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>Configuratoin 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 seperated 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 arbitary 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 behavoir 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 options 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 pacakge
  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 Immedate 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>Get</Term>
 130      <ListItem><Para>
 131      The Get subsection controls the &apt-get; tool, please see its
 132      documentation for more information about the options here.
 133      </VarListEntry>
 134
 135      <VarListEntry><Term>Cache</Term>
 136      <ListItem><Para>
 137      The Cache subsection controls the &apt-cache; tool, please see its
 138      documentation for more information about the options here.
 139      </VarListEntry>
 140
 141      <VarListEntry><Term>CDROM</Term>
 142      <ListItem><Para>
 143      The CDROM subsection controls the &apt-cdrom; tool, please see its
 144      documentation for more information about the options here.
 145      </VarListEntry>
 146    </VariableList>
 147  </RefSect1>
 148
 149  <RefSect1><Title>The Acquire Group</>
 150    <para>
 151    The <literal/Acquire/ group of options controls the download of packages
 152    and the URI handlers.
 153
 154    <VariableList>
 155      <VarListEntry><Term>Queue-Mode</Term>
 156      <ListItem><Para>
 157      Queuing mode; <literal/Queue-Mode/ can be one of <literal/host/ or
 158      <literal/access/ which determins how APT parallelizes outgoing
 159      connections. <literal/host/ means that one connection per target host
 160      will be opened, <literal/access/ means that one connection per URI type
 161      will be opened.
 162      </VarListEntry>
 163
 164      <VarListEntry><Term>Retries</Term>
 165      <ListItem><Para>
 166      Number of retries to perform. If this is non-zero APT will retry failed
 167      files the given number of times.
 168      </VarListEntry>
 169
 170      <VarListEntry><Term>Source-Symlinks</Term>
 171      <ListItem><Para>
 172      Use symlinks for source archives. If set to true then source archives will
 173      be symlinked when possible instead of copying. True is the default
 174      </VarListEntry>
 175
 176      <VarListEntry><Term>http</Term>
 177      <ListItem><Para>
 178      HTTP URIs; http::Proxy is the default http proxy to use. It is in the
 179      standard form of <literal>http://[[user][:pass]@]host[:port]/</>. Per
 180      host proxies can also be specified by using the form
 181      <literal/http::Proxy::&lt;host&gt;/ with the special keyword <literal/DIRECT/
 182      meaning to use no proxies. The <envar/http_proxy/ environment variable
 183      will override all settings.
 184      <para>
 185      Three settings are provided for cache control with HTTP/1.1 complient
 186      proxy caches. <literal/No-Cache/ tells the proxy to not used its cached
 187      response under any circumstances, <literal/Max-Age/ is sent only for
 188      index files and tells the cache to refresh its object if it is older than
 189      the given number of seconds. Debian updates its index files daily so the
 190      default is 1 day. <literal/No-Store/ specifies that the cache should never
 191      store this request, it is only set for archive files. This may be useful
 192      to prevent polluting a proxy cache with very large .deb files. Note:
 193      Squid 2.0.2 does not support any of these options.
 194      <para>
 195      The option <literal/timeout/ sets the timeout timer used by the method,
 196      this applies to all things including connection timeout and data timeout.
 197      <para>
 198      One setting is provided to control the pipeline depth in cases where the
 199      remote server is not RFC conforming or buggy (such as Squid 2.0.2)
 200      <literal/Acquire::http::Pipeline-Depth/ can be a value from 0 to 5
 201      indicating how many outstanding requests APT should send. A value of
 202      zero MUST be specified if the remote host does not properly linger
 203      on TCP connections - otherwise data corruption will occure. Hosts which
 204      require this are in violation of RFC 2068.
 205      </VarListEntry>
 206
 207      <VarListEntry><Term>ftp</Term>
 208      <ListItem><Para>
 209      FTP URis; ftp::Proxy is the default proxy server to use. It is in the
 210      standard form of <literal>ftp://[[user][:pass]@]host[:port]/</> and is
 211      overriden by the <envar/ftp_proxy/ environment variable. To use a ftp
 212      proxy you will have to set the <literal/ftp::ProxyLogin/ script in the
 213      configuration file. This entry specifies the commands to send to tell
 214      the proxy server what to connect to. Please see
 215      &configureindex; for an example of
 216      how to do this. The subsitution variables available are
 217      <literal/$(PROXY_USER)/, <literal/$(PROXY_PASS)/, <literal/$(SITE_USER)/,
 218      <literal/$(SITE_PASS)/, <literal/$(SITE)/, and <literal/$(SITE_PORT)/.
 219      Each is taken from it's respective URI component.
 220      <para>
 221      The option <literal/timeout/ sets the timeout timer used by the method,
 222      this applies to all things including connection timeout and data timeout.
 223      <para>
 224      Several settings are provided to control passive mode. Generally it is
 225      safe to leave passive mode on, it works in nearly every environment.
 226      However some situations require that passive mode be disabled and port
 227      mode ftp used instead. This can be done globally, for connections that
 228      go through a proxy or for a specific host (See the sample config file
 229      for examples)
 230      <para>
 231      It is possible to proxy FTP over HTTP by setting the <envar/ftp_proxy/
 232      environment variable to a http url - see the discussion of the http method
 233      above for syntax. You cannot set this in the configuration file and it is
 234      not recommended to use FTP over HTTP due to its low efficiency.
 235      <para>
 236      The setting <literal/ForceExtended/ controls the use of RFC2428
 237      <literal/EPSV/ and <literal/EPRT/ commands. The defaut is false, which means
 238      these commands are only used if the control connection is IPv6. Setting this
 239      to true forces their use even on IPv4 connections. Note that most FTP servers
 240      do not support RFC2428.
 241      </VarListEntry>
 242
 243      <VarListEntry><Term>cdrom</Term>
 244      <ListItem><Para>
 245      CDROM URIs; the only setting for CDROM URIs is the mount point,
 246      <literal/cdrom::Mount/ which must be the mount point for the CDROM drive
 247      as specified in <filename>/etc/fstab</>. It is possible to provide
 248      alternate mount and unmount commands if your mount point cannot be listed
 249      in the fstab (such as an SMB mount and old mount packages). The syntax
 250      is to put <literallayout>"/cdrom/"::Mount "foo";</literallayout> within
 251      the cdrom block. It is important to have the trailing slash. Unmount
 252      commands can be specified using UMount.
 253      </VarListEntry>
 254    </VariableList>
 255  </RefSect1>
 256
 257  <RefSect1><Title>Directories</>
 258    <para>
 259    The <literal/Dir::State/ section has directories that pertain to local
 260    state information. <literal/lists/ is the directory to place downloaded
 261    package lists in and <literal/status/ is the name of the dpkg status file.
 262    <literal/preferences/ is the name of the APT preferencse file.
 263    <literal/Dir::State/ contains the default directory to prefix on all sub
 264    items if they do not start with <filename>/</> or <filename>./</>.
 265    <para>
 266    <literal/Dir::Cache/ contains locations pertaining to local cache
 267    information, such as the two package caches <literal/srcpkgcache/ and
 268    <literal/pkgcache/ as well as the location to place downloaded archives,
 269    <literal/Dir::Cache::archives/. Generation of caches can be turned off
 270    by setting their names to be blank. This will slow down startup but
 271    save disk space. It is probably prefered to turn off the pkgcache rather
 272    than the srcpkgcache. Like <literal/Dir::State/ the default
 273    directory is contained in <literal/Dir::Cache/
 274    <para>
 275    <literal/Dir::Etc/ contains the location of configuration files,
 276    <literal/sourcelist/ gives the location of the sourcelist and
 277    <literal/main/ is the default configuration file (setting has no effect,
 278    unless it is done from the config file specified by
 279    <envar/APT_CONFIG/).
 280    <para>
 281    The <literal/Dir::Parts/ setting reads in all the config fragments in
 282    lexical order from the directory specified. After this is done then the
 283    main config file is loaded.
 284    <para>
 285    Binary programs are pointed to by <literal/Dir::Bin/. <literal/methods/
 286    specifies the location of the method handlers and <literal/gzip/,
 287    <literal/dpkg/, <literal/apt-get/, <literal/dpkg-source/,
 288    <literal/dpkg-buildpackage/ and <literal/apt-cache/ specify the location
 289    of the respective programs.
 290  </RefSect1>
 291
 292  <RefSect1><Title>APT in DSelect</>
 293    <para>
 294    When APT is used as a &dselect; method several configuration directives
 295    control the default behavoir. These are in the <literal/DSelect/ section.
 296
 297    <VariableList>
 298      <VarListEntry><Term>Clean</Term>
 299      <ListItem><Para>
 300      Cache Clean mode; this value may be one of always, prompt, auto,
 301      pre-auto and never.  always and prompt will remove all packages from
 302      the cache after upgrading, prompt (the default) does so conditionally.
 303      auto removes only those packages which are no longer downloadable
 304      (replaced with a new version for instance).  pre-auto performs this
 305      action before downloading new packages.
 306      </VarListEntry>
 307
 308      <VarListEntry><Term>Options</Term>
 309      <ListItem><Para>
 310      The contents of this variable is passed to &apt-get; as command line
 311      options when it is run for the install phase.
 312      </VarListEntry>
 313
 314      <VarListEntry><Term>UpdateOptions</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 update phase.
 318      </VarListEntry>
 319
 320      <VarListEntry><Term>PromptAfterUpdate</Term>
 321      <ListItem><Para>
 322      If true the [U]pdate operation in &dselect; will always prompt to continue.
 323      The default is to prompt only on error.
 324      </VarListEntry>
 325    </VariableList>
 326  </RefSect1>
 327
 328  <RefSect1><Title>How APT calls dpkg</>
 329    <para>
 330    Several configuration directives control how APT invokes &dpkg;. These are
 331    in the <literal/DPkg/ section.
 332
 333    <VariableList>
 334      <VarListEntry><Term>Options</Term>
 335      <ListItem><Para>
 336      This is a list of options to pass to dpkg. The options must be specified
 337      using the list notation and each list item is passed as a single arugment
 338      to &dpkg;.
 339      </VarListEntry>
 340
 341      <VarListEntry><Term>Pre-Invoke</Term><Term>Post-Invoke</Term>
 342      <ListItem><Para>
 343      This is a list of shell commands to run before/after invoking &dpkg;.
 344      Like <literal/Options/ this must be specified in list notation. The
 345      commands are invoked in order using <filename>/bin/sh</>, should any
 346      fail APT will abort.
 347      </VarListEntry>
 348
 349      <VarListEntry><Term>Pre-Install-Pkgs</Term>
 350      <ListItem><Para>
 351      This is a list of shell commands to run before invoking dpkg. Like
 352      <literal/Options/ this must be specified in list notation. The commands
 353      are invoked in order using <filename>/bin/sh</>, should any fail APT
 354      will abort. APT will pass to the commands on standard input the
 355      filenames of all .deb files it is going to install, one per line.
 356      <para>
 357      Version 2 of this protocol dumps more information, including the
 358      protocol version, the APT configuration space and the packages, files
 359      and versions being changed. Version 2 is enabled by setting
 360      <literal/DPkg::Tools::Options::cmd::Version/ to 2. <literal/cmd/ is a
 361      command given to <literal/Pre-Install-Pkgs/.
 362      </VarListEntry>
 363
 364      <VarListEntry><Term>Run-Directory</Term>
 365      <ListItem><Para>
 366      APT chdirs to this directory before invoking dpkg, the default is
 367      <filename>/</>.
 368      </VarListEntry>
 369
 370      <VarListEntry><Term>Build-Options</Term>
 371      <ListItem><Para>
 372      These options are passed to &dpkg-buildpackage; when compiling packages,
 373      the default is to disable signing and produce all binaries.
 374      </VarListEntry>
 375    </VariableList>
 376  </RefSect1>
 377
 378  <RefSect1><Title>Debug Options</>
 379    <para>
 380    Most of the options in the <literal/debug/ section are not interesting to
 381    the normal user, however <literal/Debug::pkgProblemResolver/ shows
 382    interesting output about the decisions dist-upgrade makes.
 383    <literal/Debug::NoLocking/ disables file locking so APT can do some
 384    operations as non-root and <literal/Debug::pkgDPkgPM/ will print out the
 385    command line for each dpkg invokation. <literal/Debug::IdentCdrom/ will
 386    disable the inclusion of statfs data in CDROM IDs.
 387  </RefSect1>
 388
 389  <RefSect1><Title>Examples</>
 390    <para>
 391    &configureindex; contains a
 392    sample configuration file showing the default values for all possible
 393    options.
 394  </RefSect1>
 395
 396  <RefSect1><Title>Files</>
 397    <para>
 398    <filename>/etc/apt/apt.conf</>
 399  </RefSect1>
 400
 401  <RefSect1><Title>See Also</>
 402    <para>
 403    &apt-cache;, &apt-conf;, &apt-preferences;.
 404  </RefSect1>
 405
 406  &manbugs;
 407  &manauthor;
 408
 409 </refentry>