hpaluch-pil / hello-ac

Hello world C with library example using Autoconf, automake and libtool

Helloac (Hello, Autoconf) example project

Simple project with library using old libtool automake and autoconf.

Basic concepts

To understand autoconf properly one need to know that there are actually two source distributions:

1. Maintainer source
2. End user source

Maintainer is one who develops this project and is commiting new version to repository. Maintainer needs to have installed additionally libtool, autoconf and automake to be capable to regenerate target script files (for example configure script) from templates (for example configure.in).

End user is one who just wants to build binary in his Unix environment from source. End user need just to have installed C compiler and make tool.

Setup

Tested under:

• scratchbox environment for ARM in following configuration:

  sb-conf show warpcomm
     Compiler: arm-linux-cs2010q1-202
     Devkits: autotools-legacy mtd python-legacy qemu svn git
     CPU-transparency: /scratchbox/devkits/qemu/bin/qemu-arm-sb
  
  

• Debian 6.0.6/i386 - intentionally - to have good chance that it will work also under above scratchbox (which was confirmed)

• Debian 9.8/amd64 - to verify backward compatibility. NOTE: Please ignore warning:

  autoconf input should be named 'configure.ac', not 'configure.in'
  

  This is our drawback because of full backward compatibility with old Linux versions.

Both end user and maintainer need to install basic development tools:

sudo apt-get install build-essential

Maintainer needs to additionally install:

sudo apt-get install libtool autoconf automake 

Here are necessary steps to build from repository - like maintainer.

To prepare all build scripts from this source code issue:

libtoolize
aclocal
automake -a
autoconf

Or just run:

./maintainer-setup.sh

Building sample project

For end-user: download and extract helloac-1.0.tar.gz for example using:

mkdir ~/projects
cd ~/projects
wget https://github.com/hpaluch-pil/hello-ac/archive/helloac-1.0.tar.gz
tar xzf helloac-1.0.tar.gz
cd hello-ac-helloac-1.0
# and continue below:

These steps are used for both end user and maintainer:

Example:

./configure --prefix=/opt/helloac-1.0
make
sudo make install

Create end-user source distribution

Issue this command to create source distribution archive:

make dist

And distribute created helloac-1.0.tar.gz archive. The end user than just isse ./configure and make command without need to install libtool, autoconf or automake.

Re-bootstrap

If you (as maintainer) modify any of configure.in, Makefile.am you should run this command sequence to refresh generated files:

automake; aclocal; autoconf

Maintainer clean

To clean all files that are not needed in git repository you can use this command:

./maintainer-clean.sh

WARNING!

It will work only if there is Makefile (that is the ./configure script was already run before)

Libtool versioning

WARNING!

Libtool uses its own versioning system in form current:revision:age instead of common linker major:minor:patch.

Please see for more information:

• http://blog.asleson.org/index.php/2014/07/08/libtool-library-versioning-version-info-currentrevisionage/
• https://www.gnu.org/software/libtool/manual/html_node/Updating-version-info.html#Updating-version-info
• calculator: https://www.pakin.org/~scott/ltver.html

Resources

• Author's original guide written in late 90's in college
  • https://www.linux.cz/noviny/1998-0809/clanek12.html