GNU Autoconf, Automake, and Libtool

In a small package which only uses Autoconf, your own macros are placed in the ` aclocal .m4' file--this includes macros that you may have obtained from third parties such as the Autoconf macro archive (see section 23.5.1 Autoconf macro archive). If your package additionally uses Automake, then these macros should be placed in `acinclude.m4' . The aclocal program from Automake reads in macro definitions from `acinclude.m4' when generating `aclocal.m4' . When using Automake, for instance, `aclocal.m4' will include the definitions of AM_ macros needed by Automake.

In larger projects, it's advisable to keep your custom macros in a more organized structure. Autoconf version 2.15 will introduce a new facility to explicitly include files from your `configure.in' file. The details have not solidified yet, but it will almost certainly include a mechanism for automatically included files with the correct filename extension from a subdirectory, say `m4/' .