Autotools

Autoconf and M4

The autoconf program is a rather simple shell script. About 80 percent of the shell code in the script exists simply to ensure that the shell is functional enough to perform the required tasks. The remaining 20 percent parses command-line options. The last line of the script executes the autom4te program, a Perl script that acts as a wrapper around the m4 utility. Ultimately, autom4te calls m4 like this:

$ /usr/bin/m4 --nesting-limit=1024 --include=/usr/share/autoconf \
--debug=aflq --fatal-warning --error-output=autom4te.cache/traces.0t \
--trace=AC_CANONICAL_BUILD ... --trace=sinclude \
--reload-state=/usr/.../autoconf/autoconf.m4f aclocal.m4 configure.ac

As you can see, the three files that M4 is processing are /usr/.../autoconf/autoconf.m4f ...