Ubuntu apt-get & apt-cache commands with practical examples

http://www.linuxtechi.com/ubuntu-apt-get-apt-cache-commands-examples

Apt-get & apt-cache are the command line package management utility in Ubuntu Linux. GUI version of apt-get command is the Synaptic Package Manager, in this post we are going to discuss 15 different examples of apt-get & apt-cache commands.

Example:1 List of all the available packages

linuxtechi@localhost:~$ apt-cache pkgnames
account-plugin-yahoojp
ceph-fuse
dvd+rw-tools
e3
gnome-commander-data
grub-gfxpayload-lists
gweled
.......................................

Example:2 Search Packages using keywords

This command is very helpful when you are not sure about package name , just enter the keyword and apt-get command will list packages related to the keyword.

linuxtechi@localhost:~$ apt-cache search "web server"
apache2 - Apache HTTP Server
apache2-bin - Apache HTTP Server (binary files and modules)
apache2-data - Apache HTTP Server (common files)
apache2-dbg - Apache debugging symbols
apache2-dev - Apache HTTP Server (development headers)
apache2-doc - Apache HTTP Server (on-site documentation)
apache2-utils - Apache HTTP Server (utility programs for web servers)
......................................................................

Note: If you have installed “apt-file” package then we can also search the package using config files as shown below :

linuxtechi@localhost:~$ apt-file search nagios.cfg
ganglia-nagios-bridge: /usr/share/doc/ganglia-nagios-bridge/nagios.cfg
nagios3-common: /etc/nagios3/nagios.cfg
nagios3-common: /usr/share/doc/nagios3-common/examples/nagios.cfg.gz
pnp4nagios-bin: /etc/pnp4nagios/nagios.cfg
pnp4nagios-bin: /usr/share/doc/pnp4nagios/examples/nagios.cfg

Example:3 Display the basic information of Specific package.

linuxtechi@localhost:~$ apt-cache show postfix
Package: postfix
Priority: optional
Section: mail
Installed-Size: 3524
Maintainer: LaMont Jones 
Architecture: amd64
Version: 2.11.1-1
Replaces: mail-transport-agent
Provides: default-mta, mail-transport-agent
.....................................................

Example:4 List the dependency of Package.

linuxtechi@localhost:~$ apt-cache depends postfix
postfix
 Depends: libc6
 Depends: libdb5.3
 Depends: libsasl2-2
 Depends: libsqlite3-0
 Depends: libssl1.0.0
 |Depends: debconf
 Depends: 
 cdebconf
 debconf
 Depends: netbase
 Depends: adduser
 Depends: dpkg
............................................

Example:5 Display the Cache Statistics using apt-cache.

linuxtechi@localhost:~$ apt-cache stats 
Total package names: 60877 (1,218 k)
Total package structures: 102824 (5,758 k)
 Normal packages: 71285
 Pure virtual packages: 1102
 Single virtual packages: 9151
 Mixed virtual packages: 1827
 Missing: 19459
Total distinct versions: 74913 (5,394 k)
Total distinct descriptions: 93792 (2,251 k)
Total dependencies: 573443 (16.1 M)
Total ver/file relations: 78007 (1,872 k)
Total Desc/File relations: 93792 (2,251 k)
Total Provides mappings: 16583 (332 k)
Total globbed strings: 171 (2,263 )
Total dependency version space: 2,665 k
Total slack space: 37.3 k
Total space accounted for: 29.5 M

Example:6 Update the package repository using “apt-get update”

Using the command “apt-get update” , we can resynchronize the package index files from their sources repository. Package index are retrieved from the file located at “/etc/apt/sources.list”

linuxtechi@localhost:~$ sudo apt-get update
 Ign http://extras.ubuntu.com utopic InRelease
 Hit http://extras.ubuntu.com utopic Release.gpg
 Hit http://extras.ubuntu.com utopic Release
 Hit http://extras.ubuntu.com utopic/main Sources
 Hit http://extras.ubuntu.com utopic/main amd64 Packages
 Hit http://extras.ubuntu.com utopic/main i386 Packages
 Ign http://in.archive.ubuntu.com utopic InRelease
 Ign http://in.archive.ubuntu.com utopic-updates InRelease
 Ign http://in.archive.ubuntu.com utopic-backports InRelease
 ................................................................

Example:7 Install a package using apt-get command.

linuxtechi@localhost:~$ sudo apt-get install icinga

In the above example we are installing a package named “icinga”

Example:8 Upgrade all the Installed Packages

linuxtechi@localhost:~$ sudo apt-get upgrade

Example:9 Upgrade a Particular Package.

“install” option along with “–only-upgrade” in apt-get command is used to upgrade a particular package , example is shown below :

linuxtechi@localhost:~$ sudo apt-get install filezilla --only-upgrade

Example:10 Removing a package using apt-get command.

linuxtechi@localhost:~$ sudo apt-get remove skype

Above command will remove or delete the skype package only , if you want to delete its config files then use the “purge” option in the apt-get command. Example is shown below :

linuxtechi@localhost:~$ sudo apt-get purge skype

We can also use the combination of above commands :

linuxtechi@localhost:~$ sudo apt-get remove --purge skype

Example:11 Download the package in the Current Working Directory

linuxtechi@localhost:~$ sudo apt-get download icinga
Get:1 http://in.archive.ubuntu.com/ubuntu/ utopic/universe icinga amd64 1.11.6-1build1 [1,474 B]
Fetched 1,474 B in 1s (1,363 B/s)

Above command will download icinga package in your current working directory.

Example:12 Clear disk Space used by retrieved package files.

linuxtechi@localhost:~$ sudo apt-get clean

Above Command will clear the disk space used by apt-get command while retrieving(download) packages.

We can also use “autoclean” option in place of “clean“, the main difference between them is that autoclean removes package files that can no longer be downloaded, and are largely useless.

linuxtechi@localhost:~$ sudo apt-get autoclean
Reading package lists... Done
Building dependency tree
Reading state information... Done

Example:13 Remove Packages using “autoremove” option.

When we use “autoremove” option with apt-get command , then it will remove the packages that were installed to satisfy the dependency of other packages and are now no longer needed or used.

linuxtechi@localhost:~$ sudo apt-get autoremove icinga

Example:14 Display Changelog of a Package.

linuxtechi@localhost:~$ sudo apt-get changelog apache2
Get:1 Changelog for apache2 (http://changelogs.ubuntu.com/changelogs/pool/main/a/apache2/apache2_2.4.10-1ubuntu1/changelog) [195 kB]
Fetched 195 kB in 3s (60.9 kB/s)

Above Command will download the changelog of apache2 package and will display through sensible-pager on your screen.

Example:15 List broken dependencies using “check” option

linuxtechi@localhost:~$ sudo apt-get check
Reading package lists... Done
Building dependency tree
Reading state information... Done