m4
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This manual is for GNU M4 (version 1.4.7, 23 September 2006), a package containing an implementation of the m4 macro language.
Copyright © 1989, 1990, 1991, 1992, 1993, 1994, 2004, 2005, 2006 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License.”
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.
GNU m4 was originally written by René Seindal, with
subsequent changes by François Pinard and other volunteers
on the Internet. All names and email addresses can be found in the
files AUTHORS and THANKS from the GNU M4 distribution.
This is release 1.4.7. It is now considered stable: future releases in the 1.4.x series are only meant to fix bugs, increase speed, or improve documentation. However...
An experimental feature, which would improve m4 usefulness,
allows for changing the syntax for what is a word in m4.
You should use:
./configure --enable-changeword
if you want this feature compiled in. The current implementation
slows down m4 considerably and is hardly acceptable. In the
future, m4 2.0 will come with a different set of new features
that provide similar capabilities, but without the inefficiencies, so
changeword will go away and you should not count on it.
--- The Detailed Node Listing ---
Introduction and preliminaries
Lexical and syntactic conventions
How to invoke macros
How to define new macros
Conditionals, loops, and recursion
How to debug macros and input
Input control
File inclusion
Diverting and undiverting output
Macros for text handling
Macros for doing arithmetic
Macros for running shell commands
Miscellaneous builtin macros
Fast loading of frozen state
Compatibility with other versions of m4
How to make copies of this manual
Indices of concepts and macros