lfs-book/appendixa/m4-desc.xml

<sect2>
<title>Contents</title>

<para>
The M4 package contains the M4 processor
</para>

</sect2>

<sect2>
<title>Description</title>

<para>
M4 is a macro processor. It copies input to output expanding macros as it 
goes. Macros are either builtin or user-defined and can take any number
of arguments. Besides just doing macro expansion m4 has builtin functions 
for including named files, running UNIX commands, doing integer arithmetic, 
manipulating text in various ways, recursion, etc. M4 can be used either 
as a front-end to a compiler or as a macro processor in its own right.
</para>

</sect2>