Linux Commands Examples

A great documentation place for Linux commands


APT package handling utility -- command-line interface

see also : apt-cache - apt-cdrom - dpkg - apt-config


apt-get [-asqdyfmubV] [-o=config_string] [-c=config_file] [-t=target_release] [-a=architecture] {update | upgrade | dselect-upgrade | dist-upgrade | install pkg [{=pkg_version_number | /target_release}]... | remove pkg... | purge pkg... | source pkg [{=pkg_version_number | /target_release}]... build-dep pkg [{=pkg_version_number | /target_release}]... download pkg [{=pkg_version_number | /target_release}]... | check | clean | autoclean | autoremove | {-v | --version} | {-h | --help}}

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apt-get update
apt-get upgrade -y
apt-get -y update
apt-get -y upgrade
apt-get -y install curl
apt-get clean
apt-get update
apt-get upgrade
apt-get install drush
apt-get install $1
apt-get upgrade
apt-get dist-upgrade
sudo apt-get $@
apt-get install motion
apt-get install git
apt-get install lynx

Why use the command apt-get --purge remove over apt-get purge in Linux?

The command apt-get --purge remove has been around since APT was added to Debian and it used to be the only way to completely purge a package with apt. The command apt-get purge was finally added in the last few years, the old option was not removed, and there is still lots of documentation showing the older syntax. They do exactly the same thing.

I often still use the longer command apt-get --purge remove simply because I have used it more often, and forget that the shorter version is now available.

One other useful thing to keep in mind is that the --purge option can be used with the apt-get autoremove, and there is not equivalent apt-get autopurge. So if you use the apt-get autoremove option to remove automatically installed packages you will have lots of old crufty configs from those packages, since you just removed them.


When would you use apt-get remove over apt-get autoremove?

remove will delete the specified program whereas autoremove will include dependencies otherwise not used anymore.

Also, If you'd like to free up drive space, a useful and safe command is...

sudo apt-get clean

That removes the aptitude cache in /var/cache/apt/archives


How to fix"error while loading shared libraries:"

It's probably because some linked libraries got broken when you uninstalled several package at once. You should have run dpkg -l |grep ^rc|awk '{print $2}' before hand to know what will happen. Luckily this can be solved using sudo ldconfig. This recreates the linked libraries cache and will (hopefully) fix your libraries.

Of course, that will only works if you really have the /usr/lib/ library installed:

ls -l /usr/lib/x86_64-linux-gnu/
lrwxrwxrwx 1 root root 15 sep 18 14:03 /usr/lib/x86_64-linux-gnu/ ->
dpkg -S
libgl1-mesa-glx:i386: /usr/lib/i386-linux-gnu/mesa/
libgl1-mesa-glx:amd64: /usr/lib/x86_64-linux-gnu/mesa/
libgl1-mesa-glx:i386: /usr/lib/i386-linux-gnu/mesa/
libgl1-mesa-glx:amd64: /usr/lib/x86_64-linux-gnu/mesa/

(mine is 64bits that's why the difference.)


How to prevent Ubuntu/Debian users from accessing apt-get or downloading from the web, etc?

I'd say your best bet is to remove the binaries that you don't want your root user to use (wget, apt-get, etc).

However this can break some system fuctionnalities because some applications assume you have a functionnal wget, dpkg, etc. And, well, as long as it's root, and even with no internet connection, he can insert a cd and recopy the binaries...


How to find out which versions of a package can I install on APT

The apt-cache show <Package> shows the package descriptions of all the versions your debian installation can install (i.e. from cached list of packages available from the repos listed in sources.list). So I guess you could try something like (for e.g.):

# apt-cache show package | grep Version
Version 1.0
Version 0.9-2squeeze1

The apt-cache show would give you much more info than just versions.


When you do "apt-get install" where are the .deb files stored?

They're stored in:


unless you've issued a:

apt-get clean


How do I list the files installed by a deb package?

Yes, use the dpkg command like

  dpkg -L hadoop-0.20

The converse question (finding the package providing a given file) is answered with e.g.

  dpkg -S /usr/include/gc/gc.h

Read more about Debian packaging related tools

PS. Ubuntu (and other Linux distributions, eg Mint) is a derivative of Debian.


How to find out what files will be installed in the filesystem when installing a package with aptitude?

You can go to and search for the package you're interested in. Towards the bottom of each package's page, there's a link labeled [list of files] (one for each architecture) that will take you to the list of files to be installed. For example, here's the list of files for Python.


Nothing happens when trying to upgrade from Linux Mint 12 to 13

Clem, the Linux Mint dev, recommends a different method to upgrade. Mint has a few specialized tools that make porting your data and settings to a new installation much easier.

Doing a clean install is generally a good idea. An update may go smoothly but you are also likely to have problems. If you do, the comments here may help.

Having said that, if you still want to use apt, edit (as root, sudo) your /etc/apt/sources.lst to point to the latest release:

deb maya main upstream import
deb precise main restricted universe multiverse
deb precise-updates main restricted universe multiverse
deb precise-security main restricted universe multiverse
deb precise partner
deb precise free non-free

Save the file and then run the following commands:

$ sudo apt-get update
$ sudo apt-get dist-upgrade

Finally, reboot your computer.


Is there a shortcut to run a suggested command in a terminal?

Create an alias as appropriate for your shell. In bash, add this line to ~/.bashrc:

alias sagi="sudo apt-get install"

Then, source ~/.bashrc and execute alias to verify the alias shows up in your list. After that, just type

sagi <package>

to invoke the alias. For other shells, the format of the alias command and the name of the rc file will be different, but the source and alias should be the same.


How to upgrade to latest git on debian 7?

Since a newer version of this package is not available in wheezy-backports you have two options:

  1. Ask the package maintainers to prepare a backport. It's not guaranteed to work but some maintainers are positive about making backports, so I'd just try.

    The maintainers' e-mails could be found there.

  2. Build it yourself from the sources. This could be done two ways:

    • Build "as is" from the source tarball. Should you pick this route, be sure to configure the Git's build system to install everything under ~/git or /opt/git or something like this otherwise later you'll have a great PITA removing what you installed.

      The problem is that the conventional Unix way of installing software by spreading it across the whole filesystem is sensible but only when you have some sort of registry which "knows" which file belongs to which package and vice-versa, and packaging systems such as Debian's do exactly this. If you do "normal" install of a package built from the sources, you in most cases will have no way to uninstall this piece of software later (short of using checkinstall instead of make install, but this really is a last resort). Conversely, if you configure a source package to install everything under a single directory, you will have minor difficulties running the software (its "binary" directories won't be on your $PATH), in exchange uninstalling it later will be a no-brainer — a single rm -rf /path/to/that/dir.

    • Do backporting yourself. This is more involved but in simple cases it might just work so IMO it worth trying.

      Basically you go like this (a link to the .dsc file is taken from the package's page in unstable):

      # apt-get install devscripts
      $ mkdir ~/devel && cd $_
      $ dget
      $ dpkg-source -x git_1.8.4~rc3-1.dsc
      $ cd git

      Check if you have all the build dependencies satisfied by running

      $ dpkg-checkbuilddeps

      And install everything that tool says is presently missing. Sometimes a package might refer to a version of something too fresh to be available in the distro you're backporting to; in this case it's okay to try to cheat and fix the version of such a package in the debian/control file.

      Now fix up the version of the packages about to be built. The best way to achieve this is to have a tool do the right thing:

      $ dch --bpo

      It will add an entry to the debian/changelog file and open your text editor of choice to oversee it. Just close the editor — the version for the packages to be built is taken from the top entry in this file.

      Now let's actually attempt to build:

      $ dpkg-buildpackage -uc -us -b

      If you're lucky, at this point you'll have a bunch of shiny new Git .deb packages in .., which you can just install using dpkg -i <packagename> ....

      (Run debuild clean to get rid of the built crud or just remove the git directory completely. You might also want to remove whatever you installed after running dpkg-checkbuilddep.)

      Unfortunately, if building fails for some reason, it takes certain knowledge to attempt to fix but this is out of scope of this discussion.


Problems with apt-get(unmet dependencies)

After a lot of searching round the internet, I have finally found a solution for my problem. I directly used dpkg to remove skype:i386. In a terminal type:

sudo dpkg -r skype:i386

Hope this will save the day I wasted on this for someone.


Failed to symbolic-link /boot/initrd.img-3.2.0-24-generic to initrd.img: File exists


sudo apt-get -f install [package]

This will force the upgrade. It's worth a try at least. Doing an

sudo apt-get update

can't hurt either.


GPG error when updating Linux Mint 9

The most direct method is to use apt itself:

$ apt-key update

The Ubuntu Forums have a couple things to say about this using more roundabout methods, if apt doesn't do it properly.

ok. I figured it out.

do this:


and then open up synaptic and go to settings>repos>authentication and "import file key" browse the key and click ok.

and then sudo aptitude update

And this:

sudo wget -O - | sudo apt-key add -

This is the link to my Google search - there's quite a bit much there to put in a single response.


apt-get is the command-line tool for handling packages, and may be considered the user's "back-end" to other tools using the APT library. Several "front-end" interfaces exist, such as dselect(1), aptitude(8), synaptic(8) and wajig(1).

Unless the -h, or --help option is given, one of the commands below must be present.


update is used to resynchronize the package index files from their sources. The indexes of available packages are fetched from the location(s) specified in /etc/apt/sources.list. For example, when using a Debian archive, this command retrieves and scans the Packages.gz files, so that information about new and updated packages is available. An update should always be performed before an upgrade or dist-upgrade. Please be aware that the overall progress meter will be incorrect as the size of the package files cannot be known in advance.


upgrade is used to install the newest versions of all packages currently installed on the system from the sources enumerated in /etc/apt/sources.list. Packages currently installed with new versions available are retrieved and upgraded; under no circumstances are currently installed packages removed, or packages not already installed retrieved and installed. New versions of currently installed packages that cannot be upgraded without changing the install status of another package will be left at their current version. An update must be performed first so that apt-get knows that new versions of packages are available.


dist-upgrade in addition to performing the function of upgrade, also intelligently handles changing dependencies with new versions of packages; apt-get has a "smart" conflict resolution system, and it will attempt to upgrade the most important packages at the expense of less important ones if necessary. The dist-upgrade command may therefore remove some packages. The /etc/apt/sources.list file contains a list of locations from which to retrieve desired package files. See also apt_preferences(5) for a mechanism for overriding the general settings for individual packages.


dselect-upgrade is used in conjunction with the traditional Debian packaging front-end, dselect(1). dselect-upgrade follows the changes made by dselect(1) to the Status field of available packages, and performs the actions necessary to realize that state (for instance, the removal of old and the installation of new packages).


install is followed by one or more packages desired for installation or upgrading. Each package is a package name, not a fully qualified filename (for instance, in a Debian system, apt-utils would be the argument provided, not apt-utils_0.9.7.7ubuntu4_amd64.deb). All packages required by the package(s) specified for installation will also be retrieved and installed. The /etc/apt/sources.list file is used to locate the desired packages. If a hyphen is appended to the package name (with no intervening space), the identified package will be removed if it is installed. Similarly a plus sign can be used to designate a package to install. These latter features may be used to override decisions made by apt-get's conflict resolution system.

A specific version of a package can be selected for installation by following the package name with an equals and the version of the package to select. This will cause that version to be located and selected for install. Alternatively a specific distribution can be selected by following the package name with a slash and the version of the distribution or the Archive name (stable, testing, unstable).

Both of the version selection mechanisms can downgrade packages and must be used with care.

This is also the target to use if you want to upgrade one or more already-installed packages without upgrading every package you have on your system. Unlike the "upgrade" target, which installs the newest version of all currently installed packages, "install" will install the newest version of only the package(s) specified. Simply provide the name of the package(s) you wish to upgrade, and if a newer version is available, it (and its dependencies, as described above) will be downloaded and installed.

Finally, the apt_preferences(5) mechanism allows you to create an alternative installation policy for individual packages.

If no package matches the given expression and the expression contains one of '.', '?' or '*' then it is assumed to be a POSIX regular expression, and it is applied to all package names in the database. Any matches are then installed (or removed). Note that matching is done by substring so 'lo.*' matches 'how-lo' and 'lowest'. If this is undesired, anchor the regular expression with a '^' or '$' character, or create a more specific regular expression.


remove is identical to install except that packages are removed instead of installed. Note that removing a package leaves its configuration files on the system. If a plus sign is appended to the package name (with no intervening space), the identified package will be installed instead of removed.


purge is identical to remove except that packages are removed and purged (any configuration files are deleted too).


source causes apt-get to fetch source packages. APT will examine the available packages to decide which source package to fetch. It will then find and download into the current directory the newest available version of that source package while respecting the default release, set with the option APT::Default-Release, the -t option or per package with the pkg/release syntax, if possible.

Source packages are tracked separately from binary packages via deb-src lines in the sources.list(5) file. This means that you will need to add such a line for each repository you want to get sources from; otherwise you will probably get either the wrong (too old/too new) source versions or none at all.

If the --compile option is specified then the package will be compiled to a binary .deb using dpkg-buildpackage for the architecture as defined by the --host-architecture option. If --download-only is specified then the source package will not be unpacked.

A specific source version can be retrieved by postfixing the source name with an equals and then the version to fetch, similar to the mechanism used for the package files. This enables exact matching of the source package name and version, implicitly enabling the APT::Get::Only-Source option.

Note that source packages are not installed and tracked in the dpkg database like binary packages; they are simply downloaded to the current directory, like source tarballs.


build-dep causes apt-get to install/remove packages in an attempt to satisfy the build dependencies for a source package. By default the dependencies are satisfied to build the package natively. If desired a host-architecture can be specified with the --host-architecture option instead.


check is a diagnostic tool; it updates the package cache and checks for broken dependencies.


download will download the given binary package into the current directory.


clean clears out the local repository of retrieved package files. It removes everything but the lock file from /var/cache/apt/archives/ and /var/cache/apt/archives/partial/. When APT is used as a dselect(1) method, clean is run automatically. Those who do not use dselect will likely want to run apt-get clean from time to time to free up disk space.


Like clean, autoclean clears out the local repository of retrieved package files. The difference is that it only removes package files that can no longer be downloaded, and are largely useless. This allows a cache to be maintained over a long period without it growing out of control. The configuration option APT::Clean-Installed will prevent installed packages from being erased if it is set to off.


autoremove is used to remove packages that were automatically installed to satisfy dependencies for other packages and are now no longer needed.


changelog downloads a package changelog and displays it through sensible-pager. The server name and base directory is defined in the APT::Changelogs::Server variable (e.g. [1] for Debian or [2] for Ubuntu). By default it displays the changelog for the version that is installed. However, you can specify the same options as for the install command.


All command line options may be set using the configuration file, the descriptions indicate the configuration option to set. For boolean options you can override the config file by using something like -f-,--no-f, -f=no or several other variations.


Do not consider recommended packages as a dependency for installing. Configuration Item: APT::Install-Recommends.


Consider suggested packages as a dependency for installing. Configuration Item: APT::Install-Suggests.

-d, --download-only

Download only; package files are only retrieved, not unpacked or installed. Configuration Item: APT::Get::Download-Only.

-f, --fix-broken

Fix; attempt to correct a system with broken dependencies in place. This option, when used with install/remove, can omit any packages to permit APT to deduce a likely solution. If packages are specified, these have to completely correct the problem. The option is sometimes necessary when running APT for the first time; APT itself does not allow broken package dependencies to exist on a system. It is possible that a system's dependency structure can be so corrupt as to require manual intervention (which usually means using dselect(1) or dpkg --remove to eliminate some of the offending packages). Use of this option together with -m may produce an error in some situations. Configuration Item: APT::Get::Fix-Broken.

-m, --ignore-missing, --fix-missing

Ignore missing packages; if packages cannot be retrieved or fail the integrity check after retrieval (corrupted package files), hold back those packages and handle the result. Use of this option together with -f may produce an error in some situations. If a package is selected for installation (particularly if it is mentioned on the command line) and it could not be downloaded then it will be silently held back. Configuration Item: APT::Get::Fix-Missing.


Disables downloading of packages. This is best used with --ignore-missing to force APT to use only the .debs it has already downloaded. Configuration Item: APT::Get::Download.

-q, --quiet

Quiet; produces output suitable for logging, omitting progress indicators. More q's will produce more quiet up to a maximum of 2. You can also use -q=# to set the quiet level, overriding the configuration file. Note that quiet level 2 implies -y; you should never use -qq without a no-action modifier such as -d, --print-uris or -s as APT may decide to do something you did not expect. Configuration Item: quiet.

-s, --simulate, --just-print, --dry-run, --recon, --no-act

No action; perform a simulation of events that would occur but do not actually change the system. Configuration Item: APT::Get::Simulate.

Simulated runs performed as a user will automatically deactivate locking (Debug::NoLocking), and if the option APT::Get::Show-User-Simulation-Note is set (as it is by default) a notice will also be displayed indicating that this is only a simulation. Runs performed as root do not trigger either NoLocking or the notice - superusers should know what they are doing without further warnings from apt-get.

Simulated runs print out a series of lines, each representing a dpkg operation: configure (Conf), remove (Remv) or unpack (Inst). Square brackets indicate broken packages, and empty square brackets indicate breaks that are of no consequence (rare).

-y, --yes, --assume-yes

Automatic yes to prompts; assume "yes" as answer to all prompts and run non-interactively. If an undesirable situation, such as changing a held package, trying to install a unauthenticated package or removing an essential package occurs then apt-get will abort. Configuration Item: APT::Get::Assume-Yes.


Automatic "no" to all prompts. Configuration Item: APT::Get::Assume-No.

-u, --show-upgraded

Show upgraded packages; print out a list of all packages that are to be upgraded. Configuration Item: APT::Get::Show-Upgraded.

-V, --verbose-versions

Show full versions for upgraded and installed packages. Configuration Item: APT::Get::Show-Versions.

-a, --host-architecture

This option controls the architecture packages are built for by apt-get source --compile and how cross-builddependencies are satisfied. By default is it not set which means that the host architecture is the same as the build architecture (which is defined by APT::Architecture). Configuration Item: APT::Get::Host-Architecture

-b, --compile, --build

Compile source packages after downloading them. Configuration Item: APT::Get::Compile.


Ignore package holds; this causes apt-get to ignore a hold placed on a package. This may be useful in conjunction with dist-upgrade to override a large number of undesired holds. Configuration Item: APT::Ignore-Hold.


Do not upgrade packages; when used in conjunction with install, no-upgrade will prevent packages on the command line from being upgraded if they are already installed. Configuration Item: APT::Get::Upgrade.


Do not install new packages; when used in conjunction with install, only-upgrade will install upgrades for already installed packages only and ignore requests to install new packages. Configuration Item: APT::Get::Only-Upgrade.


Force yes; this is a dangerous option that will cause apt to continue without prompting if it is doing something potentially harmful. It should not be used except in very special situations. Using force-yes can potentially destroy your system! Configuration Item: APT::Get::force-yes.


Instead of fetching the files to install their URIs are printed. Each URI will have the path, the destination file name, the size and the expected MD5 hash. Note that the file name to write to will not always match the file name on the remote site! This also works with the source and update commands. When used with the update command the MD5 and size are not included, and it is up to the user to decompress any compressed files. Configuration Item: APT::Get::Print-URIs.


Use purge instead of remove for anything that would be removed. An asterisk ("*") will be displayed next to packages which are scheduled to be purged. remove --purge is equivalent to the purge command. Configuration Item: APT::Get::Purge.


Re-install packages that are already installed and at the newest version. Configuration Item: APT::Get::ReInstall.


This option is on by default; use --no-list-cleanup to turn it off. When it is on, apt-get will automatically manage the contents of /var/lib/apt/lists to ensure that obsolete files are erased. The only reason to turn it off is if you frequently change your sources list. Configuration Item: APT::Get::List-Cleanup.

-t, --target-release, --default-release

This option controls the default input to the policy engine; it creates a default pin at priority 990 using the specified release string. This overrides the general settings in /etc/apt/preferences. Specifically pinned packages are not affected by the value of this option. In short, this option lets you have simple control over which distribution packages will be retrieved from. Some common examples might be -t '2.1*', -t unstable or -t sid. Configuration Item: APT::Default-Release; see also the apt_preferences(5) manual page.


Only perform operations that are 'trivial'. Logically this can be considered related to --assume-yes; where --assume-yes will answer yes to any prompt, --trivial-only will answer no. Configuration Item: APT::Get::Trivial-Only.


If any packages are to be removed apt-get immediately aborts without prompting. Configuration Item: APT::Get::Remove.


If the command is either install or remove, then this option acts like running the autoremove command, removing unused dependency packages. Configuration Item: APT::Get::AutomaticRemove.


Only has meaning for the source and build-dep commands. Indicates that the given source names are not to be mapped through the binary table. This means that if this option is specified, these commands will only accept source package names as arguments, rather than accepting binary package names and looking up the corresponding source package. Configuration Item: APT::Get::Only-Source.

--diff-only, --dsc-only, --tar-only

Download only the diff, dsc, or tar file of a source archive. Configuration Item: APT::Get::Diff-Only, APT::Get::Dsc-Only, and APT::Get::Tar-Only.


Only process architecture-dependent build-dependencies. Configuration Item: APT::Get::Arch-Only.


Ignore if packages can't be authenticated and don't prompt about it. This is useful for tools like pbuilder. Configuration Item: APT::Get::AllowUnauthenticated.

-h, --help

Show a short usage summary.

-v, --version

Show the program version.

-c, --config-file

Configuration File; Specify a configuration file to use. The program will read the default configuration file and then this configuration file. If configuration settings need to be set before the default configuration files are parsed specify a file with the APT_CONFIG environment variable. See apt.conf(5) for syntax information.

-o, --option

Set a Configuration Option; This will set an arbitrary configuration option. The syntax is -o Foo::Bar=bar. -o and --option can be used multiple times to set different options.


apt-get returns zero on normal operation, decimal 100 on error.



Locations to fetch packages from. Configuration Item: Dir::Etc::SourceList.


File fragments for locations to fetch packages from. Configuration Item: Dir::Etc::SourceParts.


APT configuration file. Configuration Item: Dir::Etc::Main.


APT configuration file fragments. Configuration Item: Dir::Etc::Parts.


Version preferences file. This is where you would specify "pinning", i.e. a preference to get certain packages from a separate source or from a different version of a distribution. Configuration Item: Dir::Etc::Preferences.


File fragments for the version preferences. Configuration Item: Dir::Etc::PreferencesParts.


Storage area for retrieved package files. Configuration Item: Dir::Cache::Archives.


Storage area for package files in transit. Configuration Item: Dir::Cache::Archives (partial will be implicitly appended)


Storage area for state information for each package resource specified in sources.list(5) Configuration Item: Dir::State::Lists.


Storage area for state information in transit. Configuration Item: Dir::State::Lists (partial will be implicitly appended)





APT bug page


APT bug page [3] . If you wish to report a bug in APT, please see /usr/share/doc/debian/bug-reporting.txt or the reportbug(1) command.

see also

apt-cache , apt-cdrom , dpkg , dselect, sources.list, apt.conf, apt-config , apt-secure, The APT User's guide in /usr/share/doc/apt-doc/, apt_preferences, the APT Howto.


Jason Gunthorpe

APT team

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