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>The names of the configuration items are not case-sensitive. So in the previous example
  79    you could use <literal>dpkg::pre-install-pkgs</literal>.</para>
  80
  81    <para>Two specials are allowed, <literal>#include</literal> and <literal>#clear</literal>
  82    <literal>#include</literal> will include the given file, unless the filename
  83    ends in a slash, then the whole directory is included.
  84    <literal>#clear</literal> is used to erase a list of names.</para>
  85
  86    <para>All of the APT tools take a -o option which allows an arbitrary configuration
  87    directive to be specified on the command line. The syntax is a full option
  88    name (<literal>APT::Get::Assume-Yes</literal> for instance) followed by an equals
  89    sign then the new value of the option. Lists can be appended too by adding
  90    a trailing :: to the list name.</para>
  91  </refsect1>
  92
  93  <refsect1><title>The APT Group</title>
  94    <para>This group of options controls general APT behavior as well as holding the
  95    options for all of the tools.</para>
  96
  97    <variablelist>
  98      <varlistentry><term>Architecture</term>
  99      <listitem><para>System Architecture; sets the architecture to use when fetching files and
 100      parsing package lists. The internal default is the architecture apt was
 101      compiled for.</para></listitem>
 102      </varlistentry>
 103
 104      <varlistentry><term>Default-Release</term>
 105          <listitem><para>Default release to install packages from if more than one
 106          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>
 107      </varlistentry>
 108
 109      <varlistentry><term>Ignore-Hold</term>
 110      <listitem><para>Ignore Held packages; This global option causes the problem resolver to
 111      ignore held packages in its decision making.</para></listitem>
 112      </varlistentry>
 113
 114      <varlistentry><term>Clean-Installed</term>
 115      <listitem><para>Defaults to on. When turned on the autoclean feature will remove any packages
 116      which can no longer be downloaded from the cache. If turned off then
 117      packages that are locally installed are also excluded from cleaning - but
 118      note that APT provides no direct means to reinstall them.</para></listitem>
 119      </varlistentry>
 120
 121      <varlistentry><term>Immediate-Configure</term>
 122      <listitem><para>Disable Immediate Configuration; This dangerous option disables some
 123      of APT's ordering code to cause it to make fewer dpkg calls. Doing
 124      so may be necessary on some extremely slow single user systems but
 125      is very dangerous and may cause package install scripts to fail or worse.
 126      Use at your own risk.</para></listitem>
 127      </varlistentry>
 128
 129      <varlistentry><term>Force-LoopBreak</term>
 130      <listitem><para>Never Enable this option unless you -really- know what you are doing. It
 131      permits APT to temporarily remove an essential package to break a
 132      Conflicts/Conflicts or Conflicts/Pre-Depend loop between two essential
 133      packages. SUCH A LOOP SHOULD NEVER EXIST AND IS A GRAVE BUG. This option
 134      will work if the essential packages are not tar, gzip, libc, dpkg, bash or
 135      anything that those packages depend on.</para></listitem>
 136      </varlistentry>
 137
 138      <varlistentry><term>Cache-Limit</term>
 139      <listitem><para>APT uses a fixed size memory mapped cache file to store the 'available'
 140      information. This sets the size of that cache (in bytes).</para></listitem>
 141      </varlistentry>
 142
 143      <varlistentry><term>Build-Essential</term>
 144      <listitem><para>Defines which package(s) are considered essential build dependencies.</para></listitem>
 145      </varlistentry>
 146
 147      <varlistentry><term>Get</term>
 148      <listitem><para>The Get subsection controls the &apt-get; tool, please see its
 149      documentation for more information about the options here.</para></listitem>
 150      </varlistentry>
 151
 152      <varlistentry><term>Cache</term>
 153      <listitem><para>The Cache subsection controls the &apt-cache; tool, please see its
 154      documentation for more information about the options here.</para></listitem>
 155      </varlistentry>
 156
 157      <varlistentry><term>CDROM</term>
 158      <listitem><para>The CDROM subsection controls the &apt-cdrom; tool, please see its
 159      documentation for more information about the options here.</para></listitem>
 160      </varlistentry>
 161    </variablelist>
 162  </refsect1>
 163
 164  <refsect1><title>The Acquire Group</title>
 165    <para>The <literal>Acquire</literal> group of options controls the download of packages
 166    and the URI handlers.
 167
 168    <variablelist>
 169      <varlistentry><term>PDiffs</term>
 170          <listitem><para>Try do download deltas called <literal>PDiffs</literal> for
 171          Packages or Sources files instead of downloading whole ones. True
 172          by default.</para></listitem>
 173      </varlistentry>
 174
 175      <varlistentry><term>Queue-Mode</term>
 176      <listitem><para>Queuing mode; <literal>Queue-Mode</literal> can be one of <literal>host</literal> or
 177      <literal>access</literal> which determines how  APT parallelizes outgoing
 178      connections. <literal>host</literal> means that one connection per target host
 179      will be opened, <literal>access</literal> means that one connection per URI type
 180      will be opened.</para></listitem>
 181      </varlistentry>
 182
 183      <varlistentry><term>Retries</term>
 184      <listitem><para>Number of retries to perform. If this is non-zero APT will retry failed
 185      files the given number of times.</para></listitem>
 186      </varlistentry>
 187
 188      <varlistentry><term>Source-Symlinks</term>
 189      <listitem><para>Use symlinks for source archives. If set to true then source archives will
 190      be symlinked when possible instead of copying. True is the default.</para></listitem>
 191      </varlistentry>
 192
 193      <varlistentry><term>http</term>
 194      <listitem><para>HTTP URIs; http::Proxy is the default http proxy to use. It is in the
 195      standard form of <literal>http://[[user][:pass]@]host[:port]/</literal>. Per
 196      host proxies can also be specified by using the form
 197      <literal>http::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal>
 198      meaning to use no proxies. The <envar>http_proxy</envar> environment variable
 199      will override all settings.</para>
 200
 201      <para>Three settings are provided for cache control with HTTP/1.1 compliant
 202      proxy caches. <literal>No-Cache</literal> tells the proxy to not use its cached
 203      response under any circumstances, <literal>Max-Age</literal> is sent only for
 204      index files and tells the cache to refresh its object if it is older than
 205      the given number of seconds. Debian updates its index files daily so the
 206      default is 1 day. <literal>No-Store</literal> specifies that the cache should never
 207      store this request, it is only set for archive files. This may be useful
 208      to prevent polluting a proxy cache with very large .deb files. Note:
 209      Squid 2.0.2 does not support any of these options.</para>
 210
 211      <para>The option <literal>timeout</literal> sets the timeout timer used by the method,
 212      this applies to all things including connection timeout and data timeout.</para>
 213
 214      <para>One setting is provided to control the pipeline depth in cases where the
 215      remote server is not RFC conforming or buggy (such as Squid 2.0.2)
 216      <literal>Acquire::http::Pipeline-Depth</literal> can be a value from 0 to 5
 217      indicating how many outstanding requests APT should send. A value of
 218      zero MUST be specified if the remote host does not properly linger
 219      on TCP connections - otherwise data corruption will occur. Hosts which
 220      require this are in violation of RFC 2068.</para></listitem>
 221      </varlistentry>
 222
 223      <varlistentry><term>ftp</term>
 224      <listitem><para>FTP URIs; ftp::Proxy is the default proxy server to use. It is in the
 225      standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal> and is
 226      overridden by the <envar>ftp_proxy</envar> environment variable. To use a ftp
 227      proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the
 228      configuration file. This entry specifies the commands to send to tell
 229      the proxy server what to connect to. Please see
 230      &configureindex; for an example of
 231      how to do this. The substitution variables available are
 232      <literal>$(PROXY_USER)</literal> <literal>$(PROXY_PASS)</literal> <literal>$(SITE_USER)</literal>
 233      <literal>$(SITE_PASS)</literal> <literal>$(SITE)</literal> and <literal>$(SITE_PORT)</literal>
 234      Each is taken from it's respective URI component.</para>
 235
 236      <para>The option <literal>timeout</literal> sets the timeout timer used by the method,
 237      this applies to all things including connection timeout and data timeout.</para>
 238
 239      <para>Several settings are provided to control passive mode. Generally it is
 240      safe to leave passive mode on, it works in nearly every environment.
 241      However some situations require that passive mode be disabled and port
 242      mode ftp used instead. This can be done globally, for connections that
 243      go through a proxy or for a specific host (See the sample config file
 244      for examples).</para>
 245
 246      <para>It is possible to proxy FTP over HTTP by setting the <envar>ftp_proxy</envar>
 247      environment variable to a http url - see the discussion of the http method
 248      above for syntax. You cannot set this in the configuration file and it is
 249      not recommended to use FTP over HTTP due to its low efficiency.</para>
 250
 251      <para>The setting <literal>ForceExtended</literal> controls the use of RFC2428
 252      <literal>EPSV</literal> and <literal>EPRT</literal> commands. The default is false, which means
 253      these commands are only used if the control connection is IPv6. Setting this
 254      to true forces their use even on IPv4 connections. Note that most FTP servers
 255      do not support RFC2428.</para></listitem>
 256      </varlistentry>
 257
 258      <varlistentry><term>cdrom</term>
 259      <listitem><para>CDROM URIs; the only setting for CDROM URIs is the mount point,
 260      <literal>cdrom::Mount</literal> which must be the mount point for the CDROM drive
 261      as specified in <filename>/etc/fstab</filename>. It is possible to provide
 262      alternate mount and unmount commands if your mount point cannot be listed
 263      in the fstab (such as an SMB mount and old mount packages). The syntax
 264      is to put <literallayout>"/cdrom/"::Mount "foo";</literallayout> within
 265      the cdrom block. It is important to have the trailing slash. Unmount
 266      commands can be specified using UMount.</para></listitem>
 267      </varlistentry>
 268
 269      <varlistentry><term>gpgv</term>
 270      <listitem><para>GPGV URIs; the only option for GPGV URIs is the option to pass additional parameters to gpgv.
 271      <literal>gpgv::Options</literal> Additional options passed to gpgv.
 272      </para></listitem>
 273      </varlistentry>
 274
 275    </variablelist>
 276   </para>
 277  </refsect1>
 278
 279  <refsect1><title>Directories</title>
 280
 281    <para>The <literal>Dir::State</literal> section has directories that pertain to local
 282    state information. <literal>lists</literal> is the directory to place downloaded
 283    package lists in and <literal>status</literal> is the name of the dpkg status file.
 284    <literal>preferences</literal> is the name of the APT preferences file.
 285    <literal>Dir::State</literal> contains the default directory to prefix on all sub
 286    items if they do not start with <filename>/</filename> or <filename>./</filename>.</para>
 287
 288    <para><literal>Dir::Cache</literal> contains locations pertaining to local cache
 289    information, such as the two package caches <literal>srcpkgcache</literal> and
 290    <literal>pkgcache</literal> as well as the location to place downloaded archives,
 291    <literal>Dir::Cache::archives</literal>. Generation of caches can be turned off
 292    by setting their names to be blank. This will slow down startup but
 293    save disk space. It is probably preferred to turn off the pkgcache rather
 294    than the srcpkgcache. Like <literal>Dir::State</literal> the default
 295    directory is contained in <literal>Dir::Cache</literal></para>
 296
 297    <para><literal>Dir::Etc</literal> contains the location of configuration files,
 298    <literal>sourcelist</literal> gives the location of the sourcelist and
 299    <literal>main</literal> is the default configuration file (setting has no effect,
 300    unless it is done from the config file specified by
 301    <envar>APT_CONFIG</envar>).</para>
 302
 303    <para>The <literal>Dir::Parts</literal> setting reads in all the config fragments in
 304    lexical order from the directory specified. After this is done then the
 305    main config file is loaded.</para>
 306
 307    <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal>
 308    specifies the location of the method handlers and <literal>gzip</literal>,
 309    <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal>
 310    <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
 311    of the respective programs.</para>
 312
 313    <para>
 314      The configuration item <literal>RootDir</literal> has a special
 315      meaning.  If set, all paths in <literal>Dir::</literal> will be
 316      relative to <literal>RootDir</literal>, <emphasis>even paths that
 317      are specified absolutely</emphasis>.  So, for instance, if
 318      <literal>RootDir</literal> is set to
 319      <filename>/tmp/staging</filename> and
 320      <literal>Dir::State::status</literal> is set to
 321      <filename>/var/lib/dpkg/status</filename>, then the status file
 322      will be looked up in
 323      <filename>/tmp/staging/var/lib/dpkg/status</filename>.
 324    </para>
 325  </refsect1>
 326
 327  <refsect1><title>APT in DSelect</title>
 328    <para>
 329    When APT is used as a &dselect; method several configuration directives
 330    control the default behaviour. These are in the <literal>DSelect</literal> section.</para>
 331
 332    <variablelist>
 333      <varlistentry><term>Clean</term>
 334      <listitem><para>Cache Clean mode; this value may be one of always, prompt, auto,
 335      pre-auto and never.  always and prompt will remove all packages from
 336      the cache after upgrading, prompt (the default) does so conditionally.
 337      auto removes only those packages which are no longer downloadable
 338      (replaced with a new version for instance).  pre-auto performs this
 339      action before downloading new packages.</para></listitem>
 340      </varlistentry>
 341
 342      <varlistentry><term>options</term>
 343      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 344      options when it is run for the install phase.</para></listitem>
 345      </varlistentry>
 346
 347      <varlistentry><term>Updateoptions</term>
 348      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 349      options when it is run for the update phase.</para></listitem>
 350      </varlistentry>
 351
 352      <varlistentry><term>PromptAfterUpdate</term>
 353      <listitem><para>If true the [U]pdate operation in &dselect; will always prompt to continue.
 354      The default is to prompt only on error.</para></listitem>
 355      </varlistentry>
 356    </variablelist>
 357  </refsect1>
 358
 359  <refsect1><title>How APT calls dpkg</title>
 360    <para>Several configuration directives control how APT invokes &dpkg;. These are
 361    in the <literal>DPkg</literal> section.</para>
 362
 363    <variablelist>
 364      <varlistentry><term>options</term>
 365      <listitem><para>This is a list of options to pass to dpkg. The options must be specified
 366      using the list notation and each list item is passed as a single argument
 367      to &dpkg;.</para></listitem>
 368      </varlistentry>
 369
 370      <varlistentry><term>Pre-Invoke</term><term>Post-Invoke</term>
 371      <listitem><para>This is a list of shell commands to run before/after invoking &dpkg;.
 372      Like <literal>options</literal> this must be specified in list notation. The
 373      commands are invoked in order using <filename>/bin/sh</filename>, should any
 374      fail APT will abort.</para></listitem>
 375      </varlistentry>
 376
 377      <varlistentry><term>Pre-Install-Pkgs</term>
 378      <listitem><para>This is a list of shell commands to run before invoking dpkg. Like
 379      <literal>options</literal> this must be specified in list notation. The commands
 380      are invoked in order using <filename>/bin/sh</filename>, should any fail APT
 381      will abort. APT will pass to the commands on standard input the
 382      filenames of all .deb files it is going to install, one per line.</para>
 383
 384      <para>Version 2 of this protocol dumps more information, including the
 385      protocol version, the APT configuration space and the packages, files
 386      and versions being changed. Version 2 is enabled by setting
 387      <literal>DPkg::Tools::options::cmd::Version</literal> to 2. <literal>cmd</literal> is a
 388      command given to <literal>Pre-Install-Pkgs</literal>.</para></listitem>
 389      </varlistentry>
 390
 391      <varlistentry><term>Run-Directory</term>
 392      <listitem><para>APT chdirs to this directory before invoking dpkg, the default is
 393      <filename>/</filename>.</para></listitem>
 394      </varlistentry>
 395
 396      <varlistentry><term>Build-options</term>
 397      <listitem><para>These options are passed to &dpkg-buildpackage; when compiling packages,
 398      the default is to disable signing and produce all binaries.</para></listitem>
 399      </varlistentry>
 400    </variablelist>
 401  </refsect1>
 402
 403  <refsect1><title>Debug options</title>
 404    <para>Most of the options in the <literal>debug</literal> section are not interesting to
 405    the normal user, however <literal>Debug::pkgProblemResolver</literal> shows
 406    interesting output about the decisions dist-upgrade makes.
 407    <literal>Debug::NoLocking</literal> disables file locking so APT can do some
 408    operations as non-root and <literal>Debug::pkgDPkgPM</literal> will print out the
 409    command line for each dpkg invokation. <literal>Debug::IdentCdrom</literal> will
 410    disable the inclusion of statfs data in CDROM IDs.
 411    <literal>Debug::Acquire::gpgv</literal> Debugging of the gpgv method.
 412    </para>
 413  </refsect1>
 414
 415  <refsect1><title>Examples</title>
 416    <para>&configureindex; is a
 417    configuration file showing example values for all possible
 418    options.</para>
 419  </refsect1>
 420
 421  <refsect1><title>Files</title>
 422    <para><filename>/etc/apt/apt.conf</filename></para>
 423  </refsect1>
 424
 425  <refsect1><title>See Also</title>
 426    <para>&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.</para>
 427  </refsect1>
 428
 429  &manbugs;
 430
 431 </refentry>
 432