Every directory has to have a file called Makefile.am. It serves to create the Makefile for each directory. Its contents look very different to a normal Makefile. Instead of listing dependencies one by one, just the files are listed and defined what they are.

The Makefile.am on the top directory contains usually just a line pointing where the source files are:

SUBDIRS=src

The Makefile.am in the src directory could look as follows:

helloprgdir=/usr/local/bin/
helloprg_PROGRAMS=hello
hello_SOURCES=hello.c

To have the standard math library

<Program name>_LDADD= -lm

To add a man page and have it even distributed with the tar.gz file add the following:

dist_man_MANS = <mymanpage>.1

The file configure.ac contains gnu m4 macros to define what has to be done to configure the project. M4 is a scripting language with its own syntax (Perl like), see:

Start the program autoscan in the top directory of the project. Among other stuff, the file configure.scan is created that can serve as configure.ac example. This way it can be avoided to deal too much with the m4 syntax. The configure.scan has to be customized and saved as configure.ac:

Note: Older versions of autotools called the configure.ac file configure.in.

Now the autotools package is finished and is ready to be compiled and installed using the following commands:

./configure creates the makefile and config.h

make

make install

And to start:

/usr/local/bin/hello

Make can do more as:

make uninstall to remove everything put outside

make clean to clean up all stuff necessary for the compilation

make dist to clean up the directories and makes a tar.gz archive ready for shipping.

After modifying the above it would be painful to repeat the steps. Therefore the command:

autoreconf --install --force

will do the update. To not typing so much some packages have a bash script for that, e.g.:

./autogen.sh

Using autotools the source is in ./src and the library source in ./lib. Therefore create the ./lib directory and copy printhello.c there. Create a Makefile.am with the following contents:

lib_LIBRARIES = libhello.a
libhello_a_SOURCES=printhello.c

start autoscan and create configure.ac considering configure.scan make sure the following shows the lib directory:

AC_CONFIG_FILES([Makefile

lib/Makefile

src/Makefile])

Additionally to get a statically library add to configure.ac

AC_PROG_RANLIB

If you use libtool in your package you must run libtoolize

For libraries add

lib_LIBRARIES = lib<name>.a
lib<name>_a_SOURCES = <objec1>.c <object2>.c

or if you use libtool

lib_LTLIBRARIES = lib<name>.la
lib<name>_la_SOURCES = <object1>.c <object2>.c

la stands for library archive. Different systems have different format of shared libraries or not even support them.

Gnu offers libtool that automates the creation of libraries, it is called as

libtool gcc <options>

As autotools, libtool creates intermediate files .al for .a and .ol for o files. Libtool can also be used by autotools. Libtool can offer both static and dynamic libraries.

Static libraries Add AC_PROG_RANLIB to configure.ac

To build scons

To install to /usr/local scons install

To install somewhere else scons prefix=</path>

To install in a temporary directory, from where it than can be copied to the right directory when installation was successful. Gentoo does exactly this it installs first somewhere in /var/tmp/portage and then merges it (copies it):

scons install prefix=/usr destdir=/var/tmp/

Since it is python, the build process can easily be debugged. However since this file is not called directly you need a debugger with embedded debugging support as winpdb. Add the following line to the SConstruct file.

import rpdb2; rpdb2.start_embedded_debugger_interactive_password()

Then start your build command as usual, however this time SConstruct will prompt for a password and wait for an external debugger. More info can be found in the python embedded debugging section.