Re: conditionally using libtool

[Bob Friesenhahn]

On Mon, 1 May 2006, Bob Rossi wrote:
> Would you mind quicly explaining how autoconf works? Meaning what are
> the steps taken that generate a configure.sh script?

Don't be needlessly confused by the m4 "gibberish" which is often 
posted here.  It is not necessary to understand such "gibberish" in 
order to properly use autoconf.

The 'aclocal' program is used to pull in any m4 macros defined in the 
autoconf/automake/libtool system install directory, as well as any 
project-specific macros from acinclude.m4, and put them in an 
aclocal.m4 file.  The 'aclocal' program is smart and only pulls in the 
macros that configure.ac actually needs.  When autoconf is executed, 
it uses m4 to create a shell script ('configure') based on expanding 
the macros from aclocal.m4 as they are encountered in configure.ac. 
Recently it has become popular to include macros in additional .m4 
files so that the macros may be bundled in the package without 
cluttering up the project-specific acinclude.m4 file or to make it 
more clear who maintains them.  These may be placed in the same 
directory as configure.ac, or in a subdirectory, as long as autoconf 
is told where to find them.

> I understand that m4 is used. Is m4 the only tool that is run on the
> configure.in file to generate the configure script? I'm trying to better
> understand how macro's in an sh condition effect the outcome.

Long ago I wrote a magazine article on Autoconf.  Remarkably most of 
it is still correct, which shows that the GNU autoconf approach is 
quite stable.  See "http://www.byte.com/art/9711/sec4/art2.htm";.

Bob
======================================
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/