doc/apt.conf.5.xml

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   5 <!ENTITY % aptent SYSTEM "apt.ent">
   6 %aptent;
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   9
  10 <refentry>
  11
  12  <refentryinfo>
  13    &apt-author.jgunthorpe;
  14    &apt-author.team;
  15    &apt-email;
  16    &apt-product;
  17    <!-- The last update date -->
  18    <date>29 February 2004</date>
  19  </refentryinfo>
  20
  21  <refmeta>
  22    <refentrytitle>apt.conf</refentrytitle>
  23    <manvolnum>5</manvolnum>
  24  </refmeta>
  25
  26  <!-- Man page title -->
  27  <refnamediv>
  28     <refname>apt.conf</refname>
  29     <refpurpose>Configuration file for APT</refpurpose>
  30  </refnamediv>
  31
  32  <refsect1><title>Description</title>
  33    <para><filename>apt.conf</filename> is the main configuration file for the APT suite of
  34    tools, all tools make use of the configuration file and a common command line
  35    parser to provide a uniform environment. When an APT tool starts up it will
  36    read the configuration specified by the <envar>APT_CONFIG</envar> environment
  37    variable (if any) and then read the files in <literal>Dir::Etc::Parts</literal>
  38    then read the main configuration file specified by
  39    <literal>Dir::Etc::main</literal> then finally apply the
  40    command line options to override the configuration directives, possibly
  41    loading even more config files.</para>
  42
  43    <para>The configuration file is organized in a tree with options organized into
  44    functional groups. option specification is given with a double colon
  45    notation, for instance <literal>APT::Get::Assume-Yes</literal> is an option within
  46    the APT tool group, for the Get tool. options do not inherit from their
  47    parent groups.</para>
  48
  49    <para>Syntacticly the configuration language is modeled after what the ISC tools
  50    such as bind and dhcp use.  Lines starting with
  51    <literal>//</literal> are treated as comments (ignored).
  52    Each line is of the form
  53    <literal>APT::Get::Assume-Yes "true";</literal> The trailing
  54    semicolon is required and the quotes are optional. A new scope can be
  55    opened with curly braces, like:</para>
  56
  57 <informalexample><programlisting>
  58 APT {
  59   Get {
  60     Assume-Yes "true";
  61     Fix-Broken "true";
  62   };
  63 };
  64 </programlisting></informalexample>
  65
  66    <para>with newlines placed to make it more readable. Lists can be created by
  67    opening a scope and including a single word enclosed in quotes followed by a
  68    semicolon. Multiple entries can be included, each separated by a semicolon.</para>
  69
  70 <informalexample><programlisting>
  71 DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
  72 </programlisting></informalexample>
  73
  74    <para>In general the sample configuration file in
  75    <filename>&docdir;examples/apt.conf</filename> &configureindex;
  76    is a good guide for how it should look.</para>
  77
  78    <para>Two specials are allowed, <literal>#include</literal> and <literal>#clear</literal>
  79    <literal>#include</literal> will include the given file, unless the filename
  80    ends in a slash, then the whole directory is included.
  81    <literal>#clear</literal> is used to erase a list of names.</para>
  82
  83    <para>All of the APT tools take a -o option which allows an arbitrary configuration
  84    directive to be specified on the command line. The syntax is a full option
  85    name (<literal>APT::Get::Assume-Yes</literal> for instance) followed by an equals
  86    sign then the new value of the option. Lists can be appended too by adding
  87    a trailing :: to the list name.</para>
  88  </refsect1>
  89
  90  <refsect1><title>The APT Group</title>
  91    <para>This group of options controls general APT behavior as well as holding the
  92    options for all of the tools.</para>
  93
  94    <variablelist>
  95      <varlistentry><term>Architecture</term>
  96      <listitem><para>System Architecture; sets the architecture to use when fetching files and
  97      parsing package lists. The internal default is the architecture apt was
  98      compiled for.</para></listitem>
  99      </varlistentry>
 100
 101      <varlistentry><term>Ignore-Hold</term>
 102      <listitem><para>Ignore Held packages; This global option causes the problem resolver to
 103      ignore held packages in its decision making.</para></listitem>
 104      </varlistentry>
 105
 106      <varlistentry><term>Clean-Installed</term>
 107      <listitem><para>Defaults to on. When turned on the autoclean feature will remove any packages
 108      which can no longer be downloaded from the cache. If turned off then
 109      packages that are locally installed are also excluded from cleaning - but
 110      note that APT provides no direct means to reinstall them.</para></listitem>
 111      </varlistentry>
 112
 113      <varlistentry><term>Immediate-Configure</term>
 114      <listitem><para>Disable Immediate Configuration; This dangerous option disables some
 115      of APT's ordering code to cause it to make fewer dpkg calls. Doing
 116      so may be necessary on some extremely slow single user systems but
 117      is very dangerous and may cause package install scripts to fail or worse.
 118      Use at your own risk.</para></listitem>
 119      </varlistentry>
 120
 121      <varlistentry><term>Force-LoopBreak</term>
 122      <listitem><para>Never Enable this option unless you -really- know what you are doing. It
 123      permits APT to temporarily remove an essential package to break a
 124      Conflicts/Conflicts or Conflicts/Pre-Depend loop between two essential
 125      packages. SUCH A LOOP SHOULD NEVER EXIST AND IS A GRAVE BUG. This option
 126      will work if the essential packages are not tar, gzip, libc, dpkg, bash or
 127      anything that those packages depend on.</para></listitem>
 128      </varlistentry>
 129
 130      <varlistentry><term>Cache-Limit</term>
 131      <listitem><para>APT uses a fixed size memory mapped cache file to store the 'available'
 132      information. This sets the size of that cache (in bytes).</para></listitem>
 133      </varlistentry>
 134
 135      <varlistentry><term>Build-Essential</term>
 136      <listitem><para>Defines which package(s) are considered essential build dependencies.</para></listitem>
 137      </varlistentry>
 138
 139      <varlistentry><term>Get</term>
 140      <listitem><para>The Get subsection controls the &apt-get; tool, please see its
 141      documentation for more information about the options here.</para></listitem>
 142      </varlistentry>
 143
 144      <varlistentry><term>Cache</term>
 145      <listitem><para>The Cache subsection controls the &apt-cache; tool, please see its
 146      documentation for more information about the options here.</para></listitem>
 147      </varlistentry>
 148
 149      <varlistentry><term>CDROM</term>
 150      <listitem><para>The CDROM subsection controls the &apt-cdrom; tool, please see its
 151      documentation for more information about the options here.</para></listitem>
 152      </varlistentry>
 153    </variablelist>
 154  </refsect1>
 155
 156  <refsect1><title>The Acquire Group</title>
 157    <para>The <literal>Acquire</literal> 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>Queuing mode; <literal>Queue-Mode</literal> can be one of <literal>host</literal> or
 163      <literal>access</literal> which determines how  APT parallelizes outgoing
 164      connections. <literal>host</literal> means that one connection per target host
 165      will be opened, <literal>access</literal> means that one connection per URI type
 166      will be opened.</para></listitem>
 167      </varlistentry>
 168
 169      <varlistentry><term>Retries</term>
 170      <listitem><para>Number of retries to perform. If this is non-zero APT will retry failed
 171      files the given number of times.</para></listitem>
 172      </varlistentry>
 173
 174      <varlistentry><term>Source-Symlinks</term>
 175      <listitem><para>Use symlinks for source archives. If set to true then source archives will
 176      be symlinked when possible instead of copying. True is the default.</para></listitem>
 177      </varlistentry>
 178
 179      <varlistentry><term>http</term>
 180      <listitem><para>HTTP URIs; http::Proxy is the default http proxy to use. It is in the
 181      standard form of <literal>http://[[user][:pass]@]host[:port]/</literal>. Per
 182      host proxies can also be specified by using the form
 183      <literal>http::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal>
 184      meaning to use no proxies. The <envar>http_proxy</envar> environment variable
 185      will override all settings.</para>
 186
 187      <para>Three settings are provided for cache control with HTTP/1.1 compliant
 188      proxy caches. <literal>No-Cache</literal> tells the proxy to not use its cached
 189      response under any circumstances, <literal>Max-Age</literal> is sent only for
 190      index files and tells the cache to refresh its object if it is older than
 191      the given number of seconds. Debian updates its index files daily so the
 192      default is 1 day. <literal>No-Store</literal> specifies that the cache should never
 193      store this request, it is only set for archive files. This may be useful
 194      to prevent polluting a proxy cache with very large .deb files. Note:
 195      Squid 2.0.2 does not support any of these options.</para>
 196
 197      <para>The option <literal>timeout</literal> sets the timeout timer used by the method,
 198      this applies to all things including connection timeout and data timeout.</para>
 199
 200      <para>One setting is provided to control the pipeline depth in cases where the
 201      remote server is not RFC conforming or buggy (such as Squid 2.0.2)
 202      <literal>Acquire::http::Pipeline-Depth</literal> can be a value from 0 to 5
 203      indicating how many outstanding requests APT should send. A value of
 204      zero MUST be specified if the remote host does not properly linger
 205      on TCP connections - otherwise data corruption will occur. Hosts which
 206      require this are in violation of RFC 2068.</para></listitem>
 207      </varlistentry>
 208
 209      <varlistentry><term>ftp</term>
 210      <listitem><para>FTP URIs; ftp::Proxy is the default proxy server to use. It is in the
 211      standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal> and is
 212      overridden by the <envar>ftp_proxy</envar> environment variable. To use a ftp
 213      proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the
 214      configuration file. This entry specifies the commands to send to tell
 215      the proxy server what to connect to. Please see
 216      &configureindex; for an example of
 217      how to do this. The subsitution variables available are
 218      <literal>$(PROXY_USER)</literal> <literal>$(PROXY_PASS)</literal> <literal>$(SITE_USER)</literal>
 219      <literal>$(SITE_PASS)</literal> <literal>$(SITE)</literal> and <literal>$(SITE_PORT)</literal>
 220      Each is taken from it's respective URI component.</para>
 221
 222      <para>The option <literal>timeout</literal> sets the timeout timer used by the method,
 223      this applies to all things including connection timeout and data timeout.</para>
 224
 225      <para>Several settings are provided to control passive mode. Generally it is
 226      safe to leave passive mode on, it works in nearly every environment.
 227      However some situations require that passive mode be disabled and port
 228      mode ftp used instead. This can be done globally, for connections that
 229      go through a proxy or for a specific host (See the sample config file
 230      for examples).</para>
 231
 232      <para>It is possible to proxy FTP over HTTP by setting the <envar>ftp_proxy</envar>
 233      environment variable to a http url - see the discussion of the http method
 234      above for syntax. You cannot set this in the configuration file and it is
 235      not recommended to use FTP over HTTP due to its low efficiency.</para>
 236
 237      <para>The setting <literal>ForceExtended</literal> controls the use of RFC2428
 238      <literal>EPSV</literal> and <literal>EPRT</literal> commands. The defaut is false, which means
 239      these commands are only used if the control connection is IPv6. Setting this
 240      to true forces their use even on IPv4 connections. Note that most FTP servers
 241      do not support RFC2428.</para></listitem>
 242      </varlistentry>
 243
 244      <varlistentry><term>cdrom</term>
 245      <listitem><para>CDROM URIs; the only setting for CDROM URIs is the mount point,
 246      <literal>cdrom::Mount</literal> which must be the mount point for the CDROM drive
 247      as specified in <filename>/etc/fstab</filename>. 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.</para></listitem>
 253      </varlistentry>
 254    </variablelist>
 255   </para>
 256  </refsect1>
 257
 258  <refsect1><title>Directories</title>
 259
 260    <para>The <literal>Dir::State</literal> section has directories that pertain to local
 261    state information. <literal>lists</literal> is the directory to place downloaded
 262    package lists in and <literal>status</literal> is the name of the dpkg status file.
 263    <literal>preferences</literal> is the name of the APT preferences file.
 264    <literal>Dir::State</literal> contains the default directory to prefix on all sub
 265    items if they do not start with <filename>/</filename> or <filename>./</filename>.</para>
 266
 267    <para><literal>Dir::Cache</literal> contains locations pertaining to local cache
 268    information, such as the two package caches <literal>srcpkgcache</literal> and
 269    <literal>pkgcache</literal> as well as the location to place downloaded archives,
 270    <literal>Dir::Cache::archives</literal>. Generation of caches can be turned off
 271    by setting their names to be blank. This will slow down startup but
 272    save disk space. It is probably prefered to turn off the pkgcache rather
 273    than the srcpkgcache. Like <literal>Dir::State</literal> the default
 274    directory is contained in <literal>Dir::Cache</literal></para>
 275
 276    <para><literal>Dir::Etc</literal> contains the location of configuration files,
 277    <literal>sourcelist</literal> gives the location of the sourcelist and
 278    <literal>main</literal> is the default configuration file (setting has no effect,
 279    unless it is done from the config file specified by
 280    <envar>APT_CONFIG</envar>.</para>
 281
 282    <para>The <literal>Dir::Parts</literal> setting reads in all the config fragments in
 283    lexical order from the directory specified. After this is done then the
 284    main config file is loaded.</para>
 285
 286    <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal>
 287    specifies the location of the method handlers and <literal>gzip</literal>,
 288    <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal>
 289    <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
 290    of the respective programs.</para>
 291  </refsect1>
 292
 293  <refsect1><title>APT in DSelect</title>
 294    <para>
 295    When APT is used as a &dselect; method several configuration directives
 296    control the default behaviour. These are in the <literal>DSelect</literal> section.</para>
 297
 298    <variablelist>
 299      <varlistentry><term>Clean</term>
 300      <listitem><para>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.</para></listitem>
 306      </varlistentry>
 307
 308      <varlistentry><term>options</term>
 309      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 310      options when it is run for the install phase.</para></listitem>
 311      </varlistentry>
 312
 313      <varlistentry><term>Updateoptions</term>
 314      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 315      options when it is run for the update phase.</para></listitem>
 316      </varlistentry>
 317
 318      <varlistentry><term>PromptAfterUpdate</term>
 319      <listitem><para>If true the [U]pdate operation in &dselect; will always prompt to continue.
 320      The default is to prompt only on error.</para></listitem>
 321      </varlistentry>
 322    </variablelist>
 323  </refsect1>
 324
 325  <refsect1><title>How APT calls dpkg</title>
 326    <para>Several configuration directives control how APT invokes &dpkg;. These are
 327    in the <literal>DPkg</literal> section.</para>
 328
 329    <variablelist>
 330      <varlistentry><term>options</term>
 331      <listitem><para>This is a list of options to pass to dpkg. The options must be specified
 332      using the list notation and each list item is passed as a single argument
 333      to &dpkg;.</para></listitem>
 334      </varlistentry>
 335
 336      <varlistentry><term>Pre-Invoke</term><term>Post-Invoke</term>
 337      <listitem><para>This is a list of shell commands to run before/after invoking &dpkg;.
 338      Like <literal>options</literal> this must be specified in list notation. The
 339      commands are invoked in order using <filename>/bin/sh</filename>, should any
 340      fail APT will abort.</para></listitem>
 341      </varlistentry>
 342
 343      <varlistentry><term>Pre-Install-Pkgs</term>
 344      <listitem><para>This is a list of shell commands to run before invoking dpkg. Like
 345      <literal>options</literal> this must be specified in list notation. The commands
 346      are invoked in order using <filename>/bin/sh</filename>, should any fail APT
 347      will abort. APT will pass to the commands on standard input the
 348      filenames of all .deb files it is going to install, one per line.</para>
 349
 350      <para>Version 2 of this protocol dumps more information, including the
 351      protocol version, the APT configuration space and the packages, files
 352      and versions being changed. Version 2 is enabled by setting
 353      <literal>DPkg::Tools::options::cmd::Version</literal> to 2. <literal>cmd</literal> is a
 354      command given to <literal>Pre-Install-Pkgs</literal>.</para></listitem>
 355      </varlistentry>
 356
 357      <varlistentry><term>Run-Directory</term>
 358      <listitem><para>APT chdirs to this directory before invoking dpkg, the default is
 359      <filename>/</filename>.</para></listitem>
 360      </varlistentry>
 361
 362      <varlistentry><term>Build-options</term>
 363      <listitem><para>These options are passed to &dpkg-buildpackage; when compiling packages,
 364      the default is to disable signing and produce all binaries.</para></listitem>
 365      </varlistentry>
 366    </variablelist>
 367  </refsect1>
 368
 369  <refsect1><title>Debug options</title>
 370    <para>Most of the options in the <literal>debug</literal> section are not interesting to
 371    the normal user, however <literal>Debug::pkgProblemResolver</literal> shows
 372    interesting output about the decisions dist-upgrade makes.
 373    <literal>Debug::NoLocking</literal> disables file locking so APT can do some
 374    operations as non-root and <literal>Debug::pkgDPkgPM</literal> will print out the
 375    command line for each dpkg invokation. <literal>Debug::IdentCdrom</literal> will
 376    disable the inclusion of statfs data in CDROM IDs.</para>
 377  </refsect1>
 378
 379  <refsect1><title>Examples</title>
 380    <para>&configureindex; contains a
 381    sample configuration file showing the default values for all possible
 382    options.</para>
 383  </refsect1>
 384
 385  <refsect1><title>Files</title>
 386    <para><filename>/etc/apt/apt.conf</filename></para>
 387  </refsect1>
 388
 389  <refsect1><title>See Also</title>
 390    <para>&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.</para>
 391  </refsect1>
 392
 393  &manbugs;
 394
 395 </refentry>
 396