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>Syntactically 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>Default-Release</term>
 102          <listitem><para>Default release to install packages from if more than one
 103          version available. Contains release name or release version. Examples: 'stable', 'testing', 'unstable', '4.0', '5.0*'. Release codenames ('etch', 'lenny' etc.) are not allowed now. See also &apt-preferences;.</para></listitem>
 104      </varlistentry>
 105
 106      <varlistentry><term>Ignore-Hold</term>
 107      <listitem><para>Ignore Held packages; This global option causes the problem resolver to
 108      ignore held packages in its decision making.</para></listitem>
 109      </varlistentry>
 110
 111      <varlistentry><term>Clean-Installed</term>
 112      <listitem><para>Defaults to on. When turned on the autoclean feature will remove any packages
 113      which can no longer be downloaded from the cache. If turned off then
 114      packages that are locally installed are also excluded from cleaning - but
 115      note that APT provides no direct means to reinstall them.</para></listitem>
 116      </varlistentry>
 117
 118      <varlistentry><term>Immediate-Configure</term>
 119      <listitem><para>Disable Immediate Configuration; This dangerous option disables some
 120      of APT's ordering code to cause it to make fewer dpkg calls. Doing
 121      so may be necessary on some extremely slow single user systems but
 122      is very dangerous and may cause package install scripts to fail or worse.
 123      Use at your own risk.</para></listitem>
 124      </varlistentry>
 125
 126      <varlistentry><term>Force-LoopBreak</term>
 127      <listitem><para>Never Enable this option unless you -really- know what you are doing. It
 128      permits APT to temporarily remove an essential package to break a
 129      Conflicts/Conflicts or Conflicts/Pre-Depend loop between two essential
 130      packages. SUCH A LOOP SHOULD NEVER EXIST AND IS A GRAVE BUG. This option
 131      will work if the essential packages are not tar, gzip, libc, dpkg, bash or
 132      anything that those packages depend on.</para></listitem>
 133      </varlistentry>
 134
 135      <varlistentry><term>Cache-Limit</term>
 136      <listitem><para>APT uses a fixed size memory mapped cache file to store the 'available'
 137      information. This sets the size of that cache (in bytes).</para></listitem>
 138      </varlistentry>
 139
 140      <varlistentry><term>Build-Essential</term>
 141      <listitem><para>Defines which package(s) are considered essential build dependencies.</para></listitem>
 142      </varlistentry>
 143
 144      <varlistentry><term>Get</term>
 145      <listitem><para>The Get subsection controls the &apt-get; tool, please see its
 146      documentation for more information about the options here.</para></listitem>
 147      </varlistentry>
 148
 149      <varlistentry><term>Cache</term>
 150      <listitem><para>The Cache subsection controls the &apt-cache; tool, please see its
 151      documentation for more information about the options here.</para></listitem>
 152      </varlistentry>
 153
 154      <varlistentry><term>CDROM</term>
 155      <listitem><para>The CDROM subsection controls the &apt-cdrom; tool, please see its
 156      documentation for more information about the options here.</para></listitem>
 157      </varlistentry>
 158    </variablelist>
 159  </refsect1>
 160
 161  <refsect1><title>The Acquire Group</title>
 162    <para>The <literal>Acquire</literal> group of options controls the download of packages
 163    and the URI handlers.
 164
 165    <variablelist>
 166      <varlistentry><term>PDiffs</term>
 167          <listitem><para>Try do download deltas called <literal>PDiffs</literal> for
 168          Packages or Sources files instead of downloading whole ones. True
 169          by default.</para></listitem>
 170      </varlistentry>
 171
 172      <varlistentry><term>Queue-Mode</term>
 173      <listitem><para>Queuing mode; <literal>Queue-Mode</literal> can be one of <literal>host</literal> or
 174      <literal>access</literal> which determines how  APT parallelizes outgoing
 175      connections. <literal>host</literal> means that one connection per target host
 176      will be opened, <literal>access</literal> means that one connection per URI type
 177      will be opened.</para></listitem>
 178      </varlistentry>
 179
 180      <varlistentry><term>Retries</term>
 181      <listitem><para>Number of retries to perform. If this is non-zero APT will retry failed
 182      files the given number of times.</para></listitem>
 183      </varlistentry>
 184
 185      <varlistentry><term>Source-Symlinks</term>
 186      <listitem><para>Use symlinks for source archives. If set to true then source archives will
 187      be symlinked when possible instead of copying. True is the default.</para></listitem>
 188      </varlistentry>
 189
 190      <varlistentry><term>http</term>
 191      <listitem><para>HTTP URIs; http::Proxy is the default http proxy to use. It is in the
 192      standard form of <literal>http://[[user][:pass]@]host[:port]/</literal>. Per
 193      host proxies can also be specified by using the form
 194      <literal>http::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal>
 195      meaning to use no proxies. The <envar>http_proxy</envar> environment variable
 196      will override all settings.</para>
 197
 198      <para>Three settings are provided for cache control with HTTP/1.1 compliant
 199      proxy caches. <literal>No-Cache</literal> tells the proxy to not use its cached
 200      response under any circumstances, <literal>Max-Age</literal> is sent only for
 201      index files and tells the cache to refresh its object if it is older than
 202      the given number of seconds. Debian updates its index files daily so the
 203      default is 1 day. <literal>No-Store</literal> specifies that the cache should never
 204      store this request, it is only set for archive files. This may be useful
 205      to prevent polluting a proxy cache with very large .deb files. Note:
 206      Squid 2.0.2 does not support any of these options.</para>
 207
 208      <para>The option <literal>timeout</literal> sets the timeout timer used by the method,
 209      this applies to all things including connection timeout and data timeout.</para>
 210
 211      <para>One setting is provided to control the pipeline depth in cases where the
 212      remote server is not RFC conforming or buggy (such as Squid 2.0.2)
 213      <literal>Acquire::http::Pipeline-Depth</literal> can be a value from 0 to 5
 214      indicating how many outstanding requests APT should send. A value of
 215      zero MUST be specified if the remote host does not properly linger
 216      on TCP connections - otherwise data corruption will occur. Hosts which
 217      require this are in violation of RFC 2068.</para></listitem>
 218      </varlistentry>
 219
 220      <varlistentry><term>ftp</term>
 221      <listitem><para>FTP URIs; ftp::Proxy is the default proxy server to use. It is in the
 222      standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal> and is
 223      overridden by the <envar>ftp_proxy</envar> environment variable. To use a ftp
 224      proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the
 225      configuration file. This entry specifies the commands to send to tell
 226      the proxy server what to connect to. Please see
 227      &configureindex; for an example of
 228      how to do this. The substitution variables available are
 229      <literal>$(PROXY_USER)</literal> <literal>$(PROXY_PASS)</literal> <literal>$(SITE_USER)</literal>
 230      <literal>$(SITE_PASS)</literal> <literal>$(SITE)</literal> and <literal>$(SITE_PORT)</literal>
 231      Each is taken from it's respective URI component.</para>
 232
 233      <para>The option <literal>timeout</literal> sets the timeout timer used by the method,
 234      this applies to all things including connection timeout and data timeout.</para>
 235
 236      <para>Several settings are provided to control passive mode. Generally it is
 237      safe to leave passive mode on, it works in nearly every environment.
 238      However some situations require that passive mode be disabled and port
 239      mode ftp used instead. This can be done globally, for connections that
 240      go through a proxy or for a specific host (See the sample config file
 241      for examples).</para>
 242
 243      <para>It is possible to proxy FTP over HTTP by setting the <envar>ftp_proxy</envar>
 244      environment variable to a http url - see the discussion of the http method
 245      above for syntax. You cannot set this in the configuration file and it is
 246      not recommended to use FTP over HTTP due to its low efficiency.</para>
 247
 248      <para>The setting <literal>ForceExtended</literal> controls the use of RFC2428
 249      <literal>EPSV</literal> and <literal>EPRT</literal> commands. The default is false, which means
 250      these commands are only used if the control connection is IPv6. Setting this
 251      to true forces their use even on IPv4 connections. Note that most FTP servers
 252      do not support RFC2428.</para></listitem>
 253      </varlistentry>
 254
 255      <varlistentry><term>cdrom</term>
 256      <listitem><para>CDROM URIs; the only setting for CDROM URIs is the mount point,
 257      <literal>cdrom::Mount</literal> which must be the mount point for the CDROM drive
 258      as specified in <filename>/etc/fstab</filename>. It is possible to provide
 259      alternate mount and unmount commands if your mount point cannot be listed
 260      in the fstab (such as an SMB mount and old mount packages). The syntax
 261      is to put <literallayout>"/cdrom/"::Mount "foo";</literallayout> within
 262      the cdrom block. It is important to have the trailing slash. Unmount
 263      commands can be specified using UMount.</para></listitem>
 264      </varlistentry>
 265
 266      <varlistentry><term>gpgv</term>
 267      <listitem><para>GPGV URIs; the only option for GPGV URIs is the option to pass additional parameters to gpgv.
 268      <literal>gpgv::Options</literal> Additional options passed to gpgv.
 269      </para></listitem>
 270      </varlistentry>
 271
 272    </variablelist>
 273   </para>
 274  </refsect1>
 275
 276  <refsect1><title>Directories</title>
 277
 278    <para>The <literal>Dir::State</literal> section has directories that pertain to local
 279    state information. <literal>lists</literal> is the directory to place downloaded
 280    package lists in and <literal>status</literal> is the name of the dpkg status file.
 281    <literal>preferences</literal> is the name of the APT preferences file.
 282    <literal>Dir::State</literal> contains the default directory to prefix on all sub
 283    items if they do not start with <filename>/</filename> or <filename>./</filename>.</para>
 284
 285    <para><literal>Dir::Cache</literal> contains locations pertaining to local cache
 286    information, such as the two package caches <literal>srcpkgcache</literal> and
 287    <literal>pkgcache</literal> as well as the location to place downloaded archives,
 288    <literal>Dir::Cache::archives</literal>. Generation of caches can be turned off
 289    by setting their names to be blank. This will slow down startup but
 290    save disk space. It is probably preferred to turn off the pkgcache rather
 291    than the srcpkgcache. Like <literal>Dir::State</literal> the default
 292    directory is contained in <literal>Dir::Cache</literal></para>
 293
 294    <para><literal>Dir::Etc</literal> contains the location of configuration files,
 295    <literal>sourcelist</literal> gives the location of the sourcelist and
 296    <literal>main</literal> is the default configuration file (setting has no effect,
 297    unless it is done from the config file specified by
 298    <envar>APT_CONFIG</envar>).</para>
 299
 300    <para>The <literal>Dir::Parts</literal> setting reads in all the config fragments in
 301    lexical order from the directory specified. After this is done then the
 302    main config file is loaded.</para>
 303
 304    <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal>
 305    specifies the location of the method handlers and <literal>gzip</literal>,
 306    <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal>
 307    <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
 308    of the respective programs.</para>
 309
 310    <para>
 311      The configuration item <literal>RootDir</literal> has a special
 312      meaning.  If set, all paths in <literal>Dir::</literal> will be
 313      relative to <literal>RootDir</literal>, <emphasis>even paths that
 314      are specified absolutely</emphasis>.  So, for instance, if
 315      <literal>RootDir</literal> is set to
 316      <filename>/tmp/staging</filename> and
 317      <literal>Dir::State::status</literal> is set to
 318      <filename>/var/lib/dpkg/status</filename>, then the status file
 319      will be looked up in
 320      <filename>/tmp/staging/var/lib/dpkg/status</filename>.
 321    </para>
 322  </refsect1>
 323
 324  <refsect1><title>APT in DSelect</title>
 325    <para>
 326    When APT is used as a &dselect; method several configuration directives
 327    control the default behaviour. These are in the <literal>DSelect</literal> section.</para>
 328
 329    <variablelist>
 330      <varlistentry><term>Clean</term>
 331      <listitem><para>Cache Clean mode; this value may be one of always, prompt, auto,
 332      pre-auto and never.  always and prompt will remove all packages from
 333      the cache after upgrading, prompt (the default) does so conditionally.
 334      auto removes only those packages which are no longer downloadable
 335      (replaced with a new version for instance).  pre-auto performs this
 336      action before downloading new packages.</para></listitem>
 337      </varlistentry>
 338
 339      <varlistentry><term>options</term>
 340      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 341      options when it is run for the install phase.</para></listitem>
 342      </varlistentry>
 343
 344      <varlistentry><term>Updateoptions</term>
 345      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 346      options when it is run for the update phase.</para></listitem>
 347      </varlistentry>
 348
 349      <varlistentry><term>PromptAfterUpdate</term>
 350      <listitem><para>If true the [U]pdate operation in &dselect; will always prompt to continue.
 351      The default is to prompt only on error.</para></listitem>
 352      </varlistentry>
 353    </variablelist>
 354  </refsect1>
 355
 356  <refsect1><title>How APT calls dpkg</title>
 357    <para>Several configuration directives control how APT invokes &dpkg;. These are
 358    in the <literal>DPkg</literal> section.</para>
 359
 360    <variablelist>
 361      <varlistentry><term>options</term>
 362      <listitem><para>This is a list of options to pass to dpkg. The options must be specified
 363      using the list notation and each list item is passed as a single argument
 364      to &dpkg;.</para></listitem>
 365      </varlistentry>
 366
 367      <varlistentry><term>Pre-Invoke</term><term>Post-Invoke</term>
 368      <listitem><para>This is a list of shell commands to run before/after invoking &dpkg;.
 369      Like <literal>options</literal> this must be specified in list notation. The
 370      commands are invoked in order using <filename>/bin/sh</filename>, should any
 371      fail APT will abort.</para></listitem>
 372      </varlistentry>
 373
 374      <varlistentry><term>Pre-Install-Pkgs</term>
 375      <listitem><para>This is a list of shell commands to run before invoking dpkg. Like
 376      <literal>options</literal> this must be specified in list notation. The commands
 377      are invoked in order using <filename>/bin/sh</filename>, should any fail APT
 378      will abort. APT will pass to the commands on standard input the
 379      filenames of all .deb files it is going to install, one per line.</para>
 380
 381      <para>Version 2 of this protocol dumps more information, including the
 382      protocol version, the APT configuration space and the packages, files
 383      and versions being changed. Version 2 is enabled by setting
 384      <literal>DPkg::Tools::options::cmd::Version</literal> to 2. <literal>cmd</literal> is a
 385      command given to <literal>Pre-Install-Pkgs</literal>.</para></listitem>
 386      </varlistentry>
 387
 388      <varlistentry><term>Run-Directory</term>
 389      <listitem><para>APT chdirs to this directory before invoking dpkg, the default is
 390      <filename>/</filename>.</para></listitem>
 391      </varlistentry>
 392
 393      <varlistentry><term>Build-options</term>
 394      <listitem><para>These options are passed to &dpkg-buildpackage; when compiling packages,
 395      the default is to disable signing and produce all binaries.</para></listitem>
 396      </varlistentry>
 397    </variablelist>
 398  </refsect1>
 399
 400  <refsect1><title>Debug options</title>
 401    <para>Most of the options in the <literal>debug</literal> section are not interesting to
 402    the normal user, however <literal>Debug::pkgProblemResolver</literal> shows
 403    interesting output about the decisions dist-upgrade makes.
 404    <literal>Debug::NoLocking</literal> disables file locking so APT can do some
 405    operations as non-root and <literal>Debug::pkgDPkgPM</literal> will print out the
 406    command line for each dpkg invokation. <literal>Debug::IdentCdrom</literal> will
 407    disable the inclusion of statfs data in CDROM IDs.
 408    <literal>Debug::Acquire::gpgv</literal> Debugging of the gpgv method.
 409    </para>
 410  </refsect1>
 411
 412  <refsect1><title>Examples</title>
 413    <para>&configureindex; is a
 414    configuration file showing example values for all possible
 415    options.</para>
 416  </refsect1>
 417
 418  <refsect1><title>Files</title>
 419    <para><filename>/etc/apt/apt.conf</filename></para>
 420  </refsect1>
 421
 422  <refsect1><title>See Also</title>
 423    <para>&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.</para>
 424  </refsect1>
 425
 426  &manbugs;
 427
 428 </refentry>
 429