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