7.5.2.2.1. What are Debian packages?

This package format is the default on Debian GNU/Linux, where dselect, and, nowadays more common, aptitude, is the standard tool for managing the packages. It is used to select packages that you want to install or upgrade, but it will also run during the installation of a Debian system and help you to define the access method to use, to list available packages and to configure packages.

The Debian web site contains all information you need, including a "dselect Documentation for Beginners".

According to the latest news, the Debian package format is becoming more and more popular. At the time of this writing, 5 of the top-10 distributions use it. Also apt-get (see Section 7.5.3.2 is becoming extremely popular, also on non-DEB systems.

7.5.2.2.2. Examples with DEB tools

Checking whether a package is installed is done using the dpkg command. For instance, if you want to know which version of the Gallery software is installed on your machine:

nghtwsh@gorefest:~$ dpkg -l *gallery*
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Installed/Config-files/Unpacked/Failed-config/Half-installed
|/ Err?=(none)/Hold/Reinst-required/X=both-problems (Status,Err: uppercase=bad)
||/ Name           Version        Description
+++-==============-==============-============================================
ii  gallery        1.5-1sarge2    a web-based photo album written in php

The "ii" prefix means the package is installed. Should you see "un" as a prefix, that means that the package is known in the list that your computer keeps, but that it is not installed.

Searching which package a file belongs to is done using the -S to dpkg:

nghtwsh@gorefest:~$ dpkg -S /bin/cat
coreutils: /bin/cat

More information can be found in the Info pages for dpkg.