M4++ is a hard fork from GNU M4. It adds some object-oriented-style extensions based on hashing and cmph based minimal perfect
hash functions.
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 built-in 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, from Denmark.
This is a beta release on the stable branch.
If GNU m4 is meant to serve GNU autoconf, beware that m4
should be fully installed prior to configuring autoconf itself.
Likewise, if you intend on hacking GNU m4 from git, the bootstrap
process requires that you first install a released copy of GNU m4.
If you are just trying to build m4 from a released tarball, you
should not normally need to run ./bootstrap or autoreconf; just go
ahead and start with ./configure. If you are trying to build m4
from git, more information can be found in the version-control-only
file HACKING.
M4 has an optional dependency on the libsigsegv library:
https://www.gnu.org/software/libsigsegv/
If the library has not been installed in the standard location, you
can use ./configure --with-libsigsegv-prefix=/path/to/dir, to make
the build of m4 use /path/to/dir/include/sigsegv.h as appropriate.
The use of this library is optional; the only difference in having it
available is that it increases the number of platforms where m4 can
correctly distinguish stack overflow from an internal bug. It is
recommended that you use version 2.9 or newer.
In the subdirectory examples you will find various m4 files, ranging
from trivial test files to rather advanced macros. If you intend to
use m4 seriously, you might find useful material down there.
See file COPYING for copying conditions. Note that M4 is distributed
under the GNU Public License version 3 or later. Some files in the
distribution are copied from the gnulib project, and hence bear the
designation version 2 or later because they are unmodified from gnulib;
however, if you modify these files using M4 rather than gnulib as the
source, you must update the license to be GPLv3 or later.
See file INSTALL for compilation and installation instructions.
See file NEWS for a list of major changes in the current release.
See file THANKS for a list of contributors.
By default, the syscmd and esyscmd macros try to use the first
instance of sh found by command -p getconf PATH at configure time,
with a default of /bin/sh. If that default is inappropriate, you
can use ./configure --with-syscmd-shell=location to specify the
shell to use.
Send bug reports to bug-m4@gnu.org. A bug report is an adequate
description of the problem: your input, what you expected, what you got,
and why this is wrong. Diffs are welcome, but they only describe a
solution, from which the problem might be uneasy to infer.
For any copyright year range specified as YYYY-ZZZZ in this package note that the range specifies every single year in that closed interval.
GNU M4 is part of the GNU Operating System, developed by the GNU Project.
If you are the author of an awesome program and want to join us in writing Free (libre) Software, please consider making it an official GNU program and become a GNU Maintainer. Instructions on how to do this are here: https://www.gnu.org/help/evaluation
Don't have a program to contribute? Look at all the other ways to help: https://www.gnu.org/help/help.html
And to learn more about Free (libre) Software in general, please read and share this page: https://gnu.org/philosophy/free-sw.html
We are looking forward to hacking with you!
Copyright (C) 2000, 2005-2014, 2016-2017, 2020-2025 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 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the GNU Free Documentation License file as part of this distribution.