A Short Apt-Get / Dpkg Tutorial For New Debian Users

This is a short tutorial (Primer) on using Apt-get and Dpkg tools to manage software packages in Debian and, Debian-based Linux distributions such as Ubuntu.

What is Package Management ?

A 'Package Management System' or 'Package Manager' is a collection of tools used to automate the process of installing, updating, configuring, and removing of software packages for a computer's operating system in a consistent manner. Different operating systems have their own package managers. For instance, this is a list of package management tools used by different operating systems. [Courtesy: Wikipedia]

Things you should know

Debian uses the Deb package format for packing together files belonging to an application. You can look at it as something like the Setup installer (Eg: Installshield) in Microsoft Windows.

Software meant to be installed in Debian Linux has the file extension '.deb'.

Debian, (and most other Linux distributions), use a publicly accessible place on the Internet - called a repository - to store all their software packages.

The file /etc/apt/sources.list contain a list of web addresses pointing to the Debian repository.

The web address has the following syntax :

deb  [web address] [distribution name] [options]

An example of a web address pointing to the Ubuntu repository is shown below.

deb  http://in.archive.ubuntu.com/ubuntu  breezy  main restricted

Managing software in Debian

Debian (and related) Linux (distributions) use two important command line tools to manage deb packages. They are -

1. Dpkg, and
2. Advanced Packaging Tools or APT

Dpkg - The low level package management tool

Here are a few ways of using dpkg in Debian Linux.

Install a package

dpkg -i <package-name>

Example : Let's say you want to install Gedit text editor in Debian and you have downloaded its deb package from the Gedit website. The package is named gedit-2.12.1.deb. To install it in Debian, open a terminal and move to the directory containing the deb file and execute the command :

# dpkg -i gedit-2.12.1.deb

You can also use --install instead of -i.

Remove a package

To remove an installed package, the syntax is :

dpkg [-r | -P] <program name>

-r - Will remove the program but leave its configuration files intact. You can also use --remove instead of -r.

-P - Will completely remove the package including the configuration files. You can also use --purge instead of -P.

Continuing with the previous example, to remove Gedit (but not its configuration files) from Debian -

# dpkg -r gedit

To remove Gedit completely -

# dpkg -P gedit

Get more information

To see the contents of a deb package (Eg: gedit-2.12.1.deb), use the -c option.

# dpkg -c gedit-2.12.1.deb

To get more information about a deb package such as - the authors name,the year of compilation, a short description of its use, and so on, use the -I option.

# dpkg -I gedit-2.12.1.deb

To check if a program is installed in Debian, use the -s option.

# dpkg -s gedit

The above command also provides other details about the program such as the package maintainer, dependencies, installed version, a small description of the package and so on.

To know where all the files associated with a program are installed, use the -L option.

# dpkg -L gedit

Advanced Packaging Tool (APT)

APT is the Advanced Package Tool and provides the apt-get program. apt-get provides a simple way to retrieve and install packages from multiple sources using the command line.

Unlike dpkg, apt-get does not understand .deb files, it works with the packages proper name and can only install .deb archives from a source specified in '/etc/apt/sources.list'.

apt-get will call dpkg directly after downloading the .deb archives from the configured sources.

Some common ways to using apt-get are shown below :

To update the list of packages known by your system, do the following :

# apt-get update

You should update your package lists regularly by running the above command.

To upgrade all the installed packages on your system -

# apt-get upgrade

To install the gedit package and all its dependencies -

# apt-get install gedit

To remove the gedit package from your system -

# apt-get remove gedit

To remove gedit and also its configuration files -

# apt-get --purge remove gedit

Upgrading Debian to a new version can be done with the command -

# apt-get dist-upgrade

Saving valuable hard disk space

Each time you install an application using apt-get, the corresponding deb package is downloaded and stored in a location on your hard disk - usually in the directory '/var/cache/apt/archives/'.

The following command will remove all the archives and free up hard disk space -

# apt-get clean

To delete only those packages in the cache which are found useless or partially complete, do -

# apt-get autoclean

Another tool in the APT tool suite is apt-cache.

apt-cache tool can be used to search for and find packages, and it supports use of regular expressions.

To find all packages that contain the word "editor", do the following -

$ apt-cache search editor

To print detailed information about a package, the syntax is -

apt-cache show <package name>

To print the packages that a given package depends on, the syntax is -

apt-cache depends <package name>

To print detailed information of the versions available for a package and the packages that reverse-depends on it -

apt-cache showpkg <package name>

To get statistics of the packages available in the repositories -

$ apt-cache stats

I hope you have enjoyed reading this concise tutorial on apt-get and dpkg which will help you manage the packages in Debian Linux.