Introduction

APT (Advanced Packaging Tool)

APT the Mechanism

• http://www.apt-get.org/
• http://www.debian.org/doc/manuals/apt-howto/index.en.html#contents

APT relies on the concept of repositories in order to find software and resolve dependencies. For APT the library and APT the toolset, a repository is a directory containing packages along with an index file. This can be specified as a networked or local (CDROM, HDD, USB stick, etc.) location. As of now, October 2008, the Debian project keeps a central repository of over 25000 software packages ready for download and installation.

APT the Library

This subsection is about APT (Advanced Packaging Tool) the library as opposed to apt-* (set of tools) to make use APT the library.

Files

/etc/apt has the APT configuration folders and files. apt-config is the APT configuration query program. apt-config dump shows the configuration.

• /etc/apt/sources.list, locations to fetch packages from.
• /etc/apt/sources.list.d/, additional source list fragments.
• /etc/apt/apt.conf, APT configuration file.
• /etc/apt/apt.conf.d/, APT configuration file fragments.
• /etc/apt/preferences, version preferences file. This is where we would specify pinning, i.e. a preference to get certain packages from a separate source location than the one specified in /etc/apt/sources.list or from a different release version than the one installed.
• /var/cache/apt/archives/, storage area for retrieved package files.
• /var/cache/apt/archives/partial/, storage area for package files in transit.
• /var/lib/apt/lists/, storage area for state information for each package resource specified in sources.list
• /var/lib/apt/lists/partial/, storage area for state information in transit.

Apt vs Aptitude

Questions

• Can aptitude remove dependencies of software installed by apt-get?
  • No. It must be installed by aptitude in order to remove the dependencies cleanly.
• Can there consistency problems arise by using both?
  • No, that is a myth. However, in case we had used apt-get in the past and now we want to switch to aptitude... well, no problem, we can start using aptitude instead of apt-get. aptitude will not remove dependencies installed by apt-get. We will need deborphan to remove those. From here on out, however, we can use aptitude to install and administer all of our packages.

Nice things about Aptitude

1. Human-readable logs in /var/logs/aptitude.log. Those who have ever tried to see which packages have been installed/removed/etc in dpkg.log probably know what I am talking about.
2. aptitude search will list packages as well as their status, whether installed or not.

Differences between apt-* and aptitude

Generally, we need to know that there is aptitude, a single tool, and that there is the whole set of apt-* tools.

From my point of view apt-* is really advanced, in the sense that it can do a lot more than just performing the most commonly used options provided by APT (Advanced Packaging Tool). It is a set of tools for both, users and developers, novice and advanced. The downside however is that it is a set of tools and therefore it makes things harder for people to understand and use it to its full potential.

aptitude on the other side presents the more commonly used options of APT (Advanced Packaging Tool) and most importantly is just a single tool. As ever, there is no better, it is all about situation, skillets and personal likings etc.

aptitude lacks some of the power that the whole apt-* set of tools provide. For example, aptitude does not have equivalents of these apt-cache options: madison, policy, depends, rdepends. Also, there is no aptitude equivalent of apt-file.

Completion

Apt

Aptitude

• aptitude-create-state-bundle produces a compressed archive storing the files that are required to replicate the current package archive state.
• aptitude-run-state-bundle unpacks the given aptitude state bundle created by aptitude-create-state-bundle(1) to a temporary directory, invokes <program> on it with the supplied arguments, and removes the temporary directory afterwards. If <program> is not supplied, it defaults to aptitude(8).

Wrappers

• feta
• wajig

Packaging Software

This section is about how to create Debian packages (also known as dot debs respectively .debs). Furthermore, it provides an insight on the works a Debian Developer also known as Debian Maintainer does in order to provide the community with up to date software.

There are many things aside from packaging new software for Debian but packaging is certainly at the core of things the community does in order to deliver one of the best (if not the best) operating system available today.

In essence, packaging makes sure that everyone using Debian gets free software delivered onto his computer with practically no effort at all i.e. apt-get update && apt-get upgrade respectively aptitude update && aptitude full-upgrade does the trick. This way the main effort behind packaging becomes invisible to any Debian user i.e. instead of making sure (by running time consuming tests etc.) the yet to be installed code/software integrates smoothly into our existing, yet up and running Debian system, all the user has to do is to run the afore mentioned commands.

Also, what most novices seem to overlook sometimes, one of the package maintainers duties is to make sure that only free software goes into packages. This way the user can be certain of getting a system consisting of nothing but FLOSS (Free/Libre Open Source Software)... I am talking about freedom ladies and gentlemen!

So, packaging really is one of the main pillars of our community effort to steadily improve a yet already world-class operating system since it saves us all a lot of time, provides us with pre-tested code and last but not least ensures we all remain with free software only.

With this subsection, I am going to provide a pretty much straight forward tutorial for packaging software for Debian. I will mention what is mandatory and also add a few hints for good practices. Also, with the information provides here anyone will finally be able to package software the way any official Debian developer does on a daily basis. Furthermore, I am going to talk about non-technical matters with regards to packaging as well because there is a whole lot more than just the technical aspect to packaging software for Debian.

Mandatory Knowledge

Whoever wants to start packaging software must know this. It is about all the basics concerning the mechanism of the package management system called APT (Advanced Packaging Tool) and related things. If this knowledge is already know (are you sure?) then one might proceed with a more specific, debian developer intended, manual.

For those who would rather skip all this stuff... well, that would mean not just skipping the basics but also not to care about what Debian really is which is of course unacceptable.

Fortunately, the Debian new maintainer process ensures that only people who are really skilled, seriously determined with a long-term goal in mind, and which have a great attitude about the philosophy behind Debian are allowed to become official Debian developers — sounds a bit though but then it simply ensures a state of the art OS plus even more importantly, this way it saves a lot of folks (you/us) a lot of time and troubles — I think there simply is no other way to ensure a certain quality... Also, before I forget, I do have a dedicated section which tells about common tools most probably needed in the process in maintaining software for Debian.

Good to know

Package Life-cycle

GIT

Miscellaneous

This section is about miscellaneous subjects with regards to Debian packages

BTS (Bug Tracking System)

Please go here for more information.

Package Tracking

Please go here.

Snapshots

What are so-called snapshots? They are available here.

Backports

What are so-called backports? They are available here and here.

Maintaining your Debian Repository

• http://www.debian-administration.org/articles/286
• http://www.debian-administration.org/tag/apt%20repositories
• http://www.debian-administration.org/articles/174

debian-el

This is a GNU Emacs package i.e. GNU Emacs capabilities towards Debian in order to carry out a variety of tasks focusing on development and maintaining software and its related parts with DebianGNU/*. However, this information is only of interest to folks using both — DebianGNU/* and GNU Emacs.