doc/apt.conf.5.sgml

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   9 <refentry>
  10  &apt-docinfo;
  11
  12  <refmeta>
  13    <refentrytitle>apt.conf</>
  14    <manvolnum>5</>
  15  </refmeta>
  16
  17  <!-- Man page title -->
  18  <refnamediv>
  19     <refname>apt.conf</>
  20     <refpurpose>Configuration file for APT</>
  21  </refnamediv>
  22
  23  <RefSect1><Title>Description</>
  24    <para>
  25    <filename/apt.conf/ is the main configuration file for the APT suite of
  26    tools, all tools make use of the configuration file and a common command line
  27    parser to provide a uniform environment. When an APT tool starts up it will
  28    read the configuration specified by the <envar/APT_CONFIG/ environment
  29    variable (if any) and then read the files in <literal/Dir::Etc::Parts/
  30    then read the main configuration file specified by
  31    <literal/Dir::Etc::main/ then finally apply the
  32    command line options to override the configuration directives, possibly
  33    loading even more config files.
  34    <para>
  35    The configuration file is organized in a tree with options organized into
  36    functional groups. Option specification is given with a double colon
  37    notation, for instance <literal/APT::Get::Assume-Yes/ is an option within
  38    the APT tool group, for the Get tool. Options do not inherit from their
  39    parent groups.
  40    <para>
  41    Syntacticly the configuration language is modeled after what the ISC tools
  42    such as bind and dhcp use. Each line is of the form
  43    <literallayout>APT::Get::Assume-Yes "true";</literallayout> The trailing
  44    semicolon is required and the quotes are optional. A new scope can be
  45    opened with curly braces, like:
  46 <informalexample><programlisting>
  47 APT {
  48   Get {
  49     Assume-Yes "true";
  50     Fix-Broken "true";
  51   };
  52 };
  53 </programlisting></informalexample>
  54    with newlines placed to make it more readable. Lists can be created by
  55    opening a scope and including a single word enclosed in quotes followed by a
  56    semicolon. Multiple entries can be included, each separated by a semicolon.
  57 <informalexample><programlisting>
  58 DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
  59 </programlisting></informalexample>
  60    <para>
  61    In general the sample configuration file in
  62    <filename>&docdir;examples/apt.conf</> &configureindex;
  63    is a good guide for how it should look.
  64    <para>
  65    Two specials are allowed, <literal/#include/ and <literal/#clear/.
  66    <literal/#include/ will include the given file, unless the filename
  67    ends in a slash, then the whole directory is included.
  68    <literal/#clear/ is used to erase a list of names.
  69    <para>
  70    All of the APT tools take a -o option which allows an arbitrary configuration
  71    directive to be specified on the command line. The syntax is a full option
  72    name (<literal/APT::Get::Assume-Yes/ for instance) followed by an equals
  73    sign then the new value of the option. Lists can be appended too by adding
  74    a trailing :: to the list name.
  75  </RefSect1>
  76
  77  <RefSect1><Title>The APT Group</>
  78    <para>
  79    This group of options controls general APT behavior as well as holding the
  80    options for all of the tools.
  81
  82    <VariableList>
  83      <VarListEntry><Term>Architecture</Term>
  84      <ListItem><Para>
  85      System Architecture; sets the architecture to use when fetching files and
  86      parsing package lists. The internal default is the architecture apt was
  87      compiled for.
  88      </VarListEntry>
  89
  90      <VarListEntry><Term>Ignore-Hold</Term>
  91      <ListItem><Para>
  92      Ignore Held packages; This global option causes the problem resolver to
  93      ignore held packages in its decision making.
  94      </VarListEntry>
  95
  96      <VarListEntry><Term>Clean-Installed</Term>
  97      <ListItem><Para>
  98      Defaults to on. When turned on the autoclean feature will remove any packages
  99      which can no longer be downloaded from the cache. If turned off then
 100      packages that are locally installed are also excluded from cleaning - but
 101      note that APT provides no direct means to reinstall them.
 102      </VarListEntry>
 103
 104      <VarListEntry><Term>Immediate-Configure</Term>
 105      <ListItem><Para>
 106      Disable Immediate Configuration; This dangerous option disables some
 107      of APT's ordering code to cause it to make fewer dpkg calls. Doing
 108      so may be necessary on some extremely slow single user systems but
 109      is very dangerous and may cause package install scripts to fail or worse.
 110      Use at your own risk.
 111      </VarListEntry>
 112
 113      <VarListEntry><Term>Force-LoopBreak</Term>
 114      <ListItem><Para>
 115      Never Enable this option unless you -really- know what you are doing. It
 116      permits APT to temporarily remove an essential package to break a
 117      Conflicts/Conflicts or Conflicts/Pre-Depend loop between two essential
 118      packages. SUCH A LOOP SHOULD NEVER EXIST AND IS A GRAVE BUG. This option
 119      will work if the essential packages are not tar, gzip, libc, dpkg, bash or
 120      anything that those packages depend on.
 121      </VarListEntry>
 122
 123      <VarListEntry><Term>Cache-Limit</Term>
 124      <ListItem><Para>
 125      APT uses a fixed size memory mapped cache file to store the 'available'
 126      information. This sets the size of that cache.
 127      </VarListEntry>
 128
 129      <VarListEntry><Term>Build-Essential</Term>
 130      <ListItem><Para>
 131      Defines which package(s) are considered essential build dependencies.
 132      </VarListEntry>
 133
 134      <VarListEntry><Term>Get</Term>
 135      <ListItem><Para>
 136      The Get subsection controls the &apt-get; tool, please see its
 137      documentation for more information about the options here.
 138      </VarListEntry>
 139
 140      <VarListEntry><Term>Cache</Term>
 141      <ListItem><Para>
 142      The Cache subsection controls the &apt-cache; tool, please see its
 143      documentation for more information about the options here.
 144      </VarListEntry>
 145
 146      <VarListEntry><Term>CDROM</Term>
 147      <ListItem><Para>
 148      The CDROM subsection controls the &apt-cdrom; tool, please see its
 149      documentation for more information about the options here.
 150      </VarListEntry>
 151    </VariableList>
 152  </RefSect1>
 153
 154  <RefSect1><Title>The Acquire Group</>
 155    <para>
 156    The <literal/Acquire/ group of options controls the download of packages
 157    and the URI handlers.
 158
 159    <VariableList>
 160      <VarListEntry><Term>Queue-Mode</Term>
 161      <ListItem><Para>
 162      Queuing mode; <literal/Queue-Mode/ can be one of <literal/host/ or
 163      <literal/access/ which determines how  APT parallelizes outgoing
 164      connections. <literal/host/ means that one connection per target host
 165      will be opened, <literal/access/ means that one connection per URI type
 166      will be opened.
 167      </VarListEntry>
 168
 169      <VarListEntry><Term>Retries</Term>
 170      <ListItem><Para>
 171      Number of retries to perform. If this is non-zero APT will retry failed
 172      files the given number of times.
 173      </VarListEntry>
 174
 175      <VarListEntry><Term>Source-Symlinks</Term>
 176      <ListItem><Para>
 177      Use symlinks for source archives. If set to true then source archives will
 178      be symlinked when possible instead of copying. True is the default
 179      </VarListEntry>
 180
 181      <VarListEntry><Term>http</Term>
 182      <ListItem><Para>
 183      HTTP URIs; http::Proxy is the default http proxy to use. It is in the
 184      standard form of <literal>http://[[user][:pass]@]host[:port]/</>. Per
 185      host proxies can also be specified by using the form
 186      <literal/http::Proxy::&lt;host&gt;/ with the special keyword <literal/DIRECT/
 187      meaning to use no proxies. The <envar/http_proxy/ environment variable
 188      will override all settings.
 189      <para>
 190      Three settings are provided for cache control with HTTP/1.1 compliant
 191      proxy caches. <literal/No-Cache/ tells the proxy to not use its cached
 192      response under any circumstances, <literal/Max-Age/ is sent only for
 193      index files and tells the cache to refresh its object if it is older than
 194      the given number of seconds. Debian updates its index files daily so the
 195      default is 1 day. <literal/No-Store/ specifies that the cache should never
 196      store this request, it is only set for archive files. This may be useful
 197      to prevent polluting a proxy cache with very large .deb files. Note:
 198      Squid 2.0.2 does not support any of these options.
 199      <para>
 200      The option <literal/timeout/ sets the timeout timer used by the method,
 201      this applies to all things including connection timeout and data timeout.
 202      <para>
 203      One setting is provided to control the pipeline depth in cases where the
 204      remote server is not RFC conforming or buggy (such as Squid 2.0.2)
 205      <literal/Acquire::http::Pipeline-Depth/ can be a value from 0 to 5
 206      indicating how many outstanding requests APT should send. A value of
 207      zero MUST be specified if the remote host does not properly linger
 208      on TCP connections - otherwise data corruption will occur. Hosts which
 209      require this are in violation of RFC 2068.
 210      </VarListEntry>
 211
 212      <VarListEntry><Term>ftp</Term>
 213      <ListItem><Para>
 214      FTP URIs; ftp::Proxy is the default proxy server to use. It is in the
 215      standard form of <literal>ftp://[[user][:pass]@]host[:port]/</> and is
 216      overridden by the <envar/ftp_proxy/ environment variable. To use a ftp
 217      proxy you will have to set the <literal/ftp::ProxyLogin/ script in the
 218      configuration file. This entry specifies the commands to send to tell
 219      the proxy server what to connect to. Please see
 220      &configureindex; for an example of
 221      how to do this. The subsitution variables available are
 222      <literal/$(PROXY_USER)/, <literal/$(PROXY_PASS)/, <literal/$(SITE_USER)/,
 223      <literal/$(SITE_PASS)/, <literal/$(SITE)/, and <literal/$(SITE_PORT)/.
 224      Each is taken from it's respective URI component.
 225      <para>
 226      The option <literal/timeout/ sets the timeout timer used by the method,
 227      this applies to all things including connection timeout and data timeout.
 228      <para>
 229      Several settings are provided to control passive mode. Generally it is
 230      safe to leave passive mode on, it works in nearly every environment.
 231      However some situations require that passive mode be disabled and port
 232      mode ftp used instead. This can be done globally, for connections that
 233      go through a proxy or for a specific host (See the sample config file
 234      for examples)
 235      <para>
 236      It is possible to proxy FTP over HTTP by setting the <envar/ftp_proxy/
 237      environment variable to a http url - see the discussion of the http method
 238      above for syntax. You cannot set this in the configuration file and it is
 239      not recommended to use FTP over HTTP due to its low efficiency.
 240      <para>
 241      The setting <literal/ForceExtended/ controls the use of RFC2428
 242      <literal/EPSV/ and <literal/EPRT/ commands. The defaut is false, which means
 243      these commands are only used if the control connection is IPv6. Setting this
 244      to true forces their use even on IPv4 connections. Note that most FTP servers
 245      do not support RFC2428.
 246      </VarListEntry>
 247
 248      <VarListEntry><Term>cdrom</Term>
 249      <ListItem><Para>
 250      CDROM URIs; the only setting for CDROM URIs is the mount point,
 251      <literal/cdrom::Mount/ which must be the mount point for the CDROM drive
 252      as specified in <filename>/etc/fstab</>. It is possible to provide
 253      alternate mount and unmount commands if your mount point cannot be listed
 254      in the fstab (such as an SMB mount and old mount packages). The syntax
 255      is to put <literallayout>"/cdrom/"::Mount "foo";</literallayout> within
 256      the cdrom block. It is important to have the trailing slash. Unmount
 257      commands can be specified using UMount.
 258      </VarListEntry>
 259    </VariableList>
 260  </RefSect1>
 261
 262  <RefSect1><Title>Directories</>
 263    <para>
 264    The <literal/Dir::State/ section has directories that pertain to local
 265    state information. <literal/lists/ is the directory to place downloaded
 266    package lists in and <literal/status/ is the name of the dpkg status file.
 267    <literal/preferences/ is the name of the APT preferences file.
 268    <literal/Dir::State/ contains the default directory to prefix on all sub
 269    items if they do not start with <filename>/</> or <filename>./</>.
 270    <para>
 271    <literal/Dir::Cache/ contains locations pertaining to local cache
 272    information, such as the two package caches <literal/srcpkgcache/ and
 273    <literal/pkgcache/ as well as the location to place downloaded archives,
 274    <literal/Dir::Cache::archives/. Generation of caches can be turned off
 275    by setting their names to be blank. This will slow down startup but
 276    save disk space. It is probably prefered to turn off the pkgcache rather
 277    than the srcpkgcache. Like <literal/Dir::State/ the default
 278    directory is contained in <literal/Dir::Cache/
 279    <para>
 280    <literal/Dir::Etc/ contains the location of configuration files,
 281    <literal/sourcelist/ gives the location of the sourcelist and
 282    <literal/main/ is the default configuration file (setting has no effect,
 283    unless it is done from the config file specified by
 284    <envar/APT_CONFIG/).
 285    <para>
 286    The <literal/Dir::Parts/ setting reads in all the config fragments in
 287    lexical order from the directory specified. After this is done then the
 288    main config file is loaded.
 289    <para>
 290    Binary programs are pointed to by <literal/Dir::Bin/. <literal/methods/
 291    specifies the location of the method handlers and <literal/gzip/,
 292    <literal/dpkg/, <literal/apt-get/, <literal/dpkg-source/,
 293    <literal/dpkg-buildpackage/ and <literal/apt-cache/ specify the location
 294    of the respective programs.
 295  </RefSect1>
 296
 297  <RefSect1><Title>APT in DSelect</>
 298    <para>
 299    When APT is used as a &dselect; method several configuration directives
 300    control the default behaviour. These are in the <literal/DSelect/ section.
 301
 302    <VariableList>
 303      <VarListEntry><Term>Clean</Term>
 304      <ListItem><Para>
 305      Cache Clean mode; this value may be one of always, prompt, auto,
 306      pre-auto and never.  always and prompt will remove all packages from
 307      the cache after upgrading, prompt (the default) does so conditionally.
 308      auto removes only those packages which are no longer downloadable
 309      (replaced with a new version for instance).  pre-auto performs this
 310      action before downloading new packages.
 311      </VarListEntry>
 312
 313      <VarListEntry><Term>Options</Term>
 314      <ListItem><Para>
 315      The contents of this variable is passed to &apt-get; as command line
 316      options when it is run for the install phase.
 317      </VarListEntry>
 318
 319      <VarListEntry><Term>UpdateOptions</Term>
 320      <ListItem><Para>
 321      The contents of this variable is passed to &apt-get; as command line
 322      options when it is run for the update phase.
 323      </VarListEntry>
 324
 325      <VarListEntry><Term>PromptAfterUpdate</Term>
 326      <ListItem><Para>
 327      If true the [U]pdate operation in &dselect; will always prompt to continue.
 328      The default is to prompt only on error.
 329      </VarListEntry>
 330    </VariableList>
 331  </RefSect1>
 332
 333  <RefSect1><Title>How APT calls dpkg</>
 334    <para>
 335    Several configuration directives control how APT invokes &dpkg;. These are
 336    in the <literal/DPkg/ section.
 337
 338    <VariableList>
 339      <VarListEntry><Term>Options</Term>
 340      <ListItem><Para>
 341      This is a list of options to pass to dpkg. The options must be specified
 342      using the list notation and each list item is passed as a single argument
 343      to &dpkg;.
 344      </VarListEntry>
 345
 346      <VarListEntry><Term>Pre-Invoke</Term><Term>Post-Invoke</Term>
 347      <ListItem><Para>
 348      This is a list of shell commands to run before/after invoking &dpkg;.
 349      Like <literal/Options/ this must be specified in list notation. The
 350      commands are invoked in order using <filename>/bin/sh</>, should any
 351      fail APT will abort.
 352      </VarListEntry>
 353
 354      <VarListEntry><Term>Pre-Install-Pkgs</Term>
 355      <ListItem><Para>
 356      This is a list of shell commands to run before invoking dpkg. Like
 357      <literal/Options/ this must be specified in list notation. The commands
 358      are invoked in order using <filename>/bin/sh</>, should any fail APT
 359      will abort. APT will pass to the commands on standard input the
 360      filenames of all .deb files it is going to install, one per line.
 361      <para>
 362      Version 2 of this protocol dumps more information, including the
 363      protocol version, the APT configuration space and the packages, files
 364      and versions being changed. Version 2 is enabled by setting
 365      <literal/DPkg::Tools::Options::cmd::Version/ to 2. <literal/cmd/ is a
 366      command given to <literal/Pre-Install-Pkgs/.
 367      </VarListEntry>
 368
 369      <VarListEntry><Term>Run-Directory</Term>
 370      <ListItem><Para>
 371      APT chdirs to this directory before invoking dpkg, the default is
 372      <filename>/</>.
 373      </VarListEntry>
 374
 375      <VarListEntry><Term>Build-Options</Term>
 376      <ListItem><Para>
 377      These options are passed to &dpkg-buildpackage; when compiling packages,
 378      the default is to disable signing and produce all binaries.
 379      </VarListEntry>
 380    </VariableList>
 381  </RefSect1>
 382
 383  <RefSect1><Title>Debug Options</>
 384    <para>
 385    Most of the options in the <literal/debug/ section are not interesting to
 386    the normal user, however <literal/Debug::pkgProblemResolver/ shows
 387    interesting output about the decisions dist-upgrade makes.
 388    <literal/Debug::NoLocking/ disables file locking so APT can do some
 389    operations as non-root and <literal/Debug::pkgDPkgPM/ will print out the
 390    command line for each dpkg invokation. <literal/Debug::IdentCdrom/ will
 391    disable the inclusion of statfs data in CDROM IDs.
 392  </RefSect1>
 393
 394  <RefSect1><Title>Examples</>
 395    <para>
 396    &configureindex; contains a
 397    sample configuration file showing the default values for all possible
 398    options.
 399  </RefSect1>
 400
 401  <RefSect1><Title>Files</>
 402    <para>
 403    <filename>/etc/apt/apt.conf</>
 404  </RefSect1>
 405
 406  <RefSect1><Title>See Also</>
 407    <para>
 408    &apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.
 409  </RefSect1>
 410
 411  &manbugs;
 412  &manauthor;
 413
 414 </refentry>