autoconf

    The GNU project's tool that configures a
   source code distribution to compile and run on a different
   platform.

   Among open source hackers, a mere running binary of a
   program is not considered a full release; what's interesting
   is a source tree that can be built into binaries using
   standard tools.  Since the mid-1990s, autoconf, automake,
   and libtools have been the standard way to make a
   distribution portable so that it can be built on multiple
   operating systems without change.

   (2002-09-20)