14 Manual Configuration

A few kinds of features can’t be guessed automatically by running test programs. For example, the details of the object-file format, or special options that need to be passed to the compiler or linker. Autoconf provides a uniform method for handling unguessable features, by giving each operating system a canonical system type, also known as a canonical name or target triplet.

If you use any of the macros described in this chapter, you must distribute the helper scripts config.guess and config.sub along with your source code. Some Autoconf macros use these macros internally, so you may need to distribute these scripts even if you do not use any of these macros yourself. See Input, for information about the AC_CONFIG_AUX_DIR macro which you can use to control in which directory configure looks for helper scripts, and where to get the scripts from.