Debian package example

Happy new year! It’s been around a year since I’ve made a post, but by no means has it been a quiet one. This is a short post that describes how to make a simple Debain package, and mainly acts as a reminder to me for those rare occasions where I do find the need to make one.

There are at least a few advantages to using a Debian package. Firstly, a well made package can be installed without any understanding of how an application works. Secondly, a relatively stateless application install can be cleanly uninstalled with relative ease. Lastly, it’s a good way to declaratively describe the dependencies for the APT package manager; not all humans read the accompanied README files.

However, I’ve always felt that making a Debian package required some understanding and experience of the APT system. For instance, an introduction to Debian packaging is 86 slides[1]. The detail provided is superb, yet still seems overkill for my limited needs. It doesn’t cleanly separate the minimal viable package from all the extras that can make a smart package, and extensive reading on the subject could quickly outweight the benefits. So this short post is a gross simplification of how to make a Debian package. I recommend the slides and the full Debian documentation for those with further interest on the matter.

A subdirectory titled DEBIAN is required, though it isn’t case-sensitive. Within here you include scripts that provide auxiliary functions during installation. At the very least, you must include a file called control. Here are some some example fields that should be included:

Package: helloworld
Depends: bash
Version: 0.0.1
Section: blogpost
Architecture: all
Essential: no
Maintainer: adrianlshaw
Description: This is an example Debian package

Once that is done. You need to replicate subdirectories that will be used on your target system. For instance, if you intend to have your file installed in /usr/local/bin then you should recreate those folders within your package root.

Here is the final example layout of a bare minimum (uncompressed) package:

$ tree
.
├── DEBIAN
│   └── control
└── usr
    └── local
        └── bin
            └── helloworld

You can optionally provide other scripts that can be invoked before or after the files have been copied. These scripts, respectively known as preinst and postinst should be included in the DEBIAN directory.

Finally:

$ dpkg-deb --build package

Where package is the name of the directory of your package contents. It should go without saying that you should also provide documentation using man pages or HTML within your package, but that is outside the scope of this post. Ta-ra!

[1] “Debian Packaging Tutorial”, https://www.debian.org/doc/manuals/packaging-tutorial/packaging-tutorial.en.pdf

Written on January 10, 2016