apt/doc/apt-cache.8.sgml

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 &apt-docinfo;
 
 <refmeta>
   <refentrytitle>apt-cache</>
   <manvolnum>8</>
 </refmeta>
 
 <!-- Man page title -->
 <refnamediv>
    <refname>apt-cache</>
    <refpurpose>APT package handling utility -- cache manipulator</>
 </refnamediv>

 <!-- Arguments -->
 <refsynopsisdiv>
   <cmdsynopsis>
      <command>apt-cache</>
      <arg><option>-hvsn</></arg>
      <arg><option>-o=<replaceable/config string/</></arg>
      <arg><option>-c=<replaceable/file/</></arg>
      <group choice=req>
         <arg>add <arg choice="plain" rep="repeat"><replaceable>file</replaceable></arg></arg>
         <arg>gencaches</>
         <arg>showpkg <arg choice="plain" rep="repeat"><replaceable>pkg</replaceable></arg></arg>
         <arg>showsrc <arg choice="plain" rep="repeat"><replaceable>pkg</replaceable></arg></arg>
         <arg>stats</>
         <arg>dump</>
         <arg>dumpavail</>
         <arg>unmet</>
         <arg>search <arg choice="plain"><replaceable>regex</replaceable></arg></arg>
         <arg>show <arg choice="plain" rep="repeat"><replaceable>pkg</replaceable></arg></arg>
         <arg>showpkg <arg choice="plain" rep="repeat"><replaceable>pkg</replaceable></arg></arg>
         <arg>depends <arg choice="plain" rep="repeat"><replaceable>pkg</replaceable></arg></arg>
         <arg>pkgnames <arg choice="plain"><replaceable>prefix</replaceable></arg></arg>
         <arg>dotty <arg choice="plain" rep="repeat"><replaceable>pkg</replaceable></arg></arg>
         <arg>policy <arg choice="plain" rep="repeat"><replaceable>pkgs</replaceable></arg></arg>
      </group>   
   </cmdsynopsis>
 </refsynopsisdiv>
 
 <RefSect1><Title>Description</>
   <para>
   <command/apt-cache/ performs a variety of operations on APT's package 
   cache. <command/apt-cache/ does not manipulate the state of the system 
   but does provide operations to search and generate interesting output 
   from the package metadata.

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

   <VariableList>
     <VarListEntry><Term>add</Term>
     <ListItem><Para>
     <literal/add/ adds the named package index files to the package cache.
     This is for debugging only.
     </VarListEntry>
     
     <VarListEntry><Term>gencaches</Term>
     <ListItem><Para>
     <literal/gencaches/ performs the same opration as 
     <command/apt-get check/. It builds the source and package caches from 
     the sources in &sources-list; and from <filename>/var/lib/dpkg/status</>.
     </VarListEntry>

     <VarListEntry><Term>showpkg</Term>
     <ListItem><Para>
     <literal/showpkg/ displays information about the packages listed on the 
     command line. Remaining arguments are package names. The available 
     versions and reverse dependencies of each package listed are listed, as 
     well as forward dependencies for each version. Forward (normal) 
     dependencies are those packages upon which the package in question 
     depends; reverse dependencies are those packages that depend upon the 
     package in question. Thus, forward dependencies must be satisfied for a 
     package, but reverse dependencies need not be.
     For instance, <command>apt-cache showpkg libreadline2</> would produce 
     output similar to the following:
     
<informalexample><programlisting>
Package: libreadline2
Versions: 2.1-12(/var/state/apt/lists/foo_Packages),
Reverse Depends: 
  libreadlineg2,libreadline2
  libreadline2-altdev,libreadline2
Dependencies:
2.1-12 - libc5 (2 5.4.0-0) ncurses3.0 (0 (null))
Provides:
2.1-12 - 
Reverse Provides: 
</programlisting></informalexample>
			    
     <para>
     Thus it may be seen that libreadline2, version 2.1-12, depends on libc5 and
     ncurses3.0 which must be installed for libreadline2 to work. 
     In turn, libreadlineg2 and libreadline2-altdev depend on libreadline2. If
     libreadline2 is installed, libc5, ncurses3.0, and ldso must also be
     installed; libreadlineg2 and libreadline2-altdev do not have to be
     installed. For the specific meaning of the remainder of the output it
     is best to consult the apt source code.
     </VarListEntry>

     <VarListEntry><Term>stats</Term>
     <ListItem><Para>
     <literal/stats/ displays some statistics about the cache.
     No further arguments are expected. Statistics reported are:
     <itemizedlist>
       <listitem><para>
       <literal/Total package names/ is the number of package names found 
       in the cache.
       </listitem>
       
       <listitem><para>
       <literal/Normal packages/ is the number of regular, ordinary package 
       names; these are packages that bear a one-to-one correspondence between 
       their names and the names used by other packages for them in 
       dependencies. The majority of packages fall into this category.
       </listitem>

       <listitem><para>
       <literal/Pure virtual packages/ is the number of packages that exist 
       only as a virtual package name; that is, packages only "provide" the 
       virtual package name, and no package actually uses the name. For 
       instance, "mail-transport-agent" in the Debian GNU/Linux system is a 
       pure virtual package; several packages provide "mail-transport-agent", 
       but there is no package named "mail-transport-agent".
       </listitem>
   
       <listitem><para>
       <literal/Single virtual packages/ is the number of packages with only 
       one package providing a particular virtual package. For example, in the
       Debian GNU/Linux system, "X11-text-viewer" is a virtual package, but 
       only one package, xless, provides "X11-text-viewer".
       </listitem>

       <listitem><para>
       <literal/Mixed virtual packages/ is the number of packages that either 
       provide a particular virtual package or have the virtual package name 
       as the package name. For instance, in the Debian GNU/Linux system, 
       debconf is both an actual package, and provided by the debconf-tiny
       package.
       </listitem>
   
       <listitem><para>
       <literal/Missing/ is the number of package names that were referenced in
       a dependency but were not provided by any package. Missing packages may 
       be in evidence if a full distribution is not accesssed, or if a package
       (real or virtual) has been dropped from the distribution. Usually they
       are referenced from Conflicts statements.
       </listitem>

       <listitem><para>
       <literal/Total distinct/ versions is the number of package versions 
       found in the cache; this value is therefore at least equal to the 
       number of total package names. If more than one distribution (both 
       "stable" and "unstable", for instance), is being accessed, this value 
       can be considerably larger than the number of total package names.
       </listitem>

       <listitem><para>
       <literal/Total dependencies/ is the number of dependency relationships 
       claimed by all of the packages in the cache.
       </listitem>
     </itemizedlist>
     </VarListEntry>
     
     <VarListEntry><Term>showsrc</Term>
     <ListItem><Para>
     <literal/showsrc/ displays all the source package records that match
     the given package names. All versions are shown, as well as all 
     records that declare the name to be a Binary.
     named packages.
     </VarListEntry>
     
     <VarListEntry><Term>dump</Term>
     <ListItem><Para>
     <literal/dump/ shows a short listing of every package in the cache. It is 
     primarily for debugging.
     </VarListEntry>

     <VarListEntry><Term>dumpavail</Term>
     <ListItem><Para>
     <literal/dumpavail/ prints out an available list to stdout. This is 
     suitable for use with &dpkg; and is used by the &dselect; method.
     </VarListEntry>

     <VarListEntry><Term>unmet</Term>
     <ListItem><Para>
     <literal/unmet/ displays a summary of all unmet dependencies in the 
     package cache.
     </VarListEntry>

     <VarListEntry><Term>show</Term>
     <ListItem><Para>
     <literal/show/ performs a function similar to 
     <command>dpkg --print-avail</>, it displays the package records for the 
     named packages.
     </VarListEntry>

     <VarListEntry><Term>search</Term>
     <ListItem><Para>
     <literal/search/ performs a full text search on all available package 
     files for the regex pattern given. It searchs the package names and the 
     descriptions for an occurance of the string and prints out the package 
     name and the short description. If <option/--full/ is given then output 
     identical to <literal/show/ is produced for each matched package and 
     if <option/--names-only/ is given then the long description is not 
     searched, only the package name is.
     <para>
     Seperate arguments can be used to specified multiple search patterns that 
     are and'd together.
     </VarListEntry>

     <VarListEntry><Term>depends</Term>
     <ListItem><Para>
     <literal/depends/ shows a listing of each dependency a package has 
     and all the possible other packages that can fullfill that dependency.
     </VarListEntry>

     <VarListEntry><Term>pkgnames</Term>
     <ListItem><Para>
     This command prints the name of each package in the system. The optional
     argument is a prefix match to filter the name list. The output is suitable
     for use in a shell tab complete function and the output is generated 
     extremly quickly. This command is best used with the 
     <option/--generate/ option.
     </VarListEntry>
     
     <VarListEntry><Term>dotty</Term>
     <ListItem><Para>
     <literal/dotty/ takes a list of packages on the command line and 
     gernerates output suitable for use by dotty from the 
     <ulink url="http://www.research.att.com/sw/tools/graphviz/">GraphViz</>
     package. The result will be a set of nodes and edges representing the 
     relationships between the packages. By default the given packages will 
     trace out all dependent packages which can produce a very large graph. 
     This can be turned off by setting the 
     <literal>APT::Cache::GivenOnly</> option.

     <para>
     The resulting nodes will have several shapse, normal packages are boxes,
     pure provides are triangles, mixed provides are diamonds, 
     hexagons are missing packages. Orange boxes mean recursion was stopped 
     [leaf packages], blue lines are prre-depends, green lines are conflicts.

     <para>
     Caution, dotty cannot graph larger sets of packages.
     
     <VarListEntry><Term>policy</Term>
     <ListItem><Para>
     <literal/policy/ is ment to help debug issues relating to the 
     preferences file. With no arguments it will print out the 
     priorities of each source. Otherwise it prints out detailed information
     about the priority selection of the named package.
     </VarListEntry>
   </VariableList>
 </RefSect1>
 
 <RefSect1><Title>Options</>
   &apt-cmdblurb;
   
   <VariableList>
     <VarListEntry><term><option/-p/</><term><option/--pkg-cache/</>
     <ListItem><Para>
     Select the file to store the package cache. The package cache is the 
     primary cache used by all operations.
     Configuration Item: <literal/Dir::Cache::pkgcache/.
     </VarListEntry>

     <VarListEntry><term><option/-s/</><term><option/--src-cache/</>
     <ListItem><Para>
     Select the file to store the source cache. The source is used only by
     <literal/gencaches/ and it stores a parsed version of the package 
     information from remote sources. When building the package cache the 
     source cache is used to advoid reparsing all of the package files.
     Configuration Item: <literal/Dir::Cache::srcpkgcache/.
     </VarListEntry>

     <VarListEntry><term><option/-q/</><term><option/--quiet/</>
     <ListItem><Para>
     Quiet; produces output suitable for logging, omitting progress indicators.
     More qs will produce more quite up to a maximum of 2. You can also use
     <option/-q=#/ to set the quiet level, overriding the configuration file.
     Configuration Item: <literal/quiet/.
     </VarListEntry>

     <VarListEntry><term><option/-i/</><term><option/--important/</>
     <ListItem><Para>
     Print only important deps; for use with unmet causes only Depends and 
     Pre-Depends relations to be printed.
     Configuration Item: <literal/APT::Cache::Important/.
     </VarListEntry>

     <VarListEntry><term><option/-f/</><term><option/--full/</>
     <ListItem><Para>
     Print full package records when searching. 
     Configuration Item: <literal/APT::Cache::ShowFull/.
     </VarListEntry>

     <VarListEntry><term><option/-a/</><term><option/--all-versions/</>
     <ListItem><Para>
     Print full records for all available versions, this is only applicable to 
     the show command. 
     Configuration Item: <literal/APT::Cache::AllVersions/.
     </VarListEntry>

     <VarListEntry><term><option/-g/</><term><option/--generate/</>
     <ListItem><Para>
     Perform automatic package cache regeneration, rather than use the cache 
     as it is. This is the default, to turn it off use <option/--no-generate/.
     Configuration Item: <literal/APT::Cache::Generate/.
     </VarListEntry>

     <VarListEntry><term><option/--names-only/</><term><options/-n/</>
     <ListItem><Para>
     Only search on the package names, not the long description. 
     Configuration Item: <literal/APT::Cache::NamesOnly/.
     </VarListEntry>

     <VarListEntry><term><option/--all-names/</>
     <ListItem><Para>
     Make <literal/pkgnames/ print all names, including virtual packages 
     and missing dependencies. 
     Configuration Item: <literal/APT::Cache::AllNames/.
     </VarListEntry>

     <VarListEntry><term><option/--recurse/</>
     <ListItem><Para>
     Make <literal/depends/ recursive so that all packages mentioned are 
     printed once.
     Configuration Item: <literal/APT::Cache::RecurseDepends/.
     </VarListEntry>

     &apt-commonoptions;
     
   </VariableList>
 </RefSect1>

 <RefSect1><Title>Files</>
   <variablelist>
     <VarListEntry><term><filename>/etc/apt/sources.list</></term>
     <ListItem><Para>
     locations to fetch packages from.
     Configuration Item: <literal/Dir::Etc::SourceList/.
     </VarListEntry>
     
     <VarListEntry><term><filename>&statedir;/lists/</></term>
     <ListItem><Para>
     storage area for state information for each package resource specified in
     &sources-list;
     Configuration Item: <literal/Dir::State::Lists/.
     </VarListEntry>
  
     <VarListEntry><term><filename>&statedir;/lists/partial/</></term>
     <ListItem><Para>
     storage area for state information in transit.
     Configuration Item: <literal/Dir::State::Lists/ (implicit partial).
     </VarListEntry>     
   </variablelist>
 </RefSect1>

 <RefSect1><Title>See Also</>
   <para>
   &apt-conf;, &sources-list;, &apt-get;
 </RefSect1>

 <RefSect1><Title>Diagnostics</>
   <para>
   <command/apt-cache/ returns zero on normal operation, decimal 100 on error.
 </RefSect1>

 &manbugs;
 &manauthor;
 
</refentry>