apt-patterns - Syntax and semantics of apt search patterns
==========================================================

Description
-----------

Starting with version 2.0, ``APT`` provides support for patterns, which
can be used to query the apt cache for packages.

Logic patterns
--------------

These patterns provide the basic means to combine other patterns into
more complex expressions, as well as ``?true`` and ``?false`` patterns.

``?and(PATTERN, PATTERN, ...)``
   Selects objects where all specified patterns match.

``?false``
   Selects nothing.

``?not(PATTERN)``
   Selects objects where PATTERN does not match.

``?or(PATTERN, PATTERN, ...)``
   Selects objects where at least one of the specified patterns match.

``?true``
   Selects all objects.

Package patterns
----------------

These patterns select specific packages.

``?architecture(WILDCARD)``
   Selects packages matching the specified architecture, which may
   contain wildcards using any.

``?automatic``
   Selects packages that were installed automatically.

``?broken``
   Selects packages that have broken dependencies.

``?config-files``
   Selects packages that are not fully installed, but have solely
   residual configuration files left.

``?essential``
   Selects packages that have Essential: yes set in their control file.

``?exact-name(NAME)``
   Selects packages with the exact specified name.

``?garbage``
   Selects packages that can be removed automatically.

``?installed``
   Selects packages that are currently installed.

``?name(REGEX)``
   Selects packages where the name matches the given regular expression.

``?obsolete``
   Selects packages that no longer exist in repositories.

``?upgradable``
   Selects packages that can be upgraded (have a newer candidate).

``?virtual``
   Selects all virtual packages; that is packages without a version.
   These exist when they are referenced somewhere in the archive, for
   example because something depends on that name.

Examples
--------

``apt remove ?garbage``
   Remove all packages that are automatically installed and no longer
   needed - same as apt autoremove

``apt purge ?config-files``
   Purge all packages that only have configuration files left

Migrating from aptitude
-----------------------

Patterns in apt are heavily inspired by patterns in aptitude, but with
some tweaks:

-  Only long forms MDASH the ones starting with ? MDASH are supported

-  Syntax is uniform: If there is an opening parenthesis after a term,
   it is always assumed to be the beginning of an argument list.

   In aptitude, a syntactic form ``"?foo(bar)"`` could mean
   ``"?and(?foo,bar)"`` if foo does not take an argument. In APT, this
   will cause an error.

-  Not all patterns are supported.

-  Some additional patterns are available, for example, for finding
   gstreamer codecs.

-  Escaping terms with ``~`` is not supported.

-  A trailing comma is allowed in argument lists

See Also
--------
APT-GET, APT