NAME

       AptPkg::Cache - APT package cache interface

SYNOPSIS

       use AptPkg::Cache;

DESCRIPTION

       The AptPkg::Cache module provides an interface to APT's package cache.

   AptPkg::Cache
       The AptPkg::Cache package implements the APT pkgCacheFile class as a hash reference
       (inherits from AptPkg::hash).  The hash keys are the names of packages in the cache, and
       the values are AptPkg::Cache::Package objects (which in turn appear as hash references,
       see below).

       Constructor

       new([LOCK])
           Instantiation of the object uses configuration from the $AptPkg::Config::_config and
           $AptPkg::System::_system objects (automatically initialised if not done explicitly).

           The cache initialisation can be quite verbose--controlled by the value of
           $_config->{quiet}, which is set to "2" (quiet) if the $_config object is auto-
           initialised.

           The cache directory is locked if LOCK is true.

           It is important to note that the structure of the returned object contains self-
           referential elements, so some care must be taken if attempting to traverse it
           recursively.

       Methods

       files
           Return a list of AptPkg::Cache::PkgFile objects describing the package files.

       packages
           Return an AptPkg::PkgRecords object which may be used to retrieve additional
           information about packages.

       get, exists, keys
           These methods are used to implement the hashref abstraction: $obj->get($pack) and
           $obj->{$pack} are equivalent.

       is_multi_arch
           Cache is multi-arch enabled.

       native_arch
           Native architecture.

   AptPkg::Cache::Package
       Implements the APT pkgCache::PkgIterator class as a hash reference.

       Keys

       Name
       Section
       Arch
           Package name, section and architecture.

       FullName
           Fully qualified name, including architecture.

       ShortName
           The shortest unambiguous package name: the same as "Name" for native packages, and
           "FullName" for non-native.

       SelectedState
       InstState
       CurrentState
           Package state from the status file.

           SelectedState may be "Unknown", "Install", "Hold", "DeInstall" or "Purge".

           InstState may be "Ok", "ReInstReq", "HoldInst" or "HoldReInstReq".

           CurrentState may be "NotInstalled", "UnPacked", "HalfConfigured", "HalfInstalled",
           "ConfigFiles" or "Installed".

           In a numeric context, SelectedState, InstState and CurrentState evaluate to an
           AptPkg::State:: constant.

       VersionList
           A reference to an array of AptPkg::Cache::Version objects describing available
           versions of the package.

       CurrentVer
           An AptPkg::Cache::Version object describing the currently installed version (if any)
           of the package.

       RevDependsList
           A reference to an array of AptPkg::Cache::Depends objects describing packages which
           depend upon the current package.

       ProvidesList
           For virtual packages, this is a reference to an array of AptPkg::Cache::Provides
           objects describing packages which provide the current package.

       Flags
           A comma separated list if flags:  "Auto", "Essential" or "Important".

           In a numeric context, evaluates to a combination of AptPkg::Flag:: constants.

           [Note:  the only one of these you need worry about is "Essential", which is set based
           on the package's header of the same name.  "Auto" seems to be used internally by APT,
           and "Important" seems to only be set on the apt package.]

       Index
           Internal APT unique reference for the package record.

   AptPkg::Cache::Version
       Implements the APT pkgCache::VerIterator class as a hash reference.

       Keys

       VerStr
       Section
       Arch
           The package version, section and architecture.

       MultiArch
           Multi-arch state: "No", "All", "Foreign", "Same", "Allowed", "AllForeign" or
           "AllAllowed".

           In a numeric context, evaluates to an AptPkg::Version:: constant.

       ParentPkg
           An AptPkg::Cache::Package objct describing the package providing this version.

       DescriptionList
           A list of AptCache::Cache::Description objects describing the files which describe a
           package version.  The list includes both Package files and Translation files, which
           contain translated Description fields.

       TranslatedDescription
           An AptCache::Cache::Description object for the current locale, which will generally be
           a Translation file.

       DependsList
           A reference to an array of AptPkg::Cache::Depends objects describing packages which
           the current package depends upon.

       ProvidesList
           A reference to an array of AptPkg::Cache::Provides objects describing virtual packages
           provided by this version.

       FileList
           A reference to an array of AptPkg::Cache::VerFile objects describing the packages
           files which include the current version.

       Size
           The .deb file size, in bytes.

       InstalledSize
           The disk space used when installed, in bytes.

       Index
           Internal APT unique reference for the version record.

       Priority
           Package priority:  "important", "required", "standard", "optional" or "extra".

           In a numeric context, evaluates to an AptPkg::VerPriority:: constant.

   AptPkg::Cache::Depends
       Implements the APT pkgCache::DepIterator class as a hash reference.

       Keys

       DepType
           Type of dependency:  "Depends", "PreDepends", "Suggests", "Recommends", "Conflicts",
           "Replaces" or "Obsoletes".

           In a numeric context, evaluates to an AptPkg::Dep:: constant.

       ParentPkg
       ParentVer
           AptPkg::Cache::Package and AptPkg::Cache::Version objects describing the package
           declaring the dependency.

       TargetPkg
           AptPkg::Cache::Package object describing the depended package.

       TargetVer
           For versioned dependencies, TargetVer is a string giving the version of the target
           package required.

       CompType
       CompTypeDeb
           CompType gives a normalised comparison operator (>, >=, etc) describing the
           relationship to TargetVer ("" if none).

           CompTypeDeb returns Debian-style operators (>> rather than >).

           In a numeric context, both CompType and CompTypeDeb evaluate to an AptPkg::Dep::
           constant.

           Alternative dependencies (Depends: a | b) are identified by all but the last having
           the AptPkg::Dep::Or bit set in the numeric representation of CompType (and
           CompTypeDeb).

       Index
           Internal APT unique reference for the dependency record.

   AptPkg::Cache::Provides
       Implements the APT pkgCache::PrvIterator class as a hash reference.

       Keys

       Name
           Name of virtual package.

       OwnerPkg
       OwnerVer
           AptPkg::Cache::Package and AptPkg::Cache::Version objects describing the providing
           package.

       ProvideVersion
           Version of the virtual package.  [Not currently supported by dpkg]

       Index
           Internal APT unique reference for the provides record.

   AptPkg::Cache::VerFile
       Implements the APT pkgCache::VerFileIterator class as a hash reference.

       Keys

       File
           An AptPkg::Cache::PkgFile object describing the packages file.

       Offset
       Size
           The byte offset and length of the entry in the file.

       Index
           Internal APT unique reference for the version file record.

   AptPkg::Cache::PkgFile
       Implements the APT pkgCache::PkgFileIterator class as a hash reference.

       Keys

       FileName
           Packages file path.

       IndexType
           File type: "Debian Package Index", "Debian dpkg status file".

       Archive
       Component
       Version
       Origin
       Label
       Site
           Fields from the Release file.

       Index
           Internal APT unique reference for the package file record.

   AptPkg::Cache::DescFile
       Implements the APT pkgCache::DescFileIterator class as a hash reference.

       Keys

       File
           An AptPkg::Cache::PkgFile object describing the packages file.

SEE ALSO

       AptPkg::Config(3pm), AptPkg::System(3pm), AptPkg(3pm), AptPkg::hash(3pm),
       AptPkg::PkgRecords(3pm), AptPkg::Policy(3pm).

AUTHOR

       Brendan O'Dea <bod@debian.org>