m4: m4 (an implementation of the UNIX macro processor) m4: m4: This is GNU m4, a program which copies its input to the output, m4: expanding macros as it goes. m4 has built-in functions for including m4: named files, running commands, doing integer arithmetic, manipulating m4: text in various ways, recursion, etc... Macros can also be user- m4: defined, and can take any number of arguments. m4: m4: GNU 'm4' was originally written by Rene Seindal, from Denmark. m4: m4: