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Autoconf Macro: check_gnu_make
</title>
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<a href="http://autoconf-archive.cryp.to/check_gnu_make.m4">Download M4
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<hr>
<h1>
check_gnu_make
</h1>
<h2>
Synopsis
</h2>
<p class="indent" style="white-space:nowrap;">
<code>CHECK_GNU_MAKE()</code>
</p>
<h2>
Description
</h2>
<div class="indent">
<p>
This macro searches for a GNU version of make. If a match is found, the
makefile variable `ifGNUmake' is set to the empty string, otherwise it is
set to "#". This is useful for including a special features in a Makefile,
which cannot be handled by other versions of make. The variable
_cv_gnu_make_command is set to the command to invoke GNU make if it exists,
the empty string otherwise.
</p>
<p>
Here is an example of its use:
</p>
<p>
Makefile.in might contain:
</p>
<pre>
# A failsafe way of putting a dependency rule into a makefile
$(DEPEND):
$(CC) -MM $(srcdir)/*.c > $(DEPEND)
@ifGNUmake@ ifeq ($(DEPEND),$(wildcard $(DEPEND)))
@ifGNUmake@ include $(DEPEND)
@ifGNUmake@ endif
</pre>
<p>
Then configure.in would normally contain:
</p>
<pre>
CHECK_GNU_MAKE()
AC_OUTPUT(Makefile)
</pre>
<p>
Then perhaps to cause gnu make to override any other make, we could do
something like this (note that GNU make always looks for GNUmakefile
first):
</p>
<pre>
if ! test x$_cv_gnu_make_command = x ; then
mv Makefile GNUmakefile
echo .DEFAULT: > Makefile ;
echo \ $_cv_gnu_make_command \$@ >> Makefile;
fi
</pre>
<p>
Then, if any (well almost any) other make is called, and GNU make also
exists, then the other make wraps the GNU make.
</p>
</div>
<h2>
Author
</h2>
<p class="indent">
John Darrington <j.darrington@elvis.murdoch.edu.au>
</p>
<h2>
Last Modified
</h2>
<p class="indent">
2002-01-04
</p>
<h2>
M4 Source Code
</h2>
<div class="indent">
<pre class="m4source">
AC_DEFUN(
[CHECK_GNU_MAKE], [ AC_CACHE_CHECK( for GNU make,_cv_gnu_make_command,
_cv_gnu_make_command='' ;
dnl Search all the common names for GNU make
for a in "$MAKE" make gmake gnumake ; do
if test -z "$a" ; then continue ; fi ;
if ( sh -c "$a --version" 2> /dev/null | grep GNU 2>&1 > /dev/null ) ; then
_cv_gnu_make_command=$a ;
break;
fi
done ;
) ;
dnl If there was a GNU version, then set @ifGNUmake@ to the empty string, '#' otherwise
if test "x$_cv_gnu_make_command" != "x" ; then
ifGNUmake='' ;
else
ifGNUmake='#' ;
AC_MSG_RESULT("Not found");
fi
AC_SUBST(ifGNUmake)
] )
</pre>
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