update is used to download package information from all configured sources. Other commands operate on this data to e.g. perform package upgrades or search in and display details about all packages available for installation.

upgrade is used to install available upgrades of all packages currently installed on the system from the sources configured via sources.list(5). New packages will be installed if required to satisfy dependencies, but existing packages will never be removed. If an upgrade for a package requires the removal of an installed package the upgrade for this package isn't performed.

When a package is supplied as an argument, the package will be installed prior to the upgrade action.

full-upgrade performs the function of upgrade but will remove currently installed packages if this is needed to upgrade the system as a whole.

When a package is supplied as an argument, the package will be installed prior to the upgrade action.

Performs the requested action on one or more packages specified via regex(7), glob(7) or exact match. The requested action can be overridden for specific packages by appending a plus (+) to the package name to install this package or a minus (-) to remove it.

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. Alternatively the version from a specific release can be selected by following the package name with a forward slash (/) and codename (trixie, forky, sid ...) or suite name (stable, testing, unstable). This will also select versions from this release for dependencies of this package if needed to satisfy the request.

Removing a package removes all packaged data, but leaves usually small (modified) user configuration files behind, in case the remove was an accident. Just issuing an installation request for the accidentally removed package will restore its function as before in that case. On the other hand you can get rid of these leftovers by calling purge even on already removed packages. Note that this does not affect any data or configuration stored in your home directory.

autoremove is used to remove packages that were automatically installed to satisfy dependencies for other packages and are now no longer needed as dependencies changed or the package(s) needing them were removed in the meantime.

You should check that the list does not include applications you have grown to like even though they were once installed just as a dependency of another package. You can mark such a package as manually installed by using apt-mark(8). Packages which you have installed explicitly via install are also never proposed for automatic removal.

satisfy satisfies dependency strings, as used in Build-Depends. It also handles conflicts, by prefixing an argument with "Conflicts: ".

Example: apt satisfy "foo, bar (>= 1.0)" "Conflicts: baz, fuzz"

These commands print the reasoning path from the solver. They are similar to the equivalent aptitude commands for many use cases, but are different in that they print the actual reason the solver picked rather than the potential strongest path.

The why command determines why an installed package is installed. This provides reasonable feedback as to why an automatically installed package is installed; for a manually installed package no other reason is given. If the package is not installed, no reason can be determined.

The why-not command determines why a package was determined to not be installable. This may not always yield a result, even if a package is uninstallable.

Both commands take a single argument, the name of a package.

search can be used to search for the given regex(7) term(s) in the list of available packages and display matches. This can e.g. be useful if you are looking for packages having a specific feature. If you are looking for a package including a specific file try apt-file(1).

Show information about the given package(s) including its dependencies, installation and download size, sources the package is available from, the description of the packages content and much more. It can e.g. be helpful to look at this information before allowing apt(8) to remove a package or while searching for new packages to install.

list is somewhat similar to dpkg-query --list in that it can display a list of packages satisfying certain criteria. It supports glob(7) patterns for matching package names, apt-patterns(7), as well as options to list installed (--installed), upgradeable (--upgradeable) or all available (--all-versions) versions.

edit-sources lets you edit your sources.list(5) files in your preferred text editor while also providing basic sanity checks.

Show a short usage summary.

Show the program version.

Show audit (and notice) messages. This overrides the quiet option, but only for notice messages, not progress ones.

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.

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.

Requests a specific CLI version. This is a pattern that takes a MAJOR.MINOR version. You may omit the MINOR version, in which case the latest supported minor level will be used.

Version tracks are presented as follows: The version 3.2 has equivalent versions 0.32, 1.22, and 2.12, implementing new features for their specified major versions.

A special case is the X.9 version pattern: A version like 2.9 is followed by 3.0, but 2.10 follows directly on 2.8; given that we use odd version numbers as development series (2.9 is the 3.0 development series).

This feature has been introduced in APT 3.1.10, and replaces the binary-specific configuration. You may use the APT::Version to similar effect on older binaries, for example, use -o APT::Version=2 to make apt(8) behave like the 2.x series.

The default value is the current APT version for apt(8) and 0.(10 * major + minor) for the classic commands. The 0.X series is soft-deprecated and the other commands will roll over to the 2.x series in the future.

Turn colors on or off. Colors are on by default on supported terminals for apt(8) and can also be disabled using the NO_COLOR or APT_NO_COLOR environment variables, or further configured by the APT::Color configuration option and scope, see apt.conf(5) for information on that.