102.4 Use Debian package management

Weight: 3

Candidates should be able to perform package management using the Debian package tools.

Install, upgrade and uninstall Debian binary packages.
Find packages containing specific files or libraries which may or may not be installed.
Obtain package information like version, content, dependencies, package integrity, and installation status (Whether or not the package is installed).
Awareness of apt.

Terms and Utilities

/etc/apt/sources.list
dpkg
dpkg-reconfigure
apt-get
apt-cache

Concept of the package management system

Some people think that on GNU/Linux we have to compile all the software we need manually. This is not the case in 99% of cases and never has been the case in the last 20 years. GNU/Linux is the predecessor of what we call the App Store these days. All major distros do have huge archives of pre-compiled software called their repositories and some kind of a package manager software that takes care of searching these repositories, installing software from them, finding dependencies, installing them, resolving conflicts, and updating the system and installed software. Debian-based distros use .deb files as their "packages" and use tools like apt-get, dpkg, apt, and other tools to manage them.

Debian packages are names like NAME-VERSION-RELEASE_ARCHITECTURE.deb; Say tmux_3.2a-4build1_amd64.deb.

Repositories

But where did this package come from? How does the OS know where to look for this deb package? The answer is Repositories. Each distro has its repository of packages. It can be on a Disk, A network drive, a collection of DVDs, or most commonly, a network address on the Internet.

On debian systems, the main configuration locations are: * /etc/apt/sources.list * /etc/apt/sources.list.d/

jadi@lpicjadi:~$ cat /etc/apt/sources.list
#deb cdrom:[Ubuntu 22.04 LTS _Jammy Jellyfish_ - Beta amd64 (20220329.1)]/ jammy main restricted

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://us.archive.ubuntu.com/ubuntu/ jammy main restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://us.archive.ubuntu.com/ubuntu/ jammy-updates main restricted
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in the universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ jammy universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy universe
deb http://us.archive.ubuntu.com/ubuntu/ jammy-updates universe
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free license. Please satisfy yourself as to
## your rights to use the software. Also, please note that the software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://us.archive.ubuntu.com/ubuntu/ jammy multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy multiverse
deb http://us.archive.ubuntu.com/ubuntu/ jammy-updates multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://us.archive.ubuntu.com/ubuntu/ jammy-backports main restricted universe multiverse
# deb-src http://us.archive.ubuntu.com/ubuntu/ jammy-backports main restricted universe multiverse

deb http://security.ubuntu.com/ubuntu jammy-security main restricted
# deb-src http://security.ubuntu.com/ubuntu jammy-security main restricted
deb http://security.ubuntu.com/ubuntu jammy-security universe
# deb-src http://security.ubuntu.com/ubuntu jammy-security universe
deb http://security.ubuntu.com/ubuntu jammy-security multiverse
# deb-src http://security.ubuntu.com/ubuntu jammy-security multiverse

# This system was installed using small removable media
# (e.g. netinst, live or single CD). The matching "deb cdrom"
# entries were disabled at the end of the installation process.
# For information about how to configure apt package sources,
# see the sources.list(5) manual.

Updating sources information:

apt-get update

This will check all the sources in the configs and update the information about the latest software available there.

This won't actually Upgrade the software. The Update will only Update the information about the packages and not the packages themselves.

Installing packages

Say you have heard about this amazing terminal multiplexer called tmux and you want to give it a try.

$ tmux
The program 'tmux' is currently not installed. You can install it by typing:
sudo apt-get install tmux
$ which tmux
$ type tmux
bash: type: tmux: not found

So let's install it. If it's in the repositories it's enough to tell the package manager to install it:

apt-get install tmux

Note that

apt-get install asked for confirmation (Y)
apt-get resolved dependencies, It knows what is needed to install this package and installs them
Debian packages are something.deb

If you only want a dry-run/simulation:

apt-get install -s tmux

and this will only download the files needed into the cache without installing them:

apt-get install --download-only tmux

The downloaded packages are stored as a cache in /var/cache/apt/archive/.

If you want to download only one specific package, you can do:

apt-get download tmux

Removing debian packages

apt-get remove tmux

And if you want to remove automatically installed dependencies:

$ apt-get autoremove tmux

or even

$ apt-get autoremove
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following packages will be REMOVED:
  linux-image-3.16.0-25-generic linux-image-extra-3.16.0-25-generic
0 upgraded, 0 newly installed, 2 to remove, and 0 not upgraded.
After this operation, 203 MB of disk space will be freed.
Do you want to continue? [Y/n] y

To autoremove whatever is not needed anymore.

Notes:

Removing a package will not remove its dependencies
If removing a dependency, you'll get a warning about what will be removed alongside this package

Searching for packages

If you are using the apt suit, the search is done via apt-cache or you can use the general apt.

$ apt-cache search "tiny window"
$ apt search grub2

Upgrading

For updating a single package:

apt-get install tzdata

And for upgrading whatever is installed:

apt-get upgrade

Or going to a new distribution:

apt-get dist-upgrade

Note: like most other tools, you can configure the default configs at /etc/apt/apt.conf and there is a program apt-config for this purpose.

Reconfiguring packages

Debian packages can have configuration actions that will take after the package is installed. This is done by debconf. For example, tzdata will ask you about the timezone settings after you installed it. If you want to reconfigure a package that is already installed, you can use the dpkg-reconfigure:

 dpkg-reconfigure tzdata

Package information with dpkg

The underlying tool to work with .deb files is the dpkg. It is your to-go tool if you want to do manual actions on a deb package. The general format is:

dpkg [OPTIONS] ACTION PACKAGE

Some common actions are:

Switch	Description
-c or --contents	Show the contents of a package
-C or --audit	Search for broken installed packages and propose solutions
--configure	Reconfigure an installed package
-i or --install	Install or Upgrade a package; Wont resolve / install dependencies
-I or --info	Show Info
-l or --list	List all installed packages
-L or --listfiles	List all files related to this package
-P or --purge	Remove the package and its configuration files
-r or --remove	Remove the package; Keep the configurations
-s or --status	Display status of a package
-S or --search	Search and see which package owns this file

You can check the contents:

jadi@lpicjadi:/tmp$ dpkg --contents bzr_2.7.0+bzr6622+brz_all.deb
drwxr-xr-x root/root         0 2019-09-19 18:25 ./
drwxr-xr-x root/root         0 2019-09-19 18:25 ./usr/
drwxr-xr-x root/root         0 2019-09-19 18:25 ./usr/share/
drwxr-xr-x root/root         0 2019-09-19 18:25 ./usr/share/doc/
drwxr-xr-x root/root         0 2019-09-19 18:25 ./usr/share/doc/bzr/
-rw-r--r-- root/root       404 2019-09-19 18:25 ./usr/share/doc/bzr/NEWS.Debian.gz
-rw-r--r-- root/root      1301 2019-09-19 18:25 ./usr/share/doc/bzr/changelog.gz
-rw-r--r-- root/root      1769 2019-09-19 18:25 ./usr/share/doc/bzr/copyright

Or install a deb package (without its dependencies) or check its status:

$ dpkg -s bzr
Package: bzr
Status: deinstall ok config-files
Priority: optional
Section: vcs
Installed-Size: 102
Maintainer: Ubuntu Developers <[email protected]>
Architecture: all
Version: 2.6.0+bzr6595-1ubuntu1
Config-Version: 2.6.0+bzr6595-1ubuntu1
Depends: python-bzrlib (<= 2.6.0+bzr6595-1ubuntu1.1~), python-bzrlib (>= 2.6.0+bzr6595-1ubuntu1), python:any
Recommends: python-gpgme
Suggests: bzr-doc, bzrtools, python-bzrlib.tests
Breaks: bzr-pqm (<< 1.4.0~bzr80), bzr-xmloutput (<< 0.8.8+bzr160), python-bzrlib (<< 2.4.0~beta3~)
Conffiles:
 /etc/bash_completion.d/bzr b8d9ca95521a7c5f14860e205a854da2
Description: easy to use distributed version control system
 Bazaar is a distributed version control system designed to be easy to
 use and intuitive, able to adapt to many workflows, reliable, and
 easily extendable.
 .
 Publishing of branches can be done over plain HTTP, that is, no special
 software is needed on the server to host Bazaar branches. Branches can
 be pushed to the server via sftp (which most SSH installations come
 with), FTP, or over a custom and faster protocol if bzr is installed in
 the remote end.
 .
 Merging in Bazaar is easy, as the implementation can avoid many
 spurious conflicts deals well with repeated merges between branches,
 and can handle modifications to renamed files correctly.
 .
 Bazaar is written in Python and has a flexible plugin interface that
 can be used to extend its functionality. Many plugins exist, providing
 useful commands (bzrtools), graphical interfaces (qbzr), or native
 interaction with Subversion branches (bzr-svn).
 .
 Install python-paramiko if you are going to push branches to remote
 hosts with sftp, and python-pycurl if you'd like SSL certificates
 always to be verified.
Homepage: http://bazaar-vcs.org
Original-Maintainer: Debian Bazaar Maintainers <[email protected]>

Or even purge an installed package; Removing the package and all of its configurations. To Purge a package, use the -P or --purge switch.

There is also -L to check the files and directories a package installed:

$ dpkg -L bzr
/.
/usr
/usr/bin
/usr/bin/jcal
/usr/share
/usr/share/doc
/usr/share/doc/jcal
/usr/share/doc/jcal/README
/usr/share/doc/jcal/copyright
/usr/share/man
/usr/share/man/man1
/usr/share/man/man1/jcal.1.gz
/usr/share/doc/jcal/changelog.Debian.gz

and -S will show which package installed the given file:

$ dpkg -S /var/lib/mplayer/prefs/mirrors
mplayer: /var/lib/mplayer/prefs/mirrors

Common apt-get options

Option	Usage
autoclean	Removes unused packages
check	Check db for issues
clean	Clean the DB, you can do a `clean all` to clean everything and start afresh
dist-upgrade	Checks for new versions of the OS; Major upgrade
install	Install or upgrade packages
remove	Removes a package
source	Install the source of a package
update	Updates the information about packages from repositories
upgrade	Upgrades all packages

In some cases a package is installed but without proper dependencies (say using dpkg) or an installation is interrupted for any reason. In these cases a apt-get install -f might help, -f is for fix broken.

Common apt-cache options

Option	Usage
depends	Show dependencies
pkgnames	Shows all installed packages
search	Search
showpkg	Show information about a package
stats	Show statistics
unmet	Show unmet dependencies for all installed packages or the one you specified

Other tools

There are even more tools, the tools with fancy GUIs or text-based tools and user interface tools like aptitude.

← 102.3 Manage shared libraries

Chapter List

102.5 Use RPM and YUM package management →