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4.1 Initializing configure

Every configure script must call AC_INIT before doing anything else that produces output. Calls to silent macros, such as AC_DEFUN, may also occur prior to AC_INIT, although these are generally used via aclocal.m4, since that is implicitly included before the start of configure.ac. The only other required macro is AC_OUTPUT (see Output).

— Macro: AC_INIT (package, version, [bug-report], [tarname], [url])

Process any command-line arguments and perform various initializations and verifications.

Set the name of the package and its version. These are typically used in --version support, including that of configure. The optional argument bug-report should be the email to which users should send bug reports. The package tarname differs from package: the latter designates the full package name (e.g., ‘GNU Autoconf’), while the former is meant for distribution tar ball names (e.g., ‘autoconf’). It defaults to package with ‘GNU ’ stripped, lower-cased, and all characters other than alphanumerics and underscores are changed to ‘-’. If provided, url should be the home page for the package.

It is preferable that the arguments of AC_INIT be static, i.e., there should not be any shell computation, but they can be computed by M4.

The following M4 macros (e.g., AC_PACKAGE_NAME), output variables (e.g., PACKAGE_NAME), and preprocessor symbols (e.g., PACKAGE_NAME), are defined by AC_INIT:

AC_PACKAGE_NAME, PACKAGE_NAME
Exactly package.
AC_PACKAGE_TARNAME, PACKAGE_TARNAME
Exactly tarname, possibly generated from package.
AC_PACKAGE_VERSION, PACKAGE_VERSION
Exactly version.
AC_PACKAGE_STRING, PACKAGE_STRING
Exactly ‘package version’.
AC_PACKAGE_BUGREPORT, PACKAGE_BUGREPORT
Exactly bug-report, if one was provided.
AC_PACKAGE_URL, PACKAGE_URL
Exactly url, if one was provided. If url was empty, but package begins with ‘GNU ’, then this defaults to ‘http://www.gnu.org/software/tarname/’, otherwise, no URL is assumed.

If your configure script does its own option processing, it should inspect ‘$@’ or ‘$*’ immediately after calling AC_INIT, because other Autoconf macros liberally use the set command to process strings, and this has the side effect of updating ‘$@’ and ‘$*’. However, we suggest that you use standard macros like AC_ARG_ENABLE instead of attempting to implement your own option processing. See Site Configuration.