Autoconf

Autoconf is a tool for producing shell scripts that automatically configure software source code packages to adapt to many kinds of Unix-like systems. The configuration scripts produced by Autoconf are independent of Autoconf when they are run, so their users do not need to have Autoconf.

Together with Automake and Libtool, Autoconf forms the GNU build system.

Autoconf makes use of GNU m4 to transform a user-written configure.ac (formerly, and on older projects called configure.in ) file to a portable shell script called configure . The configure script runs non-interactively, and generates customized headers and makefiles derived from pre-written templates. You could say that autoconf compiles the m4 (language) program in configure.ac into a shell script.

= Approach =

Autoconf is similar to the Metaconfig package used by Perl. The imake system used by the X Window System is closely related, but has a different philosophy.

The autoconf approach to portability is to test for features, not for Versions. For example, the native C compiler on SunOS 4 did not support C programming language. However, it is possible for the user/administrator to have installed an ISO C compliant compiler. A pure version-based approach would not make use of the ISO C compiler, but a feature-testing approach would be able to discover that the specified compiler supported ISO C. The rationale of this approach is that

the configure script can get reasonable results on newer/unknown systems

it allows system administrators to customize their machines and have the configure script take advantage of the customizations

there s no need to keep track of minute details of versions, patch numbers, etc., to figure out whether a particular feature is supported or not

=References=

*Gary V. Vaughan, Ben Elliston, Thomas Tromey, and Ian Lance Taylor: Gnu Autoconf, Automake, and Libtool , Sams, ISBN 1-57870-190-2

=External links=

*[http://www.gnu.org/software/autoconf/ GNU Autoconf home page] *[http://www.gnu.org/software/ac-archive/ GNU Autoconf macro archive] *[http://sources.redhat.com/autobook/autobook/autobook_toc.html Online version of The Goat Book ] *Tutorial [http://www.amath.washington.edu/~lf/tutorials/autoconf/ Learning Autoconf and Automake] by Eleftherios Gkioulekas *[http://autotoolset.sourceforge.net/tutorial.html Another tutorial.] *Article [http://www.openismus.com/documents/linux/automake/automake.shtml Using Automake and Autoconf with C++] by Murray Cumming *[http://autotoolset.sourceforge.net/ Autotoolset home page]