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