m4 - 1.4.18-5 main

GNU `m4' is an implementation of the traditional UNIX macro
processor. It is mostly SVR4 compatible, although it has some
extensions (for example, handling more than 9 positional parameters to
macros). `m4' also has builtin functions for including files, running
shell commands, doing arithmetic, etc. Autoconf needs GNU `m4' for
generating `configure' scripts, but not for running them.