How to identify the packages associated with a dead source in Debian?

Question

I'm using a Debian spin (Kwheezy, based on Wheezy + KDE), that came bundled with all kinds of additional packages. The apper sources list includes a bunch of extraneous ones. The distro is getting long-in-the-tooth and the maintainer has moved on; some of the apper sources no longer exist. One of these days, I'll bite the bullet and attempt an upgrade, but I'd like to limp along as long as possible because everything is rock-solid.

In recent times, I've received occasional messages from apper that one of its sources wasn't available. I disabled these sources to stop the warning messages. However, that means whatever packages were being maintained from that source are no longer being maintained. I want to at least keep my eye on security issues or possibly find another source (or uninstall those packages if necessary).

How do I identify what packages on my system are associated with a specific source (that no longer exists, so I can't go to the source to see what packages it used to contain)?

Answer 1

Alternative procedures using the package manager

1) Using Synaptic the graphical package manager, you can find the list of obsolete packages by clicking on the “Status” button and selecting “Installed (local or obsolete)”

2)From the command line:

• using aptitude:

  apt-get install aptitude

  aptitude search '~o'

• Using apt-show-version:

  apt-get install apt-show-version

  apt-show-versions | grep 'No available version'

Explanation

The package manager bases package "status" on the repositories in its list (and what it was responsible for installing; i.e., if a package is available from a listed repository but you installed it manually from somewhere else, the package manager won't maintain it as "one of its own").

Packages can be not included in one of the specified repositories for several reasons:

• The package can be no longer included in the repository, or the repository no longer exists, which is referred to as "obsolete".

• If you manually installed the package (e.g., from a downloaded tarball), the package manager hooks won't have been created and the source won't have been added to the repository list; the package is referred to as "locally installed".

The package manager just focuses on the job it is supposed to do, it doesn't distinguish between the reasons for a package not being in one of its specified repositories. It can give you a list of what's installed that it can't maintain, Installed (local or obsolete), which is what the instructions, above, provide.

It isn't limited to the obsolete packages, but it provides a relatively short list. The included packages are grouped in alphabetical order, so it's easy to recognize and distinguish what you manually installed.