6.28 Building Source Packages

You can download the source code for any Debian package from the Debian archive. You can then modify it, if you wish, and then generate your own deb file for installation. Or perhaps, like Gentoo, you are interested in building the package with your local compilation optimisations to suit your system specifically. This is all quite easy with Debian.

The steps involved include: Install dependencies; Obtain the source; Unpack the source; Apply the patches; Compile the source code; Build the Debian package.

A use case here was that gnome-shell had been updated to 3.36.3 but not yet available for the specific release:

$ wajig builddeps gnome-shell
$ wget http://archive.ubuntu.com/ubuntu/pool/main/g/gnome-shell/gnome-shell_3.36.3.orig.tar.xz
$ wget http://archive.ubuntu.com/ubuntu/pool/main/g/gnome-shell/gnome-shell_3.36.3-1ubuntu2.debian.tar.xz
$ tar xvf gnome-shell_3.36.3.orig.tar.xz
$ cd gnome-shell_3.36.3
$ tar xvf ../gnome-shell_3.36.3-1ubuntu2.debian.tar.xz
$ dpkg-buildpackage -us -uc -nc
$ cd ..
$ wajig install gnome-shell_3.36.3-1ubuntu2_amd64.deb gnome-shell-common_3.36.3-1ubuntu2_all.deb  gnome-shell-extension-prefs_3.36.3-1ubuntu2_amd64.deb

Install dependencies:

$ wajig builddeps <package-name>                (apt-get source

Sources should be specified in /etc/apt/sources.list with the appropriate deb-src lines:

  deb-src http://archive.ubuntu.com/ubuntu/ focal main restricted

Obtain and unpack the source Debian package:

  $ wajig source <package names>                (apt-get source)

This will download tar.gz (source code), dsc (test packaging), and possibly diff (patches). It then extracts the source code into a subdirectory of the package name and version, and applies the patches.

The patching can be reversed:

  $  zcat <pkg>_<version>.diff.gz | patch -R -p0

To go one step further and also configure and compile the package, and then generate a default Debian deb package from the source code then use:

  $ wajig build <package names>         (apt-get source -b)

This will allow you to apply any optimisations during the compilation process to suit your own environment. This is similar to Gentoo, allowing for automatic optimisation and customisation to suit the user. To tune the build edit the file /etc/apt/apt-build.conf.

If you need to modify the source to the package (e.g., the package most) in some way and thus need to rebuild the deb package, the steps would be:

  $ wajig update
  $ wajig source most
  $ cd most_4.9.5

Now modify the source code to your own liking, then generate the Debian package with:

  $ fakeroot dpkg-buildpackage -b -uc -us

This leaves a new most_4.9.5-1_i386.deb in the parent directory, and you can install it directly:

  $ cd ..
  $ wajig install most_4.9.5-1_i386.deb

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