any directory included in the colon-separated environment variable 'ACLOCAL_PATH' is added to the search path and takes precedence over system directories (including those found via 'dirlist'), with the exception of the versioned directory ACDIR-APIVERSION (*note Macro Search Path::). However, directories passed via '-I' will take precedence over directories in 'ACLOCAL_PATH'. Also note that, if the '--install' option is used, any '.m4' file containing a required macro that is found in a directory listed in 'ACLOCAL_PATH' will be installed locally. In this case, serial numbers in '.m4' are honoured too, *note Serials::. Conversely to 'dirlist', 'ACLOCAL_PATH' is useful if you are using a global copy of Automake and want 'aclocal' to look for macros somewhere under your home directory. Planned future incompatibilities ................................ The order in which the directories in the macro search path are currently looked up is confusing and/or suboptimal in various aspects, and is probably going to be changed in the future Automake release. In particular, directories in 'ACLOCAL_PATH' and 'ACDIR' might end up taking precedence over 'ACDIR-APIVERSION', and directories in 'ACDIR/dirlist' might end up taking precedence over 'ACDIR'. _This is a possible future incompatibility!_ 6.3.3 Writing your own aclocal macros ------------------------------------- The 'aclocal' program doesn't have any built-in knowledge of any macros, so it is easy to extend it with your own macros. This can be used by libraries that want to supply their own Autoconf macros for use by other programs. For instance, the 'gettext' library supplies a macro 'AM_GNU_GETTEXT' that should be used by any package using 'gettext'. When the library is installed, it installs this macro so that 'aclocal' will find it. A macro file's name should end in '.m4'. Such files should be installed in '$(datadir)/aclocal'. This is as simple as writing: aclocaldir = $(datadir)/aclocal aclocal_DATA = mymacro.m4 myothermacro.m4 Please do use '$(datadir)/aclocal', and not something based on the result of 'aclocal --print-ac-dir' (*note Hard-Coded Install Paths::, for arguments). It might also be helpful to suggest to the user to add the '$(datadir)/aclocal' directory to his 'ACLOCAL_PATH' variable (*note ACLOCAL_PATH::) so that 'aclocal' will find the '.m4' files installed by your package automatically. A file of macros should be a series of properly quoted 'AC_DEFUN''s (*note (autoconf)Macro Definitions::). The 'aclocal' programs also understands 'AC_REQUIRE' (*note (autoconf)Prerequisite Macros::), so it is safe to put each macro in a separate file. Each file should have no side effects but macro definitions. Especially, any call to 'AC_PREREQ' should be done inside the defined macro, not at the beginning of the file. Starting with Automake 1.8, 'aclocal' will warn about all underquoted calls to 'AC_DEFUN'. We realize this will annoy a lot of people, because 'aclocal' was not so strict in the past and many third party macros are underquoted; and we have to apologize for this temporary inconvenience. The reason we have to be stricter is that a future implementation of 'aclocal' (*note Future of aclocal::) will have to temporarily include all these third party '.m4' files, maybe several times, including even files that are not actually needed. Doing so should alleviate many problems of the current implementation, however it requires a stricter style from the macro authors. Hopefully it is easy to revise the existing macros. For instance, # bad style AC_PREREQ(2.57) AC_DEFUN(AX_FOOBAR, [AC_REQUIRE([AX_SOMETHING])dnl AX_FOO AX_BAR ]) should be rewritten as AC_DEFUN([AX_FOOBAR], [AC_PREREQ([2.57])dnl AC_REQUIRE([AX_SOMETHING])dnl AX_FOO AX_BAR ]) Wrapping the 'AC_PREREQ' call inside the macro ensures that Autoconf 2.57 will not be required if 'AX_FOOBAR' is not actually used. Most importantly, quoting the first argument of 'AC_DEFUN' allows the macro to be redefined or included twice (otherwise this first argument would be expanded during the second definition). For consistency we like to quote even arguments such as '2.57' that do not require it. If you have been directed here by the 'aclocal' diagnostic but are not the maintainer of the implicated macro, you will want to contact the maintainer of that macro. Please make sure you have the latest version of the macro and that the problem hasn't already been reported before doing so: people tend to work faster when they aren't flooded by mails. Another situation where 'aclocal' is commonly used is to manage macros that are used locally by the package, *note Local Macros::. 6.3.4 Handling Local Macros --------------------------- Feature tests offered by Autoconf do not cover all needs. People often have to supplement existing tests with their own macros, or with third-party macros. There are two ways to organize custom macros in a package. The first possibility (the historical practice) is to list all your macros in 'acinclude.m4'. This file will be included in 'aclocal.m4' when you run 'aclocal', and its macro(s) will henceforth be visible to 'autoconf'. However if it contains numerous macros, it will rapidly become difficult to maintain, and it will be almost impossible to share macros between packages. The second possibility, which we do recommend, is to write each macro in its own file and gather all these files in a directory. This directory is usually called 'm4/'. To build 'aclocal.m4', one should therefore instruct 'aclocal' to scan 'm4/'. From the command line, this is done with 'aclocal -I m4'. The top-level 'Makefile.am' should also be updated to define ACLOCAL_AMFLAGS = -I m4 'ACLOCAL_AMFLAGS' contains options to pass to 'aclocal' when 'aclocal.m4' is to be rebuilt by 'make'. This line is also used by 'autoreconf' (*note Using 'autoreconf' to Update 'configure' Scripts: (autoconf)autoreconf Invocation.) to run 'aclocal' with suitable options, or by 'autopoint' (*note Invoking the 'autopoint' Program: (gettext)autopoint Invocation.) and 'gettextize' (*note Invoking the 'gettextize' Program: (gettext)gettextize Invocation.) to locate the place where Gettext's macros should be installed. So even if you do not really care about the rebuild rules, you should define 'ACLOCAL_AMFLAGS'. When 'aclocal -I m4' is run, it will build an 'aclocal.m4' that 'm4_include's any file from 'm4/' that defines a required macro. Macros not found locally will still be searched in system-wide directories, as explained in *note Macro Search Path::. Custom macros should be distributed for the same reason that 'configure.ac' is: so that other people have all the sources of your package if they want to work on it. Actually, this distribution happens automatically because all 'm4_include'd files are distributed. However there is no consensus on the distribution of third-party macros that your package may use. Many libraries install their own macro in the system-wide 'aclocal' directory (*note Extending aclocal::). For instance, Guile ships with a file called 'guile.m4' that contains the macro 'GUILE_FLAGS' that can be used to define setup compiler and linker flags appropriate for using Guile. Using 'GUILE_FLAGS' in 'configure.ac' will cause 'aclocal' to copy 'guile.m4' into 'aclocal.m4', but as 'guile.m4' is not part of the project, it will not be distributed. Technically, that means a user who needs to rebuild 'aclocal.m4' will have to install Guile first. This is probably OK, if Guile already is a requirement to build the package. However, if Guile is only an optional feature, or if your package might run on architectures where Guile cannot be installed, this requirement will hinder development. An easy solution is to copy such third-party macros in your local 'm4/' directory so they get distributed. Since Automake 1.10, 'aclocal' offers an option to copy these system-wide third-party macros in your local macro directory, solving the above problem. Simply use: ACLOCAL_AMFLAGS = -I m4 --install With this setup, system-wide macros will be copied to 'm4/' the first time you run 'autoreconf'. Then the locally installed macros will have precedence over the system-wide installed macros each time 'aclocal' is run again. One reason why you should keep '--install' in the flags even after the first run is that when you later edit 'configure.ac' and depend on a new macro, this macro will be installed in your 'm4/' automatically. Another one is that serial numbers (*note Serials::) can be used to update the macros in your source tree automatically when new system-wide versions are installed. A serial number should be a single line of the form #serial NNN where NNN contains only digits and dots. It should appear in the M4 file before any macro definition. It is a good practice to maintain a serial number for each macro you distribute, even if you do not use the '--install' option of 'aclocal': this allows other people to use it. 6.3.5 Serial Numbers -------------------- Because third-party macros defined in '*.m4' files are naturally shared between multiple projects, some people like to version them. This makes it easier to tell which of two M4 files is newer. Since at least 1996, the tradition is to use a '#serial' line for this. A serial number should be a single line of the form # serial VERSION where VERSION is a version number containing only digits and dots. Usually people use a single integer, and they increment it each time they change the macro (hence the name of "serial"). Such a line should appear in the M4 file before any macro definition. The '#' must be the first character on the line, and it is OK to have extra words after the version, as in #serial VERSION GARBAGE Normally these serial numbers are completely ignored by 'aclocal' and 'autoconf', like any genuine comment. However when using 'aclocal''s '--install' feature, these serial numbers will modify the way 'aclocal' selects the macros to install in the package: if two files with the same basename exist in your search path, and if at least one of them uses a '#serial' line, 'aclocal' will ignore the file that has the older '#serial' line (or the file that has none). Note that a serial number applies to a whole M4 file, not to any macro it contains. A file can contains multiple macros, but only one serial. Here is a use case that illustrates the use of '--install' and its interaction with serial numbers. Let's assume we maintain a package called MyPackage, the 'configure.ac' of which requires a third-party macro 'AX_THIRD_PARTY' defined in '/usr/share/aclocal/thirdparty.m4' as follows: # serial 1 AC_DEFUN([AX_THIRD_PARTY], [...]) MyPackage uses an 'm4/' directory to store local macros as explained in *note Local Macros::, and has ACLOCAL_AMFLAGS = -I m4 --install in its top-level 'Makefile.am'. Initially the 'm4/' directory is empty. The first time we run 'autoreconf', it will fetch the options to pass to 'aclocal' in 'Makefile.am', and run 'aclocal -I m4 --install'. 'aclocal' will notice that * 'configure.ac' uses 'AX_THIRD_PARTY' * No local macros define 'AX_THIRD_PARTY' * '/usr/share/aclocal/thirdparty.m4' defines 'AX_THIRD_PARTY' with serial 1. Because '/usr/share/aclocal/thirdparty.m4' is a system-wide macro and 'aclocal' was given the '--install' option, it will copy this file in 'm4/thirdparty.m4', and output an 'aclocal.m4' that contains 'm4_include([m4/thirdparty.m4])'. The next time 'aclocal -I m4 --install' is run (either via 'autoreconf', by hand, or from the 'Makefile' rebuild rules) something different happens. 'aclocal' notices that * 'configure.ac' uses 'AX_THIRD_PARTY' * 'm4/thirdparty.m4' defines 'AX_THIRD_PARTY' with serial 1. * '/usr/share/aclocal/thirdparty.m4' defines 'AX_THIRD_PARTY' with serial 1. Because both files have the same serial number, 'aclocal' uses the first it found in its search path order (*note Macro Search Path::). 'aclocal' therefore ignores '/usr/share/aclocal/thirdparty.m4' and outputs an 'aclocal.m4' that contains 'm4_include([m4/thirdparty.m4])'. Local directories specified with '-I' are always searched before system-wide directories, so a local file will always be preferred to the system-wide file in case of equal serial numbers. Now suppose the system-wide third-party macro is changed. This can happen if the package installing this macro is updated. Let's suppose the new macro has serial number 2. The next time 'aclocal -I m4 --install' is run the situation is the following: * 'configure.ac' uses 'AX_THIRD_PARTY' * 'm4/thirdparty.m4' defines 'AX_THIRD_PARTY' with serial 1. * '/usr/share/aclocal/thirdparty.m4' defines 'AX_THIRD_PARTY' with serial 2. When 'aclocal' sees a greater serial number, it immediately forgets anything it knows from files that have the same basename and a smaller serial number. So after it has found '/usr/share/aclocal/thirdparty.m4' with serial 2, 'aclocal' will proceed as if it had never seen 'm4/thirdparty.m4'. This brings us back to a situation similar to that at the beginning of our example, where no local file defined the macro. 'aclocal' will install the new version of the macro in 'm4/thirdparty.m4', in this case overriding the old version. MyPackage just had its macro updated as a side effect of running 'aclocal'. If you are leery of letting 'aclocal' update your local macro, you can run 'aclocal -I m4 --diff' to review the changes 'aclocal -I m4 --install' would perform on these macros. Finally, note that the '--force' option of 'aclocal' has absolutely no effect on the files installed by '--install'. For instance, if you have modified your local macros, do not expect '--install --force' to replace the local macros by their system-wide versions. If you want to do so, simply erase the local macros you want to revert, and run 'aclocal -I m4 --install'. 6.3.6 The Future of 'aclocal' ----------------------------- 'aclocal' is expected to disappear. This feature really should not be offered by Automake. Automake should focus on generating 'Makefile's; dealing with M4 macros really is Autoconf's job. The fact that some people install Automake just to use 'aclocal', but do not use 'automake' otherwise is an indication of how that feature is misplaced. The new implementation will probably be done slightly differently. For instance, it could enforce the 'm4/'-style layout discussed in *note Local Macros::. We have no idea when and how this will happen. This has been discussed several times in the past, but someone still has to commit to that non-trivial task. From the user point of view, 'aclocal''s removal might turn out to be painful. There is a simple precaution that you may take to make that switch more seamless: never call 'aclocal' yourself. Keep this guy under the exclusive control of 'autoreconf' and Automake's rebuild rules. Hopefully you won't need to worry about things breaking, when 'aclocal' disappears, because everything will have been taken care of. If otherwise you used to call 'aclocal' directly yourself or from some script, you will quickly notice the change. Many packages come with a script called 'bootstrap.sh' or 'autogen.sh', that will just call 'aclocal', 'libtoolize', 'gettextize' or 'autopoint', 'autoconf', 'autoheader', and 'automake' in the right order. Actually this is precisely what 'autoreconf' can do for you. If your package has such a 'bootstrap.sh' or 'autogen.sh' script, consider using 'autoreconf'. That should simplify its logic a lot (less things to maintain, yum!), it's even likely you will not need the script anymore, and more to the point you will not call 'aclocal' directly anymore. For the time being, third-party packages should continue to install public macros into '/usr/share/aclocal/'. If 'aclocal' is replaced by another tool it might make sense to rename the directory, but supporting '/usr/share/aclocal/' for backward compatibility should be really easy provided all macros are properly written (*note Extending aclocal::). 6.4 Autoconf macros supplied with Automake ========================================== Automake ships with several Autoconf macros that you can use from your 'configure.ac'. When you use one of them it will be included by 'aclocal' in 'aclocal.m4'. 6.4.1 Public Macros ------------------- 'AM_ENABLE_MULTILIB' This is used when a "multilib" library is being built. Please be aware that multilib support _will be removed_ from the Automake core in the next major release, and then _this macro will go away as well_ (even if a "frozen" version of will remain available in the 'contrib/' directory of the Automake distribution). The first optional argument is the name of the 'Makefile' being generated; it defaults to 'Makefile'. The second optional argument is used to find the top source directory; it defaults to the empty string (generally this should not be used unless you are familiar with the internals). *Note Multilibs::. 'AM_INIT_AUTOMAKE([OPTIONS])' 'AM_INIT_AUTOMAKE(PACKAGE, VERSION, [NO-DEFINE])' Runs many macros required for proper operation of the generated Makefiles. This macro has two forms, the first of which is preferred. In this form, 'AM_INIT_AUTOMAKE' is called with a single argument: a space-separated list of Automake options that should be applied to every 'Makefile.am' in the tree. The effect is as if each option were listed in 'AUTOMAKE_OPTIONS' (*note Options::). The second, deprecated, form of 'AM_INIT_AUTOMAKE' has two required arguments: the package and the version number. This form is obsolete because the PACKAGE and VERSION can be obtained from Autoconf's 'AC_INIT' macro (which itself has an old and a new form). If your 'configure.ac' has: AC_INIT([src/foo.c]) AM_INIT_AUTOMAKE([mumble], [1.5]) you can modernize it as follows: AC_INIT([mumble], [1.5]) AC_CONFIG_SRCDIR([src/foo.c]) AM_INIT_AUTOMAKE Note that if you're upgrading your 'configure.ac' from an earlier version of Automake, it is not always correct to simply move the package and version arguments from 'AM_INIT_AUTOMAKE' directly to 'AC_INIT', as in the example above. The first argument to 'AC_INIT' should be the name of your package (e.g., 'GNU Automake'), not the tarball name (e.g., 'automake') that you used to pass to 'AM_INIT_AUTOMAKE'. Autoconf tries to derive a tarball name from the package name, which should work for most but not all package names. (If it doesn't work for yours, you can use the four-argument form of 'AC_INIT' to provide the tarball name explicitly). By default this macro 'AC_DEFINE''s 'PACKAGE' and 'VERSION'. This can be avoided by passing the 'no-define' option, as in: AM_INIT_AUTOMAKE([gnits 1.5 no-define dist-bzip2]) or by passing a third non-empty argument to the obsolete form. 'AM_PATH_LISPDIR' Searches for the program 'emacs', and, if found, sets the output variable 'lispdir' to the full path to Emacs' site-lisp directory. Note that this test assumes the 'emacs' found to be a version that supports Emacs Lisp (such as GNU Emacs or XEmacs). Other emacsen can cause this test to hang (some, like old versions of MicroEmacs, start up in interactive mode, requiring 'C-x C-c' to exit, which is hardly obvious for a non-emacs user). In most cases, however, you should be able to use 'C-c' to kill the test. In order to avoid problems, you can set 'EMACS' to "no" in the environment, or use the '--with-lispdir' option to 'configure' to explicitly set the correct path (if you're sure you have an 'emacs' that supports Emacs Lisp). 'AM_PROG_AR([ACT-IF-FAIL])' You must use this macro when you use the archiver in your project, if you want support for unusual archivers such as Microsoft 'lib'. The content of the optional argument is executed if the archiver interface is not recognized; the default action is to abort configure with an error message. 'AM_PROG_AS' Use this macro when you have assembly code in your project. This will choose the assembler for you (by default the C compiler) and set 'CCAS', and will also set 'CCASFLAGS' if required. 'AM_PROG_CC_C_O' This is like 'AC_PROG_CC_C_O', but it generates its results in the manner required by Automake. You must use this instead of 'AC_PROG_CC_C_O' when you need this functionality, that is, when using per-target flags or subdir-objects with C sources. 'AM_PROG_LEX' Like 'AC_PROG_LEX' (*note Particular Program Checks: (autoconf)Particular Programs.), but uses the 'missing' script on systems that do not have 'lex'. HP-UX 10 is one such system. 'AM_PROG_GCJ' This macro finds the 'gcj' program or causes an error. It sets 'GCJ' and 'GCJFLAGS'. 'gcj' is the Java front-end to the GNU Compiler Collection. 'AM_PROG_UPC([COMPILER-SEARCH-LIST])' Find a compiler for Unified Parallel C and define the 'UPC' variable. The default COMPILER-SEARCH-LIST is 'upcc upc'. This macro will abort 'configure' if no Unified Parallel C compiler is found. 'AM_SILENT_RULES' Enable the machinery for less verbose build output (*note Options::). 'AM_WITH_DMALLOC' Add support for the Dmalloc package (http://dmalloc.com/). If the user runs 'configure' with '--with-dmalloc', then define 'WITH_DMALLOC' and add '-ldmalloc' to 'LIBS'. 6.4.2 Obsolete Macros --------------------- Although using some of the following macros was required in past releases, you should not use any of them in new code. Running 'autoupdate' should adjust your 'configure.ac' automatically (*note Using 'autoupdate' to Modernize 'configure.ac': (autoconf)autoupdate Invocation.). 'AM_C_PROTOTYPES' Check to see if function prototypes are understood by the compiler. If so, define 'PROTOTYPES' and set the output variables 'U' and 'ANSI2KNR' to the empty string. Otherwise, set 'U' to '_' and 'ANSI2KNR' to './ansi2knr'. Automake used these values to implement the deprecated de-ANSI-fication feature; however, support for _that feature will be removed_ in the next major Automake release, and then _these macros and variables will go away as well_. 'AM_CONFIG_HEADER' Automake will generate rules to automatically regenerate the config header. This obsolete macro is a synonym of 'AC_CONFIG_HEADERS' today (*note Optional::). 'AM_HEADER_TIOCGWINSZ_NEEDS_SYS_IOCTL' If the use of 'TIOCGWINSZ' requires '', then define 'GWINSZ_IN_SYS_IOCTL'. Otherwise 'TIOCGWINSZ' can be found in ''. This macro is obsolete, you should use Autoconf's 'AC_HEADER_TIOCGWINSZ' instead. 'AM_PROG_MKDIR_P' From Automake 1.8 to 1.9.6 this macro used to define the output variable 'mkdir_p' to one of 'mkdir -p', 'install-sh -d', or 'mkinstalldirs'. Nowadays Autoconf provides a similar functionality with 'AC_PROG_MKDIR_P' (*note Particular Program Checks: (autoconf)Particular Programs.), however this defines the output variable 'MKDIR_P' instead. Therefore 'AM_PROG_MKDIR_P' has been rewritten as a thin wrapper around 'AC_PROG_MKDIR_P' to define 'mkdir_p' to the same value as 'MKDIR_P' for backward compatibility. If you are using Automake, there is normally no reason to call this macro, because 'AM_INIT_AUTOMAKE' already does so. However, make sure that the custom rules in your 'Makefile's use '$(MKDIR_P)' and not '$(mkdir_p)'. Even if both variables still work, the latter should be considered obsolete. If you are not using Automake, please call 'AC_PROG_MKDIR_P' instead of 'AM_PROG_MKDIR_P'. 'AM_SYS_POSIX_TERMIOS' Check to see if POSIX termios headers and functions are available on the system. If so, set the shell variable 'am_cv_sys_posix_termios' to 'yes'. If not, set the variable to 'no'. This macro is obsolete, you should use Autoconf's 'AC_SYS_POSIX_TERMIOS' instead. 'AM_WITH_REGEX' Adds '--with-regex' to the 'configure' command line. If specified (the default), then the 'regex' regular expression library is used, 'regex.o' is put into 'LIBOBJS', and 'WITH_REGEX' is defined. If '--without-regex' is given, then the 'rx' regular expression library is used, and 'rx.o' is put into 'LIBOBJS'. This macro is obsolete now (since 'rx' doesn't seem to be maintained), and _will be removed the next major version of Automake_. Consider using gnulib if you need regex functionality. 6.4.3 Private Macros -------------------- The following macros are private macros you should not call directly. They are called by the other public macros when appropriate. Do not rely on them, as they might be changed in a future version. Consider them as implementation details; or better, do not consider them at all: skip this section! '_AM_DEPENDENCIES' 'AM_SET_DEPDIR' 'AM_DEP_TRACK' 'AM_OUTPUT_DEPENDENCY_COMMANDS' These macros are used to implement Automake's automatic dependency tracking scheme. They are called automatically by Automake when required, and there should be no need to invoke them manually. 'AM_MAKE_INCLUDE' This macro is used to discover how the user's 'make' handles 'include' statements. This macro is automatically invoked when needed; there should be no need to invoke it manually. 'AM_PROG_INSTALL_STRIP' This is used to find a version of 'install' that can be used to strip a program at installation time. This macro is automatically included when required. 'AM_SANITY_CHECK' This checks to make sure that a file created in the build directory is newer than a file in the source directory. This can fail on systems where the clock is set incorrectly. This macro is automatically run from 'AM_INIT_AUTOMAKE'. 7 Directories ************* For simple projects that distribute all files in the same directory it is enough to have a single 'Makefile.am' that builds everything in place. In larger projects it is common to organize files in different directories, in a tree. For instance one directory per program, per library or per module. The traditional approach is to build these subdirectories recursively: each directory contains its 'Makefile' (generated from 'Makefile.am'), and when 'make' is run from the top level directory it enters each subdirectory in turn to build its contents. 7.1 Recursing subdirectories ============================ In packages with subdirectories, the top level 'Makefile.am' must tell Automake which subdirectories are to be built. This is done via the 'SUBDIRS' variable. The 'SUBDIRS' variable holds a list of subdirectories in which building of various sorts can occur. The rules for many targets (e.g., 'all') in the generated 'Makefile' will run commands both locally and in all specified subdirectories. Note that the directories listed in 'SUBDIRS' are not required to contain 'Makefile.am's; only 'Makefile's (after configuration). This allows inclusion of libraries from packages that do not use Automake (such as 'gettext'; see also *note Third-Party Makefiles::). In packages that use subdirectories, the top-level 'Makefile.am' is often very short. For instance, here is the 'Makefile.am' from the GNU Hello distribution: EXTRA_DIST = BUGS ChangeLog.O README-alpha SUBDIRS = doc intl po src tests When Automake invokes 'make' in a subdirectory, it uses the value of the 'MAKE' variable. It passes the value of the variable 'AM_MAKEFLAGS' to the 'make' invocation; this can be set in 'Makefile.am' if there are flags you must always pass to 'make'. The directories mentioned in 'SUBDIRS' are usually direct children of the current directory, each subdirectory containing its own 'Makefile.am' with a 'SUBDIRS' pointing to deeper subdirectories. Automake can be used to construct packages of arbitrary depth this way. By default, Automake generates 'Makefiles' that work depth-first in postfix order: the subdirectories are built before the current directory. However, it is possible to change this ordering. You can do this by putting '.' into 'SUBDIRS'. For instance, putting '.' first will cause a prefix ordering of directories. Using SUBDIRS = lib src . test will cause 'lib/' to be built before 'src/', then the current directory will be built, finally the 'test/' directory will be built. It is customary to arrange test directories to be built after everything else since they are meant to test what has been constructed. All 'clean' rules are run in reverse order of build rules. 7.2 Conditional Subdirectories ============================== It is possible to define the 'SUBDIRS' variable conditionally if, like in the case of GNU Inetutils, you want to only build a subset of the entire package. To illustrate how this works, let's assume we have two directories 'src/' and 'opt/'. 'src/' should always be built, but we want to decide in 'configure' whether 'opt/' will be built or not. (For this example we will assume that 'opt/' should be built when the variable '$want_opt' was set to 'yes'.) Running 'make' should thus recurse into 'src/' always, and then maybe in 'opt/'. However 'make dist' should always recurse into both 'src/' and 'opt/'. Because 'opt/' should be distributed even if it is not needed in the current configuration. This means 'opt/Makefile' should be created _unconditionally_. There are two ways to setup a project like this. You can use Automake conditionals (*note Conditionals::) or use Autoconf 'AC_SUBST' variables (*note Setting Output Variables: (autoconf)Setting Output Variables.). Using Automake conditionals is the preferred solution. Before we illustrate these two possibilities, let's introduce 'DIST_SUBDIRS'. 7.2.1 'SUBDIRS' vs. 'DIST_SUBDIRS' ---------------------------------- Automake considers two sets of directories, defined by the variables 'SUBDIRS' and 'DIST_SUBDIRS'. 'SUBDIRS' contains the subdirectories of the current directory that must be built (*note Subdirectories::). It must be defined manually; Automake will never guess a directory is to be built. As we will see in the next two sections, it is possible to define it conditionally so that some directory will be omitted from the build. 'DIST_SUBDIRS' is used in rules that need to recurse in all directories, even those that have been conditionally left out of the build. Recall our example where we may not want to build subdirectory 'opt/', but yet we want to distribute it? This is where 'DIST_SUBDIRS' comes into play: 'opt' may not appear in 'SUBDIRS', but it must appear in 'DIST_SUBDIRS'. Precisely, 'DIST_SUBDIRS' is used by 'make maintainer-clean', 'make distclean' and 'make dist'. All other recursive rules use 'SUBDIRS'. If 'SUBDIRS' is defined conditionally using Automake conditionals, Automake will define 'DIST_SUBDIRS' automatically from the possible values of 'SUBDIRS' in all conditions. If 'SUBDIRS' contains 'AC_SUBST' variables, 'DIST_SUBDIRS' will not be defined correctly because Automake does not know the possible values of these variables. In this case 'DIST_SUBDIRS' needs to be defined manually. 7.2.2 Subdirectories with 'AM_CONDITIONAL' ------------------------------------------ 'configure' should output the 'Makefile' for each directory and define a condition into which 'opt/' should be built. ... AM_CONDITIONAL([COND_OPT], [test "$want_opt" = yes]) AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile]) ... Then 'SUBDIRS' can be defined in the top-level 'Makefile.am' as follows. if COND_OPT MAYBE_OPT = opt endif SUBDIRS = src $(MAYBE_OPT) As you can see, running 'make' will rightly recurse into 'src/' and maybe 'opt/'. As you can't see, running 'make dist' will recurse into both 'src/' and 'opt/' directories because 'make dist', unlike 'make all', doesn't use the 'SUBDIRS' variable. It uses the 'DIST_SUBDIRS' variable. In this case Automake will define 'DIST_SUBDIRS = src opt' automatically because it knows that 'MAYBE_OPT' can contain 'opt' in some condition. 7.2.3 Subdirectories with 'AC_SUBST' ------------------------------------ Another possibility is to define 'MAYBE_OPT' from './configure' using 'AC_SUBST': ... if test "$want_opt" = yes; then MAYBE_OPT=opt else MAYBE_OPT= fi AC_SUBST([MAYBE_OPT]) AC_CONFIG_FILES([Makefile src/Makefile opt/Makefile]) ... In this case the top-level 'Makefile.am' should look as follows. SUBDIRS = src $(MAYBE_OPT) DIST_SUBDIRS = src opt The drawback is that since Automake cannot guess what the possible values of 'MAYBE_OPT' are, it is necessary to define 'DIST_SUBDIRS'. 7.2.4 Unconfigured Subdirectories --------------------------------- The semantics of 'DIST_SUBDIRS' are often misunderstood by some users that try to _configure and build_ subdirectories conditionally. Here by configuring we mean creating the 'Makefile' (it might also involve running a nested 'configure' script: this is a costly operation that explains why people want to do it conditionally, but only the 'Makefile' is relevant to the discussion). The above examples all assume that every 'Makefile' is created, even in directories that are not going to be built. The simple reason is that we want 'make dist' to distribute even the directories that are not being built (e.g., platform-dependent code), hence 'make dist' must recurse into the subdirectory, hence this directory must be configured and appear in 'DIST_SUBDIRS'. Building packages that do not configure every subdirectory is a tricky business, and we do not recommend it to the novice as it is easy to produce an incomplete tarball by mistake. We will not discuss this topic in depth here, yet for the adventurous here are a few rules to remember. * 'SUBDIRS' should always be a subset of 'DIST_SUBDIRS'. It makes little sense to have a directory in 'SUBDIRS' that is not in 'DIST_SUBDIRS'. Think of the former as a way to tell which directories listed in the latter should be built. * Any directory listed in 'DIST_SUBDIRS' and 'SUBDIRS' must be configured. I.e., the 'Makefile' must exists or the recursive 'make' rules will not be able to process the directory. * Any configured directory must be listed in 'DIST_SUBDIRS'. So that the cleaning rules remove the generated 'Makefile's. It would be correct to see 'DIST_SUBDIRS' as a variable that lists all the directories that have been configured. In order to prevent recursion in some unconfigured directory you must therefore ensure that this directory does not appear in 'DIST_SUBDIRS' (and 'SUBDIRS'). For instance, if you define 'SUBDIRS' conditionally using 'AC_SUBST' and do not define 'DIST_SUBDIRS' explicitly, it will be default to '$(SUBDIRS)'; another possibility is to force 'DIST_SUBDIRS = $(SUBDIRS)'. Of course, directories that are omitted from 'DIST_SUBDIRS' will not be distributed unless you make other arrangements for this to happen (for instance, always running 'make dist' in a configuration where all directories are known to appear in 'DIST_SUBDIRS'; or writing a 'dist-hook' target to distribute these directories). In few packages, unconfigured directories are not even expected to be distributed. Although these packages do not require the aforementioned extra arrangements, there is another pitfall. If the name of a directory appears in 'SUBDIRS' or 'DIST_SUBDIRS', 'automake' will make sure the directory exists. Consequently 'automake' cannot be run on such a distribution when one directory has been omitted. One way to avoid this check is to use the 'AC_SUBST' method to declare conditional directories; since 'automake' does not know the values of 'AC_SUBST' variables it cannot ensure the corresponding directory exists. 7.3 An Alternative Approach to Subdirectories ============================================= If you've ever read Peter Miller's excellent paper, Recursive Make Considered Harmful (http://miller.emu.id.au/pmiller/books/rmch/), the preceding sections on the use of subdirectories will probably come as unwelcome advice. For those who haven't read the paper, Miller's main thesis is that recursive 'make' invocations are both slow and error-prone. Automake provides sufficient cross-directory support (1) to enable you to write a single 'Makefile.am' for a complex multi-directory package. By default an installable file specified in a subdirectory will have its directory name stripped before installation. For instance, in this example, the header file will be installed as '$(includedir)/stdio.h': include_HEADERS = inc/stdio.h However, the 'nobase_' prefix can be used to circumvent this path stripping. In this example, the header file will be installed as '$(includedir)/sys/types.h': nobase_include_HEADERS = sys/types.h 'nobase_' should be specified first when used in conjunction with either 'dist_' or 'nodist_' (*note Fine-grained Distribution Control::). For instance: nobase_dist_pkgdata_DATA = images/vortex.pgm sounds/whirl.ogg Finally, note that a variable using the 'nobase_' prefix can often be replaced by several variables, one for each destination directory (*note Uniform::). For instance, the last example could be rewritten as follows: imagesdir = $(pkgdatadir)/images soundsdir = $(pkgdatadir)/sounds dist_images_DATA = images/vortex.pgm dist_sounds_DATA = sounds/whirl.ogg This latter syntax makes it possible to change one destination directory without changing the layout of the source tree. Currently, 'nobase_*_LTLIBRARIES' are the only exception to this rule, in that there is no particular installation order guarantee for an otherwise equivalent set of variables without 'nobase_' prefix. ---------- Footnotes ---------- (1) We believe. This work is new and there are probably warts. *Note Introduction::, for information on reporting bugs. 7.4 Nesting Packages ==================== In the GNU Build System, packages can be nested to arbitrary depth. This means that a package can embed other packages with their own 'configure', 'Makefile's, etc. These other packages should just appear as subdirectories of their parent package. They must be listed in 'SUBDIRS' like other ordinary directories. However the subpackage's 'Makefile's should be output by its own 'configure' script, not by the parent's 'configure'. This is achieved using the 'AC_CONFIG_SUBDIRS' Autoconf macro (*note AC_CONFIG_SUBDIRS: (autoconf)Subdirectories.). Here is an example package for an 'arm' program that links with a 'hand' library that is a nested package in subdirectory 'hand/'. 'arm''s 'configure.ac': AC_INIT([arm], [1.0]) AC_CONFIG_AUX_DIR([.]) AM_INIT_AUTOMAKE AC_PROG_CC AC_CONFIG_FILES([Makefile]) # Call hand's ./configure script recursively. AC_CONFIG_SUBDIRS([hand]) AC_OUTPUT 'arm''s 'Makefile.am': # Build the library in the hand subdirectory first. SUBDIRS = hand # Include hand's header when compiling this directory. AM_CPPFLAGS = -I$(srcdir)/hand bin_PROGRAMS = arm arm_SOURCES = arm.c # link with the hand library. arm_LDADD = hand/libhand.a Now here is 'hand''s 'hand/configure.ac': AC_INIT([hand], [1.2]) AC_CONFIG_AUX_DIR([.]) AM_INIT_AUTOMAKE AC_PROG_CC AM_PROG_AR AC_PROG_RANLIB AC_CONFIG_FILES([Makefile]) AC_OUTPUT and its 'hand/Makefile.am': lib_LIBRARIES = libhand.a libhand_a_SOURCES = hand.c When 'make dist' is run from the top-level directory it will create an archive 'arm-1.0.tar.gz' that contains the 'arm' code as well as the 'hand' subdirectory. This package can be built and installed like any ordinary package, with the usual './configure && make && make install' sequence (the 'hand' subpackage will be built and installed by the process). When 'make dist' is run from the hand directory, it will create a self-contained 'hand-1.2.tar.gz' archive. So although it appears to be embedded in another package, it can still be used separately. The purpose of the 'AC_CONFIG_AUX_DIR([.])' instruction is to force Automake and Autoconf to search for auxiliary scripts in the current directory. For instance, this means that there will be two copies of 'install-sh': one in the top-level of the 'arm' package, and another one in the 'hand/' subdirectory for the 'hand' package. The historical default is to search for these auxiliary scripts in the parent directory and the grandparent directory. So if the 'AC_CONFIG_AUX_DIR([.])' line was removed from 'hand/configure.ac', that subpackage would share the auxiliary script of the 'arm' package. This may looks like a gain in size (a few kilobytes), but it is actually a loss of modularity as the 'hand' subpackage is no longer self-contained ('make dist' in the subdirectory will not work anymore). Packages that do not use Automake need more work to be integrated this way. *Note Third-Party Makefiles::. 8 Building Programs and Libraries ********************************* A large part of Automake's functionality is dedicated to making it easy to build programs and libraries. 8.1 Building a program ====================== In order to build a program, you need to tell Automake which sources are part of it, and which libraries it should be linked with. This section also covers conditional compilation of sources or programs. Most of the comments about these also apply to libraries (*note A Library::) and libtool libraries (*note A Shared Library::). 8.1.1 Defining program sources ------------------------------ In a directory containing source that gets built into a program (as opposed to a library or a script), the 'PROGRAMS' primary is used. Programs can be installed in 'bindir', 'sbindir', 'libexecdir', 'pkglibexecdir', or not at all ('noinst_'). They can also be built only for 'make check', in which case the prefix is 'check_'. For instance: bin_PROGRAMS = hello In this simple case, the resulting 'Makefile.in' will contain code to generate a program named 'hello'. Associated with each program are several assisting variables that are named after the program. These variables are all optional, and have reasonable defaults. Each variable, its use, and default is spelled out below; we use the "hello" example throughout. The variable 'hello_SOURCES' is used to specify which source files get built into an executable: hello_SOURCES = hello.c version.c getopt.c getopt1.c getopt.h system.h This causes each mentioned '.c' file to be compiled into the corresponding '.o'. Then all are linked to produce 'hello'. If 'hello_SOURCES' is not specified, then it defaults to the single file 'hello.c' (*note Default _SOURCES::). Multiple programs can be built in a single directory. Multiple programs can share a single source file, which must be listed in each '_SOURCES' definition. Header files listed in a '_SOURCES' definition will be included in the distribution but otherwise ignored. In case it isn't obvious, you should not include the header file generated by 'configure' in a '_SOURCES' variable; this file should not be distributed. Lex ('.l') and Yacc ('.y') files can also be listed; see *note Yacc and Lex::. 8.1.2 Linking the program ------------------------- If you need to link against libraries that are not found by 'configure', you can use 'LDADD' to do so. This variable is used to specify additional objects or libraries to link with; it is inappropriate for specifying specific linker flags, you should use 'AM_LDFLAGS' for this purpose. Sometimes, multiple programs are built in one directory but do not share the same link-time requirements. In this case, you can use the 'PROG_LDADD' variable (where PROG is the name of the program as it appears in some '_PROGRAMS' variable, and usually written in lowercase) to override 'LDADD'. If this variable exists for a given program, then that program is not linked using 'LDADD'. For instance, in GNU cpio, 'pax', 'cpio' and 'mt' are linked against the library 'libcpio.a'. However, 'rmt' is built in the same directory, and has no such link requirement. Also, 'mt' and 'rmt' are only built on certain architectures. Here is what cpio's 'src/Makefile.am' looks like (abridged): bin_PROGRAMS = cpio pax $(MT) libexec_PROGRAMS = $(RMT) EXTRA_PROGRAMS = mt rmt LDADD = ../lib/libcpio.a $(INTLLIBS) rmt_LDADD = cpio_SOURCES = ... pax_SOURCES = ... mt_SOURCES = ... rmt_SOURCES = ... 'PROG_LDADD' is inappropriate for passing program-specific linker flags (except for '-l', '-L', '-dlopen' and '-dlpreopen'). So, use the 'PROG_LDFLAGS' variable for this purpose. It is also occasionally useful to have a program depend on some other target that is not actually part of that program. This can be done using either the 'PROG_DEPENDENCIES' or the 'EXTRA_PROG_DEPENDENCIES' variable. Each program depends on the contents both variables, but no further interpretation is done. Since these dependencies are associated to the link rule used to create the programs they should normally list files used by the link command. That is '*.$(OBJEXT)', '*.a', or '*.la' files. In rare cases you may need to add other kinds of files such as linker scripts, but _listing a source file in '_DEPENDENCIES' is wrong_. If some source file needs to be built before all the components of a program are built, consider using the 'BUILT_SOURCES' variable instead (*note Sources::). If 'PROG_DEPENDENCIES' is not supplied, it is computed by Automake. The automatically-assigned value is the contents of 'PROG_LDADD', with most configure substitutions, '-l', '-L', '-dlopen' and '-dlpreopen' options removed. The configure substitutions that are left in are only '$(LIBOBJS)' and '$(ALLOCA)'; these are left because it is known that they will not cause an invalid value for 'PROG_DEPENDENCIES' to be generated. *note Conditional Sources:: shows a situation where '_DEPENDENCIES' may be used. The 'EXTRA_PROG_DEPENDENCIES' may be useful for cases where you merely want to augment the 'automake'-generated 'PROG_DEPENDENCIES' rather than replacing it. We recommend that you avoid using '-l' options in 'LDADD' or 'PROG_LDADD' when referring to libraries built by your package. Instead, write the file name of the library explicitly as in the above 'cpio' example. Use '-l' only to list third-party libraries. If you follow this rule, the default value of 'PROG_DEPENDENCIES' will list all your local libraries and omit the other ones. 8.1.3 Conditional compilation of sources ---------------------------------------- You can't put a configure substitution (e.g., '@FOO@' or '$(FOO)' where 'FOO' is defined via 'AC_SUBST') into a '_SOURCES' variable. The reason for this is a bit hard to explain, but suffice to say that it simply won't work. Automake will give an error if you try to do this. Fortunately there are two other ways to achieve the same result. One is to use configure substitutions in '_LDADD' variables, the other is to use an Automake conditional. Conditional Compilation using '_LDADD' Substitutions .................................................... Automake must know all the source files that could possibly go into a program, even if not all the files are built in every circumstance. Any files that are only conditionally built should be listed in the appropriate 'EXTRA_' variable. For instance, if 'hello-linux.c' or 'hello-generic.c' were conditionally included in 'hello', the 'Makefile.am' would contain: bin_PROGRAMS = hello hello_SOURCES = hello-common.c EXTRA_hello_SOURCES = hello-linux.c hello-generic.c hello_LDADD = $(HELLO_SYSTEM) hello_DEPENDENCIES = $(HELLO_SYSTEM) You can then setup the '$(HELLO_SYSTEM)' substitution from 'configure.ac': ... case $host in *linux*) HELLO_SYSTEM='hello-linux.$(OBJEXT)' ;; *) HELLO_SYSTEM='hello-generic.$(OBJEXT)' ;; esac AC_SUBST([HELLO_SYSTEM]) ... In this case, the variable 'HELLO_SYSTEM' should be replaced by either 'hello-linux.o' or 'hello-generic.o', and added to both 'hello_DEPENDENCIES' and 'hello_LDADD' in order to be built and linked in. Conditional Compilation using Automake Conditionals ................................................... An often simpler way to compile source files conditionally is to use Automake conditionals. For instance, you could use this 'Makefile.am' construct to build the same 'hello' example: bin_PROGRAMS = hello if LINUX hello_SOURCES = hello-linux.c hello-common.c else hello_SOURCES = hello-generic.c hello-common.c endif In this case, 'configure.ac' should setup the 'LINUX' conditional using 'AM_CONDITIONAL' (*note Conditionals::). When using conditionals like this you don't need to use the 'EXTRA_' variable, because Automake will examine the contents of each variable to construct the complete list of source files. If your program uses a lot of files, you will probably prefer a conditional '+='. bin_PROGRAMS = hello hello_SOURCES = hello-common.c if LINUX hello_SOURCES += hello-linux.c else hello_SOURCES += hello-generic.c endif 8.1.4 Conditional compilation of programs ----------------------------------------- Sometimes it is useful to determine the programs that are to be built at configure time. For instance, GNU 'cpio' only builds 'mt' and 'rmt' under special circumstances. The means to achieve conditional compilation of programs are the same you can use to compile source files conditionally: substitutions or conditionals. Conditional Programs using 'configure' Substitutions .................................................... In this case, you must notify Automake of all the programs that can possibly be built, but at the same time cause the generated 'Makefile.in' to use the programs specified by 'configure'. This is done by having 'configure' substitute values into each '_PROGRAMS' definition, while listing all optionally built programs in 'EXTRA_PROGRAMS'. bin_PROGRAMS = cpio pax $(MT) libexec_PROGRAMS = $(RMT) EXTRA_PROGRAMS = mt rmt As explained in *note EXEEXT::, Automake will rewrite 'bin_PROGRAMS', 'libexec_PROGRAMS', and 'EXTRA_PROGRAMS', appending '$(EXEEXT)' to each binary. Obviously it cannot rewrite values obtained at run-time through 'configure' substitutions, therefore you should take care of appending '$(EXEEXT)' yourself, as in 'AC_SUBST([MT], ['mt${EXEEXT}'])'. Conditional Programs using Automake Conditionals ................................................ You can also use Automake conditionals (*note Conditionals::) to select programs to be built. In this case you don't have to worry about '$(EXEEXT)' or 'EXTRA_PROGRAMS'. bin_PROGRAMS = cpio pax if WANT_MT bin_PROGRAMS += mt endif if WANT_RMT libexec_PROGRAMS = rmt endif 8.2 Building a library ====================== Building a library is much like building a program. In this case, the name of the primary is 'LIBRARIES'. Libraries can be installed in 'libdir' or 'pkglibdir'. *Note A Shared Library::, for information on how to build shared libraries using libtool and the 'LTLIBRARIES' primary. Each '_LIBRARIES' variable is a list of the libraries to be built. For instance, to create a library named 'libcpio.a', but not install it, you would write: noinst_LIBRARIES = libcpio.a libcpio_a_SOURCES = ... The sources that go into a library are determined exactly as they are for programs, via the '_SOURCES' variables. Note that the library name is canonicalized (*note Canonicalization::), so the '_SOURCES' variable corresponding to 'libcpio.a' is 'libcpio_a_SOURCES', not 'libcpio.a_SOURCES'. Extra objects can be added to a library using the 'LIBRARY_LIBADD' variable. This should be used for objects determined by 'configure'. Again from 'cpio': libcpio_a_LIBADD = $(LIBOBJS) $(ALLOCA) In addition, sources for extra objects that will not exist until configure-time must be added to the 'BUILT_SOURCES' variable (*note Sources::). Building a static library is done by compiling all object files, then by invoking '$(AR) $(ARFLAGS)' followed by the name of the library and the list of objects, and finally by calling '$(RANLIB)' on that library. You should call 'AC_PROG_RANLIB' from your 'configure.ac' to define 'RANLIB' (Automake will complain otherwise). You should also call 'AM_PROG_AR' to define 'AR', in order to support unusual archivers such as Microsoft lib. 'ARFLAGS' will default to 'cru'; you can override this variable by setting it in your 'Makefile.am' or by 'AC_SUBST'ing it from your 'configure.ac'. You can override the 'AR' variable by defining a per-library 'maude_AR' variable (*note Program and Library Variables::). Be careful when selecting library components conditionally. Because building an empty library is not portable, you should ensure that any library always contains at least one object. To use a static library when building a program, add it to 'LDADD' for this program. In the following example, the program 'cpio' is statically linked with the library 'libcpio.a'. noinst_LIBRARIES = libcpio.a libcpio_a_SOURCES = ... bin_PROGRAMS = cpio cpio_SOURCES = cpio.c ... cpio_LDADD = libcpio.a 8.3 Building a Shared Library ============================= Building shared libraries portably is a relatively complex matter. For this reason, GNU Libtool (*note Introduction: (libtool)Top.) was created to help build shared libraries in a platform-independent way. 8.3.1 The Libtool Concept ------------------------- Libtool abstracts shared and static libraries into a unified concept henceforth called "libtool libraries". Libtool libraries are files using the '.la' suffix, and can designate a static library, a shared library, or maybe both. Their exact nature cannot be determined until './configure' is run: not all platforms support all kinds of libraries, and users can explicitly select which libraries should be built. (However the package's maintainers can tune the default, *note The 'AC_PROG_LIBTOOL' macro: (libtool)AC_PROG_LIBTOOL.) Because object files for shared and static libraries must be compiled differently, libtool is also used during compilation. Object files built by libtool are called "libtool objects": these are files using the '.lo' suffix. Libtool libraries are built from these libtool objects. You should not assume anything about the structure of '.la' or '.lo' files and how libtool constructs them: this is libtool's concern, and the last thing one wants is to learn about libtool's guts. However the existence of these files matters, because they are used as targets and dependencies in 'Makefile's rules when building libtool libraries. There are situations where you may have to refer to these, for instance when expressing dependencies for building source files conditionally (*note Conditional Libtool Sources::). People considering writing a plug-in system, with dynamically loaded modules, should look into 'libltdl': libtool's dlopening library (*note Using libltdl: (libtool)Using libltdl.). This offers a portable dlopening facility to load libtool libraries dynamically, and can also achieve static linking where unavoidable. Before we discuss how to use libtool with Automake in details, it should be noted that the libtool manual also has a section about how to use Automake with libtool (*note Using Automake with Libtool: (libtool)Using Automake.). 8.3.2 Building Libtool Libraries -------------------------------- Automake uses libtool to build libraries declared with the 'LTLIBRARIES' primary. Each '_LTLIBRARIES' variable is a list of libtool libraries to build. For instance, to create a libtool library named 'libgettext.la', and install it in 'libdir', write: lib_LTLIBRARIES = libgettext.la libgettext_la_SOURCES = gettext.c gettext.h ... Automake predefines the variable 'pkglibdir', so you can use 'pkglib_LTLIBRARIES' to install libraries in '$(libdir)/@PACKAGE@/'. If 'gettext.h' is a public header file that needs to be installed in order for people to use the library, it should be declared using a '_HEADERS' variable, not in 'libgettext_la_SOURCES'. Headers listed in the latter should be internal headers that are not part of the public interface. lib_LTLIBRARIES = libgettext.la libgettext_la_SOURCES = gettext.c ... include_HEADERS = gettext.h ... A package can build and install such a library along with other programs that use it. This dependency should be specified using 'LDADD'. The following example builds a program named 'hello' that is linked with 'libgettext.la'. lib_LTLIBRARIES = libgettext.la libgettext_la_SOURCES = gettext.c ... bin_PROGRAMS = hello hello_SOURCES = hello.c ... hello_LDADD = libgettext.la Whether 'hello' is statically or dynamically linked with 'libgettext.la' is not yet known: this will depend on the configuration of libtool and the capabilities of the host. 8.3.3 Building Libtool Libraries Conditionally ---------------------------------------------- Like conditional programs (*note Conditional Programs::), there are two main ways to build conditional libraries: using Automake conditionals or using Autoconf 'AC_SUBST'itutions. The important implementation detail you have to be aware of is that the place where a library will be installed matters to libtool: it needs to be indicated _at link-time_ using the '-rpath' option. For libraries whose destination directory is known when Automake runs, Automake will automatically supply the appropriate '-rpath' option to libtool. This is the case for libraries listed explicitly in some installable '_LTLIBRARIES' variables such as 'lib_LTLIBRARIES'. However, for libraries determined at configure time (and thus mentioned in 'EXTRA_LTLIBRARIES'), Automake does not know the final installation directory. For such libraries you must add the '-rpath' option to the appropriate '_LDFLAGS' variable by hand. The examples below illustrate the differences between these two methods. Here is an example where 'WANTEDLIBS' is an 'AC_SUBST'ed variable set at './configure'-time to either 'libfoo.la', 'libbar.la', both, or none. Although '$(WANTEDLIBS)' appears in the 'lib_LTLIBRARIES', Automake cannot guess it relates to 'libfoo.la' or 'libbar.la' at the time it creates the link rule for these two libraries. Therefore the '-rpath' argument must be explicitly supplied. EXTRA_LTLIBRARIES = libfoo.la libbar.la lib_LTLIBRARIES = $(WANTEDLIBS) libfoo_la_SOURCES = foo.c ... libfoo_la_LDFLAGS = -rpath '$(libdir)' libbar_la_SOURCES = bar.c ... libbar_la_LDFLAGS = -rpath '$(libdir)' Here is how the same 'Makefile.am' would look using Automake conditionals named 'WANT_LIBFOO' and 'WANT_LIBBAR'. Now Automake is able to compute the '-rpath' setting itself, because it's clear that both libraries will end up in '$(libdir)' if they are installed. lib_LTLIBRARIES = if WANT_LIBFOO lib_LTLIBRARIES += libfoo.la endif if WANT_LIBBAR lib_LTLIBRARIES += libbar.la endif libfoo_la_SOURCES = foo.c ... libbar_la_SOURCES = bar.c ... 8.3.4 Libtool Libraries with Conditional Sources ------------------------------------------------ Conditional compilation of sources in a library can be achieved in the same way as conditional compilation of sources in a program (*note Conditional Sources::). The only difference is that '_LIBADD' should be used instead of '_LDADD' and that it should mention libtool objects ('.lo' files). So, to mimic the 'hello' example from *note Conditional Sources::, we could build a 'libhello.la' library using either 'hello-linux.c' or 'hello-generic.c' with the following 'Makefile.am'. lib_LTLIBRARIES = libhello.la libhello_la_SOURCES = hello-common.c EXTRA_libhello_la_SOURCES = hello-linux.c hello-generic.c libhello_la_LIBADD = $(HELLO_SYSTEM) libhello_la_DEPENDENCIES = $(HELLO_SYSTEM) And make sure 'configure' defines 'HELLO_SYSTEM' as either 'hello-linux.lo' or 'hello-generic.lo'. Or we could simply use an Automake conditional as follows. lib_LTLIBRARIES = libhello.la libhello_la_SOURCES = hello-common.c if LINUX libhello_la_SOURCES += hello-linux.c else libhello_la_SOURCES += hello-generic.c endif 8.3.5 Libtool Convenience Libraries ----------------------------------- Sometimes you want to build libtool libraries that should not be installed. These are called "libtool convenience libraries" and are typically used to encapsulate many sublibraries, later gathered into one big installed library. Libtool convenience libraries are declared by directory-less variables such as 'noinst_LTLIBRARIES', 'check_LTLIBRARIES', or even 'EXTRA_LTLIBRARIES'. Unlike installed libtool libraries they do not need an '-rpath' flag at link time (actually this is the only difference). Convenience libraries listed in 'noinst_LTLIBRARIES' are always built. Those listed in 'check_LTLIBRARIES' are built only upon 'make check'. Finally, libraries listed in 'EXTRA_LTLIBRARIES' are never built explicitly: Automake outputs rules to build them, but if the library does not appear as a Makefile dependency anywhere it won't be built (this is why 'EXTRA_LTLIBRARIES' is used for conditional compilation). Here is a sample setup merging libtool convenience libraries from subdirectories into one main 'libtop.la' library. # -- Top-level Makefile.am -- SUBDIRS = sub1 sub2 ... lib_LTLIBRARIES = libtop.la libtop_la_SOURCES = libtop_la_LIBADD = \ sub1/libsub1.la \ sub2/libsub2.la \ ... # -- sub1/Makefile.am -- noinst_LTLIBRARIES = libsub1.la libsub1_la_SOURCES = ... # -- sub2/Makefile.am -- # showing nested convenience libraries SUBDIRS = sub2.1 sub2.2 ... noinst_LTLIBRARIES = libsub2.la libsub2_la_SOURCES = libsub2_la_LIBADD = \ sub21/libsub21.la \ sub22/libsub22.la \ ... When using such setup, beware that 'automake' will assume 'libtop.la' is to be linked with the C linker. This is because 'libtop_la_SOURCES' is empty, so 'automake' picks C as default language. If 'libtop_la_SOURCES' was not empty, 'automake' would select the linker as explained in *note How the Linker is Chosen::. If one of the sublibraries contains non-C source, it is important that the appropriate linker be chosen. One way to achieve this is to pretend that there is such a non-C file among the sources of the library, thus forcing 'automake' to select the appropriate linker. Here is the top-level 'Makefile' of our example updated to force C++ linking. SUBDIRS = sub1 sub2 ... lib_LTLIBRARIES = libtop.la libtop_la_SOURCES = # Dummy C++ source to cause C++ linking. nodist_EXTRA_libtop_la_SOURCES = dummy.cxx libtop_la_LIBADD = \ sub1/libsub1.la \ sub2/libsub2.la \ ... 'EXTRA_*_SOURCES' variables are used to keep track of source files that might be compiled (this is mostly useful when doing conditional compilation using 'AC_SUBST', *note Conditional Libtool Sources::), and the 'nodist_' prefix means the listed sources are not to be distributed (*note Program and Library Variables::). In effect the file 'dummy.cxx' does not need to exist in the source tree. Of course if you have some real source file to list in 'libtop_la_SOURCES' there is no point in cheating with 'nodist_EXTRA_libtop_la_SOURCES'. 8.3.6 Libtool Modules --------------------- These are libtool libraries meant to be dlopened. They are indicated to libtool by passing '-module' at link-time. pkglib_LTLIBRARIES = mymodule.la mymodule_la_SOURCES = doit.c mymodule_la_LDFLAGS = -module Ordinarily, Automake requires that a library's name start with 'lib'. However, when building a dynamically loadable module you might wish to use a "nonstandard" name. Automake will not complain about such nonstandard names if it knows the library being built is a libtool module, i.e., if '-module' explicitly appears in the library's '_LDFLAGS' variable (or in the common 'AM_LDFLAGS' variable when no per-library '_LDFLAGS' variable is defined). As always, 'AC_SUBST' variables are black boxes to Automake since their values are not yet known when 'automake' is run. Therefore if '-module' is set via such a variable, Automake cannot notice it and will proceed as if the library was an ordinary libtool library, with strict naming. If 'mymodule_la_SOURCES' is not specified, then it defaults to the single file 'mymodule.c' (*note Default _SOURCES::). 8.3.7 '_LIBADD', '_LDFLAGS', and '_LIBTOOLFLAGS' ------------------------------------------------ As shown in previous sections, the 'LIBRARY_LIBADD' variable should be used to list extra libtool objects ('.lo' files) or libtool libraries ('.la') to add to LIBRARY. The 'LIBRARY_LDFLAGS' variable is the place to list additional libtool linking flags, such as '-version-info', '-static', and a lot more. *Note Link mode: (libtool)Link mode. The 'libtool' command has two kinds of options: mode-specific options and generic options. Mode-specific options such as the aforementioned linking flags should be lumped with the other flags passed to the tool invoked by 'libtool' (hence the use of 'LIBRARY_LDFLAGS' for libtool linking flags). Generic options include '--tag=TAG' and '--silent' (*note Invoking 'libtool': (libtool)Invoking libtool. for more options) should appear before the mode selection on the command line; in 'Makefile.am's they should be listed in the 'LIBRARY_LIBTOOLFLAGS' variable. If 'LIBRARY_LIBTOOLFLAGS' is not defined, then the variable 'AM_LIBTOOLFLAGS' is used instead. These flags are passed to libtool after the '--tag=TAG' option computed by Automake (if any), so 'LIBRARY_LIBTOOLFLAGS' (or 'AM_LIBTOOLFLAGS') is a good place to override or supplement the '--tag=TAG' setting. The libtool rules also use a 'LIBTOOLFLAGS' variable that should not be set in 'Makefile.am': this is a user variable (*note Flag Variables Ordering::. It allows users to run 'make LIBTOOLFLAGS=--silent', for instance. Note that the verbosity of 'libtool' can also be influenced with the Automake 'silent-rules' option (*note Options::). 8.3.8 'LTLIBOBJS' and 'LTALLOCA' -------------------------------- Where an ordinary library might include '$(LIBOBJS)' or '$(ALLOCA)' (*note LIBOBJS::), a libtool library must use '$(LTLIBOBJS)' or '$(LTALLOCA)'. This is required because the object files that libtool operates on do not necessarily end in '.o'. Nowadays, the computation of 'LTLIBOBJS' from 'LIBOBJS' is performed automatically by Autoconf (*note 'AC_LIBOBJ' vs. 'LIBOBJS': (autoconf)AC_LIBOBJ vs LIBOBJS.). 8.3.9 Common Issues Related to Libtool's Use -------------------------------------------- 8.3.9.1 Error: 'required file `./ltmain.sh' not found' ...................................................... Libtool comes with a tool called 'libtoolize' that will install libtool's supporting files into a package. Running this command will install 'ltmain.sh'. You should execute it before 'aclocal' and 'automake'. People upgrading old packages to newer autotools are likely to face this issue because older Automake versions used to call 'libtoolize'. Therefore old build scripts do not call 'libtoolize'. Since Automake 1.6, it has been decided that running 'libtoolize' was none of Automake's business. Instead, that functionality has been moved into the 'autoreconf' command (*note Using 'autoreconf': (autoconf)autoreconf Invocation.). If you do not want to remember what to run and when, just learn the 'autoreconf' command. Hopefully, replacing existing 'bootstrap.sh' or 'autogen.sh' scripts by a call to 'autoreconf' should also free you from any similar incompatible change in the future. 8.3.9.2 Objects 'created with both libtool and without' ....................................................... Sometimes, the same source file is used both to build a libtool library and to build another non-libtool target (be it a program or another library). Let's consider the following 'Makefile.am'. bin_PROGRAMS = prog prog_SOURCES = prog.c foo.c ... lib_LTLIBRARIES = libfoo.la libfoo_la_SOURCES = foo.c ... (In this trivial case the issue could be avoided by linking 'libfoo.la' with 'prog' instead of listing 'foo.c' in 'prog_SOURCES'. But let's assume we really want to keep 'prog' and 'libfoo.la' separate.) Technically, it means that we should build 'foo.$(OBJEXT)' for 'prog', and 'foo.lo' for 'libfoo.la'. The problem is that in the course of creating 'foo.lo', libtool may erase (or replace) 'foo.$(OBJEXT)', and this cannot be avoided. Therefore, when Automake detects this situation it will complain with a message such as object `foo.$(OBJEXT)' created both with libtool and without A workaround for this issue is to ensure that these two objects get different basenames. As explained in *note Renamed Objects::, this happens automatically when per-targets flags are used. bin_PROGRAMS = prog prog_SOURCES = prog.c foo.c ... prog_CFLAGS = $(AM_CFLAGS) lib_LTLIBRARIES = libfoo.la libfoo_la_SOURCES = foo.c ... Adding 'prog_CFLAGS = $(AM_CFLAGS)' is almost a no-op, because when the 'prog_CFLAGS' is defined, it is used instead of 'AM_CFLAGS'. However as a side effect it will cause 'prog.c' and 'foo.c' to be compiled as 'prog-prog.$(OBJEXT)' and 'prog-foo.$(OBJEXT)', which solves the issue. 8.4 Program and Library Variables ================================= Associated with each program is a collection of variables that can be used to modify how that program is built. There is a similar list of such variables for each library. The canonical name of the program (or library) is used as a base for naming these variables. In the list below, we use the name "maude" to refer to the program or library. In your 'Makefile.am' you would replace this with the canonical name of your program. This list also refers to "maude" as a program, but in general the same rules apply for both static and dynamic libraries; the documentation below notes situations where programs and libraries differ. 'maude_SOURCES' This variable, if it exists, lists all the source files that are compiled to build the program. These files are added to the distribution by default. When building the program, Automake will cause each source file to be compiled to a single '.o' file (or '.lo' when using libtool). Normally these object files are named after the source file, but other factors can change this. If a file in the '_SOURCES' variable has an unrecognized extension, Automake will do one of two things with it. If a suffix rule exists for turning files with the unrecognized extension into '.o' files, then 'automake' will treat this file as it will any other source file (*note Support for Other Languages::). Otherwise, the file will be ignored as though it were a header file. The prefixes 'dist_' and 'nodist_' can be used to control whether files listed in a '_SOURCES' variable are distributed. 'dist_' is redundant, as sources are distributed by default, but it can be specified for clarity if desired. It is possible to have both 'dist_' and 'nodist_' variants of a given '_SOURCES' variable at once; this lets you easily distribute some files and not others, for instance: nodist_maude_SOURCES = nodist.c dist_maude_SOURCES = dist-me.c By default the output file (on Unix systems, the '.o' file) will be put into the current build directory. However, if the option 'subdir-objects' is in effect in the current directory then the '.o' file will be put into the subdirectory named after the source file. For instance, with 'subdir-objects' enabled, 'sub/dir/file.c' will be compiled to 'sub/dir/file.o'. Some people prefer this mode of operation. You can specify 'subdir-objects' in 'AUTOMAKE_OPTIONS' (*note Options::). 'EXTRA_maude_SOURCES' Automake needs to know the list of files you intend to compile _statically_. For one thing, this is the only way Automake has of knowing what sort of language support a given 'Makefile.in' requires. (1) This means that, for example, you can't put a configure substitution like '@my_sources@' into a '_SOURCES' variable. If you intend to conditionally compile source files and use 'configure' to substitute the appropriate object names into, e.g., '_LDADD' (see below), then you should list the corresponding source files in the 'EXTRA_' variable. This variable also supports 'dist_' and 'nodist_' prefixes. For instance, 'nodist_EXTRA_maude_SOURCES' would list extra sources that may need to be built, but should not be distributed. 'maude_AR' A static library is created by default by invoking '$(AR) $(ARFLAGS)' followed by the name of the library and then the objects being put into the library. You can override this by setting the '_AR' variable. This is usually used with C++; some C++ compilers require a special invocation in order to instantiate all the templates that should go into a library. For instance, the SGI C++ compiler likes this variable set like so: libmaude_a_AR = $(CXX) -ar -o 'maude_LIBADD' Extra objects can be added to a _library_ using the '_LIBADD' variable. For instance, this should be used for objects determined by 'configure' (*note A Library::). In the case of libtool libraries, 'maude_LIBADD' can also refer to other libtool libraries. 'maude_LDADD' Extra objects ('*.$(OBJEXT)') and libraries ('*.a', '*.la') can be added to a _program_ by listing them in the '_LDADD' variable. For instance, this should be used for objects determined by 'configure' (*note Linking::). '_LDADD' and '_LIBADD' are inappropriate for passing program-specific linker flags (except for '-l', '-L', '-dlopen' and '-dlpreopen'). Use the '_LDFLAGS' variable for this purpose. For instance, if your 'configure.ac' uses 'AC_PATH_XTRA', you could link your program against the X libraries like so: maude_LDADD = $(X_PRE_LIBS) $(X_LIBS) $(X_EXTRA_LIBS) We recommend that you use '-l' and '-L' only when referring to third-party libraries, and give the explicit file names of any library built by your package. Doing so will ensure that 'maude_DEPENDENCIES' (see below) is correctly defined by default. 'maude_LDFLAGS' This variable is used to pass extra flags to the link step of a program or a shared library. It overrides the 'AM_LDFLAGS' variable. 'maude_LIBTOOLFLAGS' This variable is used to pass extra options to 'libtool'. It overrides the 'AM_LIBTOOLFLAGS' variable. These options are output before 'libtool''s '--mode=MODE' option, so they should not be mode-specific options (those belong to the compiler or linker flags). *Note Libtool Flags::. 'maude_DEPENDENCIES' 'EXTRA_maude_DEPENDENCIES' It is also occasionally useful to have a target (program or library) depend on some other file that is not actually part of that target. This can be done using the '_DEPENDENCIES' variable. Each target depends on the contents of such a variable, but no further interpretation is done. Since these dependencies are associated to the link rule used to create the programs they should normally list files used by the link command. That is '*.$(OBJEXT)', '*.a', or '*.la' files for programs; '*.lo' and '*.la' files for Libtool libraries; and '*.$(OBJEXT)' files for static libraries. In rare cases you may need to add other kinds of files such as linker scripts, but _listing a source file in '_DEPENDENCIES' is wrong_. If some source file needs to be built before all the components of a program are built, consider using the 'BUILT_SOURCES' variable (*note Sources::). If '_DEPENDENCIES' is not supplied, it is computed by Automake. The automatically-assigned value is the contents of '_LDADD' or '_LIBADD', with most configure substitutions, '-l', '-L', '-dlopen' and '-dlpreopen' options removed. The configure substitutions that are left in are only '$(LIBOBJS)' and '$(ALLOCA)'; these are left because it is known that they will not cause an invalid value for '_DEPENDENCIES' to be generated. '_DEPENDENCIES' is more likely used to perform conditional compilation using an 'AC_SUBST' variable that contains a list of objects. *Note Conditional Sources::, and *note Conditional Libtool Sources::. The 'EXTRA_*_DEPENDENCIES' variable may be useful for cases where you merely want to augment the 'automake'-generated '_DEPENDENCIES' variable rather than replacing it. 'maude_LINK' You can override the linker on a per-program basis. By default the linker is chosen according to the languages used by the program. For instance, a program that includes C++ source code would use the C++ compiler to link. The '_LINK' variable must hold the name of a command that can be passed all the '.o' file names and libraries to link against as arguments. Note that the name of the underlying program is _not_ passed to '_LINK'; typically one uses '$@': maude_LINK = $(CCLD) -magic -o $@ If a '_LINK' variable is not supplied, it may still be generated and used by Automake due to the use of per-target link flags such as '_CFLAGS', '_LDFLAGS' or '_LIBTOOLFLAGS', in cases where they apply. 'maude_CCASFLAGS' 'maude_CFLAGS' 'maude_CPPFLAGS' 'maude_CXXFLAGS' 'maude_FFLAGS' 'maude_GCJFLAGS' 'maude_LFLAGS' 'maude_OBJCFLAGS' 'maude_RFLAGS' 'maude_UPCFLAGS' 'maude_YFLAGS' Automake allows you to set compilation flags on a per-program (or per-library) basis. A single source file can be included in several programs, and it will potentially be compiled with different flags for each program. This works for any language directly supported by Automake. These "per-target compilation flags" are '_CCASFLAGS', '_CFLAGS', '_CPPFLAGS', '_CXXFLAGS', '_FFLAGS', '_GCJFLAGS', '_LFLAGS', '_OBJCFLAGS', '_RFLAGS', '_UPCFLAGS', and '_YFLAGS'. When using a per-target compilation flag, Automake will choose a different name for the intermediate object files. Ordinarily a file like 'sample.c' will be compiled to produce 'sample.o'. However, if the program's '_CFLAGS' variable is set, then the object file will be named, for instance, 'maude-sample.o'. (See also *note Renamed Objects::.) The use of per-target compilation flags with C sources requires that the macro 'AM_PROG_CC_C_O' be called from 'configure.ac'. In compilations with per-target flags, the ordinary 'AM_' form of the flags variable is _not_ automatically included in the compilation (however, the user form of the variable _is_ included). So for instance, if you want the hypothetical 'maude' compilations to also use the value of 'AM_CFLAGS', you would need to write: maude_CFLAGS = ... your flags ... $(AM_CFLAGS) *Note Flag Variables Ordering::, for more discussion about the interaction between user variables, 'AM_' shadow variables, and per-target variables. 'maude_SHORTNAME' On some platforms the allowable file names are very short. In order to support these systems and per-target compilation flags at the same time, Automake allows you to set a "short name" that will influence how intermediate object files are named. For instance, in the following example, bin_PROGRAMS = maude maude_CPPFLAGS = -DSOMEFLAG maude_SHORTNAME = m maude_SOURCES = sample.c ... the object file would be named 'm-sample.o' rather than 'maude-sample.o'. This facility is rarely needed in practice, and we recommend avoiding it until you find it is required. ---------- Footnotes ---------- (1) There are other, more obscure reasons for this limitation as well. 8.5 Default '_SOURCES' ====================== '_SOURCES' variables are used to specify source files of programs (*note A Program::), libraries (*note A Library::), and Libtool libraries (*note A Shared Library::). When no such variable is specified for a target, Automake will define one itself. The default is to compile a single C file whose base name is the name of the target itself, with any extension replaced by 'AM_DEFAULT_SOURCE_EXT', which defaults to '.c'. For example if you have the following somewhere in your 'Makefile.am' with no corresponding 'libfoo_a_SOURCES': lib_LIBRARIES = libfoo.a sub/libc++.a 'libfoo.a' will be built using a default source file named 'libfoo.c', and 'sub/libc++.a' will be built from 'sub/libc++.c'. (In older versions 'sub/libc++.a' would be built from 'sub_libc___a.c', i.e., the default source was the canonized name of the target, with '.c' appended. We believe the new behavior is more sensible, but for backward compatibility 'automake' will use the old name if a file or a rule with that name exists and 'AM_DEFAULT_SOURCE_EXT' is not used.) Default sources are mainly useful in test suites, when building many test programs each from a single source. For instance, in check_PROGRAMS = test1 test2 test3 AM_DEFAULT_SOURCE_EXT = .cpp 'test1', 'test2', and 'test3' will be built from 'test1.cpp', 'test2.cpp', and 'test3.cpp'. Without the last line, they will be built from 'test1.c', 'test2.c', and 'test3.c'. Another case where this is convenient is building many Libtool modules ('moduleN.la'), each defined in its own file ('moduleN.c'). AM_LDFLAGS = -module lib_LTLIBRARIES = module1.la module2.la module3.la Finally, there is one situation where this default source computation needs to be avoided: when a target should not be built from sources. We already saw such an example in *note true::; this happens when all the constituents of a target have already been compiled and just need to be combined using a '_LDADD' variable. Then it is necessary to define an empty '_SOURCES' variable, so that 'automake' does not compute a default. bin_PROGRAMS = target target_SOURCES = target_LDADD = libmain.a libmisc.a 8.6 Special handling for 'LIBOBJS' and 'ALLOCA' =============================================== The '$(LIBOBJS)' and '$(ALLOCA)' variables list object files that should be compiled into the project to provide an implementation for functions that are missing or broken on the host system. They are substituted by 'configure'. These variables are defined by Autoconf macros such as 'AC_LIBOBJ', 'AC_REPLACE_FUNCS' (*note Generic Function Checks: (autoconf)Generic Functions.), or 'AC_FUNC_ALLOCA' (*note Particular Function Checks: (autoconf)Particular Functions.). Many other Autoconf macros call 'AC_LIBOBJ' or 'AC_REPLACE_FUNCS' to populate '$(LIBOBJS)'. Using these variables is very similar to doing conditional compilation using 'AC_SUBST' variables, as described in *note Conditional Sources::. That is, when building a program, '$(LIBOBJS)' and '$(ALLOCA)' should be added to the associated '*_LDADD' variable, or to the '*_LIBADD' variable when building a library. However there is no need to list the corresponding sources in 'EXTRA_*_SOURCES' nor to define '*_DEPENDENCIES'. Automake automatically adds '$(LIBOBJS)' and '$(ALLOCA)' to the dependencies, and it will discover the list of corresponding source files automatically (by tracing the invocations of the 'AC_LIBSOURCE' Autoconf macros). If you have already defined '*_DEPENDENCIES' explicitly for an unrelated reason, then you either need to add these variables manually, or use 'EXTRA_*_DEPENDENCIES' instead of '*_DEPENDENCIES'. These variables are usually used to build a portability library that is linked with all the programs of the project. We now review a sample setup. First, 'configure.ac' contains some checks that affect either 'LIBOBJS' or 'ALLOCA'. # configure.ac ... AC_CONFIG_LIBOBJ_DIR([lib]) ... AC_FUNC_MALLOC dnl May add malloc.$(OBJEXT) to LIBOBJS AC_FUNC_MEMCMP dnl May add memcmp.$(OBJEXT) to LIBOBJS AC_REPLACE_FUNCS([strdup]) dnl May add strdup.$(OBJEXT) to LIBOBJS AC_FUNC_ALLOCA dnl May add alloca.$(OBJEXT) to ALLOCA ... AC_CONFIG_FILES([ lib/Makefile src/Makefile ]) AC_OUTPUT The 'AC_CONFIG_LIBOBJ_DIR' tells Autoconf that the source files of these object files are to be found in the 'lib/' directory. Automake can also use this information, otherwise it expects the source files are to be in the directory where the '$(LIBOBJS)' and '$(ALLOCA)' variables are used. The 'lib/' directory should therefore contain 'malloc.c', 'memcmp.c', 'strdup.c', 'alloca.c'. Here is its 'Makefile.am': # lib/Makefile.am noinst_LIBRARIES = libcompat.a libcompat_a_SOURCES = libcompat_a_LIBADD = $(LIBOBJS) $(ALLOCA) The library can have any name, of course, and anyway it is not going to be installed: it just holds the replacement versions of the missing or broken functions so we can later link them in. Many projects also include extra functions, specific to the project, in that library: they are simply added on the '_SOURCES' line. There is a small trap here, though: '$(LIBOBJS)' and '$(ALLOCA)' might be empty, and building an empty library is not portable. You should ensure that there is always something to put in 'libcompat.a'. Most projects will also add some utility functions in that directory, and list them in 'libcompat_a_SOURCES', so in practice 'libcompat.a' cannot be empty. Finally here is how this library could be used from the 'src/' directory. # src/Makefile.am # Link all programs in this directory with libcompat.a LDADD = ../lib/libcompat.a bin_PROGRAMS = tool1 tool2 ... tool1_SOURCES = ... tool2_SOURCES = ... When option 'subdir-objects' is not used, as in the above example, the variables '$(LIBOBJS)' or '$(ALLOCA)' can only be used in the directory where their sources lie. E.g., here it would be wrong to use '$(LIBOBJS)' or '$(ALLOCA)' in 'src/Makefile.am'. However if both 'subdir-objects' and 'AC_CONFIG_LIBOBJ_DIR' are used, it is OK to use these variables in other directories. For instance 'src/Makefile.am' could be changed as follows. # src/Makefile.am AUTOMAKE_OPTIONS = subdir-objects LDADD = $(LIBOBJS) $(ALLOCA) bin_PROGRAMS = tool1 tool2 ... tool1_SOURCES = ... tool2_SOURCES = ... Because '$(LIBOBJS)' and '$(ALLOCA)' contain object file names that end with '.$(OBJEXT)', they are not suitable for Libtool libraries (where the expected object extension is '.lo'): 'LTLIBOBJS' and 'LTALLOCA' should be used instead. 'LTLIBOBJS' is defined automatically by Autoconf and should not be defined by hand (as in the past), however at the time of writing 'LTALLOCA' still needs to be defined from 'ALLOCA' manually. *Note 'AC_LIBOBJ' vs. 'LIBOBJS': (autoconf)AC_LIBOBJ vs LIBOBJS. 8.7 Variables used when building a program ========================================== Occasionally it is useful to know which 'Makefile' variables Automake uses for compilations, and in which order (*note Flag Variables Ordering::); for instance, you might need to do your own compilation in some special cases. Some variables are inherited from Autoconf; these are 'CC', 'CFLAGS', 'CPPFLAGS', 'DEFS', 'LDFLAGS', and 'LIBS'. There are some additional variables that Automake defines on its own: 'AM_CPPFLAGS' The contents of this variable are passed to every compilation that invokes the C preprocessor; it is a list of arguments to the preprocessor. For instance, '-I' and '-D' options should be listed here. Automake already provides some '-I' options automatically, in a separate variable that is also passed to every compilation that invokes the C preprocessor. In particular it generates '-I.', '-I$(srcdir)', and a '-I' pointing to the directory holding 'config.h' (if you've used 'AC_CONFIG_HEADERS' or 'AM_CONFIG_HEADER'). You can disable the default '-I' options using the 'nostdinc' option. When a file to be included is generated during the build and not part of a distribution tarball, its location is under '$(builddir)', not under '$(srcdir)'. This matters especially for packages that use header files placed in sub-directories and want to allow builds outside the source tree (*note VPATH Builds::). In that case we recommend to use a pair of '-I' options, such as, e.g., '-Isome/subdir -I$(srcdir)/some/subdir' or '-I$(top_builddir)/some/subdir -I$(top_srcdir)/some/subdir'. Note that the reference to the build tree should come before the reference to the source tree, so that accidentally leftover generated files in the source directory are ignored. 'AM_CPPFLAGS' is ignored in preference to a per-executable (or per-library) '_CPPFLAGS' variable if it is defined. 'INCLUDES' This does the same job as 'AM_CPPFLAGS' (or any per-target '_CPPFLAGS' variable if it is used). It is an older name for the same functionality. This variable is deprecated; we suggest using 'AM_CPPFLAGS' and per-target '_CPPFLAGS' instead. 'AM_CFLAGS' This is the variable the 'Makefile.am' author can use to pass in additional C compiler flags. It is more fully documented elsewhere. In some situations, this is not used, in preference to the per-executable (or per-library) '_CFLAGS'. 'COMPILE' This is the command used to actually compile a C source file. The file name is appended to form the complete command line. 'AM_LDFLAGS' This is the variable the 'Makefile.am' author can use to pass in additional linker flags. In some situations, this is not used, in preference to the per-executable (or per-library) '_LDFLAGS'. 'LINK' This is the command used to actually link a C program. It already includes '-o $@' and the usual variable references (for instance, 'CFLAGS'); it takes as "arguments" the names of the object files and libraries to link in. This variable is not used when the linker is overridden with a per-target '_LINK' variable or per-target flags cause Automake to define such a '_LINK' variable. 8.8 Yacc and Lex support ======================== Automake has somewhat idiosyncratic support for Yacc and Lex. Automake assumes that the '.c' file generated by 'yacc' (or 'lex') should be named using the basename of the input file. That is, for a yacc source file 'foo.y', Automake will cause the intermediate file to be named 'foo.c' (as opposed to 'y.tab.c', which is more traditional). The extension of a yacc source file is used to determine the extension of the resulting C or C++ file. Files with the extension '.y' will be turned into '.c' files; likewise, '.yy' will become '.cc'; '.y++', 'c++'; '.yxx', '.cxx'; and '.ypp', '.cpp'. Likewise, lex source files can be used to generate C or C++; the extensions '.l', '.ll', '.l++', '.lxx', and '.lpp' are recognized. You should never explicitly mention the intermediate (C or C++) file in any 'SOURCES' variable; only list the source file. The intermediate files generated by 'yacc' (or 'lex') will be included in any distribution that is made. That way the user doesn't need to have 'yacc' or 'lex'. If a 'yacc' source file is seen, then your 'configure.ac' must define the variable 'YACC'. This is most easily done by invoking the macro 'AC_PROG_YACC' (*note Particular Program Checks: (autoconf)Particular Programs.). When 'yacc' is invoked, it is passed 'AM_YFLAGS' and 'YFLAGS'. The latter is a user variable and the former is intended for the 'Makefile.am' author. 'AM_YFLAGS' is usually used to pass the '-d' option to 'yacc'. Automake knows what this means and will automatically adjust its rules to update and distribute the header file built by 'yacc -d'(1). What Automake cannot guess, though, is where this header will be used: it is up to you to ensure the header gets built before it is first used. Typically this is necessary in order for dependency tracking to work when the header is included by another file. The common solution is listing the header file in 'BUILT_SOURCES' (*note Sources::) as follows. BUILT_SOURCES = parser.h AM_YFLAGS = -d bin_PROGRAMS = foo foo_SOURCES = ... parser.y ... If a 'lex' source file is seen, then your 'configure.ac' must define the variable 'LEX'. You can use 'AC_PROG_LEX' to do this (*note Particular Program Checks: (autoconf)Particular Programs.), but using 'AM_PROG_LEX' macro (*note Macros::) is recommended. When 'lex' is invoked, it is passed 'AM_LFLAGS' and 'LFLAGS'. The latter is a user variable and the former is intended for the 'Makefile.am' author. When 'AM_MAINTAINER_MODE' (*note maintainer-mode::) is used, the rebuild rule for distributed Yacc and Lex sources are only used when 'maintainer-mode' is enabled, or when the files have been erased. When 'lex' or 'yacc' sources are used, 'automake -i' automatically installs an auxiliary program called 'ylwrap' in your package (*note Auxiliary Programs::). This program is used by the build rules to rename the output of these tools, and makes it possible to include multiple 'yacc' (or 'lex') source files in a single directory. (This is necessary because yacc's output file name is fixed, and a parallel make could conceivably invoke more than one instance of 'yacc' simultaneously.) For 'yacc', simply managing locking is insufficient. The output of 'yacc' always uses the same symbol names internally, so it isn't possible to link two 'yacc' parsers into the same executable. We recommend using the following renaming hack used in 'gdb': #define yymaxdepth c_maxdepth #define yyparse c_parse #define yylex c_lex #define yyerror c_error #define yylval c_lval #define yychar c_char #define yydebug c_debug #define yypact c_pact #define yyr1 c_r1 #define yyr2 c_r2 #define yydef c_def #define yychk c_chk #define yypgo c_pgo #define yyact c_act #define yyexca c_exca #define yyerrflag c_errflag #define yynerrs c_nerrs #define yyps c_ps #define yypv c_pv #define yys c_s #define yy_yys c_yys #define yystate c_state #define yytmp c_tmp #define yyv c_v #define yy_yyv c_yyv #define yyval c_val #define yylloc c_lloc #define yyreds c_reds #define yytoks c_toks #define yylhs c_yylhs #define yylen c_yylen #define yydefred c_yydefred #define yydgoto c_yydgoto #define yysindex c_yysindex #define yyrindex c_yyrindex #define yygindex c_yygindex #define yytable c_yytable #define yycheck c_yycheck #define yyname c_yyname #define yyrule c_yyrule For each define, replace the 'c_' prefix with whatever you like. These defines work for 'bison', 'byacc', and traditional 'yacc's. If you find a parser generator that uses a symbol not covered here, please report the new name so it can be added to the list. ---------- Footnotes ---------- (1) Please note that 'automake' recognizes '-d' in 'AM_YFLAGS' only if it is not clustered with other options; for example, it won't be recognized if 'AM_YFLAGS' is '-dt', but it will be if 'AM_YFLAGS' is '-d -t' or '-d -t' 8.9 C++ Support =============== Automake includes full support for C++. Any package including C++ code must define the output variable 'CXX' in 'configure.ac'; the simplest way to do this is to use the 'AC_PROG_CXX' macro (*note Particular Program Checks: (autoconf)Particular Programs.). A few additional variables are defined when a C++ source file is seen: 'CXX' The name of the C++ compiler. 'CXXFLAGS' Any flags to pass to the C++ compiler. 'AM_CXXFLAGS' The maintainer's variant of 'CXXFLAGS'. 'CXXCOMPILE' The command used to actually compile a C++ source file. The file name is appended to form the complete command line. 'CXXLINK' The command used to actually link a C++ program. 8.10 Objective C Support ======================== Automake includes some support for Objective C. Any package including Objective C code must define the output variable 'OBJC' in 'configure.ac'; the simplest way to do this is to use the 'AC_PROG_OBJC' macro (*note Particular Program Checks: (autoconf)Particular Programs.). A few additional variables are defined when an Objective C source file is seen: 'OBJC' The name of the Objective C compiler. 'OBJCFLAGS' Any flags to pass to the Objective C compiler. 'AM_OBJCFLAGS' The maintainer's variant of 'OBJCFLAGS'. 'OBJCCOMPILE' The command used to actually compile an Objective C source file. The file name is appended to form the complete command line. 'OBJCLINK' The command used to actually link an Objective C program. 8.11 Unified Parallel C Support =============================== Automake includes some support for Unified Parallel C. Any package including Unified Parallel C code must define the output variable 'UPC' in 'configure.ac'; the simplest way to do this is to use the 'AM_PROG_UPC' macro (*note Public Macros::). A few additional variables are defined when a Unified Parallel C source file is seen: 'UPC' The name of the Unified Parallel C compiler. 'UPCFLAGS' Any flags to pass to the Unified Parallel C compiler. 'AM_UPCFLAGS' The maintainer's variant of 'UPCFLAGS'. 'UPCCOMPILE' The command used to actually compile a Unified Parallel C source file. The file name is appended to form the complete command line. 'UPCLINK' The command used to actually link a Unified Parallel C program. 8.12 Assembly Support ===================== Automake includes some support for assembly code. There are two forms of assembler files: normal ('*.s') and preprocessed by 'CPP' ('*.S' or '*.sx'). The variable 'CCAS' holds the name of the compiler used to build assembly code. This compiler must work a bit like a C compiler; in particular it must accept '-c' and '-o'. The values of 'CCASFLAGS' and 'AM_CCASFLAGS' (or its per-target definition) is passed to the compilation. For preprocessed files, 'DEFS', 'DEFAULT_INCLUDES', 'INCLUDES', 'CPPFLAGS' and 'AM_CPPFLAGS' are also used. The autoconf macro 'AM_PROG_AS' will define 'CCAS' and 'CCASFLAGS' for you (unless they are already set, it simply sets 'CCAS' to the C compiler and 'CCASFLAGS' to the C compiler flags), but you are free to define these variables by other means. Only the suffixes '.s', '.S', and '.sx' are recognized by 'automake' as being files containing assembly code. 8.13 Fortran 77 Support ======================= Automake includes full support for Fortran 77. Any package including Fortran 77 code must define the output variable 'F77' in 'configure.ac'; the simplest way to do this is to use the 'AC_PROG_F77' macro (*note Particular Program Checks: (autoconf)Particular Programs.). A few additional variables are defined when a Fortran 77 source file is seen: 'F77' The name of the Fortran 77 compiler. 'FFLAGS' Any flags to pass to the Fortran 77 compiler. 'AM_FFLAGS' The maintainer's variant of 'FFLAGS'. 'RFLAGS' Any flags to pass to the Ratfor compiler. 'AM_RFLAGS' The maintainer's variant of 'RFLAGS'. 'F77COMPILE' The command used to actually compile a Fortran 77 source file. The file name is appended to form the complete command line. 'FLINK' The command used to actually link a pure Fortran 77 program or shared library. Automake can handle preprocessing Fortran 77 and Ratfor source files in addition to compiling them(1). Automake also contains some support for creating programs and shared libraries that are a mixture of Fortran 77 and other languages (*note Mixing Fortran 77 With C and C++::). These issues are covered in the following sections. ---------- Footnotes ---------- (1) Much, if not most, of the information in the following sections pertaining to preprocessing Fortran 77 programs was taken almost verbatim from *note Catalogue of Rules: (make)Catalogue of Rules. 8.13.1 Preprocessing Fortran 77 ------------------------------- 'N.f' is made automatically from 'N.F' or 'N.r'. This rule runs just the preprocessor to convert a preprocessable Fortran 77 or Ratfor source file into a strict Fortran 77 source file. The precise command used is as follows: '.F' '$(F77) -F $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_FFLAGS) $(FFLAGS)' '.r' '$(F77) -F $(AM_FFLAGS) $(FFLAGS) $(AM_RFLAGS) $(RFLAGS)' 8.13.2 Compiling Fortran 77 Files --------------------------------- 'N.o' is made automatically from 'N.f', 'N.F' or 'N.r' by running the Fortran 77 compiler. The precise command used is as follows: '.f' '$(F77) -c $(AM_FFLAGS) $(FFLAGS)' '.F' '$(F77) -c $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_FFLAGS) $(FFLAGS)' '.r' '$(F77) -c $(AM_FFLAGS) $(FFLAGS) $(AM_RFLAGS) $(RFLAGS)' 8.13.3 Mixing Fortran 77 With C and C++ --------------------------------------- Automake currently provides _limited_ support for creating programs and shared libraries that are a mixture of Fortran 77 and C and/or C++. However, there are many other issues related to mixing Fortran 77 with other languages that are _not_ (currently) handled by Automake, but that are handled by other packages(1). Automake can help in two ways: 1. Automatic selection of the linker depending on which combinations of source code. 2. Automatic selection of the appropriate linker flags (e.g., '-L' and '-l') to pass to the automatically selected linker in order to link in the appropriate Fortran 77 intrinsic and run-time libraries. These extra Fortran 77 linker flags are supplied in the output variable 'FLIBS' by the 'AC_F77_LIBRARY_LDFLAGS' Autoconf macro supplied with newer versions of Autoconf (Autoconf version 2.13 and later). *Note Fortran Compiler Characteristics: (autoconf)Fortran Compiler. If Automake detects that a program or shared library (as mentioned in some '_PROGRAMS' or '_LTLIBRARIES' primary) contains source code that is a mixture of Fortran 77 and C and/or C++, then it requires that the macro 'AC_F77_LIBRARY_LDFLAGS' be called in 'configure.ac', and that either '$(FLIBS)' appear in the appropriate '_LDADD' (for programs) or '_LIBADD' (for shared libraries) variables. It is the responsibility of the person writing the 'Makefile.am' to make sure that '$(FLIBS)' appears in the appropriate '_LDADD' or '_LIBADD' variable. For example, consider the following 'Makefile.am': bin_PROGRAMS = foo foo_SOURCES = main.cc foo.f foo_LDADD = libfoo.la $(FLIBS) pkglib_LTLIBRARIES = libfoo.la libfoo_la_SOURCES = bar.f baz.c zardoz.cc libfoo_la_LIBADD = $(FLIBS) In this case, Automake will insist that 'AC_F77_LIBRARY_LDFLAGS' is mentioned in 'configure.ac'. Also, if '$(FLIBS)' hadn't been mentioned in 'foo_LDADD' and 'libfoo_la_LIBADD', then Automake would have issued a warning. ---------- Footnotes ---------- (1) For example, the cfortran package (http://www-zeus.desy.de/~burow/cfortran/) addresses all of these inter-language issues, and runs under nearly all Fortran 77, C and C++ compilers on nearly all platforms. However, 'cfortran' is not yet Free Software, but it will be in the next major release. 8.13.3.1 How the Linker is Chosen ................................. When a program or library mixes several languages, Automake choose the linker according to the following priorities. (The names in parentheses are the variables containing the link command.) 1. Native Java ('GCJLINK') 2. C++ ('CXXLINK') 3. Fortran 77 ('F77LINK') 4. Fortran ('FCLINK') 5. Objective C ('OBJCLINK') 6. Unified Parallel C ('UPCLINK') 7. C ('LINK') For example, if Fortran 77, C and C++ source code is compiled into a program, then the C++ linker will be used. In this case, if the C or Fortran 77 linkers required any special libraries that weren't included by the C++ linker, then they must be manually added to an '_LDADD' or '_LIBADD' variable by the user writing the 'Makefile.am'. Automake only looks at the file names listed in '_SOURCES' variables to choose the linker, and defaults to the C linker. Sometimes this is inconvenient because you are linking against a library written in another language and would like to set the linker more appropriately. *Note Libtool Convenience Libraries::, for a trick with 'nodist_EXTRA_..._SOURCES'. A per-target '_LINK' variable will override the above selection. Per-target link flags will cause Automake to write a per-target '_LINK' variable according to the language chosen as above. 8.14 Fortran 9x Support ======================= Automake includes support for Fortran 9x. Any package including Fortran 9x code must define the output variable 'FC' in 'configure.ac'; the simplest way to do this is to use the 'AC_PROG_FC' macro (*note Particular Program Checks: (autoconf)Particular Programs.). A few additional variables are defined when a Fortran 9x source file is seen: 'FC' The name of the Fortran 9x compiler. 'FCFLAGS' Any flags to pass to the Fortran 9x compiler. 'AM_FCFLAGS' The maintainer's variant of 'FCFLAGS'. 'FCCOMPILE' The command used to actually compile a Fortran 9x source file. The file name is appended to form the complete command line. 'FCLINK' The command used to actually link a pure Fortran 9x program or shared library. 8.14.1 Compiling Fortran 9x Files --------------------------------- 'FILE.o' is made automatically from 'FILE.f90', 'FILE.f95', 'FILE.f03', or 'FILE.f08' by running the Fortran 9x compiler. The precise command used is as follows: '.f90' '$(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f90) $<' '.f95' '$(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f95) $<' '.f03' '$(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f03) $<' '.f08' '$(FC) $(AM_FCFLAGS) $(FCFLAGS) -c $(FCFLAGS_f08) $<' 8.15 Compiling Java sources using gcj ===================================== Automake includes support for natively compiled Java, using 'gcj', the Java front end to the GNU Compiler Collection (rudimentary support for compiling Java to bytecode using the 'javac' compiler is also present, _albeit deprecated_; *note Java::). Any package including Java code to be compiled must define the output variable 'GCJ' in 'configure.ac'; the variable 'GCJFLAGS' must also be defined somehow (either in 'configure.ac' or 'Makefile.am'). The simplest way to do this is to use the 'AM_PROG_GCJ' macro. By default, programs including Java source files are linked with 'gcj'. As always, the contents of 'AM_GCJFLAGS' are passed to every compilation invoking 'gcj' (in its role as an ahead-of-time compiler, when invoking it to create '.class' files, 'AM_JAVACFLAGS' is used instead). If it is necessary to pass options to 'gcj' from 'Makefile.am', this variable, and not the user variable 'GCJFLAGS', should be used. 'gcj' can be used to compile '.java', '.class', '.zip', or '.jar' files. When linking, 'gcj' requires that the main class be specified using the '--main=' option. The easiest way to do this is to use the '_LDFLAGS' variable for the program. 8.16 Vala Support ================= Automake provides initial support for Vala (). This requires valac version 0.7.0 or later, and currently requires the user to use GNU 'make'. foo_SOURCES = foo.vala bar.vala zardoc.c Any '.vala' file listed in a '_SOURCES' variable will be compiled into C code by the Vala compiler. The generated '.c' files are distributed. The end user does not need to have a Vala compiler installed. Automake ships with an Autoconf macro called 'AM_PROG_VALAC' that will locate the Vala compiler and optionally check its version number. -- Macro: AM_PROG_VALAC ([MINIMUM-VERSION]) Try to find a Vala compiler in 'PATH'. If it is found, the variable 'VALAC' is set. Optionally a minimum release number of the compiler can be requested: AM_PROG_VALAC([0.7.0]) There are a few variables that are used when compiling Vala sources: 'VALAC' Path to the Vala compiler. 'VALAFLAGS' Additional arguments for the Vala compiler. 'AM_VALAFLAGS' The maintainer's variant of 'VALAFLAGS'. lib_LTLIBRARIES = libfoo.la libfoo_la_SOURCES = foo.vala Note that currently, you cannot use per-target '*_VALAFLAGS' (*note Renamed Objects::) to produce different C files from one Vala source file. 8.17 Support for Other Languages ================================ Automake currently only includes full support for C, C++ (*note C++ Support::), Objective C (*note Objective C Support::), Fortran 77 (*note Fortran 77 Support::), Fortran 9x (*note Fortran 9x Support::), and Java (*note Java Support with gcj::). There is only rudimentary support for other languages, support for which will be improved based on user demand. Some limited support for adding your own languages is available via the suffix rule handling (*note Suffixes::). 8.18 Automatic de-ANSI-fication (deprecated, soon to be removed) ================================================================ _The features described in this section are deprecated; you must not use any of them in new code, and remove their use from older but still maintained code: they will be withdrawn in the next major Automake release._ When the C language was standardized in 1989, there was a long transition period where package developers needed to worry about porting to older systems that did not support ANSI C by default. These older systems are no longer in practical use and are no longer supported by their original suppliers, so developers need not worry about this problem any more. Automake allows you to write packages that are portable to K&R C by "de-ANSI-fying" each source file before the actual compilation takes place. If the 'Makefile.am' variable 'AUTOMAKE_OPTIONS' (*note Options::) contains the option 'ansi2knr' then code to handle de-ANSI-fication is inserted into the generated 'Makefile.in'. This causes each C source file in the directory to be treated as ANSI C. If an ANSI C compiler is available, it is used. If no ANSI C compiler is available, the 'ansi2knr' program is used to convert the source files into K&R C, which is then compiled. The 'ansi2knr' program is simple-minded. It assumes the source code will be formatted in a particular way; see the 'ansi2knr' man page for details. Support for the obsolete de-ANSI-fication feature requires the source files 'ansi2knr.c' and 'ansi2knr.1' to be in the same package as the ANSI C source; these files are distributed with Automake. Also, the package 'configure.ac' must call the macro 'AM_C_PROTOTYPES' (*note Macros::). Automake also handles finding the 'ansi2knr' support files in some other directory in the current package. This is done by prepending the relative path to the appropriate directory to the 'ansi2knr' option. For instance, suppose the package has ANSI C code in the 'src' and 'lib' subdirectories. The files 'ansi2knr.c' and 'ansi2knr.1' appear in 'lib'. Then this could appear in 'src/Makefile.am': AUTOMAKE_OPTIONS = ../lib/ansi2knr If no directory prefix is given, the files are assumed to be in the current directory. Note that automatic de-ANSI-fication will not work when the package is being built for a different host architecture. That is because 'automake' currently has no way to build 'ansi2knr' for the build machine. Using 'LIBOBJS' with source de-ANSI-fication used to require hand-crafted code in 'configure' to append '$U' to basenames in 'LIBOBJS'. This is no longer true today. Starting with version 2.54, Autoconf takes care of rewriting 'LIBOBJS' and 'LTLIBOBJS'. (*note 'AC_LIBOBJ' vs. 'LIBOBJS': (autoconf)AC_LIBOBJ vs LIBOBJS.) 8.19 Automatic dependency tracking ================================== As a developer it is often painful to continually update the 'Makefile.am' whenever the include-file dependencies change in a project. Automake supplies a way to automatically track dependency changes (*note Dependency Tracking::). Automake always uses complete dependencies for a compilation, including system headers. Automake's model is that dependency computation should be a side effect of the build. To this end, dependencies are computed by running all compilations through a special wrapper program called 'depcomp'. 'depcomp' understands how to coax many different C and C++ compilers into generating dependency information in the format it requires. 'automake -a' will install 'depcomp' into your source tree for you. If 'depcomp' can't figure out how to properly invoke your compiler, dependency tracking will simply be disabled for your build. Experience with earlier versions of Automake (*note Dependency Tracking Evolution::) taught us that it is not reliable to generate dependencies only on the maintainer's system, as configurations vary too much. So instead Automake implements dependency tracking at build time. Automatic dependency tracking can be suppressed by putting 'no-dependencies' in the variable 'AUTOMAKE_OPTIONS', or passing 'no-dependencies' as an argument to 'AM_INIT_AUTOMAKE' (this should be the preferred way). Or, you can invoke 'automake' with the '-i' option. Dependency tracking is enabled by default. The person building your package also can choose to disable dependency tracking by configuring with '--disable-dependency-tracking'. 8.20 Support for executable extensions ====================================== On some platforms, such as Windows, executables are expected to have an extension such as '.exe'. On these platforms, some compilers (GCC among them) will automatically generate 'foo.exe' when asked to generate 'foo'. Automake provides mostly-transparent support for this. Unfortunately _mostly_ doesn't yet mean _fully_. Until the English dictionary is revised, you will have to assist Automake if your package must support those platforms. One thing you must be aware of is that, internally, Automake rewrites something like this: bin_PROGRAMS = liver to this: bin_PROGRAMS = liver$(EXEEXT) The targets Automake generates are likewise given the '$(EXEEXT)' extension. The variables 'TESTS' and 'XFAIL_TESTS' (*note Simple Tests::) are also rewritten if they contain filenames that have been declared as programs in the same 'Makefile'. (This is mostly useful when some programs from 'check_PROGRAMS' are listed in 'TESTS'.) However, Automake cannot apply this rewriting to 'configure' substitutions. This means that if you are conditionally building a program using such a substitution, then your 'configure.ac' must take care to add '$(EXEEXT)' when constructing the output variable. With Autoconf 2.13 and earlier, you must explicitly use 'AC_EXEEXT' to get this support. With Autoconf 2.50, 'AC_EXEEXT' is run automatically if you configure a compiler (say, through 'AC_PROG_CC'). Sometimes maintainers like to write an explicit link rule for their program. Without executable extension support, this is easy--you simply write a rule whose target is the name of the program. However, when executable extension support is enabled, you must instead add the '$(EXEEXT)' suffix. Unfortunately, due to the change in Autoconf 2.50, this means you must always add this extension. However, this is a problem for maintainers who know their package will never run on a platform that has executable extensions. For those maintainers, the 'no-exeext' option (*note Options::) will disable this feature. This works in a fairly ugly way; if 'no-exeext' is seen, then the presence of a rule for a target named 'foo' in 'Makefile.am' will override an 'automake'-generated rule for 'foo$(EXEEXT)'. Without the 'no-exeext' option, this use will give a diagnostic. 9 Other Derived Objects *********************** Automake can handle derived objects that are not C programs. Sometimes the support for actually building such objects must be explicitly supplied, but Automake will still automatically handle installation and distribution. 9.1 Executable Scripts ====================== It is possible to define and install programs that are scripts. Such programs are listed using the 'SCRIPTS' primary name. When the script is distributed in its final, installable form, the 'Makefile' usually looks as follows: # Install my_script in $(bindir) and distribute it. dist_bin_SCRIPTS = my_script Scripts are not distributed by default; as we have just seen, those that should be distributed can be specified using a 'dist_' prefix as with other primaries. Scripts can be installed in 'bindir', 'sbindir', 'libexecdir', 'pkglibexecdir', or 'pkgdatadir'. Scripts that need not be installed can be listed in 'noinst_SCRIPTS', and among them, those which are needed only by 'make check' should go in 'check_SCRIPTS'. When a script needs to be built, the 'Makefile.am' should include the appropriate rules. For instance the 'automake' program itself is a Perl script that is generated from 'automake.in'. Here is how this is handled: bin_SCRIPTS = automake CLEANFILES = $(bin_SCRIPTS) EXTRA_DIST = automake.in do_subst = sed -e 's,[@]datadir[@],$(datadir),g' \ -e 's,[@]PERL[@],$(PERL),g' \ -e 's,[@]PACKAGE[@],$(PACKAGE),g' \ -e 's,[@]VERSION[@],$(VERSION),g' \ ... automake: automake.in Makefile $(do_subst) < $(srcdir)/automake.in > automake chmod +x automake Such scripts for which a build rule has been supplied need to be deleted explicitly using 'CLEANFILES' (*note Clean::), and their sources have to be distributed, usually with 'EXTRA_DIST' (*note Basics of Distribution::). Another common way to build scripts is to process them from 'configure' with 'AC_CONFIG_FILES'. In this situation Automake knows which files should be cleaned and distributed, and what the rebuild rules should look like. For instance if 'configure.ac' contains AC_CONFIG_FILES([src/my_script], [chmod +x src/my_script]) to build 'src/my_script' from 'src/my_script.in', then a 'src/Makefile.am' to install this script in '$(bindir)' can be as simple as bin_SCRIPTS = my_script CLEANFILES = $(bin_SCRIPTS) There is no need for 'EXTRA_DIST' or any build rule: Automake infers them from 'AC_CONFIG_FILES' (*note Requirements::). 'CLEANFILES' is still useful, because by default Automake will clean targets of 'AC_CONFIG_FILES' in 'distclean', not 'clean'. Although this looks simpler, building scripts this way has one drawback: directory variables such as '$(datadir)' are not fully expanded and may refer to other directory variables. 9.2 Header files ================ Header files that must be installed are specified by the 'HEADERS' family of variables. Headers can be installed in 'includedir', 'oldincludedir', 'pkgincludedir' or any other directory you may have defined (*note Uniform::). For instance, include_HEADERS = foo.h bar/bar.h will install the two files as '$(includedir)/foo.h' and '$(includedir)/bar.h'. The 'nobase_' prefix is also supported, nobase_include_HEADERS = foo.h bar/bar.h will install the two files as '$(includedir)/foo.h' and '$(includedir)/bar/bar.h' (*note Alternative::). Usually, only header files that accompany installed libraries need to be installed. Headers used by programs or convenience libraries are not installed. The 'noinst_HEADERS' variable can be used for such headers. However when the header actually belongs to a single convenience library or program, we recommend listing it in the program's or library's '_SOURCES' variable (*note Program Sources::) instead of in 'noinst_HEADERS'. This is clearer for the 'Makefile.am' reader. 'noinst_HEADERS' would be the right variable to use in a directory containing only headers and no associated library or program. All header files must be listed somewhere; in a '_SOURCES' variable or in a '_HEADERS' variable. Missing ones will not appear in the distribution. For header files that are built and must not be distributed, use the 'nodist_' prefix as in 'nodist_include_HEADERS' or 'nodist_prog_SOURCES'. If these generated headers are needed during the build, you must also ensure they exist before they are used (*note Sources::). 9.3 Architecture-independent data files ======================================= Automake supports the installation of miscellaneous data files using the 'DATA' family of variables. Such data can be installed in the directories 'datadir', 'sysconfdir', 'sharedstatedir', 'localstatedir', or 'pkgdatadir'. By default, data files are _not_ included in a distribution. Of course, you can use the 'dist_' prefix to change this on a per-variable basis. Here is how Automake declares its auxiliary data files: dist_pkgdata_DATA = clean-kr.am clean.am ... 9.4 Built Sources ================= Because Automake's automatic dependency tracking works as a side-effect of compilation (*note Dependencies::) there is a bootstrap issue: a target should not be compiled before its dependencies are made, but these dependencies are unknown until the target is first compiled. Ordinarily this is not a problem, because dependencies are distributed sources: they preexist and do not need to be built. Suppose that 'foo.c' includes 'foo.h'. When it first compiles 'foo.o', 'make' only knows that 'foo.o' depends on 'foo.c'. As a side-effect of this compilation 'depcomp' records the 'foo.h' dependency so that following invocations of 'make' will honor it. In these conditions, it's clear there is no problem: either 'foo.o' doesn't exist and has to be built (regardless of the dependencies), or accurate dependencies exist and they can be used to decide whether 'foo.o' should be rebuilt. It's a different story if 'foo.h' doesn't exist by the first 'make' run. For instance, there might be a rule to build 'foo.h'. This time 'file.o''s build will fail because the compiler can't find 'foo.h'. 'make' failed to trigger the rule to build 'foo.h' first by lack of dependency information. The 'BUILT_SOURCES' variable is a workaround for this problem. A source file listed in 'BUILT_SOURCES' is made on 'make all' or 'make check' (or even 'make install') before other targets are processed. However, such a source file is not _compiled_ unless explicitly requested by mentioning it in some other '_SOURCES' variable. So, to conclude our introductory example, we could use 'BUILT_SOURCES = foo.h' to ensure 'foo.h' gets built before any other target (including 'foo.o') during 'make all' or 'make check'. 'BUILT_SOURCES' is actually a bit of a misnomer, as any file which must be created early in the build process can be listed in this variable. Moreover, all built sources do not necessarily have to be listed in 'BUILT_SOURCES'. For instance, a generated '.c' file doesn't need to appear in 'BUILT_SOURCES' (unless it is included by another source), because it's a known dependency of the associated object. It might be important to emphasize that 'BUILT_SOURCES' is honored only by 'make all', 'make check' and 'make install'. This means you cannot build a specific target (e.g., 'make foo') in a clean tree if it depends on a built source. However it will succeed if you have run 'make all' earlier, because accurate dependencies are already available. The next section illustrates and discusses the handling of built sources on a toy example. 9.4.1 Built Sources Example --------------------------- Suppose that 'foo.c' includes 'bindir.h', which is installation-dependent and not distributed: it needs to be built. Here 'bindir.h' defines the preprocessor macro 'bindir' to the value of the 'make' variable 'bindir' (inherited from 'configure'). We suggest several implementations below. It's not meant to be an exhaustive listing of all ways to handle built sources, but it will give you a few ideas if you encounter this issue. First Try ......... This first implementation will illustrate the bootstrap issue mentioned in the previous section (*note Sources::). Here is a tentative 'Makefile.am'. # This won't work. bin_PROGRAMS = foo foo_SOURCES = foo.c nodist_foo_SOURCES = bindir.h CLEANFILES = bindir.h bindir.h: Makefile echo '#define bindir "$(bindir)"' >$@ This setup doesn't work, because Automake doesn't know that 'foo.c' includes 'bindir.h'. Remember, automatic dependency tracking works as a side-effect of compilation, so the dependencies of 'foo.o' will be known only after 'foo.o' has been compiled (*note Dependencies::). The symptom is as follows. % make source='foo.c' object='foo.o' libtool=no \ depfile='.deps/foo.Po' tmpdepfile='.deps/foo.TPo' \ depmode=gcc /bin/sh ./depcomp \ gcc -I. -I. -g -O2 -c `test -f 'foo.c' || echo './'`foo.c foo.c:2: bindir.h: No such file or directory make: *** [foo.o] Error 1 In this example 'bindir.h' is not distributed nor installed, and it is not even being built on-time. One may wonder if the 'nodist_foo_SOURCES = bindir.h' line has any use at all. This line simply states that 'bindir.h' is a source of 'foo', so for instance, it should be inspected while generating tags (*note Tags::). In other words, it does not help our present problem, and the build would fail identically without it. Using 'BUILT_SOURCES' ..................... A solution is to require 'bindir.h' to be built before anything else. This is what 'BUILT_SOURCES' is meant for (*note Sources::). bin_PROGRAMS = foo foo_SOURCES = foo.c nodist_foo_SOURCES = bindir.h BUILT_SOURCES = bindir.h CLEANFILES = bindir.h bindir.h: Makefile echo '#define bindir "$(bindir)"' >$@ See how 'bindir.h' gets built first: % make echo '#define bindir "/usr/local/bin"' >bindir.h make all-am make[1]: Entering directory `/home/adl/tmp' source='foo.c' object='foo.o' libtool=no \ depfile='.deps/foo.Po' tmpdepfile='.deps/foo.TPo' \ depmode=gcc /bin/sh ./depcomp \ gcc -I. -I. -g -O2 -c `test -f 'foo.c' || echo './'`foo.c gcc -g -O2 -o foo foo.o make[1]: Leaving directory `/home/adl/tmp' However, as said earlier, 'BUILT_SOURCES' applies only to the 'all', 'check', and 'install' targets. It still fails if you try to run 'make foo' explicitly: % make clean test -z "bindir.h" || rm -f bindir.h test -z "foo" || rm -f foo rm -f *.o % : > .deps/foo.Po # Suppress previously recorded dependencies % make foo source='foo.c' object='foo.o' libtool=no \ depfile='.deps/foo.Po' tmpdepfile='.deps/foo.TPo' \ depmode=gcc /bin/sh ./depcomp \ gcc -I. -I. -g -O2 -c `test -f 'foo.c' || echo './'`foo.c foo.c:2: bindir.h: No such file or directory make: *** [foo.o] Error 1 Recording Dependencies manually ............................... Usually people are happy enough with 'BUILT_SOURCES' because they never build targets such as 'make foo' before 'make all', as in the previous example. However if this matters to you, you can avoid 'BUILT_SOURCES' and record such dependencies explicitly in the 'Makefile.am'. bin_PROGRAMS = foo foo_SOURCES = foo.c nodist_foo_SOURCES = bindir.h foo.$(OBJEXT): bindir.h CLEANFILES = bindir.h bindir.h: Makefile echo '#define bindir "$(bindir)"' >$@ You don't have to list _all_ the dependencies of 'foo.o' explicitly, only those that might need to be built. If a dependency already exists, it will not hinder the first compilation and will be recorded by the normal dependency tracking code. (Note that after this first compilation the dependency tracking code will also have recorded the dependency between 'foo.o' and 'bindir.h'; so our explicit dependency is really useful to the first build only.) Adding explicit dependencies like this can be a bit dangerous if you are not careful enough. This is due to the way Automake tries not to overwrite your rules (it assumes you know better than it). 'foo.$(OBJEXT): bindir.h' supersedes any rule Automake may want to output to build 'foo.$(OBJEXT)'. It happens to work in this case because Automake doesn't have to output any 'foo.$(OBJEXT):' target: it relies on a suffix rule instead (i.e., '.c.$(OBJEXT):'). Always check the generated 'Makefile.in' if you do this. Build 'bindir.h' from 'configure' ................................. It's possible to define this preprocessor macro from 'configure', either in 'config.h' (*note Defining Directories: (autoconf)Defining Directories.), or by processing a 'bindir.h.in' file using 'AC_CONFIG_FILES' (*note Configuration Actions: (autoconf)Configuration Actions.). At this point it should be clear that building 'bindir.h' from 'configure' works well for this example. 'bindir.h' will exist before you build any target, hence will not cause any dependency issue. The Makefile can be shrunk as follows. We do not even have to mention 'bindir.h'. bin_PROGRAMS = foo foo_SOURCES = foo.c However, it's not always possible to build sources from 'configure', especially when these sources are generated by a tool that needs to be built first. Build 'bindir.c', not 'bindir.h'. ................................. Another attractive idea is to define 'bindir' as a variable or function exported from 'bindir.o', and build 'bindir.c' instead of 'bindir.h'. noinst_PROGRAMS = foo foo_SOURCES = foo.c bindir.h nodist_foo_SOURCES = bindir.c CLEANFILES = bindir.c bindir.c: Makefile echo 'const char bindir[] = "$(bindir)";' >$@ 'bindir.h' contains just the variable's declaration and doesn't need to be built, so it won't cause any trouble. 'bindir.o' is always dependent on 'bindir.c', so 'bindir.c' will get built first. Which is best? .............. There is no panacea, of course. Each solution has its merits and drawbacks. You cannot use 'BUILT_SOURCES' if the ability to run 'make foo' on a clean tree is important to you. You won't add explicit dependencies if you are leery of overriding an Automake rule by mistake. Building files from './configure' is not always possible, neither is converting '.h' files into '.c' files. 10 Other GNU Tools ****************** Since Automake is primarily intended to generate 'Makefile.in's for use in GNU programs, it tries hard to interoperate with other GNU tools. 10.1 Emacs Lisp =============== Automake provides some support for Emacs Lisp. The 'LISP' primary is used to hold a list of '.el' files. Possible prefixes for this primary are 'lisp_' and 'noinst_'. Note that if 'lisp_LISP' is defined, then 'configure.ac' must run 'AM_PATH_LISPDIR' (*note Macros::). Lisp sources are not distributed by default. You can prefix the 'LISP' primary with 'dist_', as in 'dist_lisp_LISP' or 'dist_noinst_LISP', to indicate that these files should be distributed. Automake will byte-compile all Emacs Lisp source files using the Emacs found by 'AM_PATH_LISPDIR', if any was found. Byte-compiled Emacs Lisp files are not portable among all versions of Emacs, so it makes sense to turn this off if you expect sites to have more than one version of Emacs installed. Furthermore, many packages don't actually benefit from byte-compilation. Still, we recommend that you byte-compile your Emacs Lisp sources. It is probably better for sites with strange setups to cope for themselves than to make the installation less nice for everybody else. There are two ways to avoid byte-compiling. Historically, we have recommended the following construct. lisp_LISP = file1.el file2.el ELCFILES = 'ELCFILES' is an internal Automake variable that normally lists all '.elc' files that must be byte-compiled. Automake defines 'ELCFILES' automatically from 'lisp_LISP'. Emptying this variable explicitly prevents byte-compilation. Since Automake 1.8, we now recommend using 'lisp_DATA' instead: lisp_DATA = file1.el file2.el Note that these two constructs are not equivalent. '_LISP' will not install a file if Emacs is not installed, while '_DATA' will always install its files. 10.2 Gettext ============ If 'AM_GNU_GETTEXT' is seen in 'configure.ac', then Automake turns on support for GNU gettext, a message catalog system for internationalization (*note Introduction: (gettext)Top.). The 'gettext' support in Automake requires the addition of one or two subdirectories to the package: 'po' and possibly also 'intl'. The latter is needed if 'AM_GNU_GETTEXT' is not invoked with the 'external' argument, or if 'AM_GNU_GETTEXT_INTL_SUBDIR' is used. Automake ensures that these directories exist and are mentioned in 'SUBDIRS'. 10.3 Libtool ============ Automake provides support for GNU Libtool (*note Introduction: (libtool)Top.) with the 'LTLIBRARIES' primary. *Note A Shared Library::. 10.4 Java bytecode compilation (deprecated) =========================================== Automake provides some minimal support for Java bytecode compilation with the 'JAVA' primary (in addition to the support for compiling Java to native machine code; *note Java Support with gcj::). Note however that _the interface and most features described here are deprecated_; the next automake release will strive to provide a better and cleaner interface, which however _won't be backward-compatible_; the present interface will probably be removed altogether in future automake releases (1.13 or later), so don't use it in new code. Any '.java' files listed in a '_JAVA' variable will be compiled with 'JAVAC' at build time. By default, '.java' files are not included in the distribution, you should use the 'dist_' prefix to distribute them. Here is a typical setup for distributing '.java' files and installing the '.class' files resulting from their compilation. javadir = $(datadir)/java dist_java_JAVA = a.java b.java ... Currently Automake enforces the restriction that only one '_JAVA' primary can be used in a given 'Makefile.am'. The reason for this restriction is that, in general, it isn't possible to know which '.class' files were generated from which '.java' files, so it would be impossible to know which files to install where. For instance, a '.java' file can define multiple classes; the resulting '.class' file names cannot be predicted without parsing the '.java' file. There are a few variables that are used when compiling Java sources: 'JAVAC' The name of the Java compiler. This defaults to 'javac'. 'JAVACFLAGS' The flags to pass to the compiler. This is considered to be a user variable (*note User Variables::). 'AM_JAVACFLAGS' More flags to pass to the Java compiler. This, and not 'JAVACFLAGS', should be used when it is necessary to put Java compiler flags into 'Makefile.am'. 'JAVAROOT' The value of this variable is passed to the '-d' option to 'javac'. It defaults to '$(top_builddir)'. 'CLASSPATH_ENV' This variable is a shell expression that is used to set the 'CLASSPATH' environment variable on the 'javac' command line. (In the future we will probably handle class path setting differently.) 10.5 Python =========== Automake provides support for Python compilation with the 'PYTHON' primary. A typical setup is to call 'AM_PATH_PYTHON' in 'configure.ac' and use a line like the following in 'Makefile.am': python_PYTHON = tree.py leave.py Any files listed in a '_PYTHON' variable will be byte-compiled with 'py-compile' at install time. 'py-compile' actually creates both standard ('.pyc') and optimized ('.pyo') byte-compiled versions of the source files. Note that because byte-compilation occurs at install time, any files listed in 'noinst_PYTHON' will not be compiled. Python source files are included in the distribution by default, prepend 'nodist_' (as in 'nodist_python_PYTHON') to omit them. Automake ships with an Autoconf macro called 'AM_PATH_PYTHON' that will determine some Python-related directory variables (see below). If you have called 'AM_PATH_PYTHON' from 'configure.ac', then you may use the variables 'python_PYTHON' or 'pkgpython_PYTHON' to list Python source files in your 'Makefile.am', depending on where you want your files installed (see the definitions of 'pythondir' and 'pkgpythondir' below). -- Macro: AM_PATH_PYTHON ([VERSION], [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND]) Search for a Python interpreter on the system. This macro takes three optional arguments. The first argument, if present, is the minimum version of Python required for this package: 'AM_PATH_PYTHON' will skip any Python interpreter that is older than VERSION. If an interpreter is found and satisfies VERSION, then ACTION-IF-FOUND is run. Otherwise, ACTION-IF-NOT-FOUND is run. If ACTION-IF-NOT-FOUND is not specified, as in the following example, the default is to abort 'configure'. AM_PATH_PYTHON([2.2]) This is fine when Python is an absolute requirement for the package. If Python >= 2.5 was only _optional_ to the package, 'AM_PATH_PYTHON' could be called as follows. AM_PATH_PYTHON([2.5],, [:]) If the 'PYTHON' variable is set when 'AM_PATH_PYTHON' is called, then that will be the only Python interpreter that is tried. 'AM_PATH_PYTHON' creates the following output variables based on the Python installation found during configuration. 'PYTHON' The name of the Python executable, or ':' if no suitable interpreter could be found. Assuming ACTION-IF-NOT-FOUND is used (otherwise './configure' will abort if Python is absent), the value of 'PYTHON' can be used to setup a conditional in order to disable the relevant part of a build as follows. AM_PATH_PYTHON(,, [:]) AM_CONDITIONAL([HAVE_PYTHON], [test "$PYTHON" != :]) 'PYTHON_VERSION' The Python version number, in the form MAJOR.MINOR (e.g., '2.5'). This is currently the value of 'sys.version[:3]'. 'PYTHON_PREFIX' The string '${prefix}'. This term may be used in future work that needs the contents of Python's 'sys.prefix', but general consensus is to always use the value from 'configure'. 'PYTHON_EXEC_PREFIX' The string '${exec_prefix}'. This term may be used in future work that needs the contents of Python's 'sys.exec_prefix', but general consensus is to always use the value from 'configure'. 'PYTHON_PLATFORM' The canonical name used by Python to describe the operating system, as given by 'sys.platform'. This value is sometimes needed when building Python extensions. 'pythondir' The directory name for the 'site-packages' subdirectory of the standard Python install tree. 'pkgpythondir' This is the directory under 'pythondir' that is named after the package. That is, it is '$(pythondir)/$(PACKAGE)'. It is provided as a convenience. 'pyexecdir' This is the directory where Python extension modules (shared libraries) should be installed. An extension module written in C could be declared as follows to Automake: pyexec_LTLIBRARIES = quaternion.la quaternion_la_SOURCES = quaternion.c support.c support.h quaternion_la_LDFLAGS = -avoid-version -module 'pkgpyexecdir' This is a convenience variable that is defined as '$(pyexecdir)/$(PACKAGE)'. All these directory variables have values that start with either '${prefix}' or '${exec_prefix}' unexpanded. This works fine in 'Makefiles', but it makes these variables hard to use in 'configure'. This is mandated by the GNU coding standards, so that the user can run 'make prefix=/foo install'. The Autoconf manual has a section with more details on this topic (*note Installation Directory Variables: (autoconf)Installation Directory Variables.). See also *note Hard-Coded Install Paths::. 11 Building documentation ************************* Currently Automake provides support for Texinfo and man pages. 11.1 Texinfo ============ If the current directory contains Texinfo source, you must declare it with the 'TEXINFOS' primary. Generally Texinfo files are converted into info, and thus the 'info_TEXINFOS' variable is most commonly used here. Any Texinfo source file must end in the '.texi', '.txi', or '.texinfo' extension. We recommend '.texi' for new manuals. Automake generates rules to build '.info', '.dvi', '.ps', '.pdf' and '.html' files from your Texinfo sources. Following the GNU Coding Standards, only the '.info' files are built by 'make all' and installed by 'make install' (unless you use 'no-installinfo', see below). Furthermore, '.info' files are automatically distributed so that Texinfo is not a prerequisite for installing your package. Other documentation formats can be built on request by 'make dvi', 'make ps', 'make pdf' and 'make html', and they can be installed with 'make install-dvi', 'make install-ps', 'make install-pdf' and 'make install-html' explicitly. 'make uninstall' will remove everything: the Texinfo documentation installed by default as well as all the above optional formats. All these targets can be extended using '-local' rules (*note Extending::). If the '.texi' file '@include's 'version.texi', then that file will be automatically generated. The file 'version.texi' defines four Texinfo flag you can reference using '@value{EDITION}', '@value{VERSION}', '@value{UPDATED}', and '@value{UPDATED-MONTH}'. 'EDITION' 'VERSION' Both of these flags hold the version number of your program. They are kept separate for clarity. 'UPDATED' This holds the date the primary '.texi' file was last modified. 'UPDATED-MONTH' This holds the name of the month in which the primary '.texi' file was last modified. The 'version.texi' support requires the 'mdate-sh' script; this script is supplied with Automake and automatically included when 'automake' is invoked with the '--add-missing' option. If you have multiple Texinfo files, and you want to use the 'version.texi' feature, then you have to have a separate version file for each Texinfo file. Automake will treat any include in a Texinfo file that matches 'vers*.texi' just as an automatically generated version file. Sometimes an info file actually depends on more than one '.texi' file. For instance, in GNU Hello, 'hello.texi' includes the file 'fdl.texi'. You can tell Automake about these dependencies using the 'TEXI_TEXINFOS' variable. Here is how GNU Hello does it: info_TEXINFOS = hello.texi hello_TEXINFOS = fdl.texi By default, Automake requires the file 'texinfo.tex' to appear in the same directory as the 'Makefile.am' file that lists the '.texi' files. If you used 'AC_CONFIG_AUX_DIR' in 'configure.ac' (*note Finding 'configure' Input: (autoconf)Input.), then 'texinfo.tex' is looked for there. In both cases, 'automake' then supplies 'texinfo.tex' if '--add-missing' is given, and takes care of its distribution. However, if you set the 'TEXINFO_TEX' variable (see below), it overrides the location of the file and turns off its installation into the source as well as its distribution. The option 'no-texinfo.tex' can be used to eliminate the requirement for the file 'texinfo.tex'. Use of the variable 'TEXINFO_TEX' is preferable, however, because that allows the 'dvi', 'ps', and 'pdf' targets to still work. Automake generates an 'install-info' rule; some people apparently use this. By default, info pages are installed by 'make install', so running 'make install-info' is pointless. This can be prevented via the 'no-installinfo' option. In this case, '.info' files are not installed by default, and user must request this explicitly using 'make install-info'. By default, 'make install-info' and 'make install-info' will try to run the 'install-info' program (if available) to update (or create) the '${infodir}/dir' index. If this is undesired, it can be prevented by exporting the 'AM_UPDATE_INFO_DIR' variable to "'no'". The following variables are used by the Texinfo build rules. 'MAKEINFO' The name of the program invoked to build '.info' files. This variable is defined by Automake. If the 'makeinfo' program is found on the system then it will be used by default; otherwise 'missing' will be used instead. 'MAKEINFOHTML' The command invoked to build '.html' files. Automake defines this to '$(MAKEINFO) --html'. 'MAKEINFOFLAGS' User flags passed to each invocation of '$(MAKEINFO)' and '$(MAKEINFOHTML)'. This user variable (*note User Variables::) is not expected to be defined in any 'Makefile'; it can be used by users to pass extra flags to suit their needs. 'AM_MAKEINFOFLAGS' 'AM_MAKEINFOHTMLFLAGS' Maintainer flags passed to each 'makeinfo' invocation. Unlike 'MAKEINFOFLAGS', these variables are meant to be defined by maintainers in 'Makefile.am'. '$(AM_MAKEINFOFLAGS)' is passed to 'makeinfo' when building '.info' files; and '$(AM_MAKEINFOHTMLFLAGS)' is used when building '.html' files. For instance, the following setting can be used to obtain one single '.html' file per manual, without node separators. AM_MAKEINFOHTMLFLAGS = --no-headers --no-split 'AM_MAKEINFOHTMLFLAGS' defaults to '$(AM_MAKEINFOFLAGS)'. This means that defining 'AM_MAKEINFOFLAGS' without defining 'AM_MAKEINFOHTMLFLAGS' will impact builds of both '.info' and '.html' files. 'TEXI2DVI' The name of the command that converts a '.texi' file into a '.dvi' file. This defaults to 'texi2dvi', a script that ships with the Texinfo package. 'TEXI2PDF' The name of the command that translates a '.texi' file into a '.pdf' file. This defaults to '$(TEXI2DVI) --pdf --batch'. 'DVIPS' The name of the command that builds a '.ps' file out of a '.dvi' file. This defaults to 'dvips'. 'TEXINFO_TEX' If your package has Texinfo files in many directories, you can use the variable 'TEXINFO_TEX' to tell Automake where to find the canonical 'texinfo.tex' for your package. The value of this variable should be the relative path from the current 'Makefile.am' to 'texinfo.tex': TEXINFO_TEX = ../doc/texinfo.tex 11.2 Man Pages ============== A package can also include man pages (but see the GNU standards on this matter, *note (standards)Man Pages::.) Man pages are declared using the 'MANS' primary. Generally the 'man_MANS' variable is used. Man pages are automatically installed in the correct subdirectory of 'mandir', based on the file extension. File extensions such as '.1c' are handled by looking for the valid part of the extension and using that to determine the correct subdirectory of 'mandir'. Valid section names are the digits '0' through '9', and the letters 'l' and 'n'. Sometimes developers prefer to name a man page something like 'foo.man' in the source, and then rename it to have the correct suffix, for example 'foo.1', when installing the file. Automake also supports this mode. For a valid section named SECTION, there is a corresponding directory named 'manSECTIONdir', and a corresponding '_MANS' variable. Files listed in such a variable are installed in the indicated section. If the file already has a valid suffix, then it is installed as-is; otherwise the file suffix is changed to match the section. For instance, consider this example: man1_MANS = rename.man thesame.1 alsothesame.1c In this case, 'rename.man' will be renamed to 'rename.1' when installed, but the other files will keep their names. By default, man pages are installed by 'make install'. However, since the GNU project does not require man pages, many maintainers do not expend effort to keep the man pages up to date. In these cases, the 'no-installman' option will prevent the man pages from being installed by default. The user can still explicitly install them via 'make install-man'. For fast installation, with many files it is preferable to use 'manSECTION_MANS' over 'man_MANS' as well as files that do not need to be renamed. Man pages are not currently considered to be source, because it is not uncommon for man pages to be automatically generated. Therefore they are not automatically included in the distribution. However, this can be changed by use of the 'dist_' prefix. For instance here is how to distribute and install the two man pages of GNU 'cpio' (which includes both Texinfo documentation and man pages): dist_man_MANS = cpio.1 mt.1 The 'nobase_' prefix is meaningless for man pages and is disallowed. Executables and manpages may be renamed upon installation (*note Renaming::). For manpages this can be avoided by use of the 'notrans_' prefix. For instance, suppose an executable 'foo' allowing to access a library function 'foo' from the command line. The way to avoid renaming of the 'foo.3' manpage is: man_MANS = foo.1 notrans_man_MANS = foo.3 'notrans_' must be specified first when used in conjunction with either 'dist_' or 'nodist_' (*note Fine-grained Distribution Control::). For instance: notrans_dist_man3_MANS = bar.3 12 What Gets Installed ********************** Naturally, Automake handles the details of actually installing your program once it has been built. All files named by the various primaries are automatically installed in the appropriate places when the user runs 'make install'. 12.1 Basics of Installation =========================== A file named in a primary is installed by copying the built file into the appropriate directory. The base name of the file is used when installing. bin_PROGRAMS = hello subdir/goodbye In this example, both 'hello' and 'goodbye' will be installed in '$(bindir)'. Sometimes it is useful to avoid the basename step at install time. For instance, you might have a number of header files in subdirectories of the source tree that are laid out precisely how you want to install them. In this situation you can use the 'nobase_' prefix to suppress the base name step. For example: nobase_include_HEADERS = stdio.h sys/types.h will install 'stdio.h' in '$(includedir)' and 'types.h' in '$(includedir)/sys'. For most file types, Automake will install multiple files at once, while avoiding command line length issues (*note Length Limitations::). Since some 'install' programs will not install the same file twice in one invocation, you may need to ensure that file lists are unique within one variable such as 'nobase_include_HEADERS' above. You should not rely on the order in which files listed in one variable are installed. Likewise, to cater for parallel make, you should not rely on any particular file installation order even among different file types (library dependencies are an exception here). 12.2 The Two Parts of Install ============================= Automake generates separate 'install-data' and 'install-exec' rules, in case the installer is installing on multiple machines that share directory structure--these targets allow the machine-independent parts to be installed only once. 'install-exec' installs platform-dependent files, and 'install-data' installs platform-independent files. The 'install' target depends on both of these targets. While Automake tries to automatically segregate objects into the correct category, the 'Makefile.am' author is, in the end, responsible for making sure this is done correctly. Variables using the standard directory prefixes 'data', 'info', 'man', 'include', 'oldinclude', 'pkgdata', or 'pkginclude' are installed by 'install-data'. Variables using the standard directory prefixes 'bin', 'sbin', 'libexec', 'sysconf', 'localstate', 'lib', or 'pkglib' are installed by 'install-exec'. For instance, 'data_DATA' files are installed by 'install-data', while 'bin_PROGRAMS' files are installed by 'install-exec'. Any variable using a user-defined directory prefix with 'exec' in the name (e.g., 'myexecbin_PROGRAMS') is installed by 'install-exec'. All other user-defined prefixes are installed by 'install-data'. 12.3 Extending Installation =========================== It is possible to extend this mechanism by defining an 'install-exec-local' or 'install-data-local' rule. If these rules exist, they will be run at 'make install' time. These rules can do almost anything; care is required. Automake also supports two install hooks, 'install-exec-hook' and 'install-data-hook'. These hooks are run after all other install rules of the appropriate type, exec or data, have completed. So, for instance, it is possible to perform post-installation modifications using an install hook. *Note Extending::, for some examples. 12.4 Staged Installs ==================== Automake generates support for the 'DESTDIR' variable in all install rules. 'DESTDIR' is used during the 'make install' step to relocate install objects into a staging area. Each object and path is prefixed with the value of 'DESTDIR' before being copied into the install area. Here is an example of typical DESTDIR usage: mkdir /tmp/staging && make DESTDIR=/tmp/staging install The 'mkdir' command avoids a security problem if the attacker creates a symbolic link from '/tmp/staging' to a victim area; then 'make' places install objects in a directory tree built under '/tmp/staging'. If '/gnu/bin/foo' and '/gnu/share/aclocal/foo.m4' are to be installed, the above command would install '/tmp/staging/gnu/bin/foo' and '/tmp/staging/gnu/share/aclocal/foo.m4'. This feature is commonly used to build install images and packages (*note DESTDIR::). Support for 'DESTDIR' is implemented by coding it directly into the install rules. If your 'Makefile.am' uses a local install rule (e.g., 'install-exec-local') or an install hook, then you must write that code to respect 'DESTDIR'. *Note (standards)Makefile Conventions::, for another usage example. 12.5 Install Rules for the User =============================== Automake also generates rules for targets 'uninstall', 'installdirs', and 'install-strip'. Automake supports 'uninstall-local' and 'uninstall-hook'. There is no notion of separate uninstalls for "exec" and "data", as these features would not provide additional functionality. Note that 'uninstall' is not meant as a replacement for a real packaging tool. 13 What Gets Cleaned ******************** The GNU Makefile Standards specify a number of different clean rules. *Note Standard Targets for Users: (standards)Standard Targets. Generally the files that can be cleaned are determined automatically by Automake. Of course, Automake also recognizes some variables that can be defined to specify additional files to clean. These variables are 'MOSTLYCLEANFILES', 'CLEANFILES', 'DISTCLEANFILES', and 'MAINTAINERCLEANFILES'. When cleaning involves more than deleting some hard-coded list of files, it is also possible to supplement the cleaning rules with your own commands. Simply define a rule for any of the 'mostlyclean-local', 'clean-local', 'distclean-local', or 'maintainer-clean-local' targets (*note Extending::). A common case is deleting a directory, for instance, a directory created by the test suite: clean-local: -rm -rf testSubDir Since 'make' allows only one set of rules for a given target, a more extensible way of writing this is to use a separate target listed as a dependency: clean-local: clean-local-check .PHONY: clean-local-check clean-local-check: -rm -rf testSubDir As the GNU Standards aren't always explicit as to which files should be removed by which rule, we've adopted a heuristic that we believe was first formulated by François Pinard: * If 'make' built it, and it is commonly something that one would want to rebuild (for instance, a '.o' file), then 'mostlyclean' should delete it. * Otherwise, if 'make' built it, then 'clean' should delete it. * If 'configure' built it, then 'distclean' should delete it. * If the maintainer built it (for instance, a '.info' file), then 'maintainer-clean' should delete it. However 'maintainer-clean' should not delete anything that needs to exist in order to run './configure && make'. We recommend that you follow this same set of heuristics in your 'Makefile.am'. 14 What Goes in a Distribution ****************************** 14.1 Basics of Distribution =========================== The 'dist' rule in the generated 'Makefile.in' can be used to generate a gzipped 'tar' file and other flavors of archive for distribution. The file is named based on the 'PACKAGE' and 'VERSION' variables defined by 'AM_INIT_AUTOMAKE' (*note Macros::); more precisely the gzipped 'tar' file is named 'PACKAGE-VERSION.tar.gz'. You can use the 'make' variable 'GZIP_ENV' to control how gzip is run. The default setting is '--best'. For the most part, the files to distribute are automatically found by Automake: all source files are automatically included in a distribution, as are all 'Makefile.am' and 'Makefile.in' files. Automake also has a built-in list of commonly used files that are automatically included if they are found in the current directory (either physically, or as the target of a 'Makefile.am' rule); this list is printed by 'automake --help'. Note that some files in this list are actually distributed only if other certain conditions hold (for example, the 'config.h.top' and 'config.h.bot' files are automatically distributed only if, e.g., 'AC_CONFIG_HEADERS([config.h])' is used in 'configure.ac'). Also, files that are read by 'configure' (i.e. the source files corresponding to the files specified in various Autoconf macros such as 'AC_CONFIG_FILES' and siblings) are automatically distributed. Files included in a 'Makefile.am' (using 'include') or in 'configure.ac' (using 'm4_include'), and helper scripts installed with 'automake --add-missing' are also distributed. Still, sometimes there are files that must be distributed, but which are not covered in the automatic rules. These files should be listed in the 'EXTRA_DIST' variable. You can mention files from subdirectories in 'EXTRA_DIST'. You can also mention a directory in 'EXTRA_DIST'; in this case the entire directory will be recursively copied into the distribution. Please note that this will also copy _everything_ in the directory, including, e.g., Subversion's '.svn' private directories or CVS/RCS version control files. We recommend against using this feature. If you define 'SUBDIRS', Automake will recursively include the subdirectories in the distribution. If 'SUBDIRS' is defined conditionally (*note Conditionals::), Automake will normally include all directories that could possibly appear in 'SUBDIRS' in the distribution. If you need to specify the set of directories conditionally, you can set the variable 'DIST_SUBDIRS' to the exact list of subdirectories to include in the distribution (*note Conditional Subdirectories::). 14.2 Fine-grained Distribution Control ====================================== Sometimes you need tighter control over what does _not_ go into the distribution; for instance, you might have source files that are generated and that you do not want to distribute. In this case Automake gives fine-grained control using the 'dist' and 'nodist' prefixes. Any primary or '_SOURCES' variable can be prefixed with 'dist_' to add the listed files to the distribution. Similarly, 'nodist_' can be used to omit the files from the distribution. As an example, here is how you would cause some data to be distributed while leaving some source code out of the distribution: dist_data_DATA = distribute-this bin_PROGRAMS = foo nodist_foo_SOURCES = do-not-distribute.c 14.3 The dist Hook ================== Occasionally it is useful to be able to change the distribution before it is packaged up. If the 'dist-hook' rule exists, it is run after the distribution directory is filled, but before the actual tar (or shar) file is created. One way to use this is for distributing files in subdirectories for which a new 'Makefile.am' is overkill: dist-hook: mkdir $(distdir)/random cp -p $(srcdir)/random/a1 $(srcdir)/random/a2 $(distdir)/random Another way to use this is for removing unnecessary files that get recursively included by specifying a directory in EXTRA_DIST: EXTRA_DIST = doc dist-hook: rm -rf `find $(distdir)/doc -type d -name .svn` Two variables that come handy when writing 'dist-hook' rules are '$(distdir)' and '$(top_distdir)'. '$(distdir)' points to the directory where the 'dist' rule will copy files from the current directory before creating the tarball. If you are at the top-level directory, then 'distdir = $(PACKAGE)-$(VERSION)'. When used from subdirectory named 'foo/', then 'distdir = ../$(PACKAGE)-$(VERSION)/foo'. '$(distdir)' can be a relative or absolute path, do not assume any form. '$(top_distdir)' always points to the root directory of the distributed tree. At the top-level it's equal to '$(distdir)'. In the 'foo/' subdirectory 'top_distdir = ../$(PACKAGE)-$(VERSION)'. '$(top_distdir)' too can be a relative or absolute path. Note that when packages are nested using 'AC_CONFIG_SUBDIRS' (*note Subpackages::), then '$(distdir)' and '$(top_distdir)' are relative to the package where 'make dist' was run, not to any sub-packages involved. 14.4 Checking the Distribution ============================== Automake also generates a 'distcheck' rule that can be of help to ensure that a given distribution will actually work. 'distcheck' makes a distribution, then tries to do a 'VPATH' build (*note VPATH Builds::), run the test suite, and finally make another tarball to ensure the distribution is self-contained. Building the package involves running './configure'. If you need to supply additional flags to 'configure', define them in the 'AM_DISTCHECK_CONFIGURE_FLAGS' variable in your top-level 'Makefile.am'. The user can still extend or override the flags provided there by defining the 'DISTCHECK_CONFIGURE_FLAGS' variable, on the command line when invoking 'make'. Still, developers are encouraged to strive to make their code buildable without requiring any special configure option; thus, in general, you shouldn't define 'AM_DISTCHECK_CONFIGURE_FLAGS'. However, there might be few scenarios in which the use of this variable is justified. GNU 'm4' offers an example. GNU 'm4' configures by default with its experimental and seldom used "changeword" feature disabled; so in its case it is useful to have 'make distcheck' run configure with the '--with-changeword' option, to ensure that the code for changeword support still compiles correctly. GNU 'm4' also employs the 'AM_DISTCHECK_CONFIGURE_FLAGS' variable to stress-test the use of '--program-prefix=g', since at one point the 'm4' build system had a bug where 'make installcheck' was wrongly assuming it could blindly test "'m4'", rather than the just-installed "'gm4'". If the 'distcheck-hook' rule is defined in your top-level 'Makefile.am', then it will be invoked by 'distcheck' after the new distribution has been unpacked, but before the unpacked copy is configured and built. Your 'distcheck-hook' can do almost anything, though as always caution is advised. Generally this hook is used to check for potential distribution errors not caught by the standard mechanism. Note that 'distcheck-hook' as well as 'AM_DISTCHECK_CONFIGURE_FLAGS' and 'DISTCHECK_CONFIGURE_FLAGS' are not honored in a subpackage 'Makefile.am', but the flags from 'AM_DISTCHECK_CONFIGURE_FLAGS' and 'DISTCHECK_CONFIGURE_FLAGS' are passed down to the 'configure' script of the subpackage. Speaking of potential distribution errors, 'distcheck' also ensures that the 'distclean' rule actually removes all built files. This is done by running 'make distcleancheck' at the end of the 'VPATH' build. By default, 'distcleancheck' will run 'distclean' and then make sure the build tree has been emptied by running '$(distcleancheck_listfiles)'. Usually this check will find generated files that you forgot to add to the 'DISTCLEANFILES' variable (*note Clean::). The 'distcleancheck' behavior should be OK for most packages, otherwise you have the possibility to override the definition of either the 'distcleancheck' rule, or the '$(distcleancheck_listfiles)' variable. For instance, to disable 'distcleancheck' completely, add the following rule to your top-level 'Makefile.am': distcleancheck: @: If you want 'distcleancheck' to ignore built files that have not been cleaned because they are also part of the distribution, add the following definition instead: distcleancheck_listfiles = \ find . -type f -exec sh -c 'test -f $(srcdir)/$$1 || echo $$1' \ sh '{}' ';' The above definition is not the default because it's usually an error if your Makefiles cause some distributed files to be rebuilt when the user build the package. (Think about the user missing the tool required to build the file; or if the required tool is built by your package, consider the cross-compilation case where it can't be run.) There is an entry in the FAQ about this (*note distcleancheck::), make sure you read it before playing with 'distcleancheck_listfiles'. 'distcheck' also checks that the 'uninstall' rule works properly, both for ordinary and 'DESTDIR' builds. It does this by invoking 'make uninstall', and then it checks the install tree to see if any files are left over. This check will make sure that you correctly coded your 'uninstall'-related rules. By default, the checking is done by the 'distuninstallcheck' rule, and the list of files in the install tree is generated by '$(distuninstallcheck_listfiles)' (this is a variable whose value is a shell command to run that prints the list of files to stdout). Either of these can be overridden to modify the behavior of 'distcheck'. For instance, to disable this check completely, you would write: distuninstallcheck: @: 14.5 The Types of Distributions =============================== Automake generates rules to provide archives of the project for distributions in various formats. Their targets are: 'dist-bzip2' Generate a bzip2 tar archive of the distribution. bzip2 archives are frequently smaller than gzipped archives. By default, this rule makes 'bzip2' use a compression option of '-9'. To make it use a different one, set the 'BZIP2' environment variable. For example, 'make dist-bzip2 BZIP2=-7'. 'dist-gzip' Generate a gzip tar archive of the distribution. 'dist-lzip' Generate a 'lzip' tar archive of the distribution. 'lzip' archives are frequently smaller than 'bzip2'-compressed archives. 'dist-lzma' Generate an 'lzma' tar archive of the distribution. The 'lzma' format is obsolete, you should use the 'xz' format instead. _Support for 'lzma'-compressed archives will be removed in the next major Automake release._ 'dist-shar' Generate a shar archive of the distribution. 'dist-xz' Generate an 'xz' tar archive of the distribution. 'xz' archives are frequently smaller than 'bzip2'-compressed archives. The 'xz' format displaces the obsolete 'lzma' format. By default, this rule makes 'xz' use a compression option of '-e'. To make it use a different one, set the 'XZ_OPT' environment variable. For example, run this command to use the default compression ratio, but with a progress indicator: 'make dist-xz XZ_OPT=-7e'. 'dist-zip' Generate a zip archive of the distribution. 'dist-tarZ' Generate a compressed tar archive of the distribution. The rule 'dist' (and its historical synonym 'dist-all') will create archives in all the enabled formats, *note Options::. By default, only the 'dist-gzip' target is hooked to 'dist'. 15 Support for test suites ************************** Automake supports three forms of test suites, the first two of which are very similar. 15.1 Simple Tests ================= If the variable 'TESTS' is defined, its value is taken to be a list of programs or scripts to run in order to do the testing. Programs needing data files should look for them in 'srcdir' (which is both an environment variable and a make variable) so they work when building in a separate directory (*note Build Directories: (autoconf)Build Directories.), and in particular for the 'distcheck' rule (*note Checking the Distribution::). For each of the 'TESTS', the result of execution is printed along with the test name, where 'PASS' denotes a successful test, 'FAIL' denotes a failed test, 'XFAIL' an expected failure, 'XPASS' an unexpected pass for a test that is supposed to fail, and 'SKIP' denotes a skipped test. The number of failures will be printed at the end of the run. If a given test program exits with a status of 77, then its result is ignored in the final count. This feature allows non-portable tests to be ignored in environments where they don't make sense. If the Automake option 'color-tests' is used (*note Options::) and standard output is connected to a capable terminal, then the test results and the summary are colored appropriately. The user can disable colored output by setting the 'make' variable 'AM_COLOR_TESTS=no', or force colored output even without a connecting terminal with 'AM_COLOR_TESTS=always'. Note that the semantics of some 'make' implementations when used in parallel mode (*note (autoconf)Parallel make::) can cause the automatic detection of a connection to a capable terminal to fail. In that case, you can still resort to the use of 'AM_COLOR_TESTS=always'. The variable 'TESTS_ENVIRONMENT' can be used to set environment variables for the test run; the environment variable 'srcdir' is set in the rule. If all your test programs are scripts, you can also set 'TESTS_ENVIRONMENT' to an invocation of the shell (e.g. '$(SHELL) -x' can be useful for debugging the tests), or any other interpreter. For instance, the following setup may be used to run tests with Perl: TESTS_ENVIRONMENT = $(PERL) -Mstrict -w TESTS = foo.pl bar.pl baz.pl Note that the 'parallel-tests' driver provides a more elegant way to achieve the same effect, freeing the 'TESTS_ENVIRONMENT' variable for the user to override (*note Simple Tests using parallel-tests::). You may define the variable 'XFAIL_TESTS' to a list of tests (usually a subset of 'TESTS') that are expected to fail. This will reverse the result of those tests. Automake ensures that each file listed in 'TESTS' is built before any tests are run; you can list both source and derived programs (or scripts) in 'TESTS'; the generated rule will look both in 'srcdir' and '.'. For instance, you might want to run a C program as a test. To do this you would list its name in 'TESTS' and also in 'check_PROGRAMS', and then specify it as you would any other program. Programs listed in 'check_PROGRAMS' (and 'check_LIBRARIES', 'check_LTLIBRARIES'...) are only built during 'make check', not during 'make all'. You should list there any program needed by your tests that does not need to be built by 'make all'. Note that 'check_PROGRAMS' are _not_ automatically added to 'TESTS' because 'check_PROGRAMS' usually lists programs used by the tests, not the tests themselves. Of course you can set 'TESTS = $(check_PROGRAMS)' if all your programs are test cases. 15.2 Simple Tests using 'parallel-tests' ======================================== The option 'parallel-tests' (*note Options::) enables a test suite driver that is mostly compatible to the simple test driver described in the previous section, but provides a few more features and slightly different semantics. It features concurrent execution of tests with 'make -j' and automatic collection of the test scripts output and summary thereof in '.log' files, and allows to specify inter-test dependencies, lazy reruns of tests that have not completed in a prior run, and hard errors for exceptional failures. Similar to the simple test driver, 'TESTS_ENVIRONMENT', 'AM_COLOR_TESTS', 'XFAIL_TESTS', and the 'check_*' variables are honored, and the environment variable 'srcdir' is set during test execution. This test driver is still experimental and may undergo changes in order to satisfy additional portability requirements. The driver operates by defining a set of 'make' rules to create a summary log file, 'TEST_SUITE_LOG', which defaults to 'test-suite.log' and requires a '.log' suffix. This file depends upon log files created for each single test program listed in 'TESTS', which in turn contain all output produced by the corresponding tests. Each log file is created when the corresponding test has completed. The set of log files is listed in the read-only variable 'TEST_LOGS', and defaults to 'TESTS', with the executable extension if any (*note EXEEXT::), as well as any suffix listed in 'TEST_EXTENSIONS' removed, and '.log' appended. Results are undefined if a test file name ends in several concatenated suffixes. 'TEST_EXTENSIONS' defaults to '.test'; it can be overridden by the user, in which case any extension listed in it must be constituted by a dot, followed by a non-digit alphabetic character, followed by any number of alphabetic characters. For example, '.sh', '.T' and '.t1' are valid extensions, while '.x-y', '.6c' and '.t.1' are not. For tests that match an extension '.EXT' listed in 'TEST_EXTENSIONS', you can provide a test driver using the variable 'EXT_LOG_COMPILER' (note the upper-case extension) and pass options in 'AM_EXT_LOG_FLAGS' and allow the user to pass options in 'EXT_LOG_FLAGS'. It will cause all tests with this extension to be called with this driver. For all tests without a registered extension, the variables 'LOG_COMPILER', 'AM_LOG_FLAGS', and 'LOG_FLAGS' may be used. For example, TESTS = foo.pl bar.py baz TEST_EXTENSIONS = .pl .py PL_LOG_COMPILER = $(PERL) AM_PL_LOG_FLAGS = -w PY_LOG_COMPILER = $(PYTHON) AM_PY_LOG_FLAGS = -v LOG_COMPILER = ./wrapper-script AM_LOG_FLAGS = -d will invoke '$(PERL) -w foo.pl', '$(PYTHON) -v bar.py', and './wrapper-script -d baz' to produce 'foo.log', 'bar.log', and 'baz.log', respectively. The 'TESTS_ENVIRONMENT' variable is still expanded before the driver, but should be reserved for the user. As with the simple driver above, by default one status line is printed per completed test, and a short summary after the suite has completed. However, standard output and standard error of the test are redirected to a per-test log file, so that parallel execution does not produce intermingled output. The output from failed tests is collected in the 'test-suite.log' file. If the variable 'VERBOSE' is set, this file is output after the summary. For best results, the tests should be verbose by default now. Previous versions of automake used to provide a 'check-html' target to convert the log files to HTML. This feature is now deprecated, and _will be removed_ in the next major Automake release, so don't rely on it anymore. Even in the presence of expected failures (see 'XFAIL_TESTS'), there may be conditions under which a test outcome needs attention. For example, with test-driven development, you may write tests for features that you have not implemented yet, and thus mark these tests as expected to fail. However, you may still be interested in exceptional conditions, for example, tests that fail due to a segmentation violation or another error that is independent of the feature awaiting implementation. Tests can exit with an exit status of 99 to signal such a _hard error_. Unless the variable 'DISABLE_HARD_ERRORS' is set to a nonempty value, such tests will be counted as failed. By default, the test suite driver will run all tests, but there are several ways to limit the set of tests that are run: * You can set the 'TESTS' variable, similarly to how you can with the simple test driver from the previous section. For example, you can use a command like this to run only a subset of the tests: env TESTS="foo.test bar.test" make -e check Note however that the command above will unconditionally overwrite the 'test-suite.log' file, thus clobbering the recorded results of any previous testsuite run. This might be undesirable for packages whose testsuite takes long time to execute. Luckily, this problem can easily be avoided by overriding also 'TEST_SUITE_LOG' at runtime; for example, env TEST_SUITE_LOG=partial.log TESTS="..." make -e check will write the result of the partial testsuite runs to the 'partial.log', without touching 'test-suite.log'. * You can set the 'TEST_LOGS' variable. By default, this variable is computed at 'make' run time from the value of 'TESTS' as described above. For example, you can use the following: set x subset*.log; shift env TEST_LOGS="foo.log $*" make -e check The comments made above about 'TEST_SUITE_LOG' overriding applies here too. * By default, the test driver removes all old per-test log files before it starts running tests to regenerate them. The variable 'RECHECK_LOGS' contains the set of log files which are removed. 'RECHECK_LOGS' defaults to 'TEST_LOGS', which means all tests need to be rechecked. By overriding this variable, you can choose which tests need to be reconsidered. For example, you can lazily rerun only those tests which are outdated, i.e., older than their prerequisite test files, by setting this variable to the empty value: env RECHECK_LOGS= make -e check * You can ensure that all tests are rerun which have failed or passed unexpectedly, by running 'make recheck' in the test directory. This convenience target will set 'RECHECK_LOGS' appropriately before invoking the main test driver. In order to guarantee an ordering between tests even with 'make -jN', dependencies between the corresponding log files may be specified through usual 'make' dependencies. For example, the following snippet lets the test named 'foo-execute.test' depend upon completion of the test 'foo-compile.test': TESTS = foo-compile.test foo-execute.test foo-execute.log: foo-compile.log Please note that this ordering ignores the _results_ of required tests, thus the test 'foo-execute.test' is run even if the test 'foo-compile.test' failed or was skipped beforehand. Further, please note that specifying such dependencies currently works only for tests that end in one of the suffixes listed in 'TEST_EXTENSIONS'. Tests without such specified dependencies may be run concurrently with parallel 'make -jN', so be sure they are prepared for concurrent execution. The combination of lazy test execution and correct dependencies between tests and their sources may be exploited for efficient unit testing during development. To further speed up the edit-compile-test cycle, it may even be useful to specify compiled programs in 'EXTRA_PROGRAMS' instead of with 'check_PROGRAMS', as the former allows intertwined compilation and test execution (but note that 'EXTRA_PROGRAMS' are not cleaned automatically, *note Uniform::). The variables 'TESTS' and 'XFAIL_TESTS' may contain conditional parts as well as configure substitutions. In the latter case, however, certain restrictions apply: substituted test names must end with a nonempty test suffix like '.test', so that one of the inference rules generated by 'automake' can apply. For literal test names, 'automake' can generate per-target rules to avoid this limitation. Please note that it is currently not possible to use '$(srcdir)/' or '$(top_srcdir)/' in the 'TESTS' variable. This technical limitation is necessary to avoid generating test logs in the source tree and has the unfortunate consequence that it is not possible to specify distributed tests that are themselves generated by means of explicit rules, in a way that is portable to all 'make' implementations (*note (autoconf)Make Target Lookup::, the semantics of FreeBSD and OpenBSD 'make' conflict with this). In case of doubt you may want to require to use GNU 'make', or work around the issue with inference rules to generate the tests. 15.3 DejaGnu Tests ================== If 'dejagnu' (ftp://ftp.gnu.org/gnu/dejagnu/) appears in 'AUTOMAKE_OPTIONS', then a 'dejagnu'-based test suite is assumed. The variable 'DEJATOOL' is a list of names that are passed, one at a time, as the '--tool' argument to 'runtest' invocations; it defaults to the name of the package. The variable 'RUNTESTDEFAULTFLAGS' holds the '--tool' and '--srcdir' flags that are passed to dejagnu by default; this can be overridden if necessary. The variables 'EXPECT' and 'RUNTEST' can also be overridden to provide project-specific values. For instance, you will need to do this if you are testing a compiler toolchain, because the default values do not take into account host and target names. The contents of the variable 'RUNTESTFLAGS' are passed to the 'runtest' invocation. This is considered a "user variable" (*note User Variables::). If you need to set 'runtest' flags in 'Makefile.am', you can use 'AM_RUNTESTFLAGS' instead. Automake will generate rules to create a local 'site.exp' file, defining various variables detected by 'configure'. This file is automatically read by DejaGnu. It is OK for the user of a package to edit this file in order to tune the test suite. However this is not the place where the test suite author should define new variables: this should be done elsewhere in the real test suite code. Especially, 'site.exp' should not be distributed. Still, if the package author has legitimate reasons to extend 'site.exp' at 'make' time, he can do so by defining the variable 'EXTRA_DEJAGNU_SITE_CONFIG'; the files listed there will be considered 'site.exp' prerequisites, and their content will be appended to it (in the same order in which they appear in 'EXTRA_DEJAGNU_SITE_CONFIG'). Note that files are _not_ distributed by default. For more information regarding DejaGnu test suites, see *note (dejagnu)Top::. In either case, the testing is done via 'make check'. 15.4 Install Tests ================== The 'installcheck' target is available to the user as a way to run any tests after the package has been installed. You can add tests to this by writing an 'installcheck-local' rule. 16 Rebuilding Makefiles *********************** Automake generates rules to automatically rebuild 'Makefile's, 'configure', and other derived files like 'Makefile.in'. If you are using 'AM_MAINTAINER_MODE' in 'configure.ac', then these automatic rebuilding rules are only enabled in maintainer mode. Sometimes you need to run 'aclocal' with an argument like '-I' to tell it where to find '.m4' files. Since sometimes 'make' will automatically run 'aclocal', you need a way to specify these arguments. You can do this by defining 'ACLOCAL_AMFLAGS'; this holds arguments that are passed verbatim to 'aclocal'. This variable is only useful in the top-level 'Makefile.am'. Sometimes it is convenient to supplement the rebuild rules for 'configure' or 'config.status' with additional dependencies. The variables 'CONFIGURE_DEPENDENCIES' and 'CONFIG_STATUS_DEPENDENCIES' can be used to list these extra dependencies. These variables should be defined in all 'Makefile's of the tree (because these two rebuild rules are output in all them), so it is safer and easier to 'AC_SUBST' them from 'configure.ac'. For instance, the following statement will cause 'configure' to be rerun each time 'version.sh' is changed. AC_SUBST([CONFIG_STATUS_DEPENDENCIES], ['$(top_srcdir)/version.sh']) Note the '$(top_srcdir)/' in the file name. Since this variable is to be used in all 'Makefile's, its value must be sensible at any level in the build hierarchy. Beware not to mistake 'CONFIGURE_DEPENDENCIES' for 'CONFIG_STATUS_DEPENDENCIES'. 'CONFIGURE_DEPENDENCIES' adds dependencies to the 'configure' rule, whose effect is to run 'autoconf'. This variable should be seldom used, because 'automake' already tracks 'm4_include'd files. However it can be useful when playing tricky games with 'm4_esyscmd' or similar non-recommendable macros with side effects. 'CONFIG_STATUS_DEPENDENCIES' adds dependencies to the 'config.status' rule, whose effect is to run 'configure'. This variable should therefore carry any non-standard source that may be read as a side effect of running 'configure', like 'version.sh' in the example above. Speaking of 'version.sh' scripts, we recommend against them today. They are mainly used when the version of a package is updated automatically by a script (e.g., in daily builds). Here is what some old-style 'configure.ac's may look like: AC_INIT . $srcdir/version.sh AM_INIT_AUTOMAKE([name], $VERSION_NUMBER) ... Here, 'version.sh' is a shell fragment that sets 'VERSION_NUMBER'. The problem with this example is that 'automake' cannot track dependencies (listing 'version.sh' in 'CONFIG_STATUS_DEPENDENCIES', and distributing this file is up to the user), and that it uses the obsolete form of 'AC_INIT' and 'AM_INIT_AUTOMAKE'. Upgrading to the new syntax is not straightforward, because shell variables are not allowed in 'AC_INIT''s arguments. We recommend that 'version.sh' be replaced by an M4 file that is included by 'configure.ac': m4_include([version.m4]) AC_INIT([name], VERSION_NUMBER) AM_INIT_AUTOMAKE ... Here 'version.m4' could contain something like 'm4_define([VERSION_NUMBER], [1.2])'. The advantage of this second form is that 'automake' will take care of the dependencies when defining the rebuild rule, and will also distribute the file automatically. An inconvenience is that 'autoconf' will now be rerun each time the version number is bumped, when only 'configure' had to be rerun in the previous setup. 17 Changing Automake's Behavior ******************************* Various features of Automake can be controlled by options. Except where noted otherwise, options can be specified in one of several ways: Most options can be applied on a per-'Makefile' basis when listed in a special 'Makefile' variable named 'AUTOMAKE_OPTIONS'. Some of these options only make sense when specified in the toplevel 'Makefile.am' file. Options are applied globally to all processed 'Makefile' files when listed in the first argument of 'AM_INIT_AUTOMAKE' in 'configure.ac', and some options which require changes to the 'configure' script can only be specified there. These are annotated below. Currently understood options are: 'gnits' 'gnu' 'foreign' 'cygnus' Set the strictness as appropriate. The 'gnits' option also implies options 'readme-alpha' and 'check-news'. 'ansi2knr' 'PATH/ansi2knr' Turn on the deprecated de-ANSI-fication feature (*note ANSI::). Note that that feature and this option _will be removed_ in the next major Automake release. If preceded by a path, the generated 'Makefile.in' will look in the specified directory to find the 'ansi2knr' program. The path should be a relative path to another directory in the same distribution (Automake does not check this). 'check-news' Cause 'make dist' to fail unless the current version number appears in the first few lines of the 'NEWS' file. 'color-tests' Cause output of the simple test suite (*note Simple Tests::) to be colorized on capable terminals. 'dejagnu' Cause 'dejagnu'-specific rules to be generated. *Note DejaGnu Tests::. 'dist-bzip2' Hook 'dist-bzip2' to 'dist'. 'dist-lzip' Hook 'dist-lzip' to 'dist'. 'dist-lzma' Hook 'dist-lzma' to 'dist'. Obsoleted by 'dist-xz'. 'dist-shar' Hook 'dist-shar' to 'dist'. 'dist-zip' Hook 'dist-zip' to 'dist'. 'dist-tarZ' Hook 'dist-tarZ' to 'dist'. 'filename-length-max=99' Abort if file names longer than 99 characters are found during 'make dist'. Such long file names are generally considered not to be portable in tarballs. See the 'tar-v7' and 'tar-ustar' options below. This option should be used in the top-level 'Makefile.am' or as an argument of 'AM_INIT_AUTOMAKE' in 'configure.ac', it will be ignored otherwise. It will also be ignored in sub-packages of nested packages (*note Subpackages::). 'no-define' This option is meaningful only when passed as an argument to 'AM_INIT_AUTOMAKE'. It will prevent the 'PACKAGE' and 'VERSION' variables from being 'AC_DEFINE'd. 'no-dependencies' This is similar to using '--ignore-deps' on the command line, but is useful for those situations where you don't have the necessary bits to make automatic dependency tracking work (*note Dependencies::). In this case the effect is to effectively disable automatic dependency tracking. 'no-dist' Don't emit any code related to 'dist' target. This is useful when a package has its own method for making distributions. 'no-dist-gzip' Do not hook 'dist-gzip' to 'dist'. 'no-exeext' If your 'Makefile.am' defines a rule for target 'foo', it will override a rule for a target named 'foo$(EXEEXT)'. This is necessary when 'EXEEXT' is found to be empty. However, by default 'automake' will generate an error for this use. The 'no-exeext' option will disable this error. This is intended for use only where it is known in advance that the package will not be ported to Windows, or any other operating system using extensions on executables. 'no-installinfo' The generated 'Makefile.in' will not cause info pages to be built or installed by default. However, 'info' and 'install-info' targets will still be available. This option is disallowed at 'gnu' strictness and above. 'no-installman' The generated 'Makefile.in' will not cause man pages to be installed by default. However, an 'install-man' target will still be available for optional installation. This option is disallowed at 'gnu' strictness and above. 'nostdinc' This option can be used to disable the standard '-I' options that are ordinarily automatically provided by Automake. 'no-texinfo.tex' Don't require 'texinfo.tex', even if there are texinfo files in this directory. 'parallel-tests' Enable test suite driver for 'TESTS' that can run tests in parallel (*note Simple Tests using parallel-tests::, for more information). 'readme-alpha' If this release is an alpha release, and the file 'README-alpha' exists, then it will be added to the distribution. If this option is given, version numbers are expected to follow one of two forms. The first form is 'MAJOR.MINOR.ALPHA', where each element is a number; the final period and number should be left off for non-alpha releases. The second form is 'MAJOR.MINORALPHA', where ALPHA is a letter; it should be omitted for non-alpha releases. 'silent-rules' Enable less verbose build rules. This can be used to let build rules output status lines of the form: GEN OUTPUT-FILE CC OBJECT-FILE instead of printing the command that will be executed to update OUTPUT-FILE or to compile OBJECT-FILE. It can also silence 'libtool' output. For more information about how to use, enable, or disable silent rules, *note Automake silent-rules Option::. 'std-options' Make the 'installcheck' rule check that installed scripts and programs support the '--help' and '--version' options. This also provides a basic check that the program's run-time dependencies are satisfied after installation. In a few situations, programs (or scripts) have to be exempted from this test. For instance, 'false' (from GNU coreutils) is never successful, even for '--help' or '--version'. You can list such programs in the variable 'AM_INSTALLCHECK_STD_OPTIONS_EXEMPT'. Programs (not scripts) listed in this variable should be suffixed by '$(EXEEXT)' for the sake of Win32 or OS/2. For instance, suppose we build 'false' as a program but 'true.sh' as a script, and that neither of them support '--help' or '--version': AUTOMAKE_OPTIONS = std-options bin_PROGRAMS = false ... bin_SCRIPTS = true.sh ... AM_INSTALLCHECK_STD_OPTIONS_EXEMPT = false$(EXEEXT) true.sh 'subdir-objects' If this option is specified, then objects are placed into the subdirectory of the build directory corresponding to the subdirectory of the source file. For instance, if the source file is 'subdir/file.cxx', then the output file would be 'subdir/file.o'. In order to use this option with C sources, you should add 'AM_PROG_CC_C_O' to 'configure.ac'. 'tar-v7' 'tar-ustar' 'tar-pax' These three mutually exclusive options select the tar format to use when generating tarballs with 'make dist'. (The tar file created is then compressed according to the set of 'no-dist-gzip', 'dist-bzip2', 'dist-lzip', 'dist-xz' and 'dist-tarZ' options in use.) These options must be passed as arguments to 'AM_INIT_AUTOMAKE' (*note Macros::) because they can require additional configure checks. Automake will complain if it sees such options in an 'AUTOMAKE_OPTIONS' variable. 'tar-v7' selects the old V7 tar format. This is the historical default. This antiquated format is understood by all tar implementations and supports file names with up to 99 characters. When given longer file names some tar implementations will diagnose the problem while other will generate broken tarballs or use non-portable extensions. Furthermore, the V7 format cannot store empty directories. When using this format, consider using the 'filename-length-max=99' option to catch file names too long. 'tar-ustar' selects the ustar format defined by POSIX 1003.1-1988. This format is believed to be old enough to be portable. It fully supports empty directories. It can store file names with up to 256 characters, provided that the file name can be split at directory separator in two parts, first of them being at most 155 bytes long. So, in most cases the maximum file name length will be shorter than 256 characters. However you may run against broken tar implementations that incorrectly handle file names longer than 99 characters (please report them to so we can document this accurately). 'tar-pax' selects the new pax interchange format defined by POSIX 1003.1-2001. It does not limit the length of file names. However, this format is very young and should probably be restricted to packages that target only very modern platforms. There are moves to change the pax format in an upward-compatible way, so this option may refer to a more recent version in the future. *Note Controlling the Archive Format: (tar)Formats, for further discussion about tar formats. 'configure' knows several ways to construct these formats. It will not abort if it cannot find a tool up to the task (so that the package can still be built), but 'make dist' will fail. VERSION A version number (e.g., '0.30') can be specified. If Automake is not newer than the version specified, creation of the 'Makefile.in' will be suppressed. '-WCATEGORY' or '--warnings=CATEGORY' These options behave exactly like their command-line counterpart (*note automake Invocation::). This allows you to enable or disable some warning categories on a per-file basis. You can also setup some warnings for your entire project; for instance, try 'AM_INIT_AUTOMAKE([-Wall])' in your 'configure.ac'. Unrecognized options are diagnosed by 'automake'. If you want an option to apply to all the files in the tree, you can use the 'AM_INIT_AUTOMAKE' macro in 'configure.ac'. *Note Macros::. 18 Miscellaneous Rules ********************** There are a few rules and variables that didn't fit anywhere else. 18.1 Interfacing to 'etags' =========================== Automake will generate rules to generate 'TAGS' files for use with GNU Emacs under some circumstances. If any C, C++ or Fortran 77 source code or headers are present, then 'tags' and 'TAGS' rules will be generated for the directory. All files listed using the '_SOURCES', '_HEADERS', and '_LISP' primaries will be used to generate tags. Note that generated source files that are not distributed must be declared in variables like 'nodist_noinst_HEADERS' or 'nodist_PROG_SOURCES' or they will be ignored. A 'tags' rule will be output at the topmost directory of a multi-directory package. When run from this topmost directory, 'make tags' will generate a 'TAGS' file that includes by reference all 'TAGS' files from subdirectories. The 'tags' rule will also be generated if the variable 'ETAGS_ARGS' is defined. This variable is intended for use in directories that contain taggable source that 'etags' does not understand. The user can use the 'ETAGSFLAGS' to pass additional flags to 'etags'; 'AM_ETAGSFLAGS' is also available for use in 'Makefile.am'. Here is how Automake generates tags for its source, and for nodes in its Texinfo file: ETAGS_ARGS = automake.in --lang=none \ --regex='/^@node[ \t]+\([^,]+\)/\1/' automake.texi If you add file names to 'ETAGS_ARGS', you will probably also want to define 'TAGS_DEPENDENCIES'. The contents of this variable are added directly to the dependencies for the 'tags' rule. Automake also generates a 'ctags' rule that can be used to build 'vi'-style 'tags' files. The variable 'CTAGS' is the name of the program to invoke (by default 'ctags'); 'CTAGSFLAGS' can be used by the user to pass additional flags, and 'AM_CTAGSFLAGS' can be used by the 'Makefile.am'. Automake will also generate an 'ID' rule that will run 'mkid' on the source. This is only supported on a directory-by-directory basis. Finally, Automake also emits rules to support the GNU Global Tags program (http://www.gnu.org/software/global/). The 'GTAGS' rule runs Global Tags and puts the result in the top build directory. The variable 'GTAGS_ARGS' holds arguments that are passed to 'gtags'. 18.2 Handling new file extensions ================================= It is sometimes useful to introduce a new implicit rule to handle a file type that Automake does not know about. For instance, suppose you had a compiler that could compile '.foo' files to '.o' files. You would simply define a suffix rule for your language: .foo.o: foocc -c -o $@ $< Then you could directly use a '.foo' file in a '_SOURCES' variable and expect the correct results: bin_PROGRAMS = doit doit_SOURCES = doit.foo This was the simpler and more common case. In other cases, you will have to help Automake to figure out which extensions you are defining your suffix rule for. This usually happens when your extension does not start with a dot. Then, all you have to do is to put a list of new suffixes in the 'SUFFIXES' variable *before* you define your implicit rule. For instance, the following definition prevents Automake from misinterpreting the '.idlC.cpp:' rule as an attempt to transform '.idlC' files into '.cpp' files. SUFFIXES = .idl C.cpp .idlC.cpp: # whatever As you may have noted, the 'SUFFIXES' variable behaves like the '.SUFFIXES' special target of 'make'. You should not touch '.SUFFIXES' yourself, but use 'SUFFIXES' instead and let Automake generate the suffix list for '.SUFFIXES'. Any given 'SUFFIXES' go at the start of the generated suffixes list, followed by Automake generated suffixes not already in the list. 18.3 Support for Multilibs (deprecated, soon to be removed). ============================================================ Automake used to support an obscure feature called multilibs. _This feature is now deprecated, and will be removed in the next major Automake version_. Still, its implementation will remain available in the 'contrib/' directory of the Automake distribution, so it should be very easy for motivated users to continue to use it in their projects, if they really need to. A "multilib" is a library that is built for multiple different ABIs at a single time; each time the library is built with a different target flag combination. This is only useful when the library is intended to be cross-compiled, and it is almost exclusively used for compiler support libraries. 19 Include ********** Automake supports an 'include' directive that can be used to include other 'Makefile' fragments when 'automake' is run. Note that these fragments are read and interpreted by 'automake', not by 'make'. As with conditionals, 'make' has no idea that 'include' is in use. There are two forms of 'include': 'include $(srcdir)/file' Include a fragment that is found relative to the current source directory. 'include $(top_srcdir)/file' Include a fragment that is found relative to the top source directory. Note that if a fragment is included inside a conditional, then the condition applies to the entire contents of that fragment. Makefile fragments included this way are always distributed because they are needed to rebuild 'Makefile.in'. 20 Conditionals *************** Automake supports a simple type of conditionals. These conditionals are not the same as conditionals in GNU Make. Automake conditionals are checked at configure time by the 'configure' script, and affect the translation from 'Makefile.in' to 'Makefile'. They are based on options passed to 'configure' and on results that 'configure' has discovered about the host system. GNU Make conditionals are checked at 'make' time, and are based on variables passed to the make program or defined in the 'Makefile'. Automake conditionals will work with any make program. 20.1 Usage of Conditionals ========================== Before using a conditional, you must define it by using 'AM_CONDITIONAL' in the 'configure.ac' file (*note Macros::). -- Macro: AM_CONDITIONAL (CONDITIONAL, CONDITION) The conditional name, CONDITIONAL, should be a simple string starting with a letter and containing only letters, digits, and underscores. It must be different from 'TRUE' and 'FALSE' that are reserved by Automake. The shell CONDITION (suitable for use in a shell 'if' statement) is evaluated when 'configure' is run. Note that you must arrange for _every_ 'AM_CONDITIONAL' to be invoked every time 'configure' is run. If 'AM_CONDITIONAL' is run conditionally (e.g., in a shell 'if' statement), then the result will confuse 'automake'. Conditionals typically depend upon options that the user provides to the 'configure' script. Here is an example of how to write a conditional that is true if the user uses the '--enable-debug' option. AC_ARG_ENABLE([debug], [ --enable-debug Turn on debugging], [case "${enableval}" in yes) debug=true ;; no) debug=false ;; *) AC_MSG_ERROR([bad value ${enableval} for --enable-debug]) ;; esac],[debug=false]) AM_CONDITIONAL([DEBUG], [test x$debug = xtrue]) Here is an example of how to use that conditional in 'Makefile.am': if DEBUG DBG = debug else DBG = endif noinst_PROGRAMS = $(DBG) This trivial example could also be handled using 'EXTRA_PROGRAMS' (*note Conditional Programs::). You may only test a single variable in an 'if' statement, possibly negated using '!'. The 'else' statement may be omitted. Conditionals may be nested to any depth. You may specify an argument to 'else' in which case it must be the negation of the condition used for the current 'if'. Similarly you may specify the condition that is closed on the 'endif' line: if DEBUG DBG = debug else !DEBUG DBG = endif !DEBUG Unbalanced conditions are errors. The 'if', 'else', and 'endif' statements should not be indented, i.e., start on column one. The 'else' branch of the above two examples could be omitted, since assigning the empty string to an otherwise undefined variable makes no difference. In order to allow access to the condition registered by 'AM_CONDITIONAL' inside 'configure.ac', and to allow conditional 'AC_CONFIG_FILES', 'AM_COND_IF' may be used: -- Macro: AM_COND_IF (CONDITIONAL, [IF-TRUE], [IF-FALSE]) If CONDITIONAL is fulfilled, execute IF-TRUE, otherwise execute IF-FALSE. If either branch contains 'AC_CONFIG_FILES', it will cause 'automake' to output the rules for the respective files only for the given condition. 'AM_COND_IF' macros may be nested when m4 quotation is used properly (*note (autoconf)M4 Quotation::). Here is an example of how to define a conditional config file: AM_CONDITIONAL([SHELL_WRAPPER], [test "x$with_wrapper" = xtrue]) AM_COND_IF([SHELL_WRAPPER], [AC_CONFIG_FILES([wrapper:wrapper.in])]) 20.2 Limits of Conditionals =========================== Conditionals should enclose complete statements like variables or rules definitions. Automake cannot deal with conditionals used inside a variable definition, for instance, and is not even able to diagnose this situation. The following example would not work: # This syntax is not understood by Automake AM_CPPFLAGS = \ -DFEATURE_A \ if WANT_DEBUG -DDEBUG \ endif -DFEATURE_B However the intended definition of 'AM_CPPFLAGS' can be achieved with if WANT_DEBUG DEBUGFLAGS = -DDEBUG endif AM_CPPFLAGS = -DFEATURE_A $(DEBUGFLAGS) -DFEATURE_B or AM_CPPFLAGS = -DFEATURE_A if WANT_DEBUG AM_CPPFLAGS += -DDEBUG endif AM_CPPFLAGS += -DFEATURE_B More details and examples of conditionals are described alongside various Automake features in this manual (*note Conditional Subdirectories::, *note Conditional Sources::, *note Conditional Programs::, *note Conditional Libtool Libraries::, *note Conditional Libtool Sources::). 21 Silencing 'make' ******************* 21.1 Make is verbose by default =============================== Normally, when executing the set of rules associated with a target, 'make' prints each rule before it is executed. This behaviour, while having been in place for a long time, and being even mandated by the POSIX standard, starkly violates the "silence is golden" UNIX principle(1): When a program has nothing interesting or surprising to say, it should say nothing. Well-behaved Unix programs do their jobs unobtrusively, with a minimum of fuss and bother. Silence is golden. In fact, while such verbosity of 'make' can theoretically be useful to track bugs and understand reasons of failures right away, it can also hide warning and error messages from 'make'-invoked tools, drowning them in a flood of uninteresting and seldom useful messages, and thus allowing them to go easily undetected. This problem can be very annoying, especially for developers, who usually know quite well what's going on behind the scenes, and for whom the verbose output from 'make' ends up being mostly noise that hampers the easy detection of potentially important warning messages. ---------- Footnotes ---------- (1) See also . 21.2 Standard and generic ways to silence make ============================================== Here we describe some common idioms/tricks to obtain a quieter make output, with their relative advantages and drawbacks. In the next section (*note Automake silent-rules Option::) we'll see how Automake can help in this respect. * 'make -s' This simply causes 'make' not to print _any_ rule before executing it. The '-s' flag is mandated by POSIX, universally supported, and its purpose and function are easy to understand. But it also has its serious limitations too. First of all, it embodies an "all or nothing" strategy, i.e., either everything is silenced, or nothing is; this lack of granularity can sometimes be a fatal flaw. Moreover, when the '-s' flag is used, the 'make' output might turn out to be too much terse; in case of errors, the user won't be able to easily see what rule or command have caused them, or even, in case of tools with poor error reporting, what the errors were! * 'make >/dev/null || make' Apparently, this perfectly obeys the "silence is golden" rule: warnings from stderr are passed through, output reporting is done only in case of error, and in that case it should provide a verbose-enough report to allow an easy determination of the error location and causes. However, calling 'make' two times in a row might hide errors (especially intermittent ones), or subtly change the expected semantic of the 'make' calls -- things these which can clearly make debugging and error assessment very difficult. * 'make --no-print-directory' This is GNU 'make' specific. When called with the '--no-print-directory' option, GNU 'make' will disable printing of the working directory by invoked sub-'make's (the well-known "Entering/Leaving directory ..." messages). This helps to decrease the verbosity of the output, but experience has shown that it can also often render debugging considerably harder in projects using deeply-nested 'make' recursion. As an aside, notice that the '--no-print-directory' option is automatically activated if the '-s' flag is used. 21.3 How Automake can help in silencing make ============================================ The tricks and idioms for silencing 'make' described in the previous section can be useful from time to time, but we've seen that they all have their serious drawbacks and limitations. That's why automake provides support for a more advanced and flexible way of obtaining quieter output from 'make': the 'silent-rules' mode. To give the gist of what 'silent-rules' can do, here is a simple comparison between a typical 'make' output (where silent rules are disabled) and one with silent rules enabled: % cat Makefile.am bin_PROGRAMS = foo foo_SOURCES = main.c func.c % cat main.c int main (void) { return func (); } /* func used undeclared */ % cat func.c int func (void) { int i; return i; } /* i used uninitialized */ The make output is by default very verbose. This causes warnings from the compiler to be somewhat hidden, and not immediate to spot. % make CFLAGS=-Wall gcc -DPACKAGE_NAME=\"foo\" -DPACKAGE_TARNAME=\"foo\" ... -DPACKAGE_STRING=\"foo\ 1.0\" -DPACKAGE_BUGREPORT=\"\" ... -DPACKAGE=\"foo\" -DVERSION=\"1.0\" -I. -Wall -MT main.o -MD -MP -MF .deps/main.Tpo -c -o main.o main.c main.c: In function ‘main’: main.c:3:3: warning: implicit declaration of function ‘func’ mv -f .deps/main.Tpo .deps/main.Po gcc -DPACKAGE_NAME=\"foo\" -DPACKAGE_TARNAME=\"foo\" ... -DPACKAGE_STRING=\"foo\ 1.0\" -DPACKAGE_BUGREPORT=\"\" ... -DPACKAGE=\"foo\" -DVERSION=\"1.0\" -I. -Wall -MT func.o -MD -MP -MF .deps/func.Tpo -c -o func.o func.c func.c: In function ‘func’: func.c:4:3: warning: ‘i’ used uninitialized in this function mv -f .deps/func.Tpo .deps/func.Po gcc -Wall -o foo main.o func.o Clean up, so that we we can rebuild everything from scratch. % make clean test -z "foo" || rm -f foo rm -f *.o Silent rules enabled: the output is minimal but informative. In particular, the warnings from the compiler stick out very clearly. % make V=0 CFLAGS=-Wall CC main.o main.c: In function ‘main’: main.c:3:3: warning: implicit declaration of function ‘func’ CC func.o func.c: In function ‘func’: func.c:4:3: warning: ‘i’ used uninitialized in this function CCLD foo Also, in projects using 'libtool', the use of silent rules can automatically enable the 'libtool''s '--silent' option: % cat Makefile.am lib_LTLIBRARIES = libx.la % make # Both make and libtool are verbose by default. ... libtool: compile: gcc -DPACKAGE_NAME=\"foo\" ... -DLT_OBJDIR=\".libs/\" -I. -g -O2 -MT libx.lo -MD -MP -MF .deps/libx.Tpo -c libx.c -fPIC -DPIC -o .libs/libx.o mv -f .deps/libx.Tpo .deps/libx.Plo /bin/sh ./libtool --tag=CC --mode=link gcc -g -O2 -o libx.la -rpath /usr/local/lib libx.lo libtool: link: gcc -shared .libs/libx.o -Wl,-soname -Wl,libx.so.0 -o .libs/libx.so.0.0.0 libtool: link: cd .libs && rm -f libx.so && ln -s libx.so.0.0.0 libx.so ... % make V=0 CC libx.lo CCLD libx.la Let's now see how the 'silent-rules' mode interfaces with the package developer and the package user. To enable the use of 'silent-rules' in his package, a developer needs to do either of the following: * Add the 'silent-rules' option as argument to 'AM_INIT_AUTOMAKE'. * Call the 'AM_SILENT_RULES' macro from within the 'configure.ac' file. It is not possible to instead specify 'silent-rules' in a 'Makefile.am' file. If the developer has done either of the above, then the user of the package may influence the verbosity at 'configure' run time as well as at 'make' run time: * Passing '--enable-silent-rules' to 'configure' will cause build rules to be less verbose; the option '--disable-silent-rules' will cause normal verbose output. * At 'make' run time, the default chosen at 'configure' time may be overridden: 'make V=1' will produce verbose output, 'make V=0' less verbose output. Note that silent rules are _disabled_ by default; the user must enable them explicitly at either 'configure' run time or at 'make' run time. We think that this is a good policy, since it provides the casual user with enough information to prepare a good bug report in case anything breaks. Still, notwithstanding the rationales above, a developer who wants to make silent rules enabled by default in his own package can do so by adding a 'yes' argument to the 'AM_SILENT_RULES' call in 'configure.ac'. We advise against this approach, though. Users who prefer to have silent rules enabled by default can edit their 'config.site' file to make the variable 'enable_silent_rules' default to 'yes'. This should still allow disabling silent rules at 'configure' time and at 'make' time. For portability to different 'make' implementations, package authors are advised to not set the variable 'V' inside the 'Makefile.am' file, to allow the user to override the value for subdirectories as well. The current implementation of this feature normally uses nested variable expansion '$(VAR1$(V))', a 'Makefile' feature that is not required by POSIX 2008 but is widely supported in practice. The 'silent-rules' option thus turns off warnings about recursive variable expansion, which are in turn enabled by '-Wportability' (*note automake Invocation::). On the rare 'make' implementations that do not support nested variable expansion, whether rules are silent is always determined at configure time, and cannot be overridden at make time. Future versions of POSIX are likely to require nested variable expansion, so this minor limitation should go away with time. To extend the silent mode to your own rules, you have two choices: * You can use the predefined variable 'AM_V_GEN' as a prefix to commands that should output a status line in silent mode, and 'AM_V_at' as a prefix to commands that should not output anything in silent mode. When output is to be verbose, both of these variables will expand to the empty string. * You can add your own variables, so strings of your own choice are shown. The following snippet shows how you would define your own equivalent of 'AM_V_GEN': pkg_verbose = $(pkg_verbose_@AM_V@) pkg_verbose_ = $(pkg_verbose_@AM_DEFAULT_V@) pkg_verbose_0 = @echo PKG-GEN $@; foo: foo.in $(pkg_verbose)cp $(srcdir)/foo.in $@ As a final note, observe that, even when silent rules are enabled, the '--no-print-directory' option is still required with GNU 'make' if the "Entering/Leaving directory ..." messages are to be disabled. 22 The effect of '--gnu' and '--gnits' ************************************** The '--gnu' option (or 'gnu' in the 'AUTOMAKE_OPTIONS' variable) causes 'automake' to check the following: * The files 'INSTALL', 'NEWS', 'README', 'AUTHORS', and 'ChangeLog', plus one of 'COPYING.LIB', 'COPYING.LESSER' or 'COPYING', are required at the topmost directory of the package. If the '--add-missing' option is given, 'automake' will add a generic version of the 'INSTALL' file as well as the 'COPYING' file containing the text of the current version of the GNU General Public License existing at the time of this Automake release (version 3 as this is written, ). However, an existing 'COPYING' file will never be overwritten by 'automake'. * The options 'no-installman' and 'no-installinfo' are prohibited. Note that this option will be extended in the future to do even more checking; it is advisable to be familiar with the precise requirements of the GNU standards. Also, '--gnu' can require certain non-standard GNU programs to exist for use by various maintainer-only rules; for instance, in the future 'pathchk' might be required for 'make dist'. The '--gnits' option does everything that '--gnu' does, and checks the following as well: * 'make installcheck' will check to make sure that the '--help' and '--version' really print a usage message and a version string, respectively. This is the 'std-options' option (*note Options::). * 'make dist' will check to make sure the 'NEWS' file has been updated to the current version. * 'VERSION' is checked to make sure its format complies with Gnits standards. * If 'VERSION' indicates that this is an alpha release, and the file 'README-alpha' appears in the topmost directory of a package, then it is included in the distribution. This is done in '--gnits' mode, and no other, because this mode is the only one where version number formats are constrained, and hence the only mode where Automake can automatically determine whether 'README-alpha' should be included. * The file 'THANKS' is required. 23 The effect of '--cygnus' *************************** _The features described in this section are deprecated; you must not use any of them in new code, and should remove their use from older but still maintained code: they will be withdrawn in a future Automake release._ Some packages, notably GNU GCC and GNU gdb, used to have a build environment originally written at Cygnus Support (subsequently renamed Cygnus Solutions, and then later purchased by Red Hat). Packages with this ancestry are sometimes referred to as "Cygnus" trees. A Cygnus tree has slightly different rules for how a 'Makefile.in' is to be constructed. Passing '--cygnus' to 'automake' will cause any generated 'Makefile.in' to comply with Cygnus rules. Here are the precise effects of '--cygnus': * The 'foreign' strictness is implied. * The options 'no-installinfo', 'no-dependencies' and 'no-dist' are implied (*note Options::). * The macro 'AM_MAINTAINER_MODE' is required. * Info files are always created in the build directory, and not in the source directory. Packages that don't use the 'cygnus' option can emulate this effect by using the 'no-installinfo' option and listing the generated info files in the 'CLEANFILES' variable. * 'texinfo.tex' is not required if a Texinfo source file is specified. The assumption is that the file will be supplied, but in a place that Automake cannot find - it is an artifact of how Cygnus packages are typically bundled. This effect can be emulated in packages not using the 'cygnus' option with a proper definition of the 'TEXINFO_TEX' variable (*note Texinfo::). * Certain tools will be searched for in the build tree as well as in the user's 'PATH'. These tools are 'runtest', 'expect', 'makeinfo' and 'texi2dvi'. * The 'check' target doesn't depend on 'all'. 24 When Automake Isn't Enough ***************************** In some situations, where Automake is not up to one task, one has to resort to handwritten rules or even handwritten 'Makefile's. 24.1 Extending Automake Rules ============================= With some minor exceptions (for example '_PROGRAMS' variables, 'TESTS', or 'XFAIL_TESTS') being rewritten to append '$(EXEEXT)'), the contents of a 'Makefile.am' is copied to 'Makefile.in' verbatim. These copying semantics mean that many problems can be worked around by simply adding some 'make' variables and rules to 'Makefile.am'. Automake will ignore these additions. Since a 'Makefile.in' is built from data gathered from three different places ('Makefile.am', 'configure.ac', and 'automake' itself), it is possible to have conflicting definitions of rules or variables. When building 'Makefile.in' the following priorities are respected by 'automake' to ensure the user always has the last word: * User defined variables in 'Makefile.am' have priority over variables 'AC_SUBST'ed from 'configure.ac', and 'AC_SUBST'ed variables have priority over 'automake'-defined variables. * As far as rules are concerned, a user-defined rule overrides any 'automake'-defined rule for the same target. These overriding semantics make it possible to fine tune some default settings of Automake, or replace some of its rules. Overriding Automake rules is often inadvisable, particularly in the topmost directory of a package with subdirectories. The '-Woverride' option (*note automake Invocation::) comes in handy to catch overridden definitions. Note that Automake does not make any distinction between rules with commands and rules that only specify dependencies. So it is not possible to append new dependencies to an 'automake'-defined target without redefining the entire rule. However, various useful targets have a '-local' version you can specify in your 'Makefile.am'. Automake will supplement the standard target with these user-supplied targets. The targets that support a local version are 'all', 'info', 'dvi', 'ps', 'pdf', 'html', 'check', 'install-data', 'install-dvi', 'install-exec', 'install-html', 'install-info', 'install-pdf', 'install-ps', 'uninstall', 'installdirs', 'installcheck' and the various 'clean' targets ('mostlyclean', 'clean', 'distclean', and 'maintainer-clean'). Note that there are no 'uninstall-exec-local' or 'uninstall-data-local' targets; just use 'uninstall-local'. It doesn't make sense to uninstall just data or just executables. For instance, here is one way to erase a subdirectory during 'make clean' (*note Clean::). clean-local: -rm -rf testSubDir You may be tempted to use 'install-data-local' to install a file to some hard-coded location, but you should avoid this (*note Hard-Coded Install Paths::). With the '-local' targets, there is no particular guarantee of execution order; typically, they are run early, but with parallel make, there is no way to be sure of that. In contrast, some rules also have a way to run another rule, called a "hook"; hooks are always executed after the main rule's work is done. The hook is named after the principal target, with '-hook' appended. The targets allowing hooks are 'install-data', 'install-exec', 'uninstall', 'dist', and 'distcheck'. For instance, here is how to create a hard link to an installed program: install-exec-hook: ln $(DESTDIR)$(bindir)/program$(EXEEXT) \ $(DESTDIR)$(bindir)/proglink$(EXEEXT) Although cheaper and more portable than symbolic links, hard links will not work everywhere (for instance, OS/2 does not have 'ln'). Ideally you should fall back to 'cp -p' when 'ln' does not work. An easy way, if symbolic links are acceptable to you, is to add 'AC_PROG_LN_S' to 'configure.ac' (*note Particular Program Checks: (autoconf)Particular Programs.) and use '$(LN_S)' in 'Makefile.am'. For instance, here is how you could install a versioned copy of a program using '$(LN_S)': install-exec-hook: cd $(DESTDIR)$(bindir) && \ mv -f prog$(EXEEXT) prog-$(VERSION)$(EXEEXT) && \ $(LN_S) prog-$(VERSION)$(EXEEXT) prog$(EXEEXT) Note that we rename the program so that a new version will erase the symbolic link, not the real binary. Also we 'cd' into the destination directory in order to create relative links. When writing 'install-exec-hook' or 'install-data-hook', please bear in mind that the exec/data distinction is based on the installation directory, not on the primary used (*note The Two Parts of Install::). So a 'foo_SCRIPTS' will be installed by 'install-data', and a 'barexec_SCRIPTS' will be installed by 'install-exec'. You should define your hooks consequently. 24.2 Third-Party 'Makefile's ============================ In most projects all 'Makefile's are generated by Automake. In some cases, however, projects need to embed subdirectories with handwritten 'Makefile's. For instance, one subdirectory could be a third-party project with its own build system, not using Automake. It is possible to list arbitrary directories in 'SUBDIRS' or 'DIST_SUBDIRS' provided each of these directories has a 'Makefile' that recognizes all the following recursive targets. When a user runs one of these targets, that target is run recursively in all subdirectories. This is why it is important that even third-party 'Makefile's support them. 'all' Compile the entire package. This is the default target in Automake-generated 'Makefile's, but it does not need to be the default in third-party 'Makefile's. 'distdir' Copy files to distribute into '$(distdir)', before a tarball is constructed. Of course this target is not required if the 'no-dist' option (*note Options::) is used. The variables '$(top_distdir)' and '$(distdir)' (*note The dist Hook::) will be passed from the outer package to the subpackage when the 'distdir' target is invoked. These two variables have been adjusted for the directory that is being recursed into, so they are ready to use. 'install' 'install-data' 'install-exec' 'uninstall' Install or uninstall files (*note Install::). 'install-dvi' 'install-html' 'install-info' 'install-ps' 'install-pdf' Install only some specific documentation format (*note Texinfo::). 'installdirs' Create install directories, but do not install any files. 'check' 'installcheck' Check the package (*note Tests::). 'mostlyclean' 'clean' 'distclean' 'maintainer-clean' Cleaning rules (*note Clean::). 'dvi' 'pdf' 'ps' 'info' 'html' Build the documentation in various formats (*note Texinfo::). 'tags' 'ctags' Build 'TAGS' and 'CTAGS' (*note Tags::). If you have ever used Gettext in a project, this is a good example of how third-party 'Makefile's can be used with Automake. The 'Makefile's 'gettextize' puts in the 'po/' and 'intl/' directories are handwritten 'Makefile's that implement all these targets. That way they can be added to 'SUBDIRS' in Automake packages. Directories that are only listed in 'DIST_SUBDIRS' but not in 'SUBDIRS' need only the 'distclean', 'maintainer-clean', and 'distdir' rules (*note Conditional Subdirectories::). Usually, many of these rules are irrelevant to the third-party subproject, but they are required for the whole package to work. It's OK to have a rule that does nothing, so if you are integrating a third-party project with no documentation or tag support, you could simply augment its 'Makefile' as follows: EMPTY_AUTOMAKE_TARGETS = dvi pdf ps info html tags ctags .PHONY: $(EMPTY_AUTOMAKE_TARGETS) $(EMPTY_AUTOMAKE_TARGETS): Another aspect of integrating third-party build systems is whether they support VPATH builds (*note VPATH Builds::). Obviously if the subpackage does not support VPATH builds the whole package will not support VPATH builds. This in turns means that 'make distcheck' will not work, because it relies on VPATH builds. Some people can live without this (actually, many Automake users have never heard of 'make distcheck'). Other people may prefer to revamp the existing 'Makefile's to support VPATH. Doing so does not necessarily require Automake, only Autoconf is needed (*note Build Directories: (autoconf)Build Directories.). The necessary substitutions: '@srcdir@', '@top_srcdir@', and '@top_builddir@' are defined by 'configure' when it processes a 'Makefile' (*note Preset Output Variables: (autoconf)Preset Output Variables.), they are not computed by the Makefile like the aforementioned '$(distdir)' and '$(top_distdir)' variables. It is sometimes inconvenient to modify a third-party 'Makefile' to introduce the above required targets. For instance, one may want to keep the third-party sources untouched to ease upgrades to new versions. Here are two other ideas. If GNU make is assumed, one possibility is to add to that subdirectory a 'GNUmakefile' that defines the required targets and includes the third-party 'Makefile'. For this to work in VPATH builds, 'GNUmakefile' must lie in the build directory; the easiest way to do this is to write a 'GNUmakefile.in' instead, and have it processed with 'AC_CONFIG_FILES' from the outer package. For example if we assume 'Makefile' defines all targets except the documentation targets, and that the 'check' target is actually called 'test', we could write 'GNUmakefile' (or 'GNUmakefile.in') like this: # First, include the real Makefile include Makefile # Then, define the other targets needed by Automake Makefiles. .PHONY: dvi pdf ps info html check dvi pdf ps info html: check: test A similar idea that does not use 'include' is to write a proxy 'Makefile' that dispatches rules to the real 'Makefile', either with '$(MAKE) -f Makefile.real $(AM_MAKEFLAGS) target' (if it's OK to rename the original 'Makefile') or with 'cd subdir && $(MAKE) $(AM_MAKEFLAGS) target' (if it's OK to store the subdirectory project one directory deeper). The good news is that this proxy 'Makefile' can be generated with Automake. All we need are '-local' targets (*note Extending::) that perform the dispatch. Of course the other Automake features are available, so you could decide to let Automake perform distribution or installation. Here is a possible 'Makefile.am': all-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) all check-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) test clean-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) clean # Assuming the package knows how to install itself install-data-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) install-data install-exec-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) install-exec uninstall-local: cd subdir && $(MAKE) $(AM_MAKEFLAGS) uninstall # Distribute files from here. EXTRA_DIST = subdir/Makefile subdir/program.c ... Pushing this idea to the extreme, it is also possible to ignore the subproject build system and build everything from this proxy 'Makefile.am'. This might sound very sensible if you need VPATH builds but the subproject does not support them. 25 Distributing 'Makefile.in's ****************************** Automake places no restrictions on the distribution of the resulting 'Makefile.in's. We still encourage software authors to distribute their work under terms like those of the GPL, but doing so is not required to use Automake. Some of the files that can be automatically installed via the '--add-missing' switch do fall under the GPL. However, these also have a special exception allowing you to distribute them with your package, regardless of the licensing you choose. 26 Automake API Versioning ************************** New Automake releases usually include bug fixes and new features. Unfortunately they may also introduce new bugs and incompatibilities. This makes four reasons why a package may require a particular Automake version. Things get worse when maintaining a large tree of packages, each one requiring a different version of Automake. In the past, this meant that any developer (and sometimes users) had to install several versions of Automake in different places, and switch '$PATH' appropriately for each package. Starting with version 1.6, Automake installs versioned binaries. This means you can install several versions of Automake in the same '$prefix', and can select an arbitrary Automake version by running 'automake-1.6' or 'automake-1.7' without juggling with '$PATH'. Furthermore, 'Makefile''s generated by Automake 1.6 will use 'automake-1.6' explicitly in their rebuild rules. The number '1.6' in 'automake-1.6' is Automake's API version, not Automake's version. If a bug fix release is made, for instance Automake 1.6.1, the API version will remain 1.6. This means that a package that works with Automake 1.6 should also work with 1.6.1; after all, this is what people expect from bug fix releases. If your package relies on a feature or a bug fix introduced in a release, you can pass this version as an option to Automake to ensure older releases will not be used. For instance, use this in your 'configure.ac': AM_INIT_AUTOMAKE([1.6.1]) dnl Require Automake 1.6.1 or better. or, in a particular 'Makefile.am': AUTOMAKE_OPTIONS = 1.6.1 # Require Automake 1.6.1 or better. Automake will print an error message if its version is older than the requested version. What is in the API ================== Automake's programming interface is not easy to define. Basically it should include at least all *documented* variables and targets that a 'Makefile.am' author can use, any behavior associated with them (e.g., the places where '-hook''s are run), the command line interface of 'automake' and 'aclocal', ... What is not in the API ====================== Every undocumented variable, target, or command line option, is not part of the API. You should avoid using them, as they could change from one version to the other (even in bug fix releases, if this helps to fix a bug). If it turns out you need to use such an undocumented feature, contact and try to get it documented and exercised by the test-suite. 27 Upgrading a Package to a Newer Automake Version ************************************************** Automake maintains three kind of files in a package. * 'aclocal.m4' * 'Makefile.in's * auxiliary tools like 'install-sh' or 'py-compile' 'aclocal.m4' is generated by 'aclocal' and contains some Automake-supplied M4 macros. Auxiliary tools are installed by 'automake --add-missing' when needed. 'Makefile.in's are built from 'Makefile.am' by 'automake', and rely on the definitions of the M4 macros put in 'aclocal.m4' as well as the behavior of the auxiliary tools installed. Because all these files are closely related, it is important to regenerate all of them when upgrading to a newer Automake release. The usual way to do that is aclocal # with any option needed (such a -I m4) autoconf automake --add-missing --force-missing or more conveniently: autoreconf -vfi The use of '--force-missing' ensures that auxiliary tools will be overridden by new versions (*note automake Invocation::). It is important to regenerate all these files each time Automake is upgraded, even between bug fixes releases. For instance, it is not unusual for a bug fix to involve changes to both the rules generated in 'Makefile.in' and the supporting M4 macros copied to 'aclocal.m4'. Presently 'automake' is able to diagnose situations where 'aclocal.m4' has been generated with another version of 'aclocal'. However it never checks whether auxiliary scripts are up-to-date. In other words, 'automake' will tell you when 'aclocal' needs to be rerun, but it will never diagnose a missing '--force-missing'. Before upgrading to a new major release, it is a good idea to read the file 'NEWS'. This file lists all changes between releases: new features, obsolete constructs, known incompatibilities, and workarounds. 28 Frequently Asked Questions about Automake ******************************************** This chapter covers some questions that often come up on the mailing lists. 28.1 CVS and generated files ============================ Background: distributed generated Files --------------------------------------- Packages made with Autoconf and Automake ship with some generated files like 'configure' or 'Makefile.in'. These files were generated on the developer's host and are distributed so that end-users do not have to install the maintainer tools required to rebuild them. Other generated files like Lex scanners, Yacc parsers, or Info documentation, are usually distributed on similar grounds. Automake outputs rules in 'Makefile's to rebuild these files. For instance, 'make' will run 'autoconf' to rebuild 'configure' whenever 'configure.ac' is changed. This makes development safer by ensuring a 'configure' is never out-of-date with respect to 'configure.ac'. As generated files shipped in packages are up-to-date, and because 'tar' preserves times-tamps, these rebuild rules are not triggered when a user unpacks and builds a package. Background: CVS and Timestamps ------------------------------ Unless you use CVS keywords (in which case files must be updated at commit time), CVS preserves timestamp during 'cvs commit' and 'cvs import -d' operations. When you check out a file using 'cvs checkout' its timestamp is set to that of the revision that is being checked out. However, during 'cvs update', files will have the date of the update, not the original timestamp of this revision. This is meant to make sure that 'make' notices sources files have been updated. This timestamp shift is troublesome when both sources and generated files are kept under CVS. Because CVS processes files in lexical order, 'configure.ac' will appear newer than 'configure' after a 'cvs update' that updates both files, even if 'configure' was newer than 'configure.ac' when it was checked in. Calling 'make' will then trigger a spurious rebuild of 'configure'. Living with CVS in Autoconfiscated Projects ------------------------------------------- There are basically two clans amongst maintainers: those who keep all distributed files under CVS, including generated files, and those who keep generated files _out_ of CVS. All Files in CVS ................ * The CVS repository contains all distributed files so you know exactly what is distributed, and you can checkout any prior version entirely. * Maintainers can see how generated files evolve (for instance, you can see what happens to your 'Makefile.in's when you upgrade Automake and make sure they look OK). * Users do not need the autotools to build a checkout of the project, it works just like a released tarball. * If users use 'cvs update' to update their copy, instead of 'cvs checkout' to fetch a fresh one, timestamps will be inaccurate. Some rebuild rules will be triggered and attempt to run developer tools such as 'autoconf' or 'automake'. Actually, calls to such tools are all wrapped into a call to the 'missing' script discussed later (*note maintainer-mode::). 'missing' will take care of fixing the timestamps when these tools are not installed, so that the build can continue. * In distributed development, developers are likely to have different version of the maintainer tools installed. In this case rebuilds triggered by timestamp lossage will lead to spurious changes to generated files. There are several solutions to this: * All developers should use the same versions, so that the rebuilt files are identical to files in CVS. (This starts to be difficult when each project you work on uses different versions.) * Or people use a script to fix the timestamp after a checkout (the GCC folks have such a script). * Or 'configure.ac' uses 'AM_MAINTAINER_MODE', which will disable all these rebuild rules by default. This is further discussed in *note maintainer-mode::. * Although we focused on spurious rebuilds, the converse can also happen. CVS's timestamp handling can also let you think an out-of-date file is up-to-date. For instance, suppose a developer has modified 'Makefile.am' and has rebuilt 'Makefile.in', and then decides to do a last-minute change to 'Makefile.am' right before checking in both files (without rebuilding 'Makefile.in' to account for the change). This last change to 'Makefile.am' makes the copy of 'Makefile.in' out-of-date. Since CVS processes files alphabetically, when another developer 'cvs update's his or her tree, 'Makefile.in' will happen to be newer than 'Makefile.am'. This other developer will not see that 'Makefile.in' is out-of-date. Generated Files out of CVS .......................... One way to get CVS and 'make' working peacefully is to never store generated files in CVS, i.e., do not CVS-control files that are 'Makefile' targets (also called _derived_ files). This way developers are not annoyed by changes to generated files. It does not matter if they all have different versions (assuming they are compatible, of course). And finally, timestamps are not lost, changes to sources files can't be missed as in the 'Makefile.am'/'Makefile.in' example discussed earlier. The drawback is that the CVS repository is not an exact copy of what is distributed and that users now need to install various development tools (maybe even specific versions) before they can build a checkout. But, after all, CVS's job is versioning, not distribution. Allowing developers to use different versions of their tools can also hide bugs during distributed development. Indeed, developers will be using (hence testing) their own generated files, instead of the generated files that will be released actually. The developer who prepares the tarball might be using a version of the tool that produces bogus output (for instance a non-portable C file), something other developers could have noticed if they weren't using their own versions of this tool. Third-party Files ----------------- Another class of files not discussed here (because they do not cause timestamp issues) are files that are shipped with a package, but maintained elsewhere. For instance, tools like 'gettextize' and 'autopoint' (from Gettext) or 'libtoolize' (from Libtool), will install or update files in your package. These files, whether they are kept under CVS or not, raise similar concerns about version mismatch between developers' tools. The Gettext manual has a section about this, see *note CVS Issues: (gettext)CVS Issues. 28.2 'missing' and 'AM_MAINTAINER_MODE' ======================================= 'missing' --------- The 'missing' script is a wrapper around several maintainer tools, designed to warn users if a maintainer tool is required but missing. Typical maintainer tools are 'autoconf', 'automake', 'bison', etc. Because file generated by these tools are shipped with the other sources of a package, these tools shouldn't be required during a user build and they are not checked for in 'configure'. However, if for some reason a rebuild rule is triggered and involves a missing tool, 'missing' will notice it and warn the user. Besides the warning, when a tool is missing, 'missing' will attempt to fix timestamps in a way that allows the build to continue. For instance, 'missing' will touch 'configure' if 'autoconf' is not installed. When all distributed files are kept under version control, this feature of 'missing' allows a user _with no maintainer tools_ to build a package off its version control repository, bypassing any timestamp inconsistency (implied by e.g. 'cvs update' or 'git clone'). If the required tool is installed, 'missing' will run it and won't attempt to continue after failures. This is correct during development: developers love fixing failures. However, users with wrong versions of maintainer tools may get an error when the rebuild rule is spuriously triggered, halting the build. This failure to let the build continue is one of the arguments of the 'AM_MAINTAINER_MODE' advocates. 'AM_MAINTAINER_MODE' -------------------- 'AM_MAINTAINER_MODE' allows you to choose whether the so called "rebuild rules" should be enabled or disabled. With 'AM_MAINTAINER_MODE([enable])', they are enabled by default, otherwise they are disabled by default. In the latter case, if you have 'AM_MAINTAINER_MODE' in 'configure.ac', and run './configure && make', then 'make' will *never* attempt to rebuild 'configure', 'Makefile.in's, Lex or Yacc outputs, etc. I.e., this disables build rules for files that are usually distributed and that users should normally not have to update. The user can override the default setting by passing either '--enable-maintainer-mode' or '--disable-maintainer-mode' to 'configure'. People use 'AM_MAINTAINER_MODE' either because they do not want their users (or themselves) annoyed by timestamps lossage (*note CVS::), or because they simply can't stand the rebuild rules and prefer running maintainer tools explicitly. 'AM_MAINTAINER_MODE' also allows you to disable some custom build rules conditionally. Some developers use this feature to disable rules that need exotic tools that users may not have available. Several years ago François Pinard pointed out several arguments against this 'AM_MAINTAINER_MODE' macro. Most of them relate to insecurity. By removing dependencies you get non-dependable builds: changes to sources files can have no effect on generated files and this can be very confusing when unnoticed. He adds that security shouldn't be reserved to maintainers (what '--enable-maintainer-mode' suggests), on the contrary. If one user has to modify a 'Makefile.am', then either 'Makefile.in' should be updated or a warning should be output (this is what Automake uses 'missing' for) but the last thing you want is that nothing happens and the user doesn't notice it (this is what happens when rebuild rules are disabled by 'AM_MAINTAINER_MODE'). Jim Meyering, the inventor of the 'AM_MAINTAINER_MODE' macro was swayed by François's arguments, and got rid of 'AM_MAINTAINER_MODE' in all of his packages. Still many people continue to use 'AM_MAINTAINER_MODE', because it helps them working on projects where all files are kept under version control, and because 'missing' isn't enough if you have the wrong version of the tools. 28.3 Why doesn't Automake support wildcards? ============================================ Developers are lazy. They would often like to use wildcards in 'Makefile.am's, so that they would not need to remember to update 'Makefile.am's every time they add, delete, or rename a file. There are several objections to this: * When using CVS (or similar) developers need to remember they have to run 'cvs add' or 'cvs rm' anyway. Updating 'Makefile.am' accordingly quickly becomes a reflex. Conversely, if your application doesn't compile because you forgot to add a file in 'Makefile.am', it will help you remember to 'cvs add' it. * Using wildcards makes it easy to distribute files by mistake. For instance, some code a developer is experimenting with (a test case, say) that should not be part of the distribution. * Using wildcards it's easy to omit some files by mistake. For instance, one developer creates a new file, uses it in many places, but forgets to commit it. Another developer then checks out the incomplete project and is able to run 'make dist' successfully, even though a file is missing. By listing files, 'make dist' _will_ complain. * Wildcards are not portable to some non-GNU 'make' implementations, e.g., NetBSD 'make' will not expand globs such as '*' in prerequisites of a target. * Finally, it's really hard to _forget_ to add a file to 'Makefile.am': files that are not listed in 'Makefile.am' are not compiled or installed, so you can't even test them. Still, these are philosophical objections, and as such you may disagree, or find enough value in wildcards to dismiss all of them. Before you start writing a patch against Automake to teach it about wildcards, let's see the main technical issue: portability. Although '$(wildcard ...)' works with GNU 'make', it is not portable to other 'make' implementations. The only way Automake could support '$(wildcard ...)' is by expending '$(wildcard ...)' when 'automake' is run. The resulting 'Makefile.in's would be portable since they would list all files and not use '$(wildcard ...)'. However that means developers would need to remember to run 'automake' each time they add, delete, or rename files. Compared to editing 'Makefile.am', this is a very small gain. Sure, it's easier and faster to type 'automake; make' than to type 'emacs Makefile.am; make'. But nobody bothered enough to write a patch to add support for this syntax. Some people use scripts to generate file lists in 'Makefile.am' or in separate 'Makefile' fragments. Even if you don't care about portability, and are tempted to use '$(wildcard ...)' anyway because you target only GNU Make, you should know there are many places where Automake needs to know exactly which files should be processed. As Automake doesn't know how to expand '$(wildcard ...)', you cannot use it in these places. '$(wildcard ...)' is a black box comparable to 'AC_SUBST'ed variables as far Automake is concerned. You can get warnings about '$(wildcard ...') constructs using the '-Wportability' flag. 28.4 Limitations on File Names ============================== Automake attempts to support all kinds of file names, even those that contain unusual characters or are unusually long. However, some limitations are imposed by the underlying operating system and tools. Most operating systems prohibit the use of the null byte in file names, and reserve '/' as a directory separator. Also, they require that file names are properly encoded for the user's locale. Automake is subject to these limits. Portable packages should limit themselves to POSIX file names. These can contain ASCII letters and digits, '_', '.', and '-'. File names consist of components separated by '/'. File name components cannot begin with '-'. Portable POSIX file names cannot contain components that exceed a 14-byte limit, but nowadays it's normally safe to assume the more-generous XOPEN limit of 255 bytes. POSIX limits file names to 255 bytes (XOPEN allows 1023 bytes), but you may want to limit a source tarball to file names of 99 bytes to avoid interoperability problems with old versions of 'tar'. If you depart from these rules (e.g., by using non-ASCII characters in file names, or by using lengthy file names), your installers may have problems for reasons unrelated to Automake. However, if this does not concern you, you should know about the limitations imposed by Automake itself. These limitations are undesirable, but some of them seem to be inherent to underlying tools like Autoconf, Make, M4, and the shell. They fall into three categories: install directories, build directories, and file names. The following characters: newline " # $ ' ` should not appear in the names of install directories. For example, the operand of 'configure''s '--prefix' option should not contain these characters. Build directories suffer the same limitations as install directories, and in addition should not contain the following characters: & @ \ For example, the full name of the directory containing the source files should not contain these characters. Source and installation file names like 'main.c' are limited even further: they should conform to the POSIX/XOPEN rules described above. In addition, if you plan to port to non-POSIX environments, you should avoid file names that differ only in case (e.g., 'makefile' and 'Makefile'). Nowadays it is no longer worth worrying about the 8.3 limits of DOS file systems. 28.5 Files left in build directory after distclean ================================================== This is a diagnostic you might encounter while running 'make distcheck'. As explained in *note Checking the Distribution::, 'make distcheck' attempts to build and check your package for errors like this one. 'make distcheck' will perform a 'VPATH' build of your package (*note VPATH Builds::), and then call 'make distclean'. Files left in the build directory after 'make distclean' has run are listed after this error. This diagnostic really covers two kinds of errors: * files that are forgotten by distclean; * distributed files that are erroneously rebuilt. The former left-over files are not distributed, so the fix is to mark them for cleaning (*note Clean::), this is obvious and doesn't deserve more explanations. The latter bug is not always easy to understand and fix, so let's proceed with an example. Suppose our package contains a program for which we want to build a man page using 'help2man'. GNU 'help2man' produces simple manual pages from the '--help' and '--version' output of other commands (*note Overview: (help2man)Top.). Because we don't want to force our users to install 'help2man', we decide to distribute the generated man page using the following setup. # This Makefile.am is bogus. bin_PROGRAMS = foo foo_SOURCES = foo.c dist_man_MANS = foo.1 foo.1: foo$(EXEEXT) help2man --output=foo.1 ./foo$(EXEEXT) This will effectively distribute the man page. However, 'make distcheck' will fail with: ERROR: files left in build directory after distclean: ./foo.1 Why was 'foo.1' rebuilt? Because although distributed, 'foo.1' depends on a non-distributed built file: 'foo$(EXEEXT)'. 'foo$(EXEEXT)' is built by the user, so it will always appear to be newer than the distributed 'foo.1'. 'make distcheck' caught an inconsistency in our package. Our intent was to distribute 'foo.1' so users do not need to install 'help2man', however since this rule causes this file to be always rebuilt, users _do_ need 'help2man'. Either we should ensure that 'foo.1' is not rebuilt by users, or there is no point in distributing 'foo.1'. More generally, the rule is that distributed files should never depend on non-distributed built files. If you distribute something generated, distribute its sources. One way to fix the above example, while still distributing 'foo.1' is to not depend on 'foo$(EXEEXT)'. For instance, assuming 'foo --version' and 'foo --help' do not change unless 'foo.c' or 'configure.ac' change, we could write the following 'Makefile.am': bin_PROGRAMS = foo foo_SOURCES = foo.c dist_man_MANS = foo.1 foo.1: foo.c $(top_srcdir)/configure.ac $(MAKE) $(AM_MAKEFLAGS) foo$(EXEEXT) help2man --output=foo.1 ./foo$(EXEEXT) This way, 'foo.1' will not get rebuilt every time 'foo$(EXEEXT)' changes. The 'make' call makes sure 'foo$(EXEEXT)' is up-to-date before 'help2man'. Another way to ensure this would be to use separate directories for binaries and man pages, and set 'SUBDIRS' so that binaries are built before man pages. We could also decide not to distribute 'foo.1'. In this case it's fine to have 'foo.1' dependent upon 'foo$(EXEEXT)', since both will have to be rebuilt. However it would be impossible to build the package in a cross-compilation, because building 'foo.1' involves an _execution_ of 'foo$(EXEEXT)'. Another context where such errors are common is when distributed files are built by tools that are built by the package. The pattern is similar: distributed-file: built-tools distributed-sources build-command should be changed to distributed-file: distributed-sources $(MAKE) $(AM_MAKEFLAGS) built-tools build-command or you could choose not to distribute 'distributed-file', if cross-compilation does not matter. The points made through these examples are worth a summary: * Distributed files should never depend upon non-distributed built files. * Distributed files should be distributed with all their dependencies. * If a file is _intended_ to be rebuilt by users, then there is no point in distributing it. For desperate cases, it's always possible to disable this check by setting 'distcleancheck_listfiles' as documented in *note Checking the Distribution::. Make sure you do understand the reason why 'make distcheck' complains before you do this. 'distcleancheck_listfiles' is a way to _hide_ errors, not to fix them. You can always do better. 28.6 Flag Variables Ordering ============================ What is the difference between 'AM_CFLAGS', 'CFLAGS', and 'mumble_CFLAGS'? Why does 'automake' output 'CPPFLAGS' after 'AM_CPPFLAGS' on compile lines? Shouldn't it be the converse? My 'configure' adds some warning flags into 'CXXFLAGS'. In one 'Makefile.am' I would like to append a new flag, however if I put the flag into 'AM_CXXFLAGS' it is prepended to the other flags, not appended. Compile Flag Variables ---------------------- This section attempts to answer all the above questions. We will mostly discuss 'CPPFLAGS' in our examples, but actually the answer holds for all the compile flags used in Automake: 'CCASFLAGS', 'CFLAGS', 'CPPFLAGS', 'CXXFLAGS', 'FCFLAGS', 'FFLAGS', 'GCJFLAGS', 'LDFLAGS', 'LFLAGS', 'LIBTOOLFLAGS', 'OBJCFLAGS', 'RFLAGS', 'UPCFLAGS', and 'YFLAGS'. 'CPPFLAGS', 'AM_CPPFLAGS', and 'mumble_CPPFLAGS' are three variables that can be used to pass flags to the C preprocessor (actually these variables are also used for other languages like C++ or preprocessed Fortran). 'CPPFLAGS' is the user variable (*note User Variables::), 'AM_CPPFLAGS' is the Automake variable, and 'mumble_CPPFLAGS' is the variable specific to the 'mumble' target (we call this a per-target variable, *note Program and Library Variables::). Automake always uses two of these variables when compiling C sources files. When compiling an object file for the 'mumble' target, the first variable will be 'mumble_CPPFLAGS' if it is defined, or 'AM_CPPFLAGS' otherwise. The second variable is always 'CPPFLAGS'. In the following example, bin_PROGRAMS = foo bar foo_SOURCES = xyz.c bar_SOURCES = main.c foo_CPPFLAGS = -DFOO AM_CPPFLAGS = -DBAZ 'xyz.o' will be compiled with '$(foo_CPPFLAGS) $(CPPFLAGS)', (because 'xyz.o' is part of the 'foo' target), while 'main.o' will be compiled with '$(AM_CPPFLAGS) $(CPPFLAGS)' (because there is no per-target variable for target 'bar'). The difference between 'mumble_CPPFLAGS' and 'AM_CPPFLAGS' being clear enough, let's focus on 'CPPFLAGS'. 'CPPFLAGS' is a user variable, i.e., a variable that users are entitled to modify in order to compile the package. This variable, like many others, is documented at the end of the output of 'configure --help'. For instance, someone who needs to add '/home/my/usr/include' to the C compiler's search path would configure a package with ./configure CPPFLAGS='-I /home/my/usr/include' and this flag would be propagated to the compile rules of all 'Makefile's. It is also not uncommon to override a user variable at 'make'-time. Many installers do this with 'prefix', but this can be useful with compiler flags too. For instance, if, while debugging a C++ project, you need to disable optimization in one specific object file, you can run something like rm file.o make CXXFLAGS=-O0 file.o make The reason '$(CPPFLAGS)' appears after '$(AM_CPPFLAGS)' or '$(mumble_CPPFLAGS)' in the compile command is that users should always have the last say. It probably makes more sense if you think about it while looking at the 'CXXFLAGS=-O0' above, which should supersede any other switch from 'AM_CXXFLAGS' or 'mumble_CXXFLAGS' (and this of course replaces the previous value of 'CXXFLAGS'). You should never redefine a user variable such as 'CPPFLAGS' in 'Makefile.am'. Use 'automake -Woverride' to diagnose such mistakes. Even something like CPPFLAGS = -DDATADIR=\"$(datadir)\" @CPPFLAGS@ is erroneous. Although this preserves 'configure''s value of 'CPPFLAGS', the definition of 'DATADIR' will disappear if a user attempts to override 'CPPFLAGS' from the 'make' command line. AM_CPPFLAGS = -DDATADIR=\"$(datadir)\" is all that is needed here if no per-target flags are used. You should not add options to these user variables within 'configure' either, for the same reason. Occasionally you need to modify these variables to perform a test, but you should reset their values afterwards. In contrast, it is OK to modify the 'AM_' variables within 'configure' if you 'AC_SUBST' them, but it is rather rare that you need to do this, unless you really want to change the default definitions of the 'AM_' variables in all 'Makefile's. What we recommend is that you define extra flags in separate variables. For instance, you may write an Autoconf macro that computes a set of warning options for the C compiler, and 'AC_SUBST' them in 'WARNINGCFLAGS'; you may also have an Autoconf macro that determines which compiler and which linker flags should be used to link with library 'libfoo', and 'AC_SUBST' these in 'LIBFOOCFLAGS' and 'LIBFOOLDFLAGS'. Then, a 'Makefile.am' could use these variables as follows: AM_CFLAGS = $(WARNINGCFLAGS) bin_PROGRAMS = prog1 prog2 prog1_SOURCES = ... prog2_SOURCES = ... prog2_CFLAGS = $(LIBFOOCFLAGS) $(AM_CFLAGS) prog2_LDFLAGS = $(LIBFOOLDFLAGS) In this example both programs will be compiled with the flags substituted into '$(WARNINGCFLAGS)', and 'prog2' will additionally be compiled with the flags required to link with 'libfoo'. Note that listing 'AM_CFLAGS' in a per-target 'CFLAGS' variable is a common idiom to ensure that 'AM_CFLAGS' applies to every target in a 'Makefile.in'. Using variables like this gives you full control over the ordering of the flags. For instance, if there is a flag in $(WARNINGCFLAGS) that you want to negate for a particular target, you can use something like 'prog1_CFLAGS = $(AM_CFLAGS) -no-flag'. If all these flags had been forcefully appended to 'CFLAGS', there would be no way to disable one flag. Yet another reason to leave user variables to users. Finally, we have avoided naming the variable of the example 'LIBFOO_LDFLAGS' (with an underscore) because that would cause Automake to think that this is actually a per-target variable (like 'mumble_LDFLAGS') for some non-declared 'LIBFOO' target. Other Variables --------------- There are other variables in Automake that follow similar principles to allow user options. For instance, Texinfo rules (*note Texinfo::) use 'MAKEINFOFLAGS' and 'AM_MAKEINFOFLAGS'. Similarly, DejaGnu tests (*note DejaGnu Tests::) use 'RUNTESTDEFAULTFLAGS' and 'AM_RUNTESTDEFAULTFLAGS'. The tags and ctags rules (*note Tags::) use 'ETAGSFLAGS', 'AM_ETAGSFLAGS', 'CTAGSFLAGS', and 'AM_CTAGSFLAGS'. Java rules (*note Java::) use 'JAVACFLAGS' and 'AM_JAVACFLAGS'. None of these rules support per-target flags (yet). To some extent, even 'AM_MAKEFLAGS' (*note Subdirectories::) obeys this naming scheme. The slight difference is that 'MAKEFLAGS' is passed to sub-'make's implicitly by 'make' itself. However you should not think that all variables ending with 'FLAGS' follow this convention. For instance, 'DISTCHECK_CONFIGURE_FLAGS' (*note Checking the Distribution::) and 'ACLOCAL_AMFLAGS' (see *note Rebuilding:: and *note Local Macros::), are two variables that are only useful to the maintainer and have no user counterpart. 'ARFLAGS' (*note A Library::) is usually defined by Automake and has neither 'AM_' nor per-target cousin. Finally you should not think that the existence of a per-target variable implies the existance of an 'AM_' variable or of a user variable. For instance, the 'mumble_LDADD' per-target variable overrides the makefile-wide 'LDADD' variable (which is not a user variable), and 'mumble_LIBADD' exists only as a per-target variable. *Note Program and Library Variables::. 28.7 Why are object files sometimes renamed? ============================================ This happens when per-target compilation flags are used. Object files need to be renamed just in case they would clash with object files compiled from the same sources, but with different flags. Consider the following example. bin_PROGRAMS = true false true_SOURCES = generic.c true_CPPFLAGS = -DEXIT_CODE=0 false_SOURCES = generic.c false_CPPFLAGS = -DEXIT_CODE=1 Obviously the two programs are built from the same source, but it would be bad if they shared the same object, because 'generic.o' cannot be built with both '-DEXIT_CODE=0' _and_ '-DEXIT_CODE=1'. Therefore 'automake' outputs rules to build two different objects: 'true-generic.o' and 'false-generic.o'. 'automake' doesn't actually look whether source files are shared to decide if it must rename objects. It will just rename all objects of a target as soon as it sees per-target compilation flags used. It's OK to share object files when per-target compilation flags are not used. For instance, 'true' and 'false' will both use 'version.o' in the following example. AM_CPPFLAGS = -DVERSION=1.0 bin_PROGRAMS = true false true_SOURCES = true.c version.c false_SOURCES = false.c version.c Note that the renaming of objects is also affected by the '_SHORTNAME' variable (*note Program and Library Variables::). 28.8 Per-Object Flags Emulation =============================== One of my source files needs to be compiled with different flags. How do I do? Automake supports per-program and per-library compilation flags (see *note Program and Library Variables:: and *note Flag Variables Ordering::). With this you can define compilation flags that apply to all files compiled for a target. For instance, in bin_PROGRAMS = foo foo_SOURCES = foo.c foo.h bar.c bar.h main.c foo_CFLAGS = -some -flags 'foo-foo.o', 'foo-bar.o', and 'foo-main.o' will all be compiled with '-some -flags'. (If you wonder about the names of these object files, see *note Renamed Objects::.) Note that 'foo_CFLAGS' gives the flags to use when compiling all the C sources of the _program_ 'foo', it has nothing to do with 'foo.c' or 'foo-foo.o' specifically. What if 'foo.c' needs to be compiled into 'foo.o' using some specific flags, that none of the other files requires? Obviously per-program flags are not directly applicable here. Something like per-object flags are expected, i.e., flags that would be used only when creating 'foo-foo.o'. Automake does not support that, however this is easy to simulate using a library that contains only that object, and compiling this library with per-library flags. bin_PROGRAMS = foo foo_SOURCES = bar.c bar.h main.c foo_CFLAGS = -some -flags foo_LDADD = libfoo.a noinst_LIBRARIES = libfoo.a libfoo_a_SOURCES = foo.c foo.h libfoo_a_CFLAGS = -some -other -flags Here 'foo-bar.o' and 'foo-main.o' will all be compiled with '-some -flags', while 'libfoo_a-foo.o' will be compiled using '-some -other -flags'. Eventually, all three objects will be linked to form 'foo'. This trick can also be achieved using Libtool convenience libraries, for instance 'noinst_LTLIBRARIES = libfoo.la' (*note Libtool Convenience Libraries::). Another tempting idea to implement per-object flags is to override the compile rules 'automake' would output for these files. Automake will not define a rule for a target you have defined, so you could think about defining the 'foo-foo.o: foo.c' rule yourself. We recommend against this, because this is error prone. For instance, if you add such a rule to the first example, it will break the day you decide to remove 'foo_CFLAGS' (because 'foo.c' will then be compiled as 'foo.o' instead of 'foo-foo.o', *note Renamed Objects::). Also in order to support dependency tracking, the two '.o'/'.obj' extensions, and all the other flags variables involved in a compilation, you will end up modifying a copy of the rule previously output by 'automake' for this file. If a new release of Automake generates a different rule, your copy will need to be updated by hand. 28.9 Handling Tools that Produce Many Outputs ============================================= This section describes a 'make' idiom that can be used when a tool produces multiple output files. It is not specific to Automake and can be used in ordinary 'Makefile's. Suppose we have a program called 'foo' that will read one file called 'data.foo' and produce two files named 'data.c' and 'data.h'. We want to write a 'Makefile' rule that captures this one-to-two dependency. The naive rule is incorrect: # This is incorrect. data.c data.h: data.foo foo data.foo What the above rule really says is that 'data.c' and 'data.h' each depend on 'data.foo', and can each be built by running 'foo data.foo'. In other words it is equivalent to: # We do not want this. data.c: data.foo foo data.foo data.h: data.foo foo data.foo which means that 'foo' can be run twice. Usually it will not be run twice, because 'make' implementations are smart enough to check for the existence of the second file after the first one has been built; they will therefore detect that it already exists. However there are a few situations where it can run twice anyway: * The most worrying case is when running a parallel 'make'. If 'data.c' and 'data.h' are built in parallel, two 'foo data.foo' commands will run concurrently. This is harmful. * Another case is when the dependency (here 'data.foo') is (or depends upon) a phony target. A solution that works with parallel 'make' but not with phony dependencies is the following: data.c data.h: data.foo foo data.foo data.h: data.c The above rules are equivalent to data.c: data.foo foo data.foo data.h: data.foo data.c foo data.foo therefore a parallel 'make' will have to serialize the builds of 'data.c' and 'data.h', and will detect that the second is no longer needed once the first is over. Using this pattern is probably enough for most cases. However it does not scale easily to more output files (in this scheme all output files must be totally ordered by the dependency relation), so we will explore a more complicated solution. Another idea is to write the following: # There is still a problem with this one. data.c: data.foo foo data.foo data.h: data.c The idea is that 'foo data.foo' is run only when 'data.c' needs to be updated, but we further state that 'data.h' depends upon 'data.c'. That way, if 'data.h' is required and 'data.foo' is out of date, the dependency on 'data.c' will trigger the build. This is almost perfect, but suppose we have built 'data.h' and 'data.c', and then we erase 'data.h'. Then, running 'make data.h' will not rebuild 'data.h'. The above rules just state that 'data.c' must be up-to-date with respect to 'data.foo', and this is already the case. What we need is a rule that forces a rebuild when 'data.h' is missing. Here it is: data.c: data.foo foo data.foo data.h: data.c ## Recover from the removal of $@ @if test -f $@; then :; else \ rm -f data.c; \ $(MAKE) $(AM_MAKEFLAGS) data.c; \ fi The above scheme can be extended to handle more outputs and more inputs. One of the outputs is selected to serve as a witness to the successful completion of the command, it depends upon all inputs, and all other outputs depend upon it. For instance, if 'foo' should additionally read 'data.bar' and also produce 'data.w' and 'data.x', we would write: data.c: data.foo data.bar foo data.foo data.bar data.h data.w data.x: data.c ## Recover from the removal of $@ @if test -f $@; then :; else \ rm -f data.c; \ $(MAKE) $(AM_MAKEFLAGS) data.c; \ fi However there are now three minor problems in this setup. One is related to the timestamp ordering of 'data.h', 'data.w', 'data.x', and 'data.c'. Another one is a race condition if a parallel 'make' attempts to run multiple instances of the recover block at once. Finally, the recursive rule breaks 'make -n' when run with GNU 'make' (as well as some other 'make' implementations), as it may remove 'data.h' even when it should not (*note How the 'MAKE' Variable Works: (make)MAKE Variable.). Let us deal with the first problem. 'foo' outputs four files, but we do not know in which order these files are created. Suppose that 'data.h' is created before 'data.c'. Then we have a weird situation. The next time 'make' is run, 'data.h' will appear older than 'data.c', the second rule will be triggered, a shell will be started to execute the 'if...fi' command, but actually it will just execute the 'then' branch, that is: nothing. In other words, because the witness we selected is not the first file created by 'foo', 'make' will start a shell to do nothing each time it is run. A simple riposte is to fix the timestamps when this happens. data.c: data.foo data.bar foo data.foo data.bar data.h data.w data.x: data.c @if test -f $@; then \ touch $@; \ else \ ## Recover from the removal of $@ rm -f data.c; \ $(MAKE) $(AM_MAKEFLAGS) data.c; \ fi Another solution is to use a different and dedicated file as witness, rather than using any of 'foo''s outputs. data.stamp: data.foo data.bar @rm -f data.tmp @touch data.tmp foo data.foo data.bar @mv -f data.tmp $@ data.c data.h data.w data.x: data.stamp ## Recover from the removal of $@ @if test -f $@; then :; else \ rm -f data.stamp; \ $(MAKE) $(AM_MAKEFLAGS) data.stamp; \ fi 'data.tmp' is created before 'foo' is run, so it has a timestamp older than output files output by 'foo'. It is then renamed to 'data.stamp' after 'foo' has run, because we do not want to update 'data.stamp' if 'foo' fails. This solution still suffers from the second problem: the race condition in the recover rule. If, after a successful build, a user erases 'data.c' and 'data.h', and runs 'make -j', then 'make' may start both recover rules in parallel. If the two instances of the rule execute '$(MAKE) $(AM_MAKEFLAGS) data.stamp' concurrently the build is likely to fail (for instance, the two rules will create 'data.tmp', but only one can rename it). Admittedly, such a weird situation does not arise during ordinary builds. It occurs only when the build tree is mutilated. Here 'data.c' and 'data.h' have been explicitly removed without also removing 'data.stamp' and the other output files. 'make clean; make' will always recover from these situations even with parallel makes, so you may decide that the recover rule is solely to help non-parallel make users and leave things as-is. Fixing this requires some locking mechanism to ensure only one instance of the recover rule rebuilds 'data.stamp'. One could imagine something along the following lines. data.c data.h data.w data.x: data.stamp ## Recover from the removal of $@ @if test -f $@; then :; else \ trap 'rm -rf data.lock data.stamp' 1 2 13 15; \ ## mkdir is a portable test-and-set if mkdir data.lock 2>/dev/null; then \ ## This code is being executed by the first process. rm -f data.stamp; \ $(MAKE) $(AM_MAKEFLAGS) data.stamp; \ result=$$?; rm -rf data.lock; exit $$result; \ else \ ## This code is being executed by the follower processes. ## Wait until the first process is done. while test -d data.lock; do sleep 1; done; \ ## Succeed if and only if the first process succeeded. test -f data.stamp; \ fi; \ fi Using a dedicated witness, like 'data.stamp', is very handy when the list of output files is not known beforehand. As an illustration, consider the following rules to compile many '*.el' files into '*.elc' files in a single command. It does not matter how 'ELFILES' is defined (as long as it is not empty: empty targets are not accepted by POSIX). ELFILES = one.el two.el three.el ... ELCFILES = $(ELFILES:=c) elc-stamp: $(ELFILES) @rm -f elc-temp @touch elc-temp $(elisp_comp) $(ELFILES) @mv -f elc-temp $@ $(ELCFILES): elc-stamp @if test -f $@; then :; else \ ## Recover from the removal of $@ trap 'rm -rf elc-lock elc-stamp' 1 2 13 15; \ if mkdir elc-lock 2>/dev/null; then \ ## This code is being executed by the first process. rm -f elc-stamp; \ $(MAKE) $(AM_MAKEFLAGS) elc-stamp; \ rmdir elc-lock; \ else \ ## This code is being executed by the follower processes. ## Wait until the first process is done. while test -d elc-lock; do sleep 1; done; \ ## Succeed if and only if the first process succeeded. test -f elc-stamp; exit $$?; \ fi; \ fi These solutions all still suffer from the third problem, namely that they break the promise that 'make -n' should not cause any actual changes to the tree. For those solutions that do not create lock files, it is possible to split the recover rules into two separate recipe commands, one of which does all work but the recursion, and the other invokes the recursive '$(MAKE)'. The solutions involving locking could act upon the contents of the 'MAKEFLAGS' variable, but parsing that portably is not easy (*note (autoconf)The Make Macro MAKEFLAGS::). Here is an example: ELFILES = one.el two.el three.el ... ELCFILES = $(ELFILES:=c) elc-stamp: $(ELFILES) @rm -f elc-temp @touch elc-temp $(elisp_comp) $(ELFILES) @mv -f elc-temp $@ $(ELCFILES): elc-stamp ## Recover from the removal of $@ @dry=; for f in x $$MAKEFLAGS; do \ case $$f in \ *=*|--*);; \ *n*) dry=:;; \ esac; \ done; \ if test -f $@; then :; else \ $$dry trap 'rm -rf elc-lock elc-stamp' 1 2 13 15; \ if $$dry mkdir elc-lock 2>/dev/null; then \ ## This code is being executed by the first process. $$dry rm -f elc-stamp; \ $(MAKE) $(AM_MAKEFLAGS) elc-stamp; \ $$dry rmdir elc-lock; \ else \ ## This code is being executed by the follower processes. ## Wait until the first process is done. while test -d elc-lock && test -z "$$dry"; do \ sleep 1; \ done; \ ## Succeed if and only if the first process succeeded. $$dry test -f elc-stamp; exit $$?; \ fi; \ fi For completeness it should be noted that GNU 'make' is able to express rules with multiple output files using pattern rules (*note Pattern Rule Examples: (make)Pattern Examples.). We do not discuss pattern rules here because they are not portable, but they can be convenient in packages that assume GNU 'make'. 28.10 Installing to Hard-Coded Locations ======================================== My package needs to install some configuration file. I tried to use the following rule, but 'make distcheck' fails. Why? # Do not do this. install-data-local: $(INSTALL_DATA) $(srcdir)/afile $(DESTDIR)/etc/afile My package needs to populate the installation directory of another package at install-time. I can easily compute that installation directory in 'configure', but if I install files therein, 'make distcheck' fails. How else should I do? These two setups share their symptoms: 'make distcheck' fails because they are installing files to hard-coded paths. In the later case the path is not really hard-coded in the package, but we can consider it to be hard-coded in the system (or in whichever tool that supplies the path). As long as the path does not use any of the standard directory variables ('$(prefix)', '$(bindir)', '$(datadir)', etc.), the effect will be the same: user-installations are impossible. As a (non-root) user who wants to install a package, you usually have no right to install anything in '/usr' or '/usr/local'. So you do something like './configure --prefix ~/usr' to install a package in your own '~/usr' tree. If a package attempts to install something to some hard-coded path (e.g., '/etc/afile'), regardless of this '--prefix' setting, then the installation will fail. 'make distcheck' performs such a '--prefix' installation, hence it will fail too. Now, there are some easy solutions. The above 'install-data-local' example for installing '/etc/afile' would be better replaced by sysconf_DATA = afile by default 'sysconfdir' will be '$(prefix)/etc', because this is what the GNU Standards require. When such a package is installed on an FHS compliant system, the installer will have to set '--sysconfdir=/etc'. As the maintainer of the package you should not be concerned by such site policies: use the appropriate standard directory variable to install your files so that the installer can easily redefine these variables to match their site conventions. Installing files that should be used by another package is slightly more involved. Let's take an example and assume you want to install a shared library that is a Python extension module. If you ask Python where to install the library, it will answer something like this: % python -c 'from distutils import sysconfig; print sysconfig.get_python_lib(1,0)' /usr/lib/python2.5/site-packages If you indeed use this absolute path to install your shared library, non-root users will not be able to install the package, hence distcheck fails. Let's do better. The 'sysconfig.get_python_lib()' function actually accepts a third argument that will replace Python's installation prefix. % python -c 'from distutils import sysconfig; print sysconfig.get_python_lib(1,0,"${exec_prefix}")' ${exec_prefix}/lib/python2.5/site-packages You can also use this new path. If you do * root users can install your package with the same '--prefix' as Python (you get the behavior of the previous attempt) * non-root users can install your package too, they will have the extension module in a place that is not searched by Python but they can work around this using environment variables (and if you installed scripts that use this shared library, it's easy to tell Python were to look in the beginning of your script, so the script works in both cases). The 'AM_PATH_PYTHON' macro uses similar commands to define '$(pythondir)' and '$(pyexecdir)' (*note Python::). Of course not all tools are as advanced as Python regarding that substitution of PREFIX. So another strategy is to figure the part of the installation directory that must be preserved. For instance, here is how 'AM_PATH_LISPDIR' (*note Emacs Lisp::) computes '$(lispdir)': $EMACS -batch -q -eval '(while load-path (princ (concat (car load-path) "\n")) (setq load-path (cdr load-path)))' >conftest.out lispdir=`sed -n -e 's,/$,,' -e '/.*\/lib\/x*emacs\/site-lisp$/{ s,.*/lib/\(x*emacs/site-lisp\)$,${libdir}/\1,;p;q; }' -e '/.*\/share\/x*emacs\/site-lisp$/{ s,.*/share/\(x*emacs/site-lisp\),${datarootdir}/\1,;p;q; }' conftest.out` I.e., it just picks the first directory that looks like '*/lib/*emacs/site-lisp' or '*/share/*emacs/site-lisp' in the search path of emacs, and then substitutes '${libdir}' or '${datadir}' appropriately. The emacs case looks complicated because it processes a list and expects two possible layouts, otherwise it's easy, and the benefits for non-root users are really worth the extra 'sed' invocation. 28.11 Debugging Make Rules ========================== The rules and dependency trees generated by 'automake' can get rather complex, and leave the developer head-scratching when things don't work as expected. Besides the debug options provided by the 'make' command (*note (make)Options Summary::), here's a couple of further hints for debugging makefiles generated by 'automake' effectively: * If less verbose output has been enabled in the package with the 'silent-rules' option (*note Options::), you can use 'make V=1' to see the commands being executed. * 'make -n' can help show what would be done without actually doing it. Note however, that this will _still execute_ commands prefixed with '+', and, when using GNU 'make', commands that contain the strings '$(MAKE)' or '${MAKE}' (*note (make)Instead of Execution::). Typically, this is helpful to show what recursive rules would do, but it means that, in your own rules, you should not mix such recursion with actions that change any files.(1) Furthermore, note that GNU 'make' will update prerequisites for the 'Makefile' file itself even with '-n' (*note (make)Remaking Makefiles::). * 'make SHELL="/bin/bash -vx"' can help debug complex rules. *Note (autoconf)The Make Macro SHELL::, for some portability quirks associated with this construct. * 'echo 'print: ; @echo "$(VAR)"' | make -f Makefile -f - print' can be handy to examine the expanded value of variables. You may need to use a target other than 'print' if that is already used or a file with that name exists. * provides a modified GNU 'make' command called 'remake' that copes with complex GNU 'make'-specific Makefiles and allows to trace execution, examine variables, and call rules interactively, much like a debugger. ---------- Footnotes ---------- (1) Automake's 'dist' and 'distcheck' rules had a bug in this regard in that they created directories even with '-n', but this has been fixed in Automake 1.11. 28.12 Reporting Bugs ==================== Most nontrivial software has bugs. Automake is no exception. Although we cannot promise we can or will fix a bug, and we might not even agree that it is a bug, we want to hear about problems you encounter. Often we agree they are bugs and want to fix them. To make it possible for us to fix a bug, please report it. In order to do so effectively, it helps to know when and how to do it. Before reporting a bug, it is a good idea to see if it is already known. You can look at the GNU Bug Tracker (http://debbugs.gnu.org/) and the bug-automake mailing list archives (http://lists.gnu.org/archive/html/bug-automake/) for previous bug reports. We previously used a Gnats database (http://sourceware.org/cgi-bin/gnatsweb.pl?database=automake) for bug tracking, so some bugs might have been reported there already. Please do not use it for new bug reports, however. If the bug is not already known, it should be reported. It is very important to report bugs in a way that is useful and efficient. For this, please familiarize yourself with How to Report Bugs Effectively (http://www.chiark.greenend.org.uk/~sgtatham/bugs.html) and How to Ask Questions the Smart Way (http://catb.org/~esr/faqs/smart-questions.html). This helps you and developers to save time which can then be spent on fixing more bugs and implementing more features. For a bug report, a feature request or other suggestions, please send email to . This will then open a new bug in the bug tracker (http://debbugs.gnu.org/automake). Be sure to include the versions of Autoconf and Automake that you use. Ideally, post a minimal 'Makefile.am' and 'configure.ac' that reproduces the problem you encounter. If you have encountered test suite failures, please attach the 'tests/test-suite.log' file. 29 History of Automake ********************** This chapter presents various aspects of the history of Automake. The exhausted reader can safely skip it; this will be more of interest to nostalgic people, or to those curious to learn about the evolution of Automake. 29.1 Timeline ============= 1994-09-19 First CVS commit. If we can trust the CVS repository, David J. MacKenzie (djm) started working on Automake (or AutoMake, as it was spelt then) this Monday. The first version of the 'automake' script looks as follows. #!/bin/sh status=0 for makefile do if test ! -f ${makefile}.am; then echo "automake: ${makefile}.am: No such honkin' file" status=1 continue fi exec 4> ${makefile}.in done From this you can already see that Automake will be about reading '*.am' file and producing '*.in' files. You cannot see anything else, but if you also know that David is the one who created Autoconf two years before you can guess the rest. Several commits follow, and by the end of the day Automake is reported to work for GNU fileutils and GNU m4. The modus operandi is the one that is still used today: variable assignments in 'Makefile.am' files trigger injections of precanned 'Makefile' fragments into the generated 'Makefile.in'. The use of 'Makefile' fragments was inspired by the 4.4BSD 'make' and include files, however Automake aims to be portable and to conform to the GNU standards for 'Makefile' variables and targets. At this point, the most recent release of Autoconf is version 1.11, and David is preparing to release Autoconf 2.0 in late October. As a matter of fact, he will barely touch Automake after September. 1994-11-05 David MacKenzie's last commit. At this point Automake is a 200 line portable shell script, plus 332 lines of 'Makefile' fragments. In the 'README', David states his ambivalence between "portable shell" and "more appropriate language": I wrote it keeping in mind the possibility of it becoming an Autoconf macro, so it would run at configure-time. That would slow configuration down a bit, but allow users to modify the Makefile.am without needing to fetch the AutoMake package. And, the Makefile.in files wouldn't need to be distributed. But all of AutoMake would. So I might reimplement AutoMake in Perl, m4, or some other more appropriate language. Automake is described as "an experimental Makefile generator". There is no documentation. Adventurous users are referred to the examples and patches needed to use Automake with GNU m4 1.3, fileutils 3.9, time 1.6, and development versions of find and indent. These examples seem to have been lost. However at the time of writing (10 years later in September, 2004) the FSF still distributes a package that uses this version of Automake: check out GNU termutils 2.0. 1995-11-12 Tom Tromey's first commit. After one year of inactivity, Tom Tromey takes over the package. Tom was working on GNU cpio back then, and doing this just for fun, having trouble finding a project to contribute to. So while hacking he wanted to bring the 'Makefile.in' up to GNU standards. This was hard, and one day he saw Automake on , grabbed it and tried it out. Tom didn't talk to djm about it until later, just to make sure he didn't mind if he made a release. He did a bunch of early releases to the Gnits folks. Gnits was (and still is) totally informal, just a few GNU friends who François Pinard knew, who were all interested in making a common infrastructure for GNU projects, and shared a similar outlook on how to do it. So they were able to make some progress. It came along with Autoconf and extensions thereof, and then Automake from David and Tom (who were both gnitsians). One of their ideas was to write a document paralleling the GNU standards, that was more strict in some ways and more detailed. They never finished the GNITS standards, but the ideas mostly made their way into Automake. 1995-11-23 Automake 0.20 Besides introducing automatic dependency tracking (*note Dependency Tracking Evolution::), this version also supplies a 9-page manual. At this time 'aclocal' and 'AM_INIT_AUTOMAKE' did not exist, so many things had to be done by hand. For instance, here is what a configure.in (this is the former name of the 'configure.ac' we use today) must contain in order to use Automake 0.20: PACKAGE=cpio VERSION=2.3.911 AC_DEFINE_UNQUOTED(PACKAGE, "$PACKAGE") AC_DEFINE_UNQUOTED(VERSION, "$VERSION") AC_SUBST(PACKAGE) AC_SUBST(VERSION) AC_ARG_PROGRAM AC_PROG_INSTALL (Today all of the above is achieved by 'AC_INIT' and 'AM_INIT_AUTOMAKE'.) Here is how programs are specified in 'Makefile.am': PROGRAMS = hello hello_SOURCES = hello.c This looks pretty much like what we do today, except the 'PROGRAMS' variable has no directory prefix specifying where 'hello' should be installed: all programs are installed in '$(bindir)'. 'LIBPROGRAMS' can be used to specify programs that must be built but not installed (it is called 'noinst_PROGRAMS' nowadays). Programs can be built conditionally using 'AC_SUBST'itutions: PROGRAMS = @progs@ AM_PROGRAMS = foo bar baz ('AM_PROGRAMS' has since then been renamed to 'EXTRA_PROGRAMS'.) Similarly scripts, static libraries, and data can be built and installed using the 'LIBRARIES', 'SCRIPTS', and 'DATA' variables. However 'LIBRARIES' were treated a bit specially in that Automake did automatically supply the 'lib' and '.a' prefixes. Therefore to build 'libcpio.a', one had to write LIBRARIES = cpio cpio_SOURCES = ... Extra files to distribute must be listed in 'DIST_OTHER' (the ancestor of 'EXTRA_DIST'). Also extra directories that are to be distributed should appear in 'DIST_SUBDIRS', but the manual describes this as a temporary ugly hack (today extra directories should also be listed in 'EXTRA_DIST', and 'DIST_SUBDIRS' is used for another purpose, *note Conditional Subdirectories::). 1995-11-26 Automake 0.21 In less time than it takes to cook a frozen pizza, Tom rewrites Automake using Perl. At this time Perl 5 is only one year old, and Perl 4.036 is in use at many sites. Supporting several Perl versions has been a source of problems through the whole history of Automake. If you never used Perl 4, imagine Perl 5 without objects, without 'my' variables (only dynamically scoped 'local' variables), without function prototypes, with function calls that needs to be prefixed with '&', etc. Traces of this old style can still be found in today's 'automake'. 1995-11-28 Automake 0.22 1995-11-29 Automake 0.23 Bug fixes. 1995-12-08 Automake 0.24 1995-12-10 Automake 0.25 Releases are raining. 0.24 introduces the uniform naming scheme we use today, i.e., 'bin_PROGRAMS' instead of 'PROGRAMS', 'noinst_LIBRARIES' instead of 'LIBLIBRARIES', etc. (However 'EXTRA_PROGRAMS' does not exist yet, 'AM_PROGRAMS' is still in use; and 'TEXINFOS' and 'MANS' still have no directory prefixes.) Adding support for prefixes like that was one of the major ideas in 'automake'; it has lasted pretty well. AutoMake is renamed to Automake (Tom seems to recall it was François Pinard's doing). 0.25 fixes a Perl 4 portability bug. 1995-12-18 Jim Meyering starts using Automake in GNU Textutils. 1995-12-31 François Pinard starts using Automake in GNU tar. 1996-01-03 Automake 0.26 1996-01-03 Automake 0.27 Of the many changes and suggestions sent by François Pinard and included in 0.26, perhaps the most important is the advice that to ease customization a user rule or variable definition should always override an Automake rule or definition. Gordon Matzigkeit and Jim Meyering are two other early contributors that have been sending fixes. 0.27 fixes yet another Perl 4 portability bug. 1996-01-13 Automake 0.28 Automake starts scanning 'configure.in' for 'LIBOBJS' support. This is an important step because until this version Automake only knew about the 'Makefile.am's it processed. 'configure.in' was Autoconf's world and the link between Autoconf and Automake had to be done by the 'Makefile.am' author. For instance, if 'config.h' was generated by 'configure', it was the package maintainer's responsibility to define the 'CONFIG_HEADER' variable in each 'Makefile.am'. Succeeding releases will rely more and more on scanning 'configure.in' to better automate the Autoconf integration. 0.28 also introduces the 'AUTOMAKE_OPTIONS' variable and the '--gnu' and '--gnits' options, the latter being stricter. 1996-02-07 Automake 0.29 Thanks to 'configure.in' scanning, 'CONFIG_HEADER' is gone, and rebuild rules for 'configure'-generated file are automatically output. 'TEXINFOS' and 'MANS' converted to the uniform naming scheme. 1996-02-24 Automake 0.30 The test suite is born. It contains 9 tests. From now on test cases will be added pretty regularly (*note Releases::), and this proved to be really helpful later on. 'EXTRA_PROGRAMS' finally replaces 'AM_PROGRAMS'. All the third-party Autoconf macros, written mostly by François Pinard (and later Jim Meyering), are distributed in Automake's hand-written 'aclocal.m4' file. Package maintainers are expected to extract the necessary macros from this file. (In previous versions you had to copy and paste them from the manual...) 1996-03-11 Automake 0.31 The test suite in 0.30 was run via a long 'check-local' rule. Upon Ulrich Drepper's suggestion, 0.31 makes it an Automake rule output whenever the 'TESTS' variable is defined. 'DIST_OTHER' is renamed to 'EXTRA_DIST', and the 'check_' prefix is introduced. The syntax is now the same as today. 1996-03-15 Gordon Matzigkeit starts writing libtool. 1996-04-27 Automake 0.32 '-hook' targets are introduced; an idea from Dieter Baron. '*.info' files, which were output in the build directory are now built in the source directory, because they are distributed. It seems these files like to move back and forth as that will happen again in future versions. 1996-05-18 Automake 0.33 Gord Matzigkeit's main two contributions: * very preliminary libtool support * the distcheck rule Although they were very basic at this point, these are probably among the top features for Automake today. Jim Meyering also provides the infamous 'jm_MAINTAINER_MODE', since then renamed to 'AM_MAINTAINER_MODE' and abandoned by its author (*note maintainer-mode::). 1996-05-28 Automake 1.0 After only six months of heavy development, the 'automake' script is 3134 lines long, plus 973 lines of 'Makefile' fragments. The package has 30 pages of documentation, and 38 test cases. 'aclocal.m4' contains 4 macros. From now on and until version 1.4, new releases will occur at a rate of about one a year. 1.1 did not exist, actually 1.1b to 1.1p have been the name of beta releases for 1.2. This is the first time Automake uses suffix letters to designate beta releases, a habit that lasts. 1996-10-10 Kevin Dalley packages Automake 1.0 for Debian GNU/Linux. 1996-11-26 David J. MacKenzie releases Autoconf 2.12. Between June and October, the Autoconf development is almost stalled. Roland McGrath has been working at the beginning of the year. David comes back in November to release 2.12, but he won't touch Autoconf anymore after this year, and Autoconf then really stagnates. The desolate Autoconf 'ChangeLog' for 1997 lists only 7 commits. 1997-02-28 list alive The mailing list is announced as follows: I've created the "automake" mailing list. It is "automake@gnu.ai.mit.edu". Administrivia, as always, to automake-request@gnu.ai.mit.edu. The charter of this list is discussion of automake, autoconf, and other configuration/portability tools (e.g., libtool). It is expected that discussion will range from pleas for help all the way up to patches. This list is archived on the FSF machines. Offhand I don't know if you can get the archive without an account there. This list is open to anybody who wants to join. Tell all your friends! -- Tom Tromey Before that people were discussing Automake privately, on the Gnits mailing list (which is not public either), and less frequently on 'gnu.misc.discuss'. 'gnu.ai.mit.edu' is now 'gnu.org', in case you never noticed. The archives of the early years of the 'automake@gnu.org' list have been lost, so today it is almost impossible to find traces of discussions that occurred before 1999. This has been annoying more than once, as such discussions can be useful to understand the rationale behind a piece of uncommented code that was introduced back then. 1997-06-22 Automake 1.2 Automake developments continues, and more and more new Autoconf macros are required. Distributing them in 'aclocal.m4' and requiring people to browse this file to extract the relevant macros becomes uncomfortable. Ideally, some of them should be contributed to Autoconf so that they can be used directly, however Autoconf is currently inactive. Automake 1.2 consequently introduces 'aclocal' ('aclocal' was actually started on 1996-07-28), a tool that automatically constructs an 'aclocal.m4' file from a repository of third-party macros. Because Autoconf has stalled, Automake also becomes a kind of repository for such third-party macros, even macros completely unrelated to Automake (for instance macros that fix broken Autoconf macros). The 1.2 release contains 20 macros, including the 'AM_INIT_AUTOMAKE' macro that simplifies the creation of 'configure.in'. Libtool is fully supported using '*_LTLIBRARIES'. The missing script is introduced by François Pinard; it is meant to be a better solution than 'AM_MAINTAINER_MODE' (*note maintainer-mode::). Conditionals support was implemented by Ian Lance Taylor. At the time, Tom and Ian were working on an internal project at Cygnus. They were using ILU, which is pretty similar to CORBA. They wanted to integrate ILU into their build, which was all 'configure'-based, and Ian thought that adding conditionals to 'automake' was simpler than doing all the work in 'configure' (which was the standard at the time). So this was actually funded by Cygnus. This very useful but tricky feature will take a lot of time to stabilize. (At the time this text is written, there are still primaries that have not been updated to support conditional definitions in Automake 1.9.) The 'automake' script has almost doubled: 6089 lines of Perl, plus 1294 lines of 'Makefile' fragments. 1997-07-08 Gordon Matzigkeit releases Libtool 1.0. 1998-04-05 Automake 1.3 This is a small advance compared to 1.2. It adds support for assembly, and preliminary support for Java. Perl 5.004_04 is out, but fixes to support Perl 4 are still regularly submitted whenever Automake breaks it. 1998-09-06 'sourceware.cygnus.com' is on-line. Sourceware was setup by Jason Molenda to host open source projects. 1998-09-19 Automake CVS repository moved to 'sourceware.cygnus.com' 1998-10-26 'sourceware.cygnus.com' announces it hosts Automake: Automake is now hosted on 'sourceware.cygnus.com'. It has a publicly accessible CVS repository. This CVS repository is a copy of the one Tom was using on his machine, which in turn is based on a copy of the CVS repository of David MacKenzie. This is why we still have to full source history. (Automake was on Sourceware until 2007-10-29, when it moved to a git repository on 'savannah.gnu.org', but the Sourceware host had been renamed to 'sources.redhat.com'.) The oldest file in the administrative directory of the CVS repository that was created on Sourceware is dated 1998-09-19, while the announcement that 'automake' and 'autoconf' had joined 'sourceware' was made on 1998-10-26. They were among the first projects to be hosted there. The heedful reader will have noticed Automake was exactly 4 years old on 1998-09-19. 1999-01-05 Ben Elliston releases Autoconf 2.13. 1999-01-14 Automake 1.4 This release adds support for Fortran 77 and for the 'include' statement. Also, '+=' assignments are introduced, but it is still quite easy to fool Automake when mixing this with conditionals. These two releases, Automake 1.4 and Autoconf 2.13 make a duo that will be used together for years. 'automake' is 7228 lines, plus 1591 lines of Makefile fragment, 20 macros (some 1.3 macros were finally contributed back to Autoconf), 197 test cases, and 51 pages of documentation. 1999-03-27 The 'user-dep-branch' is created on the CVS repository. This implements a new dependency tracking schemed that should be able to handle automatic dependency tracking using any compiler (not just gcc) and any make (not just GNU 'make'). In addition, the new scheme should be more reliable than the old one, as dependencies are generated on the end user's machine. Alexandre Oliva creates depcomp for this purpose. *Note Dependency Tracking Evolution::, for more details about the evolution of automatic dependency tracking in Automake. 1999-11-21 The 'user-dep-branch' is merged into the main trunk. This was a huge problem since we also had patches going in on the trunk. The merge took a long time and was very painful. 2000-05-10 Since September 1999 and until 2003, Akim Demaille will be zealously revamping Autoconf. I think the next release should be called "3.0". Let's face it: you've basically rewritten autoconf. Every weekend there are 30 new patches. I don't see how we could call this "2.15" with a straight face. - Tom Tromey on Actually Akim works like a submarine: he will pile up patches while he works off-line during the weekend, and flush them in batch when he resurfaces on Monday. 2001-01-24 On this Wednesday, Autoconf 2.49c, the last beta before Autoconf 2.50 is out, and Akim has to find something to do during his week-end :) 2001-01-28 Akim sends a batch of 14 patches to . Aiieeee! I was dreading the day that the Demaillator turned his sights on automake... and now it has arrived! - Tom Tromey It's only the beginning: in two months he will send 192 patches. Then he would slow down so Tom can catch up and review all this. Initially Tom actually read all these patches, then he probably trustingly answered OK to most of them, and finally gave up and let Akim apply whatever he wanted. There was no way to keep up with that patch rate. Anyway the patch below won't apply since it predates Akim's sourcequake; I have yet to figure where the relevant passage has been moved :) - Alexandre Duret-Lutz All these patches were sent to and discussed on , so subscribed users were literally drowning in technical mails. Eventually, the mailing list was created in May. Year after year, Automake had drifted away from its initial design: construct 'Makefile.in' by assembling various 'Makefile' fragments. In 1.4, lots of 'Makefile' rules are being emitted at various places in the 'automake' script itself; this does not help ensuring a consistent treatment of these rules (for instance making sure that user-defined rules override Automake's own rules). One of Akim's goal was moving all these hard-coded rules to separate 'Makefile' fragments, so the logic could be centralized in a 'Makefile' fragment processor. Another significant contribution of Akim is the interface with the "trace" feature of Autoconf. The way to scan 'configure.in' at this time was to read the file and grep the various macro of interest to Automake. Doing so could break in many unexpected ways; 'automake' could miss some definition (for instance 'AC_SUBST([$1], [$2])' where the arguments are known only when M4 is run), or conversely it could detect some macro that was not expanded (because it is called conditionally). In the CVS version of Autoconf, Akim had implemented the '--trace' option, which provides accurate information about where macros are actually called and with what arguments. Akim will equip Automake with a second 'configure.in' scanner that uses this '--trace' interface. Since it was not sensible to drop the Autoconf 2.13 compatibility yet, this experimental scanner was only used when an environment variable was set, the traditional grep-scanner being still the default. 2001-04-25 Gary V. Vaughan releases Libtool 1.4 It has been more than two years since Automake 1.4, CVS Automake has suffered lot's of heavy changes and still is not ready for release. Libtool 1.4 had to be distributed with a patch against Automake 1.4. 2001-05-08 Automake 1.4-p1 2001-05-24 Automake 1.4-p2 Gary V. Vaughan, the principal Libtool maintainer, makes a "patch release" of Automake: The main purpose of this release is to have a stable automake which is compatible with the latest stable libtool. The release also contains obvious fixes for bugs in Automake 1.4, some of which were reported almost monthly. 2001-05-21 Akim Demaille releases Autoconf 2.50 2001-06-07 Automake 1.4-p3 2001-06-10 Automake 1.4-p4 2001-07-15 Automake 1.4-p5 Gary continues his patch-release series. These also add support for some new Autoconf 2.50 idioms. Essentially, Autoconf now advocates 'configure.ac' over 'configure.in', and it introduces a new syntax for 'AC_OUTPUT'ing files. 2001-08-23 Automake 1.5 A major and long-awaited release, that comes more than two years after 1.4. It brings many changes, among which: * The new dependency tracking scheme that uses 'depcomp'. Aside from the improvement on the dependency tracking itself (*note Dependency Tracking Evolution::), this also streamlines the use of 'automake'-generated 'Makefile.in's as the 'Makefile.in's used during development are now the same as those used in distributions. Before that the 'Makefile.in's generated for maintainers required GNU 'make' and GCC, they were different from the portable 'Makefile' generated for distribution; this was causing some confusion. * Support for per-target compilation flags. * Support for reference to files in subdirectories in most 'Makefile.am' variables. * Introduction of the 'dist_', 'nodist_', and 'nobase_' prefixes. * Perl 4 support is finally dropped. 1.5 did break several packages that worked with 1.4. Enough so that Linux distributions could not easily install the new Automake version without breaking many of the packages for which they had to run 'automake'. Some of these breakages were effectively bugs that would eventually be fixed in the next release. However, a lot of damage was caused by some changes made deliberately to render Automake stricter on some setup we did consider bogus. For instance, 'make distcheck' was improved to check that 'make uninstall' did remove all the files 'make install' installed, that 'make distclean' did not omit some file, and that a VPATH build would work even if the source directory was read-only. Similarly, Automake now rejects multiple definitions of the same variable (because that would mix very badly with conditionals), and '+=' assignments with no previous definition. Because these changes all occurred suddenly after 1.4 had been established for more than two years, it hurt users. To make matter worse, meanwhile Autoconf (now at version 2.52) was facing similar troubles, for similar reasons. 2002-03-05 Automake 1.6 This release introduced versioned installation (*note API Versioning::). This was mainly pushed by Havoc Pennington, taking the GNOME source tree as motive: due to incompatibilities between the autotools it's impossible for the GNOME packages to switch to Autoconf 2.53 and Automake 1.5 all at once, so they are currently stuck with Autoconf 2.13 and Automake 1.4. The idea was to call this version 'automake-1.6', call all its bug-fix versions identically, and switch to 'automake-1.7' for the next release that adds new features or changes some rules. This scheme implies maintaining a bug-fix branch in addition to the development trunk, which means more work from the maintainer, but providing regular bug-fix releases proved to be really worthwhile. Like 1.5, 1.6 also introduced a bunch of incompatibilities, intentional or not. Perhaps the more annoying was the dependence on the newly released Autoconf 2.53. Autoconf seemed to have stabilized enough since its explosive 2.50 release and included changes required to fix some bugs in Automake. In order to upgrade to Automake 1.6, people now had to upgrade Autoconf too; for some packages it was no picnic. While versioned installation helped people to upgrade, it also unfortunately allowed people not to upgrade. At the time of writing, some Linux distributions are shipping packages for Automake 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. Most of these still install 1.4 by default. Some distribution also call 1.4 the "stable" version, and present "1.9" as the development version; this does not really makes sense since 1.9 is way more solid than 1.4. All this does not help the newcomer. 2002-04-11 Automake 1.6.1 1.6, and the upcoming 1.4-p6 release were the last release by Tom. This one and those following will be handled by Alexandre Duret-Lutz. Tom is still around, and will be there until about 1.7, but his interest into Automake is drifting away towards projects like 'gcj'. Alexandre has been using Automake since 2000, and started to contribute mostly on Akim's incitement (Akim and Alexandre have been working in the same room from 1999 to 2002). In 2001 and 2002 he had a lot of free time to enjoy hacking Automake. 2002-06-14 Automake 1.6.2 2002-07-28 Automake 1.6.3 2002-07-28 Automake 1.4-p6 Two releases on the same day. 1.6.3 is a bug-fix release. Tom Tromey backported the versioned installation mechanism on the 1.4 branch, so that Automake 1.6.x and Automake 1.4-p6 could be installed side by side. Another request from the GNOME folks. 2002-09-25 Automake 1.7 This release switches to the new 'configure.ac' scanner Akim was experimenting in 1.5. 2002-10-16 Automake 1.7.1 2002-12-06 Automake 1.7.2 2003-02-20 Automake 1.7.3 2003-04-23 Automake 1.7.4 2003-05-18 Automake 1.7.5 2003-07-10 Automake 1.7.6 2003-09-07 Automake 1.7.7 2003-10-07 Automake 1.7.8 Many bug-fix releases. 1.7 lasted because the development version (upcoming 1.8) was suffering some major internal revamping. 2003-10-26 Automake on screen Episode 49, 'Repercussions', in the third season of the 'Alias' TV show is first aired. Marshall, one of the characters, is working on a computer virus that he has to modify before it gets into the wrong hands or something like that. The screenshots you see do not show any program code, they show a 'Makefile.in' 'generated by automake'... 2003-11-09 Automake 1.7.9 2003-12-10 Automake 1.8 The most striking update is probably that of 'aclocal'. 'aclocal' now uses 'm4_include' in the produced 'aclocal.m4' when the included macros are already distributed with the package (an idiom used in many packages), which reduces code duplication. Many people liked that, but in fact this change was really introduced to fix a bug in rebuild rules: 'Makefile.in' must be rebuilt whenever a dependency of 'configure' changes, but all the 'm4' files included in 'aclocal.m4' where unknown from 'automake'. Now 'automake' can just trace the 'm4_include's to discover the dependencies. 'aclocal' also starts using the '--trace' Autoconf option in order to discover used macros more accurately. This will turn out to be very tricky (later releases will improve this) as people had devised many ways to cope with the limitation of previous 'aclocal' versions, notably using handwritten 'm4_include's: 'aclocal' must make sure not to redefine a rule that is already included by such statement. Automake also has seen its guts rewritten. Although this rewriting took a lot of efforts, it is only apparent to the users in that some constructions previously disallowed by the implementation now work nicely. Conditionals, Locations, Variable and Rule definitions, Options: these items on which Automake works have been rewritten as separate Perl modules, and documented. 2004-01-11 Automake 1.8.1 2004-01-12 Automake 1.8.2 2004-03-07 Automake 1.8.3 2004-04-25 Automake 1.8.4 2004-05-16 Automake 1.8.5 2004-07-28 Automake 1.9 This release tries to simplify the compilation rules it outputs to reduce the size of the Makefile. The complaint initially come from the libgcj developers. Their 'Makefile.in' generated with Automake 1.4 and custom build rules (1.4 did not support compiled Java) is 250KB. The one generated by 1.8 was over 9MB! 1.9 gets it down to 1.2MB. Aside from this it contains mainly minor changes and bug-fixes. 2004-08-11 Automake 1.9.1 2004-09-19 Automake 1.9.2 Automake has ten years. This chapter of the manual was initially written for this occasion. 2007-10-29 Automake repository moves to 'savannah.gnu.org' and uses git as primary repository. 29.2 Dependency Tracking in Automake ==================================== Over the years Automake has deployed three different dependency tracking methods. Each method, including the current one, has had flaws of various sorts. Here we lay out the different dependency tracking methods, their flaws, and their fixes. We conclude with recommendations for tool writers, and by indicating future directions for dependency tracking work in Automake. 29.2.1 First Take on Dependency Tracking ---------------------------------------- Description ........... Our first attempt at automatic dependency tracking was based on the method recommended by GNU 'make'. (*note Generating Prerequisites Automatically: (make)Automatic Prerequisites.) This version worked by precomputing dependencies ahead of time. For each source file, it had a special '.P' file that held the dependencies. There was a rule to generate a '.P' file by invoking the compiler appropriately. All such '.P' files were included by the 'Makefile', thus implicitly becoming dependencies of 'Makefile'. Bugs .... This approach had several critical bugs. * The code to generate the '.P' file relied on 'gcc'. (A limitation, not technically a bug.) * The dependency tracking mechanism itself relied on GNU 'make'. (A limitation, not technically a bug.) * Because each '.P' file was a dependency of 'Makefile', this meant that dependency tracking was done eagerly by 'make'. For instance, 'make clean' would cause all the dependency files to be updated, and then immediately removed. This eagerness also caused problems with some configurations; if a certain source file could not be compiled on a given architecture for some reason, dependency tracking would fail, aborting the entire build. * As dependency tracking was done as a pre-pass, compile times were doubled-the compiler had to be run twice per source file. * 'make dist' re-ran 'automake' to generate a 'Makefile' that did not have automatic dependency tracking (and that was thus portable to any version of 'make'). In order to do this portably, Automake had to scan the dependency files and remove any reference that was to a source file not in the distribution. This process was error-prone. Also, if 'make dist' was run in an environment where some object file had a dependency on a source file that was only conditionally created, Automake would generate a 'Makefile' that referred to a file that might not appear in the end user's build. A special, hacky mechanism was required to work around this. Historical Note ............... The code generated by Automake is often inspired by the 'Makefile' style of a particular author. In the case of the first implementation of dependency tracking, I believe the impetus and inspiration was Jim Meyering. (I could be mistaken. If you know otherwise feel free to correct me.) 29.2.2 Dependencies As Side Effects ----------------------------------- Description ........... The next refinement of Automake's automatic dependency tracking scheme was to implement dependencies as side effects of the compilation. This was aimed at solving the most commonly reported problems with the first approach. In particular we were most concerned with eliminating the weird rebuilding effect associated with make clean. In this approach, the '.P' files were included using the '-include' command, which let us create these files lazily. This avoided the 'make clean' problem. We only computed dependencies when a file was actually compiled. This avoided the performance penalty associated with scanning each file twice. It also let us avoid the other problems associated with the first, eager, implementation. For instance, dependencies would never be generated for a source file that was not compilable on a given architecture (because it in fact would never be compiled). Bugs .... * This approach also relied on the existence of 'gcc' and GNU 'make'. (A limitation, not technically a bug.) * Dependency tracking was still done by the developer, so the problems from the first implementation relating to massaging of dependencies by 'make dist' were still in effect. * This implementation suffered from the "deleted header file" problem. Suppose a lazily-created '.P' file includes a dependency on a given header file, like this: maude.o: maude.c something.h Now suppose that you remove 'something.h' and update 'maude.c' so that this include is no longer needed. If you run 'make', you will get an error because there is no way to create 'something.h'. We fixed this problem in a later release by further massaging the output of 'gcc' to include a dummy dependency for each header file. 29.2.3 Dependencies for the User -------------------------------- Description ........... The bugs associated with 'make dist', over time, became a real problem. Packages using Automake were being built on a large number of platforms, and were becoming increasingly complex. Broken dependencies were distributed in "portable" 'Makefile.in's, leading to user complaints. Also, the requirement for 'gcc' and GNU 'make' was a constant source of bug reports. The next implementation of dependency tracking aimed to remove these problems. We realized that the only truly reliable way to automatically track dependencies was to do it when the package itself was built. This meant discovering a method portable to any version of make and any compiler. Also, we wanted to preserve what we saw as the best point of the second implementation: dependency computation as a side effect of compilation. In the end we found that most modern make implementations support some form of include directive. Also, we wrote a wrapper script that let us abstract away differences between dependency tracking methods for compilers. For instance, some compilers cannot generate dependencies as a side effect of compilation. In this case we simply have the script run the compiler twice. Currently our wrapper script ('depcomp') knows about twelve different compilers (including a "compiler" that simply invokes 'makedepend' and then the real compiler, which is assumed to be a standard Unix-like C compiler with no way to do dependency tracking). Bugs .... * Running a wrapper script for each compilation slows down the build. * Many users don't really care about precise dependencies. * This implementation, like every other automatic dependency tracking scheme in common use today (indeed, every one we've ever heard of), suffers from the "duplicated new header" bug. This bug occurs because dependency tracking tools, such as the compiler, only generate dependencies on the successful opening of a file, and not on every probe. Suppose for instance that the compiler searches three directories for a given header, and that the header is found in the third directory. If the programmer erroneously adds a header file with the same name to the first directory, then a clean rebuild from scratch could fail (suppose the new header file is buggy), whereas an incremental rebuild will succeed. What has happened here is that people have a misunderstanding of what a dependency is. Tool writers think a dependency encodes information about which files were read by the compiler. However, a dependency must actually encode information about what the compiler tried to do. This problem is not serious in practice. Programmers typically do not use the same name for a header file twice in a given project. (At least, not in C or C++. This problem may be more troublesome in Java.) This problem is easy to fix, by modifying dependency generators to record every probe, instead of every successful open. * Since Automake generates dependencies as a side effect of compilation, there is a bootstrapping problem when header files are generated by running a program. The problem is that, the first time the build is done, there is no way by default to know that the headers are required, so make might try to run a compilation for which the headers have not yet been built. This was also a problem in the previous dependency tracking implementation. The current fix is to use 'BUILT_SOURCES' to list built headers (*note Sources::). This causes them to be built before any other build rules are run. This is unsatisfactory as a general solution, however in practice it seems sufficient for most actual programs. This code is used since Automake 1.5. In GCC 3.0, we managed to convince the maintainers to add special command-line options to help Automake more efficiently do its job. We hoped this would let us avoid the use of a wrapper script when Automake's automatic dependency tracking was used with 'gcc'. Unfortunately, this code doesn't quite do what we want. In particular, it removes the dependency file if the compilation fails; we'd prefer that it instead only touch the file in any way if the compilation succeeds. Nevertheless, since Automake 1.7, when a recent 'gcc' is detected at 'configure' time, we inline the dependency-generation code and do not use the 'depcomp' wrapper script. This makes compilations faster for those using this compiler (probably our primary user base). The counterpart is that because we have to encode two compilation rules in 'Makefile' (with or without 'depcomp'), the produced 'Makefile's are larger. 29.2.4 Techniques for Computing Dependencies -------------------------------------------- There are actually several ways for a build tool like Automake to cause tools to generate dependencies. 'makedepend' This was a commonly-used method in the past. The idea is to run a special program over the source and have it generate dependency information. Traditional implementations of 'makedepend' are not completely precise; ordinarily they were conservative and discovered too many dependencies. The tool An obvious way to generate dependencies is to simply write the tool so that it can generate the information needed by the build tool. This is also the most portable method. Many compilers have an option to generate dependencies. Unfortunately, not all tools provide such an option. The file system It is possible to write a special file system that tracks opens, reads, writes, etc, and then feed this information back to the build tool. 'clearmake' does this. This is a very powerful technique, as it doesn't require cooperation from the tool. Unfortunately it is also very difficult to implement and also not practical in the general case. 'LD_PRELOAD' Rather than use the file system, one could write a special library to intercept 'open' and other syscalls. This technique is also quite powerful, but unfortunately it is not portable enough for use in 'automake'. 29.2.5 Recommendations for Tool Writers --------------------------------------- We think that every compilation tool ought to be able to generate dependencies as a side effect of compilation. Furthermore, at least while 'make'-based tools are nearly universally in use (at least in the free software community), the tool itself should generate dummy dependencies for header files, to avoid the deleted header file bug. Finally, the tool should generate a dependency for each probe, instead of each successful file open, in order to avoid the duplicated new header bug. 29.2.6 Future Directions for Dependencies ----------------------------------------- Currently, only languages and compilers understood by Automake can have dependency tracking enabled. We would like to see if it is practical (and worthwhile) to let this support be extended by the user to languages unknown to Automake. 29.3 Release Statistics ======================= The following table (inspired by 'perlhist(1)') quantifies the evolution of Automake using these metrics: Date, Rel The date and version of the release. am The number of lines of the 'automake' script. acl The number of lines of the 'aclocal' script. pm The number of lines of the 'Perl' supporting modules. '*.am' The number of lines of the 'Makefile' fragments. The number in parentheses is the number of files. m4 The number of lines (and files) of Autoconf macros. doc The number of pages of the documentation (the Postscript version). t The number of test cases in the test suite. Of those, the number in parentheses is the number of generated test cases. Date Rel am acl pm '*.am' m4 doc t ------------------------------------------------------------------------------------ 1994-09-19 CVS 141 299 (24) 1994-11-05 CVS 208 332 (28) 1995-11-23 0.20 533 458 (35) 9 1995-11-26 0.21 613 480 (36) 11 1995-11-28 0.22 1116 539 (38) 12 1995-11-29 0.23 1240 541 (38) 12 1995-12-08 0.24 1462 504 (33) 14 1995-12-10 0.25 1513 511 (37) 15 1996-01-03 0.26 1706 438 (36) 16 1996-01-03 0.27 1706 438 (36) 16 1996-01-13 0.28 1964 934 (33) 16 1996-02-07 0.29 2299 936 (33) 17 1996-02-24 0.30 2544 919 (32) 85 (1) 20 9 1996-03-11 0.31 2877 919 (32) 85 (1) 29 17 1996-04-27 0.32 3058 921 (31) 85 (1) 30 26 1996-05-18 0.33 3110 926 (31) 105 (1) 30 35 1996-05-28 1.0 3134 973 (32) 105 (1) 30 38 1997-06-22 1.2 6089 385 1294 (36) 592 (20) 37 126 1998-04-05 1.3 6415 422 1470 (39) 741 (23) 39 156 1999-01-14 1.4 7240 426 1591 (40) 734 (20) 51 197 2001-05-08 1.4-p1 7251 426 1591 (40) 734 (20) 51 197 2001-05-24 1.4-p2 7268 439 1591 (40) 734 (20) 49 197 2001-06-07 1.4-p3 7312 439 1591 (40) 734 (20) 49 197 2001-06-10 1.4-p4 7321 439 1591 (40) 734 (20) 49 198 2001-07-15 1.4-p5 7228 426 1596 (40) 734 (20) 51 198 2001-08-23 1.5 8016 475 600 2654 (39) 1166 (29) 63 327 2002-03-05 1.6 8465 475 1136 2732 (39) 1603 (27) 66 365 2002-04-11 1.6.1 8544 475 1136 2741 (39) 1603 (27) 66 372 2002-06-14 1.6.2 8575 475 1136 2800 (39) 1609 (27) 67 386 2002-07-28 1.6.3 8600 475 1153 2809 (39) 1609 (27) 67 391 2002-07-28 1.4-p6 7332 455 1596 (40) 735 (20) 49 197 2002-09-25 1.7 9189 471 1790 2965 (39) 1606 (28) 73 430 2002-10-16 1.7.1 9229 475 1790 2977 (39) 1606 (28) 73 437 2002-12-06 1.7.2 9334 475 1790 2988 (39) 1606 (28) 77 445 2003-02-20 1.7.3 9389 475 1790 3023 (39) 1651 (29) 84 448 2003-04-23 1.7.4 9429 475 1790 3031 (39) 1644 (29) 85 458 2003-05-18 1.7.5 9429 475 1790 3033 (39) 1645 (29) 85 459 2003-07-10 1.7.6 9442 475 1790 3033 (39) 1660 (29) 85 461 2003-09-07 1.7.7 9443 475 1790 3041 (39) 1660 (29) 90 467 2003-10-07 1.7.8 9444 475 1790 3041 (39) 1660 (29) 90 468 2003-11-09 1.7.9 9444 475 1790 3048 (39) 1660 (29) 90 468 2003-12-10 1.8 7171 585 7730 3236 (39) 1666 (31) 104 521 2004-01-11 1.8.1 7217 663 7726 3287 (39) 1686 (31) 104 525 2004-01-12 1.8.2 7217 663 7726 3288 (39) 1686 (31) 104 526 2004-03-07 1.8.3 7214 686 7735 3303 (39) 1695 (31) 111 530 2004-04-25 1.8.4 7214 686 7736 3310 (39) 1701 (31) 112 531 2004-05-16 1.8.5 7240 686 7736 3299 (39) 1701 (31) 112 533 2004-07-28 1.9 7508 715 7794 3352 (40) 1812 (32) 115 551 2004-08-11 1.9.1 7512 715 7794 3354 (40) 1812 (32) 115 552 2004-09-19 1.9.2 7512 715 7794 3354 (40) 1812 (32) 132 554 2004-11-01 1.9.3 7507 718 7804 3354 (40) 1812 (32) 134 556 2004-12-18 1.9.4 7508 718 7856 3361 (40) 1811 (32) 140 560 2005-02-13 1.9.5 7523 719 7859 3373 (40) 1453 (32) 142 562 2005-07-10 1.9.6 7539 699 7867 3400 (40) 1453 (32) 144 570 2006-10-15 1.10 7859 1072 8024 3512 (40) 1496 (34) 172 604 2008-01-19 1.10.1 7870 1089 8025 3520 (40) 1499 (34) 173 617 2008-11-23 1.10.2 7882 1089 8027 3540 (40) 1509 (34) 176 628 2009-05-17 1.11 8721 1092 8289 4164 (42) 1714 (37) 181 732 (20) 2009-12-07 1.10.3 7892 1089 8027 3566 (40) 1535 (34) 174 636 2009-12-07 1.11.1 8722 1092 8292 4162 (42) 1730 (37) 181 739 (20) 2011-12-21 1.11.2 8822 1112 8330 4223 (42) 1821 (38) 189 915 (22) 2012-02-01 1.11.3 8790 1068 8453 4280 (42) 1852 (38) 190 932 (22) Appendix A Copying This Manual ****************************** A.1 GNU Free Documentation License ================================== Version 1.3, 3 November 2008 Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. 0. PREAMBLE The purpose of this License is to make a manual, textbook, or other functional and useful document "free" in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others. This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software. We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference. 1. APPLICABILITY AND DEFINITIONS This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The "Document", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you". You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law. A "Modified Version" of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language. A "Secondary Section" is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document's overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (Thus, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them. The "Invariant Sections" are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License. If a section does not fit the above definition of Secondary then it is not allowed to be designated as Invariant. The Document may contain zero Invariant Sections. If the Document does not identify any Invariant Sections then there are none. The "Cover Texts" are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License. A Front-Cover Text may be at most 5 words, and a Back-Cover Text may be at most 25 words. A "Transparent" copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, that is suitable for revising the document straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup, or absence of markup, has been arranged to thwart or discourage subsequent modification by readers is not Transparent. An image format is not Transparent if used for any substantial amount of text. A copy that is not "Transparent" is called "Opaque". Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML, PostScript or PDF designed for human modification. Examples of transparent image formats include PNG, XCF and JPG. Opaque formats include proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML, PostScript or PDF produced by some word processors for output purposes only. The "Title Page" means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, "Title Page" means the text near the most prominent appearance of the work's title, preceding the beginning of the body of the text. The "publisher" means any person or entity that distributes copies of the Document to the public. A section "Entitled XYZ" means a named subunit of the Document whose title either is precisely XYZ or contains XYZ in parentheses following text that translates XYZ in another language. (Here XYZ stands for a specific section name mentioned below, such as "Acknowledgements", "Dedications", "Endorsements", or "History".) To "Preserve the Title" of such a section when you modify the Document means that it remains a section "Entitled XYZ" according to this definition. The Document may include Warranty Disclaimers next to the notice which states that this License applies to the Document. These Warranty Disclaimers are considered to be included by reference in this License, but only as regards disclaiming warranties: any other implication that these Warranty Disclaimers may have is void and has no effect on the meaning of this License. 2. VERBATIM COPYING You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3. You may also lend copies, under the same conditions stated above, and you may publicly display copies. 3. COPYING IN QUANTITY If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document's license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects. If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages. If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public. It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document. 4. MODIFICATIONS You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version: A. Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission. B. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement. C. State on the Title page the name of the publisher of the Modified Version, as the publisher. D. Preserve all the copyright notices of the Document. E. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices. F. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below. G. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document's license notice. H. Include an unaltered copy of this License. I. Preserve the section Entitled "History", Preserve its Title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section Entitled "History" in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence. J. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the "History" section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission. K. For any section Entitled "Acknowledgements" or "Dedications", Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein. L. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles. M. Delete any section Entitled "Endorsements". Such a section may not be included in the Modified Version. N. Do not retitle any existing section to be Entitled "Endorsements" or to conflict in title with any Invariant Section. O. Preserve any Warranty Disclaimers. If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles. You may add a section Entitled "Endorsements", provided it contains nothing but endorsements of your Modified Version by various parties--for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard. You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one. The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version. 5. COMBINING DOCUMENTS You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice, and that you preserve all their Warranty Disclaimers. The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work. In the combination, you must combine any sections Entitled "History" in the various original documents, forming one section Entitled "History"; likewise combine any sections Entitled "Acknowledgements", and any sections Entitled "Dedications". You must delete all sections Entitled "Endorsements." 6. COLLECTIONS OF DOCUMENTS You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects. You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document. 7. AGGREGATION WITH INDEPENDENT WORKS A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, is called an "aggregate" if the copyright resulting from the compilation is not used to limit the legal rights of the compilation's users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which are not themselves derivative works of the Document. If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one half of the entire aggregate, the Document's Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate. 8. TRANSLATION Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail. If a section in the Document is Entitled "Acknowledgements", "Dedications", or "History", the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title. 9. TERMINATION You may not copy, modify, sublicense, or distribute the Document except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense, or distribute it is void, and will automatically terminate your rights under this License. However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation. Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice. Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, receipt of a copy of some or all of the same material does not give you any rights to use it. 10. FUTURE REVISIONS OF THIS LICENSE The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See . Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation. If the Document specifies that a proxy can decide which future versions of this License can be used, that proxy's public statement of acceptance of a version permanently authorizes you to choose that version for the Document. 11. RELICENSING "Massive Multiauthor Collaboration Site" (or "MMC Site") means any World Wide Web server that publishes copyrightable works and also provides prominent facilities for anybody to edit those works. A public wiki that anybody can edit is an example of such a server. A "Massive Multiauthor Collaboration" (or "MMC") contained in the site means any set of copyrightable works thus published on the MMC site. "CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0 license published by Creative Commons Corporation, a not-for-profit corporation with a principal place of business in San Francisco, California, as well as future copyleft versions of that license published by that same organization. "Incorporate" means to publish or republish a Document, in whole or in part, as part of another Document. An MMC is "eligible for relicensing" if it is licensed under this License, and if all works that were first published under this License somewhere other than this MMC, and subsequently incorporated in whole or in part into the MMC, (1) had no cover texts or invariant sections, and (2) were thus incorporated prior to November 1, 2008. The operator of an MMC Site may republish an MMC contained in the site under CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is eligible for relicensing. ADDENDUM: How to use this License for your documents ==================================================== To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page: Copyright (C) YEAR YOUR NAME. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled ``GNU Free Documentation License''. If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the "with...Texts." line with this: with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation. If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software. Appendix B Indices ****************** B.1 Macro Index =============== * Menu: * _AM_DEPENDENCIES: Private Macros. (line 3160) * AC_CANONICAL_BUILD: Optional. (line 2158) * AC_CANONICAL_HOST: Optional. (line 2159) * AC_CANONICAL_TARGET: Optional. (line 2160) * AC_CONFIG_AUX_DIR: Optional. (line 2166) * AC_CONFIG_AUX_DIR <1>: Subpackages. (line 3481) * AC_CONFIG_FILES: Requirements. (line 2045) * AC_CONFIG_HEADERS: Optional. (line 2191) * AC_CONFIG_LIBOBJ_DIR: Optional. (line 2187) * AC_CONFIG_LIBOBJ_DIR <1>: LIBOBJS. (line 4597) * AC_CONFIG_LINKS: Optional. (line 2200) * AC_CONFIG_SUBDIRS: Subpackages. (line 3481) * AC_DEFUN: Extending aclocal. (line 2665) * AC_F77_LIBRARY_LDFLAGS: Optional. (line 2243) * AC_FC_SRCEXT: Optional. (line 2249) * AC_INIT: Public Macros. (line 2989) * AC_LIBOBJ: Optional. (line 2210) * AC_LIBOBJ <1>: LTLIBOBJS. (line 4188) * AC_LIBOBJ <2>: LIBOBJS. (line 4557) * AC_LIBSOURCE: Optional. (line 2211) * AC_LIBSOURCE <1>: LIBOBJS. (line 4563) * AC_LIBSOURCES: Optional. (line 2212) * AC_OUTPUT: Requirements. (line 2045) * AC_PREREQ: Extending aclocal. (line 2665) * AC_PROG_CC_C_O: Public Macros. (line 3051) * AC_PROG_CXX: Optional. (line 2230) * AC_PROG_F77: Optional. (line 2238) * AC_PROG_FC: Optional. (line 2254) * AC_PROG_LEX: Public Macros. (line 3057) * AC_PROG_LEX <1>: Optional. (line 2269) * AC_PROG_LIBTOOL: Optional. (line 2259) * AC_PROG_OBJC: Optional. (line 2234) * AC_PROG_RANLIB: Optional. (line 2226) * AC_PROG_YACC: Optional. (line 2263) * AC_REQUIRE_AUX_FILE: Optional. (line 2273) * AC_SUBST: Optional. (line 2281) * AM_CONDITIONAL: Optional. (line 2299) * AM_CONDITIONAL <1>: Usage of Conditionals. (line 7441) * AM_CONDITIONAL <2>: Usage of Conditionals. (line 7444) * AM_COND_IF: Optional. (line 2302) * AM_COND_IF <1>: Usage of Conditionals. (line 7501) * AM_COND_IF <2>: Usage of Conditionals. (line 7505) * AM_CONFIG_HEADER: Obsolete Macros. (line 3101) * AM_C_PROTOTYPES: Obsolete Macros. (line 3091) * AM_C_PROTOTYPES <1>: Optional. (line 2294) * AM_C_PROTOTYPES <2>: ANSI. (line 5305) * AM_DEP_TRACK: Private Macros. (line 3162) * AM_ENABLE_MULTILIB: Public Macros. (line 2965) * AM_GNU_GETTEXT: Optional. (line 2308) * AM_GNU_GETTEXT_INTL_SUBDIR: Optional. (line 2314) * AM_HEADER_TIOCGWINSZ_NEEDS_SYS_IOCTL: Obsolete Macros. (line 3106) * AM_INIT_AUTOMAKE: Requirements. (line 2036) * AM_INIT_AUTOMAKE <1>: Public Macros. (line 2980) * AM_MAINTAINER_MODE: Rebuilding. (line 6973) * AM_MAINTAINER_MODE <1>: maintainer-mode. (line 8460) * AM_MAINTAINER_MODE([DEFAULT-MODE]): Optional. (line 2319) * AM_MAKE_INCLUDE: Private Macros. (line 3168) * AM_OUTPUT_DEPENDENCY_COMMANDS: Private Macros. (line 3163) * AM_PATH_LISPDIR: Public Macros. (line 3024) * AM_PATH_PYTHON: Python. (line 5936) * AM_PROG_AR: Public Macros. (line 3039) * AM_PROG_AS: Public Macros. (line 3046) * AM_PROG_CC_C_O: Public Macros. (line 3051) * AM_PROG_GCJ: Public Macros. (line 3062) * AM_PROG_INSTALL_STRIP: Private Macros. (line 3173) * AM_PROG_LEX: Public Macros. (line 3057) * AM_PROG_MKDIR_P: Obsolete Macros. (line 3112) * AM_PROG_UPC: Public Macros. (line 3067) * AM_PROG_VALAC: Vala Support. (line 5235) * AM_SANITY_CHECK: Private Macros. (line 3178) * AM_SET_DEPDIR: Private Macros. (line 3161) * AM_SILENT_RULES: Public Macros. (line 3073) * AM_SUBST_NOTMAKE(VAR): Optional. (line 2327) * AM_SYS_POSIX_TERMIOS: Obsolete Macros. (line 3135) * AM_WITH_DMALLOC: Public Macros. (line 3077) * AM_WITH_REGEX: Obsolete Macros. (line 3142) * m4_include: Optional. (line 2337) * m4_include <1>: Basics of Distribution. (line 6433) B.2 Variable Index ================== * Menu: * _DATA: Data. (line 5544) * _HEADERS: Headers. (line 5504) * _LIBRARIES: A Library. (line 3818) * _LISP: Emacs Lisp. (line 5799) * _LOG_COMPILE: Simple Tests using parallel-tests. (line 6778) * _LOG_COMPILER: Simple Tests using parallel-tests. (line 6778) * _LOG_FLAGS: Simple Tests using parallel-tests. (line 6778) * _LTLIBRARIES: Libtool Libraries. (line 3922) * _MANS: Man Pages. (line 6180) * _PROGRAMS: Uniform. (line 1419) * _PROGRAMS <1>: Program Sources. (line 3582) * _PYTHON: Python. (line 5914) * _SCRIPTS: Scripts. (line 5433) * _SOURCES: Program Sources. (line 3608) * _SOURCES <1>: Program Sources. (line 3609) * _SOURCES <2>: Default _SOURCES. (line 4499) * _TEXINFOS: Texinfo. (line 6034) * _TEXINFOS <1>: Texinfo. (line 6087) * ACLOCAL_AMFLAGS: Local Macros. (line 2726) * ACLOCAL_AMFLAGS <1>: Rebuilding. (line 6976) * ALLOCA: LTLIBOBJS. (line 4188) * ALLOCA <1>: LIBOBJS. (line 4552) * AM_CCASFLAGS: Assembly Support. (line 4956) * AM_CFLAGS: Program Variables. (line 4712) * AM_COLOR_TESTS: Simple Tests. (line 6696) * AM_CPPFLAGS: Program Variables. (line 4677) * AM_CPPFLAGS <1>: Assembly Support. (line 4956) * AM_CXXFLAGS: C++ Support. (line 4882) * AM_DEFAULT_SOURCE_EXT: Default _SOURCES. (line 4499) * AM_DEFAULT_V: Automake silent-rules Option. (line 7774) * AM_DEFAULT_VERBOSITY: Automake silent-rules Option. (line 7774) * AM_DISTCHECK_CONFIGURE_FLAGS: Checking the Distribution. (line 6536) * AM_ETAGSFLAGS: Tags. (line 7316) * AM_EXT_LOG_FLAGS: Simple Tests using parallel-tests. (line 6778) * AM_FCFLAGS: Fortran 9x Support. (line 5158) * AM_FFLAGS: Fortran 77 Support. (line 4990) * AM_GCJFLAGS: Java Support with gcj. (line 5211) * AM_INSTALLCHECK_STD_OPTIONS_EXEMPT: Options. (line 7199) * AM_JAVACFLAGS: Java. (line 5897) * AM_LDFLAGS: Linking. (line 3628) * AM_LDFLAGS <1>: Program Variables. (line 4722) * AM_LFLAGS: Yacc and Lex. (line 4788) * AM_LIBTOOLFLAGS: Libtool Flags. (line 4153) * AM_LOG_FLAGS: Simple Tests using parallel-tests. (line 6778) * AM_MAKEFLAGS: Subdirectories. (line 3225) * AM_MAKEINFOFLAGS: Texinfo. (line 6137) * AM_MAKEINFOHTMLFLAGS: Texinfo. (line 6138) * AM_OBJCFLAGS: Objective C Support. (line 4911) * AM_RFLAGS: Fortran 77 Support. (line 4996) * AM_RUNTESTFLAGS: DejaGnu Tests. (line 6938) * AM_UPCFLAGS: Unified Parallel C Support. (line 4939) * AM_UPDATE_INFO_DIR: Texinfo. (line 6114) * AM_V: Automake silent-rules Option. (line 7774) * AM_VALAFLAGS: Vala Support. (line 5250) * AM_V_at: Automake silent-rules Option. (line 7774) * AM_V_GEN: Automake silent-rules Option. (line 7774) * AM_YFLAGS: Yacc and Lex. (line 4765) * ANSI2KNR: Obsolete Macros. (line 3091) * AR: Public Macros. (line 3039) * AUTOCONF: automake Invocation. (line 1867) * AUTOM4TE: aclocal Invocation. (line 2388) * AUTOMAKE_JOBS: automake Invocation. (line 2016) * AUTOMAKE_OPTIONS: Public Macros. (line 2983) * AUTOMAKE_OPTIONS <1>: ANSI. (line 5292) * AUTOMAKE_OPTIONS <2>: Dependencies. (line 5364) * AUTOMAKE_OPTIONS <3>: Options. (line 7058) * bin_PROGRAMS: Program Sources. (line 3582) * bin_SCRIPTS: Scripts. (line 5445) * build_triplet: Optional. (line 2161) * BUILT_SOURCES: Sources. (line 5582) * BZIP2: The Types of Distributions. (line 6626) * CC: Program Variables. (line 4673) * CCAS: Public Macros. (line 3046) * CCAS <1>: Assembly Support. (line 4956) * CCASFLAGS: Public Macros. (line 3046) * CCASFLAGS <1>: Assembly Support. (line 4956) * CFLAGS: Program Variables. (line 4673) * check_: Uniform. (line 1504) * check_LTLIBRARIES: Libtool Convenience Libraries. (line 4047) * check_PROGRAMS: Program Sources. (line 3582) * check_PROGRAMS <1>: Default _SOURCES. (line 4521) * check_SCRIPTS: Scripts. (line 5445) * CLASSPATH_ENV: Java. (line 5906) * CLEANFILES: Clean. (line 6379) * COMPILE: Program Variables. (line 4718) * CONFIGURE_DEPENDENCIES: Rebuilding. (line 6983) * CONFIG_STATUS_DEPENDENCIES: Rebuilding. (line 6983) * CPPFLAGS: Program Variables. (line 4673) * CPPFLAGS <1>: Assembly Support. (line 4956) * CXX: C++ Support. (line 4876) * CXXCOMPILE: C++ Support. (line 4885) * CXXFLAGS: C++ Support. (line 4879) * CXXLINK: C++ Support. (line 4889) * CXXLINK <1>: How the Linker is Chosen. (line 5115) * DATA: Uniform. (line 1510) * DATA <1>: Data. (line 5545) * data_DATA: Data. (line 5547) * DEFS: Program Variables. (line 4673) * DEJATOOL: DejaGnu Tests. (line 6933) * DESTDIR: DESTDIR. (line 799) * DESTDIR <1>: Staged Installs. (line 6330) * DISABLE_HARD_ERRORS: Simple Tests using parallel-tests. (line 6814) * DISTCHECK_CONFIGURE_FLAGS: Checking the Distribution. (line 6536) * distcleancheck_listfiles: Checking the Distribution. (line 6530) * distcleancheck_listfiles <1>: Checking the Distribution. (line 6569) * distcleancheck_listfiles <2>: distcleancheck. (line 8735) * DISTCLEANFILES: Clean. (line 6379) * DISTCLEANFILES <1>: Checking the Distribution. (line 6569) * distdir: The dist Hook. (line 6508) * distdir <1>: Third-Party Makefiles. (line 8019) * distuninstallcheck_listfiles: Checking the Distribution. (line 6530) * dist_: Alternative. (line 3450) * dist_ <1>: Fine-grained Distribution Control. (line 6472) * dist_lisp_LISP: Emacs Lisp. (line 5804) * dist_noinst_LISP: Emacs Lisp. (line 5804) * DIST_SUBDIRS: Subdirectories with AM_CONDITIONAL. (line 3330) * DIST_SUBDIRS <1>: Basics of Distribution. (line 6461) * DVIPS: Texinfo. (line 6163) * EMACS: Public Macros. (line 3024) * ETAGSFLAGS: Tags. (line 7316) * ETAGS_ARGS: Tags. (line 7316) * EXPECT: DejaGnu Tests. (line 6933) * EXTRA_DIST: Basics of Distribution. (line 6450) * EXTRA_maude_DEPENDENCIES: Linking. (line 3659) * EXTRA_maude_DEPENDENCIES <1>: Program and Library Variables. (line 4381) * EXTRA_maude_SOURCES: Program and Library Variables. (line 4315) * EXTRA_PROGRAMS: Conditional Programs. (line 3783) * EXT_LOG_COMPILE: Simple Tests using parallel-tests. (line 6778) * EXT_LOG_COMPILER: Simple Tests using parallel-tests. (line 6778) * EXT_LOG_FLAGS: Simple Tests using parallel-tests. (line 6778) * F77: Fortran 77 Support. (line 4984) * F77COMPILE: Fortran 77 Support. (line 4999) * F77LINK: How the Linker is Chosen. (line 5116) * FC: Fortran 9x Support. (line 5152) * FCCOMPILE: Fortran 9x Support. (line 5161) * FCFLAGS: Fortran 9x Support. (line 5155) * FCLINK: How the Linker is Chosen. (line 5117) * FCLINK <1>: Fortran 9x Support. (line 5165) * FFLAGS: Fortran 77 Support. (line 4987) * FLIBS: Mixing Fortran 77 With C and C++. (line 5069) * FLINK: Fortran 77 Support. (line 5003) * GCJ: Public Macros. (line 3062) * GCJFLAGS: Public Macros. (line 3062) * GCJFLAGS <1>: Java Support with gcj. (line 5201) * GCJLINK: How the Linker is Chosen. (line 5114) * GTAGS_ARGS: Tags. (line 7340) * GZIP_ENV: Basics of Distribution. (line 6430) * HEADERS: Uniform. (line 1510) * host_triplet: Optional. (line 2161) * INCLUDES: Program Variables. (line 4706) * include_HEADERS: Headers. (line 5504) * info_TEXINFOS: Texinfo. (line 6034) * JAVA: Uniform. (line 1510) * JAVAC: Java. (line 5890) * JAVACFLAGS: Java. (line 5893) * JAVAROOT: Java. (line 5902) * LDADD: Linking. (line 3628) * LDFLAGS: Program Variables. (line 4673) * LFLAGS: Yacc and Lex. (line 4788) * libexec_PROGRAMS: Program Sources. (line 3582) * libexec_SCRIPTS: Scripts. (line 5445) * LIBOBJS: Optional. (line 2213) * LIBOBJS <1>: LTLIBOBJS. (line 4188) * LIBOBJS <2>: LIBOBJS. (line 4552) * LIBRARIES: Uniform. (line 1510) * LIBS: Program Variables. (line 4673) * LIBTOOLFLAGS: Libtool Flags. (line 4153) * lib_LIBRARIES: A Library. (line 3818) * lib_LTLIBRARIES: Libtool Libraries. (line 3922) * LINK: Program Variables. (line 4727) * LINK <1>: How the Linker is Chosen. (line 5120) * LISP: Uniform. (line 1510) * lispdir: Public Macros. (line 3024) * lisp_LISP: Emacs Lisp. (line 5799) * localstate_DATA: Data. (line 5547) * LOG_COMPILE: Simple Tests using parallel-tests. (line 6778) * LOG_COMPILER: Simple Tests using parallel-tests. (line 6778) * LOG_FLAGS: Simple Tests using parallel-tests. (line 6778) * LTALLOCA: LTLIBOBJS. (line 4188) * LTALLOCA <1>: LIBOBJS. (line 4552) * LTLIBOBJS: LTLIBOBJS. (line 4188) * LTLIBOBJS <1>: LIBOBJS. (line 4552) * LTLIBRARIES: Uniform. (line 1510) * MAINTAINERCLEANFILES: Clean. (line 6379) * MAKE: Subdirectories. (line 3225) * MAKEINFO: Texinfo. (line 6121) * MAKEINFOFLAGS: Texinfo. (line 6131) * MAKEINFOHTML: Texinfo. (line 6127) * MANS: Uniform. (line 1510) * man_MANS: Man Pages. (line 6180) * maude_AR: Program and Library Variables. (line 4330) * maude_CCASFLAGS: Program and Library Variables. (line 4432) * maude_CFLAGS: Program and Library Variables. (line 4433) * maude_CPPFLAGS: Program and Library Variables. (line 4434) * maude_CXXFLAGS: Program and Library Variables. (line 4435) * maude_DEPENDENCIES: Linking. (line 3659) * maude_DEPENDENCIES <1>: Program and Library Variables. (line 4380) * maude_FFLAGS: Program and Library Variables. (line 4436) * maude_GCJFLAGS: Program and Library Variables. (line 4437) * maude_LDADD: Linking. (line 3635) * maude_LDADD <1>: Program and Library Variables. (line 4348) * maude_LDFLAGS: Linking. (line 3655) * maude_LDFLAGS <1>: Program and Library Variables. (line 4368) * maude_LFLAGS: Program and Library Variables. (line 4438) * maude_LIBADD: A Library. (line 3838) * maude_LIBADD <1>: Program and Library Variables. (line 4340) * maude_LIBTOOLFLAGS: Libtool Flags. (line 4153) * maude_LIBTOOLFLAGS <1>: Program and Library Variables. (line 4373) * maude_LINK: Program and Library Variables. (line 4416) * maude_OBJCFLAGS: Program and Library Variables. (line 4439) * maude_RFLAGS: Program and Library Variables. (line 4440) * maude_SHORTNAME: Program and Library Variables. (line 4473) * maude_SOURCES: Program and Library Variables. (line 4280) * maude_UPCFLAGS: Program and Library Variables. (line 4441) * maude_YFLAGS: Program and Library Variables. (line 4442) * MKDIR_P: Obsolete Macros. (line 3112) * mkdir_p: Obsolete Macros. (line 3112) * MOSTLYCLEANFILES: Clean. (line 6379) * nobase_: Alternative. (line 3444) * nodist_: Alternative. (line 3450) * nodist_ <1>: Fine-grained Distribution Control. (line 6472) * noinst_: Uniform. (line 1499) * noinst_HEADERS: Headers. (line 5504) * noinst_HEADERS <1>: Headers. (line 5521) * noinst_LIBRARIES: A Library. (line 3818) * noinst_LISP: Emacs Lisp. (line 5799) * noinst_LTLIBRARIES: Libtool Convenience Libraries. (line 4047) * noinst_PROGRAMS: Program Sources. (line 3582) * noinst_SCRIPTS: Scripts. (line 5445) * notrans_: Man Pages. (line 6228) * OBJC: Objective C Support. (line 4905) * OBJCCOMPILE: Objective C Support. (line 4914) * OBJCFLAGS: Objective C Support. (line 4908) * OBJCLINK: Objective C Support. (line 4918) * OBJCLINK <1>: How the Linker is Chosen. (line 5118) * oldinclude_HEADERS: Headers. (line 5504) * PACKAGE: Basics of Distribution. (line 6426) * pkgdatadir: Uniform. (line 1427) * pkgdata_DATA: Data. (line 5547) * pkgdata_SCRIPTS: Scripts. (line 5445) * pkgincludedir: Uniform. (line 1427) * pkginclude_HEADERS: Headers. (line 5504) * pkglibdir: Uniform. (line 1427) * pkglibexecdir: Uniform. (line 1427) * pkglibexec_PROGRAMS: Program Sources. (line 3582) * pkglibexec_SCRIPTS: Scripts. (line 5445) * pkglib_LIBRARIES: A Library. (line 3818) * pkglib_LTLIBRARIES: Libtool Libraries. (line 3922) * pkgpyexecdir: Python. (line 6013) * pkgpythondir: Python. (line 5999) * PROGRAMS: Uniform. (line 1425) * PROGRAMS <1>: Uniform. (line 1510) * pyexecdir: Python. (line 6004) * PYTHON: Uniform. (line 1510) * PYTHON <1>: Python. (line 5964) * pythondir: Python. (line 5995) * PYTHON_EXEC_PREFIX: Python. (line 5985) * PYTHON_PLATFORM: Python. (line 5990) * PYTHON_PREFIX: Python. (line 5980) * PYTHON_VERSION: Python. (line 5976) * RECHECK_LOGS: Simple Tests using parallel-tests. (line 6856) * RFLAGS: Fortran 77 Support. (line 4993) * RST2HTML: Simple Tests using parallel-tests. (line 6809) * RUNTEST: DejaGnu Tests. (line 6933) * RUNTESTDEFAULTFLAGS: DejaGnu Tests. (line 6928) * RUNTESTFLAGS: DejaGnu Tests. (line 6938) * sbin_PROGRAMS: Program Sources. (line 3582) * sbin_SCRIPTS: Scripts. (line 5445) * SCRIPTS: Uniform. (line 1510) * SCRIPTS <1>: Scripts. (line 5436) * sharedstate_DATA: Data. (line 5547) * SOURCES: Program Sources. (line 3609) * SOURCES <1>: Default _SOURCES. (line 4499) * SUBDIRS: Subdirectories. (line 3204) * SUBDIRS <1>: Basics of Distribution. (line 6461) * SUFFIXES: Suffixes. (line 7345) * sysconf_DATA: Data. (line 5547) * TAGS_DEPENDENCIES: Tags. (line 7326) * target_triplet: Optional. (line 2161) * TESTS: Simple Tests. (line 6708) * TESTS <1>: Simple Tests using parallel-tests. (line 6760) * TESTS_ENVIRONMENT: Simple Tests. (line 6708) * TEST_EXTENSIONS: Simple Tests using parallel-tests. (line 6766) * TEST_LOGS: Simple Tests using parallel-tests. (line 6766) * TEST_SUITE_HTML: Simple Tests using parallel-tests. (line 6809) * TEST_SUITE_LOG: Simple Tests using parallel-tests. (line 6760) * TEXI2DVI: Texinfo. (line 6154) * TEXI2PDF: Texinfo. (line 6159) * TEXINFOS: Uniform. (line 1510) * TEXINFOS <1>: Texinfo. (line 6087) * TEXINFO_TEX: Texinfo. (line 6167) * top_distdir: The dist Hook. (line 6508) * top_distdir <1>: Third-Party Makefiles. (line 8019) * U: Obsolete Macros. (line 3091) * UPC: Public Macros. (line 3067) * UPC <1>: Unified Parallel C Support. (line 4933) * UPCCOMPILE: Unified Parallel C Support. (line 4942) * UPCFLAGS: Unified Parallel C Support. (line 4936) * UPCLINK: Unified Parallel C Support. (line 4946) * UPCLINK <1>: How the Linker is Chosen. (line 5119) * V: Automake silent-rules Option. (line 7739) * VALAC: Vala Support. (line 5244) * VALAFLAGS: Vala Support. (line 5247) * VERBOSE: Simple Tests using parallel-tests. (line 6800) * VERSION: Basics of Distribution. (line 6426) * WARNINGS: automake Invocation. (line 2009) * WARNINGS <1>: aclocal Options. (line 2488) * WITH_DMALLOC: Public Macros. (line 3077) * WITH_REGEX: Obsolete Macros. (line 3142) * XFAIL_TESTS: Simple Tests. (line 6722) * XZ_OPT: The Types of Distributions. (line 6649) * YACC: Optional. (line 2264) * YFLAGS: Yacc and Lex. (line 4765) B.3 General Index ================= * Menu: * ## (special Automake comment): General Operation. (line 1359) * #serial syntax: Serials. (line 2801) * $(LIBOBJS) and empty libraries: LIBOBJS. (line 4618) * +=: General Operation. (line 1315) * --acdir: aclocal Options. (line 2411) * --add-missing: automake Invocation. (line 1880) * --automake-acdir: aclocal Options. (line 2402) * --build=BUILD: Cross-Compilation. (line 714) * --copy: automake Invocation. (line 1905) * --cygnus: automake Invocation. (line 1909) * --diff: aclocal Options. (line 2415) * --disable-dependency-tracking: Dependency Tracking. (line 911) * --disable-maintainer-mode: Optional. (line 2320) * --disable-silent-rules: Automake silent-rules Option. (line 7736) * --dry-run: aclocal Options. (line 2420) * --enable-debug, example: Usage of Conditionals. (line 7456) * --enable-dependency-tracking: Dependency Tracking. (line 921) * --enable-maintainer-mode: Optional. (line 2320) * --enable-silent-rules: Automake silent-rules Option. (line 7736) * --force: aclocal Options. (line 2442) * --force-missing: automake Invocation. (line 1916) * --foreign: automake Invocation. (line 1922) * --gnits: automake Invocation. (line 1926) * --gnits, complete description: Gnits. (line 7822) * --gnu: automake Invocation. (line 1930) * --gnu, complete description: Gnits. (line 7799) * --gnu, required files: Gnits. (line 7799) * --help: automake Invocation. (line 1934) * --help <1>: aclocal Options. (line 2424) * --help check: Options. (line 7193) * --help=recursive: Nested Packages. (line 953) * --host=HOST: Cross-Compilation. (line 716) * --include-deps: automake Invocation. (line 1942) * --install: aclocal Options. (line 2431) * --libdir: automake Invocation. (line 1900) * --no-force: automake Invocation. (line 1947) * --output: aclocal Options. (line 2452) * --output-dir: automake Invocation. (line 1954) * --prefix: Standard Directory Variables. (line 475) * --print-ac-dir: aclocal Options. (line 2455) * --program-prefix=PREFIX: Renaming. (line 780) * --program-suffix=SUFFIX: Renaming. (line 782) * --program-transform-name=PROGRAM: Renaming. (line 784) * --system-acdir: aclocal Options. (line 2406) * --target=TARGET: Cross-Compilation. (line 755) * --verbose: automake Invocation. (line 1961) * --verbose <1>: aclocal Options. (line 2466) * --version: automake Invocation. (line 1965) * --version <1>: aclocal Options. (line 2469) * --version check: Options. (line 7193) * --warnings: automake Invocation. (line 1969) * --warnings <1>: aclocal Options. (line 2473) * --with-dmalloc: Public Macros. (line 3077) * --with-regex: Obsolete Macros. (line 3142) * -a: automake Invocation. (line 1880) * -c: automake Invocation. (line 1904) * -f: automake Invocation. (line 1915) * -hook targets: Extending. (line 7958) * -i: automake Invocation. (line 1938) * -I: aclocal Options. (line 2427) * -l and LDADD: Linking. (line 3688) * -local targets: Extending. (line 7929) * -module, libtool: Libtool Modules. (line 4126) * -o: automake Invocation. (line 1954) * -v: automake Invocation. (line 1961) * -W: automake Invocation. (line 1969) * -W <1>: aclocal Options. (line 2473) * -Wall: amhello's configure.ac Setup Explained. (line 1161) * -Werror: amhello's configure.ac Setup Explained. (line 1161) * .la suffix, defined: Libtool Concept. (line 3885) * _DATA primary, defined: Data. (line 5544) * _DEPENDENCIES, defined: Linking. (line 3659) * _HEADERS primary, defined: Headers. (line 5504) * _JAVA primary, defined: Java. (line 5861) * _LDFLAGS, defined: Linking. (line 3655) * _LDFLAGS, libtool: Libtool Flags. (line 4153) * _LIBADD, libtool: Libtool Flags. (line 4153) * _LIBRARIES primary, defined: A Library. (line 3818) * _LIBTOOLFLAGS, libtool: Libtool Flags. (line 4153) * _LISP primary, defined: Emacs Lisp. (line 5799) * _LTLIBRARIES primary, defined: Libtool Libraries. (line 3922) * _MANS primary, defined: Man Pages. (line 6180) * _PROGRAMS primary variable: Uniform. (line 1419) * _PYTHON primary, defined: Python. (line 5914) * _SCRIPTS primary, defined: Scripts. (line 5433) * _SOURCES and header files: Program Sources. (line 3615) * _SOURCES primary, defined: Program Sources. (line 3608) * _SOURCES, default: Default _SOURCES. (line 4499) * _SOURCES, empty: Default _SOURCES. (line 4537) * _TEXINFOS primary, defined: Texinfo. (line 6034) * acinclude.m4, defined: Complete. (line 1754) * aclocal and serial numbers: Serials. (line 2801) * aclocal program, introduction: Complete. (line 1754) * aclocal search path: Macro Search Path. (line 2494) * aclocal's scheduled death: Future of aclocal. (line 2915) * aclocal, extending: Extending aclocal. (line 2635) * aclocal, Invocation: aclocal Invocation. (line 2350) * aclocal, Invoking: aclocal Invocation. (line 2350) * aclocal, Options: aclocal Options. (line 2399) * aclocal, using: configure. (line 2024) * aclocal.m4, preexisting: Complete. (line 1754) * ACLOCAL_PATH: Macro Search Path. (line 2604) * AC_CONFIG_FILES, conditional: Usage of Conditionals. (line 7514) * AC_SUBST and SUBDIRS: Subdirectories with AC_SUBST. (line 3341) * Adding new SUFFIXES: Suffixes. (line 7345) * all: Standard Targets. (line 424) * all <1>: Extending. (line 7933) * all-local: Extending. (line 7933) * ALLOCA, and Libtool: LTLIBOBJS. (line 4188) * ALLOCA, example: LIBOBJS. (line 4552) * ALLOCA, special handling: LIBOBJS. (line 4552) * amhello-1.0.tar.gz, creation: Hello World. (line 993) * amhello-1.0.tar.gz, location: Use Cases. (line 318) * amhello-1.0.tar.gz, use cases: Use Cases. (line 318) * AM_CCASFLAGS and CCASFLAGS: Flag Variables Ordering. (line 8758) * AM_CFLAGS and CFLAGS: Flag Variables Ordering. (line 8758) * AM_CONDITIONAL and SUBDIRS: Subdirectories with AM_CONDITIONAL. (line 3311) * AM_CPPFLAGS and CPPFLAGS: Flag Variables Ordering. (line 8758) * AM_CXXFLAGS and CXXFLAGS: Flag Variables Ordering. (line 8758) * AM_FCFLAGS and FCFLAGS: Flag Variables Ordering. (line 8758) * AM_FFLAGS and FFLAGS: Flag Variables Ordering. (line 8758) * AM_GCJFLAGS and GCJFLAGS: Flag Variables Ordering. (line 8758) * AM_INIT_AUTOMAKE, example use: Complete. (line 1742) * AM_LDFLAGS and LDFLAGS: Flag Variables Ordering. (line 8758) * AM_LFLAGS and LFLAGS: Flag Variables Ordering. (line 8758) * AM_LIBTOOLFLAGS and LIBTOOLFLAGS: Flag Variables Ordering. (line 8758) * AM_MAINTAINER_MODE, purpose: maintainer-mode. (line 8460) * AM_OBJCFLAGS and OBJCFLAGS: Flag Variables Ordering. (line 8758) * AM_RFLAGS and RFLAGS: Flag Variables Ordering. (line 8758) * AM_UPCFLAGS and UPCFLAGS: Flag Variables Ordering. (line 8758) * AM_YFLAGS and YFLAGS: Flag Variables Ordering. (line 8758) * ansi2knr: ANSI. (line 5292) * ansi2knr <1>: Options. (line 7070) * ansi2knr and LIBOBJS: ANSI. (line 5328) * ansi2knr and LTLIBOBJS: ANSI. (line 5328) * Append operator: General Operation. (line 1315) * ARG_MAX: Length Limitations. (line 1521) * autogen.sh and autoreconf: Error required file ltmain.sh not found. (line 4203) * autom4te: aclocal Invocation. (line 2388) * Automake constraints: Introduction. (line 227) * automake options: automake Invocation. (line 1876) * Automake parser, limitations of: General Operation. (line 1324) * Automake requirements: Introduction. (line 232) * Automake requirements <1>: Requirements. (line 2036) * automake, invocation: automake Invocation. (line 1845) * automake, invoking: automake Invocation. (line 1845) * Automake, recursive operation: General Operation. (line 1349) * Automatic dependency tracking: Dependencies. (line 5342) * Automatic linker selection: How the Linker is Chosen. (line 5110) * autoreconf and libtoolize: Error required file ltmain.sh not found. (line 4203) * autoreconf, example: Creating amhello. (line 1054) * autoscan: amhello's configure.ac Setup Explained. (line 1212) * Autotools, introduction: GNU Build System. (line 308) * Autotools, purpose: Why Autotools. (line 961) * autoupdate: Obsolete Macros. (line 3084) * Auxiliary programs: Auxiliary Programs. (line 1616) * Avoiding man page renaming: Man Pages. (line 6228) * Avoiding path stripping: Alternative. (line 3444) * Binary package: DESTDIR. (line 815) * bootstrap.sh and autoreconf: Error required file ltmain.sh not found. (line 4203) * Bugs, reporting: Introduction. (line 236) * build tree and source tree: VPATH Builds. (line 562) * BUILT_SOURCES, defined: Sources. (line 5582) * C++ support: C++ Support. (line 4866) * canonicalizing Automake variables: Canonicalization. (line 1569) * CCASFLAGS and AM_CCASFLAGS: Flag Variables Ordering. (line 8758) * CFLAGS and AM_CFLAGS: Flag Variables Ordering. (line 8758) * cfortran: Mixing Fortran 77 With C and C++. (line 5054) * check: Standard Targets. (line 439) * check <1>: Tests. (line 6671) * check <2>: Extending. (line 7933) * check-html: Simple Tests using parallel-tests. (line 6809) * check-local: Extending. (line 7933) * check-news: Options. (line 7080) * check_ primary prefix, definition: Uniform. (line 1504) * check_PROGRAMS example: Default _SOURCES. (line 4521) * clean: Standard Targets. (line 435) * clean <1>: Extending. (line 7933) * clean-local: Clean. (line 6381) * clean-local <1>: Extending. (line 7933) * color-tests: Options. (line 7084) * command line length limit: Length Limitations. (line 1521) * Comment, special to Automake: General Operation. (line 1359) * Compilation of Java to bytecode: Java. (line 5861) * Compilation of Java to native code: Java Support with gcj. (line 5191) * Compile Flag Variables: Flag Variables Ordering. (line 8758) * Complete example: Complete. (line 1737) * Conditional example, --enable-debug: Usage of Conditionals. (line 7456) * conditional libtool libraries: Conditional Libtool Libraries. (line 3962) * Conditional programs: Conditional Programs. (line 3774) * Conditional subdirectories: Conditional Subdirectories. (line 3252) * Conditional SUBDIRS: Conditional Subdirectories. (line 3252) * Conditionals: Conditionals. (line 7426) * config.guess: automake Invocation. (line 1878) * config.site example: config.site. (line 531) * configuration variables, overriding: Standard Configuration Variables. (line 494) * Configuration, basics: Basic Installation. (line 339) * configure.ac, Hello World: amhello's configure.ac Setup Explained. (line 1129) * configure.ac, scanning: configure. (line 2024) * conflicting definitions: Extending. (line 7906) * Constraints of Automake: Introduction. (line 227) * convenience libraries, libtool: Libtool Convenience Libraries. (line 4047) * copying semantics: Extending. (line 7902) * cpio example: Uniform. (line 1444) * CPPFLAGS and AM_CPPFLAGS: Flag Variables Ordering. (line 8758) * cross-compilation: Cross-Compilation. (line 706) * cross-compilation example: Cross-Compilation. (line 725) * CVS and generated files: CVS. (line 8328) * CVS and third-party files: CVS. (line 8416) * CVS and timestamps: CVS. (line 8307) * CXXFLAGS and AM_CXXFLAGS: Flag Variables Ordering. (line 8758) * cygnus: Options. (line 7064) * cygnus strictness: Cygnus. (line 7848) * DATA primary, defined: Data. (line 5544) * de-ANSI-fication, defined: ANSI. (line 5276) * debug build, example: VPATH Builds. (line 602) * debugging rules: Debugging Make Rules. (line 9399) * default source, Libtool modules example: Default _SOURCES. (line 4531) * default verbosity for silent-rules: Automake silent-rules Option. (line 7743) * default _SOURCES: Default _SOURCES. (line 4499) * definitions, conflicts: Extending. (line 7906) * dejagnu: DejaGnu Tests. (line 6933) * dejagnu <1>: Options. (line 7088) * depcomp: Dependencies. (line 5353) * dependencies and distributed files: distcleancheck. (line 8629) * Dependency tracking: Dependency Tracking. (line 884) * Dependency tracking <1>: Dependencies. (line 5342) * Dependency tracking, disabling: Dependencies. (line 5366) * directory variables: Standard Directory Variables. (line 448) * dirlist: Macro Search Path. (line 2540) * Disabling dependency tracking: Dependencies. (line 5367) * dist: Standard Targets. (line 443) * dist <1>: Basics of Distribution. (line 6426) * dist-bzip2: The Types of Distributions. (line 6631) * dist-bzip2 <1>: Options. (line 7092) * dist-bzip2 <2>: Options. (line 7092) * dist-gzip: The Types of Distributions. (line 6634) * dist-hook: The dist Hook. (line 6490) * dist-hook <1>: Extending. (line 7958) * dist-lzip: The Types of Distributions. (line 6638) * dist-lzip <1>: Options. (line 7095) * dist-lzip <2>: Options. (line 7095) * dist-lzma: The Types of Distributions. (line 6644) * dist-lzma <1>: Options. (line 7098) * dist-lzma <2>: Options. (line 7098) * dist-shar: The Types of Distributions. (line 6647) * dist-shar <1>: Options. (line 7101) * dist-shar <2>: Options. (line 7101) * dist-tarZ: The Types of Distributions. (line 6662) * dist-tarZ <1>: Options. (line 7107) * dist-tarZ <2>: Options. (line 7107) * dist-xz: The Types of Distributions. (line 6656) * dist-zip: The Types of Distributions. (line 6659) * dist-zip <1>: Options. (line 7104) * dist-zip <2>: Options. (line 7104) * distcheck: Creating amhello. (line 1094) * distcheck <1>: Checking the Distribution. (line 6530) * distcheck better than dist: Preparing Distributions. (line 850) * distcheck example: Creating amhello. (line 1094) * distcheck-hook: Checking the Distribution. (line 6557) * distclean: Standard Targets. (line 437) * distclean <1>: Extending. (line 7933) * distclean <2>: distcleancheck. (line 8629) * distclean, diagnostic: distcleancheck. (line 8629) * distclean-local: Clean. (line 6381) * distclean-local <1>: Extending. (line 7933) * distcleancheck: Checking the Distribution. (line 6569) * distcleancheck <1>: distcleancheck. (line 8629) * distdir: Third-Party Makefiles. (line 8019) * Distributions, preparation: Preparing Distributions. (line 846) * dist_ and nobase_: Alternative. (line 3450) * dist_ and notrans_: Man Pages. (line 6237) * DIST_SUBDIRS, explained: SUBDIRS vs DIST_SUBDIRS. (line 3280) * dmalloc, support for: Public Macros. (line 3077) * dvi: Texinfo. (line 6047) * dvi <1>: Extending. (line 7933) * DVI output using Texinfo: Texinfo. (line 6034) * dvi-local: Extending. (line 7933) * E-mail, bug reports: Introduction. (line 236) * EDITION Texinfo flag: Texinfo. (line 6057) * else: Usage of Conditionals. (line 7471) * Empty libraries: A Library. (line 3860) * Empty libraries and $(LIBOBJS): LIBOBJS. (line 4618) * empty _SOURCES: Default _SOURCES. (line 4537) * endif: Usage of Conditionals. (line 7471) * Example conditional --enable-debug: Usage of Conditionals. (line 7456) * Example conditional AC_CONFIG_FILES: Usage of Conditionals. (line 7514) * Example Hello World: Hello World. (line 993) * Example of recursive operation: General Operation. (line 1349) * Example of shared libraries: Libtool Libraries. (line 3922) * Example, EXTRA_PROGRAMS: Uniform. (line 1444) * Example, false and true: true. (line 1785) * Example, mixed language: Mixing Fortran 77 With C and C++. (line 5084) * Executable extension: EXEEXT. (line 5370) * Exit status 77, special interpretation: Simple Tests. (line 6691) * Exit status 99, special interpretation: Simple Tests using parallel-tests. (line 6814) * Expected test failure: Simple Tests. (line 6722) * Extending aclocal: Extending aclocal. (line 2635) * Extending list of installation directories: Uniform. (line 1464) * Extension, executable: EXEEXT. (line 5370) * Extra files distributed with Automake: automake Invocation. (line 1878) * EXTRA_, prepending: Uniform. (line 1437) * EXTRA_PROGRAMS, defined: Uniform. (line 1444) * EXTRA_PROGRAMS, defined <1>: Conditional Programs. (line 3783) * EXTRA_prog_SOURCES, defined: Conditional Sources. (line 3710) * false Example: true. (line 1785) * FCFLAGS and AM_FCFLAGS: Flag Variables Ordering. (line 8758) * Features of the GNU Build System: Use Cases. (line 318) * FFLAGS and AM_FFLAGS: Flag Variables Ordering. (line 8758) * file names, limitations on: Limitations on File Names. (line 8573) * filename-length-max=99: Options. (line 7110) * Files distributed with Automake: automake Invocation. (line 1878) * First line of Makefile.am: General Operation. (line 1365) * Flag variables, ordering: Flag Variables Ordering. (line 8744) * Flag Variables, Ordering: Flag Variables Ordering. (line 8758) * FLIBS, defined: Mixing Fortran 77 With C and C++. (line 5069) * foreign: amhello's configure.ac Setup Explained. (line 1161) * foreign <1>: Options. (line 7064) * foreign strictness: Strictness. (line 1374) * Fortran 77 support: Fortran 77 Support. (line 4974) * Fortran 77, mixing with C and C++: Mixing Fortran 77 With C and C++. (line 5054) * Fortran 77, Preprocessing: Preprocessing Fortran 77. (line 5023) * Fortran 9x support: Fortran 9x Support. (line 5142) * GCJFLAGS and AM_GCJFLAGS: Flag Variables Ordering. (line 8758) * generated files and CVS: CVS. (line 8328) * generated files, distributed: CVS. (line 8288) * Gettext support: gettext. (line 5841) * git-dist: General Operation. (line 1303) * git-dist, non-standard example: General Operation. (line 1303) * gnits: Options. (line 7064) * gnits strictness: Strictness. (line 1374) * gnu: Options. (line 7064) * GNU Build System, basics: Basic Installation. (line 339) * GNU Build System, features: Use Cases. (line 318) * GNU Build System, introduction: GNU Build System. (line 271) * GNU Build System, use cases: Use Cases. (line 318) * GNU Coding Standards: GNU Build System. (line 294) * GNU Gettext support: gettext. (line 5841) * GNU make extensions: General Operation. (line 1311) * GNU Makefile standards: Introduction. (line 217) * gnu strictness: Strictness. (line 1374) * GNUmakefile including Makefile: Third-Party Makefiles. (line 8105) * hard error: Simple Tests using parallel-tests. (line 6814) * Header files in _SOURCES: Program Sources. (line 3615) * HEADERS primary, defined: Headers. (line 5504) * HEADERS, installation directories: Headers. (line 5504) * Hello World example: Hello World. (line 993) * hook targets: Extending. (line 7958) * HP-UX 10, lex problems: Public Macros. (line 3057) * html: Texinfo. (line 6047) * html <1>: Extending. (line 7933) * HTML output using Texinfo: Texinfo. (line 6034) * html-local: Extending. (line 7933) * id: Tags. (line 7335) * if: Usage of Conditionals. (line 7471) * include: Basics of Distribution. (line 6433) * include <1>: Include. (line 7402) * include, distribution: Basics of Distribution. (line 6433) * Including Makefile fragment: Include. (line 7402) * indentation in Makefile.am: General Operation. (line 1324) * info: Options. (line 7151) * info <1>: Extending. (line 7933) * info-local: Extending. (line 7933) * install: Standard Targets. (line 426) * install <1>: The Two Parts of Install. (line 6296) * install <2>: Extending. (line 7933) * Install hook: Extending Installation. (line 6325) * Install, two parts of: The Two Parts of Install. (line 6296) * install-data: Two-Part Install. (line 664) * install-data <1>: The Two Parts of Install. (line 6296) * install-data <2>: Extending. (line 7933) * install-data-hook: Extending. (line 7958) * install-data-local: Extending Installation. (line 6319) * install-data-local <1>: Extending. (line 7933) * install-dvi: Texinfo. (line 6047) * install-dvi <1>: Extending. (line 7933) * install-dvi-local: Extending. (line 7933) * install-exec: Two-Part Install. (line 664) * install-exec <1>: The Two Parts of Install. (line 6296) * install-exec <2>: Extending. (line 7933) * install-exec-hook: Extending. (line 7958) * install-exec-local: Extending Installation. (line 6319) * install-exec-local <1>: Extending. (line 7933) * install-html: Texinfo. (line 6047) * install-html <1>: Extending. (line 7933) * install-html-local: Extending. (line 7933) * install-info: Texinfo. (line 6107) * install-info <1>: Options. (line 7151) * install-info <2>: Extending. (line 7933) * install-info target: Texinfo. (line 6107) * install-info-local: Extending. (line 7933) * install-man: Man Pages. (line 6206) * install-man <1>: Options. (line 7157) * install-man target: Man Pages. (line 6206) * install-pdf: Texinfo. (line 6047) * install-pdf <1>: Extending. (line 7933) * install-pdf-local: Extending. (line 7933) * install-ps: Texinfo. (line 6047) * install-ps <1>: Extending. (line 7933) * install-ps-local: Extending. (line 7933) * install-strip: Standard Targets. (line 429) * install-strip <1>: Install Rules for the User. (line 6360) * Installation directories, extending list: Uniform. (line 1464) * Installation support: Install. (line 6246) * Installation, basics: Basic Installation. (line 339) * installcheck: Standard Targets. (line 441) * installcheck <1>: Extending. (line 7933) * installcheck-local: Extending. (line 7933) * installdirs: Install Rules for the User. (line 6360) * installdirs <1>: Extending. (line 7933) * installdirs-local: Extending. (line 7933) * Installing headers: Headers. (line 5504) * Installing scripts: Scripts. (line 5433) * installing versioned binaries: Extending. (line 7978) * Interfacing with third-party packages: Third-Party Makefiles. (line 8000) * Invocation of aclocal: aclocal Invocation. (line 2350) * Invocation of automake: automake Invocation. (line 1845) * Invoking aclocal: aclocal Invocation. (line 2350) * Invoking automake: automake Invocation. (line 1845) * JAVA primary, defined: Java. (line 5861) * JAVA restrictions: Java. (line 5880) * Java support with gcj: Java Support with gcj. (line 5191) * Java to bytecode, compilation: Java. (line 5861) * Java to native code, compilation: Java Support with gcj. (line 5191) * lazy test execution: Simple Tests using parallel-tests. (line 6856) * LDADD and -l: Linking. (line 3688) * LDFLAGS and AM_LDFLAGS: Flag Variables Ordering. (line 8758) * lex problems with HP-UX 10: Public Macros. (line 3057) * lex, multiple lexers: Yacc and Lex. (line 4796) * LFLAGS and AM_LFLAGS: Flag Variables Ordering. (line 8758) * libltdl, introduction: Libtool Concept. (line 3908) * LIBOBJS and ansi2knr: ANSI. (line 5328) * LIBOBJS, and Libtool: LTLIBOBJS. (line 4188) * LIBOBJS, example: LIBOBJS. (line 4552) * LIBOBJS, special handling: LIBOBJS. (line 4552) * LIBRARIES primary, defined: A Library. (line 3818) * libtool convenience libraries: Libtool Convenience Libraries. (line 4047) * libtool libraries, conditional: Conditional Libtool Libraries. (line 3962) * libtool library, definition: Libtool Concept. (line 3885) * libtool modules: Libtool Modules. (line 4126) * Libtool modules, default source example: Default _SOURCES. (line 4531) * libtool, introduction: Libtool Concept. (line 3885) * LIBTOOLFLAGS and AM_LIBTOOLFLAGS: Flag Variables Ordering. (line 8758) * libtoolize and autoreconf: Error required file ltmain.sh not found. (line 4203) * libtoolize, no longer run by automake: Error required file ltmain.sh not found. (line 4203) * Limitations of automake parser: General Operation. (line 1324) * Linking Fortran 77 with C and C++: Mixing Fortran 77 With C and C++. (line 5054) * LISP primary, defined: Emacs Lisp. (line 5799) * LN_S example: Extending. (line 7978) * local targets: Extending. (line 7929) * LTALLOCA, special handling: LTLIBOBJS. (line 4188) * LTLIBOBJS and ansi2knr: ANSI. (line 5328) * LTLIBOBJS, special handling: LTLIBOBJS. (line 4188) * LTLIBRARIES primary, defined: Libtool Libraries. (line 3922) * ltmain.sh not found: Error required file ltmain.sh not found. (line 4203) * m4_include, distribution: Basics of Distribution. (line 6433) * Macro search path: Macro Search Path. (line 2494) * macro serial numbers: Serials. (line 2801) * Macros Automake recognizes: Optional. (line 2153) * maintainer-clean-local: Clean. (line 6381) * make check: Tests. (line 6671) * make clean support: Clean. (line 6372) * make dist: Basics of Distribution. (line 6426) * make distcheck: Checking the Distribution. (line 6530) * make distclean, diagnostic: distcleancheck. (line 8629) * make distcleancheck: Checking the Distribution. (line 6530) * make distuninstallcheck: Checking the Distribution. (line 6530) * make install support: Install. (line 6246) * make installcheck, testing --help and --version: Options. (line 7193) * Make rules, overriding: General Operation. (line 1337) * Make targets, overriding: General Operation. (line 1337) * Makefile fragment, including: Include. (line 7402) * Makefile.am, first line: General Operation. (line 1365) * Makefile.am, Hello World: amhello's Makefile.am Setup Explained. (line 1221) * Man page renaming, avoiding: Man Pages. (line 6228) * MANS primary, defined: Man Pages. (line 6180) * many outputs, rules with: Multiple Outputs. (line 9010) * mdate-sh: Texinfo. (line 6057) * MinGW cross-compilation example: Cross-Compilation. (line 725) * missing, purpose: maintainer-mode. (line 8433) * Mixed language example: Mixing Fortran 77 With C and C++. (line 5084) * Mixing Fortran 77 with C and C++: Mixing Fortran 77 With C and C++. (line 5054) * Mixing Fortran 77 with C and/or C++: Mixing Fortran 77 With C and C++. (line 5054) * mkdir -p, macro check: Obsolete Macros. (line 3112) * modules, libtool: Libtool Modules. (line 4126) * mostlyclean: Extending. (line 7933) * mostlyclean-local: Clean. (line 6381) * mostlyclean-local <1>: Extending. (line 7933) * multiple configurations, example: VPATH Builds. (line 602) * Multiple configure.ac files: automake Invocation. (line 1845) * Multiple lex lexers: Yacc and Lex. (line 4796) * multiple outputs, rules with: Multiple Outputs. (line 9010) * Multiple yacc parsers: Yacc and Lex. (line 4796) * Nested packages: Nested Packages. (line 929) * Nesting packages: Subpackages. (line 3481) * no-define: Public Macros. (line 3018) * no-define <1>: Options. (line 7119) * no-dependencies: Dependencies. (line 5364) * no-dependencies <1>: Options. (line 7124) * no-dist: Options. (line 7131) * no-dist-gzip: Options. (line 7135) * no-dist-gzip <1>: Options. (line 7135) * no-exeext: Options. (line 7138) * no-installinfo: Texinfo. (line 6107) * no-installinfo <1>: Options. (line 7148) * no-installinfo option: Texinfo. (line 6107) * no-installman: Man Pages. (line 6206) * no-installman <1>: Options. (line 7154) * no-installman option: Man Pages. (line 6206) * no-texinfo.tex: Options. (line 7164) * nobase_ and dist_ or nodist_: Alternative. (line 3450) * nobase_ prefix: Alternative. (line 3444) * nodist_ and nobase_: Alternative. (line 3450) * nodist_ and notrans_: Man Pages. (line 6237) * noinst_ primary prefix, definition: Uniform. (line 1499) * Non-GNU packages: Strictness. (line 1370) * Non-standard targets: General Operation. (line 1303) * nostdinc: Options. (line 7160) * notrans_ and dist_ or nodist_: Man Pages. (line 6237) * notrans_ prefix: Man Pages. (line 6228) * OBJCFLAGS and AM_OBJCFLAGS: Flag Variables Ordering. (line 8758) * Objective C support: Objective C Support. (line 4895) * Objects in subdirectory: Program and Library Variables. (line 4313) * obsolete macros: Obsolete Macros. (line 3084) * optimized build, example: VPATH Builds. (line 602) * Option, --warnings=CATEGORY: Options. (line 7278) * Option, -WCATEGORY: Options. (line 7278) * Option, ansi2knr: Options. (line 7070) * Option, check-news: Options. (line 7080) * Option, color-tests: Options. (line 7084) * Option, cygnus: Options. (line 7064) * Option, dejagnu: Options. (line 7088) * Option, dist-bzip2: Options. (line 7092) * Option, dist-lzip: Options. (line 7095) * Option, dist-lzma: Options. (line 7098) * Option, dist-shar: Options. (line 7101) * Option, dist-tarZ: Options. (line 7107) * Option, dist-zip: Options. (line 7104) * Option, filename-length-max=99: Options. (line 7110) * Option, foreign: Options. (line 7064) * Option, gnits: Options. (line 7064) * Option, gnu: Options. (line 7064) * Option, no-define: Options. (line 7119) * Option, no-dependencies: Options. (line 7124) * Option, no-dist: Options. (line 7131) * Option, no-dist-gzip: Options. (line 7135) * Option, no-exeext: Options. (line 7138) * Option, no-installinfo: Texinfo. (line 6107) * Option, no-installinfo <1>: Options. (line 7148) * Option, no-installman: Man Pages. (line 6206) * Option, no-installman <1>: Options. (line 7154) * Option, no-texinfo.tex: Options. (line 7164) * Option, nostdinc: Options. (line 7160) * Option, parallel-tests: Options. (line 7168) * Option, readme-alpha: Options. (line 7172) * Option, silent-rules: Options. (line 7181) * Option, tar-pax: Options. (line 7226) * Option, tar-ustar: Options. (line 7226) * Option, tar-v7: Options. (line 7226) * Option, VERSION: Options. (line 7273) * Option, warnings: Options. (line 7278) * Options, aclocal: aclocal Options. (line 2399) * Options, automake: automake Invocation. (line 1876) * Options, std-options: Options. (line 7193) * Options, subdir-objects: Options. (line 7214) * Ordering flag variables: Flag Variables Ordering. (line 8744) * Overriding make rules: General Operation. (line 1337) * Overriding make targets: General Operation. (line 1337) * Overriding make variables: General Operation. (line 1342) * overriding rules: Extending. (line 7918) * overriding semantics: Extending. (line 7918) * PACKAGE, directory: Uniform. (line 1427) * PACKAGE, prevent definition: Public Macros. (line 3018) * Packages, nested: Nested Packages. (line 929) * Packages, preparation: Preparing Distributions. (line 846) * Parallel build trees: VPATH Builds. (line 562) * parallel-tests: Options. (line 7168) * parallel-tests, Using: Simple Tests using parallel-tests. (line 6745) * Path stripping, avoiding: Alternative. (line 3444) * pax format: Options. (line 7226) * pdf: Texinfo. (line 6047) * pdf <1>: Extending. (line 7933) * PDF output using Texinfo: Texinfo. (line 6034) * pdf-local: Extending. (line 7933) * Per-object flags, emulated: Per-Object Flags. (line 8951) * per-target compilation flags, defined: Program and Library Variables. (line 4443) * pkgdatadir, defined: Uniform. (line 1427) * pkgincludedir, defined: Uniform. (line 1427) * pkglibdir, defined: Uniform. (line 1427) * pkglibexecdir, defined: Uniform. (line 1427) * POSIX termios headers: Obsolete Macros. (line 3135) * Preparing distributions: Preparing Distributions. (line 846) * Preprocessing Fortran 77: Preprocessing Fortran 77. (line 5023) * Primary variable, DATA: Data. (line 5544) * Primary variable, defined: Uniform. (line 1419) * Primary variable, HEADERS: Headers. (line 5504) * Primary variable, JAVA: Java. (line 5861) * Primary variable, LIBRARIES: A Library. (line 3818) * Primary variable, LISP: Emacs Lisp. (line 5799) * Primary variable, LTLIBRARIES: Libtool Libraries. (line 3922) * Primary variable, MANS: Man Pages. (line 6180) * Primary variable, PROGRAMS: Uniform. (line 1419) * Primary variable, PYTHON: Python. (line 5914) * Primary variable, SCRIPTS: Scripts. (line 5433) * Primary variable, SOURCES: Program Sources. (line 3608) * Primary variable, TEXINFOS: Texinfo. (line 6034) * PROGRAMS primary variable: Uniform. (line 1419) * Programs, auxiliary: Auxiliary Programs. (line 1616) * PROGRAMS, bindir: Program Sources. (line 3582) * Programs, conditional: Conditional Programs. (line 3774) * Programs, renaming during installation: Renaming. (line 770) * prog_LDADD, defined: Linking. (line 3630) * Proxy Makefile for third-party packages: Third-Party Makefiles. (line 8122) * ps: Texinfo. (line 6047) * ps <1>: Extending. (line 7933) * PS output using Texinfo: Texinfo. (line 6034) * ps-local: Extending. (line 7933) * PYTHON primary, defined: Python. (line 5914) * Ratfor programs: Preprocessing Fortran 77. (line 5023) * read-only source tree: VPATH Builds. (line 645) * readme-alpha: Options. (line 7172) * README-alpha: Gnits. (line 7835) * rebuild rules: Rebuilding. (line 6970) * rebuild rules <1>: CVS. (line 8288) * recheck: Simple Tests using parallel-tests. (line 6868) * Recognized macros by Automake: Optional. (line 2153) * Recursive operation of Automake: General Operation. (line 1349) * recursive targets and third-party Makefiles: Third-Party Makefiles. (line 8009) * regex package: Obsolete Macros. (line 3142) * Renaming programs: Renaming. (line 770) * Reporting bugs: Introduction. (line 236) * Requirements of Automake: Requirements. (line 2036) * Requirements, Automake: Introduction. (line 232) * Restrictions for JAVA: Java. (line 5880) * RFLAGS and AM_RFLAGS: Flag Variables Ordering. (line 8758) * rules with multiple outputs: Multiple Outputs. (line 9010) * rules, conflicting: Extending. (line 7906) * rules, debugging: Debugging Make Rules. (line 9399) * rules, overriding: Extending. (line 7918) * rx package: Obsolete Macros. (line 3142) * Scanning configure.ac: configure. (line 2024) * SCRIPTS primary, defined: Scripts. (line 5433) * SCRIPTS, installation directories: Scripts. (line 5445) * Selecting the linker automatically: How the Linker is Chosen. (line 5110) * serial number and --install: aclocal Options. (line 2435) * serial numbers in macros: Serials. (line 2801) * Shared libraries, support for: A Shared Library. (line 3878) * Silencing make: Silencing Make. (line 7560) * Silent make: Silencing Make. (line 7560) * Silent make rules: Silencing Make. (line 7560) * Silent rules: Silencing Make. (line 7560) * silent-rules: Options. (line 7181) * silent-rules and libtool: Automake silent-rules Option. (line 7696) * site.exp: DejaGnu Tests. (line 6940) * source tree and build tree: VPATH Builds. (line 562) * source tree, read-only: VPATH Builds. (line 645) * SOURCES primary, defined: Program Sources. (line 3608) * Special Automake comment: General Operation. (line 1359) * Staged installation: DESTDIR. (line 807) * std-options: Options. (line 7193) * Strictness, command line: automake Invocation. (line 1876) * Strictness, defined: Strictness. (line 1374) * Strictness, foreign: Strictness. (line 1374) * Strictness, gnits: Strictness. (line 1374) * Strictness, gnu: Strictness. (line 1374) * su, before make install: Basic Installation. (line 382) * subdir-objects: Options. (line 7214) * Subdirectories, building conditionally: Conditional Subdirectories. (line 3252) * Subdirectories, configured conditionally: Unconfigured Subdirectories. (line 3365) * Subdirectories, not distributed: Unconfigured Subdirectories. (line 3414) * Subdirectory, objects in: Program and Library Variables. (line 4313) * SUBDIRS and AC_SUBST: Subdirectories with AC_SUBST. (line 3341) * SUBDIRS and AM_CONDITIONAL: Subdirectories with AM_CONDITIONAL. (line 3311) * SUBDIRS, conditional: Conditional Subdirectories. (line 3252) * SUBDIRS, explained: Subdirectories. (line 3202) * Subpackages: Nested Packages. (line 929) * Subpackages <1>: Subpackages. (line 3481) * suffix .la, defined: Libtool Concept. (line 3885) * suffix .lo, defined: Libtool Concept. (line 3894) * SUFFIXES, adding: Suffixes. (line 7345) * Support for C++: C++ Support. (line 4866) * Support for Fortran 77: Fortran 77 Support. (line 4974) * Support for Fortran 9x: Fortran 9x Support. (line 5142) * Support for GNU Gettext: gettext. (line 5841) * Support for Java with gcj: Java Support with gcj. (line 5191) * Support for Objective C: Objective C Support. (line 4895) * Support for Unified Parallel C: Unified Parallel C Support. (line 4924) * Support for Vala: Vala Support. (line 5221) * tags: Tags. (line 7300) * TAGS support: Tags. (line 7297) * tar formats: Options. (line 7226) * tar-pax: Options. (line 7226) * tar-ustar: Options. (line 7226) * tar-v7: Options. (line 7226) * Target, install-info: Texinfo. (line 6107) * Target, install-man: Man Pages. (line 6206) * termios POSIX headers: Obsolete Macros. (line 3135) * Test suites: Tests. (line 6671) * Tests, expected failure: Simple Tests. (line 6722) * Texinfo flag, EDITION: Texinfo. (line 6057) * Texinfo flag, UPDATED: Texinfo. (line 6057) * Texinfo flag, UPDATED-MONTH: Texinfo. (line 6057) * Texinfo flag, VERSION: Texinfo. (line 6057) * texinfo.tex: Texinfo. (line 6092) * TEXINFOS primary, defined: Texinfo. (line 6034) * third-party files and CVS: CVS. (line 8416) * Third-party packages, interfacing with: Third-Party Makefiles. (line 8000) * timestamps and CVS: CVS. (line 8307) * Transforming program names: Renaming. (line 770) * trees, source vs. build: VPATH Builds. (line 562) * true Example: true. (line 1785) * underquoted AC_DEFUN: Extending aclocal. (line 2665) * Unified Parallel C support: Unified Parallel C Support. (line 4924) * Uniform naming scheme: Uniform. (line 1414) * uninstall: Standard Targets. (line 432) * uninstall <1>: Install Rules for the User. (line 6360) * uninstall <2>: Extending. (line 7933) * uninstall-hook: Extending. (line 7958) * uninstall-local: Extending. (line 7933) * Unit tests: Simple Tests using parallel-tests. (line 6892) * Unpacking: Basic Installation. (line 360) * UPCFLAGS and AM_UPCFLAGS: Flag Variables Ordering. (line 8758) * UPDATED Texinfo flag: Texinfo. (line 6057) * UPDATED-MONTH Texinfo flag: Texinfo. (line 6057) * Use Cases for the GNU Build System: Use Cases. (line 318) * user variables: User Variables. (line 1589) * Using aclocal: configure. (line 2024) * ustar format: Options. (line 7226) * v7 tar format: Options. (line 7226) * Vala Support: Vala Support. (line 5221) * variables, conflicting: Extending. (line 7906) * Variables, overriding: General Operation. (line 1342) * variables, reserved for the user: User Variables. (line 1589) * VERSION Texinfo flag: Texinfo. (line 6057) * VERSION, prevent definition: Public Macros. (line 3018) * version.m4, example: Rebuilding. (line 6983) * version.sh, example: Rebuilding. (line 6983) * versioned binaries, installing: Extending. (line 7978) * VPATH builds: VPATH Builds. (line 562) * wildcards: Wildcards. (line 8507) * Windows: EXEEXT. (line 5370) * yacc, multiple parsers: Yacc and Lex. (line 4796) * YFLAGS and AM_YFLAGS: Flag Variables Ordering. (line 8758) * ylwrap: Yacc and Lex. (line 4796) * zardoz example: Complete. (line 1766)