-- Posting mainly for Debian users --

An easy way to make free some extra disk space on your machine running Debian GNU/Linux is to get rid of some package files (.deb) that can no longer be downloaded, and are largely useless. The configuration option APT::Clean-Installed will prevent installed packages from being erased if it is set to off. The package files itself are stored in /var/cache/apt/archives/.

The command that should do the trick :

apt-get --option APT::Clean-Installed=off autoclean


Especially Debian users running the 'testing' or 'unstable' repository can really make use of this command to free some extra disk space.