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 release is considered stable.

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 BACKLOG' for a summary of pending mail and articles. 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.

By using ./configure --enable-changeword', you get an experimental feature which allows for changing the syntax of what is a "word" in m4'. This feature will not be present in m4 2.0, but will be replaced by other new features which provide similar capability, so do not count on it.

Send bug reports to `[email protected]'. 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 Project notice

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

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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!

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