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>https</term>
 224          <listitem><para>HTTPS URIs. Cache-control and proxy options are the same as for
 225          <literal>http</literal> method.
 226          <literal>Pipeline-Depth</literal> option is not supported yet.</para>
 227
 228          <para><literal>CaInfo</literal> suboption specifies place of file that
 229          holds info about trusted certificates.
 230          <literal>&lt;host&gt;::CaInfo</literal> is corresponding per-host option.
 231          <literal>Verify-Peer</literal> boolean suboption determines whether verify
 232          server's host certificate against trusted certificates or not.
 233          <literal>&lt;host&gt;::Verify-Peer</literal> is corresponding per-host option.
 234          <literal>Verify-Host</literal> boolean suboption determines whether verify
 235          server's hostname or not.
 236          <literal>&lt;host&gt;::Verify-Host</literal> is corresponding per-host option.
 237          <literal>SslCert</literal> determines what certificate to use for client
 238          authentication. <literal>&lt;host&gt;::SslCert</literal> is corresponding per-host option.
 239          <literal>SslKey</literal> determines what private key to use for client
 240          authentication. <literal>&lt;host&gt;::SslKey</literal> is corresponding per-host option.
 241          <literal>SslForceVersion</literal> overrides default SSL version to use.
 242          Can contain 'TLSv1' or 'SSLv3' string.
 243          <literal>&lt;host&gt;::SslForceVersion</literal> is corresponding per-host option.
 244          </para></listitem></varlistentry>
 245
 246      <varlistentry><term>ftp</term>
 247      <listitem><para>FTP URIs; ftp::Proxy is the default proxy server to use. It is in the
 248      standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal> and is
 249      overridden by the <envar>ftp_proxy</envar> environment variable. To use a ftp
 250      proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the
 251      configuration file. This entry specifies the commands to send to tell
 252      the proxy server what to connect to. Please see
 253      &configureindex; for an example of
 254      how to do this. The substitution variables available are
 255      <literal>$(PROXY_USER)</literal> <literal>$(PROXY_PASS)</literal> <literal>$(SITE_USER)</literal>
 256      <literal>$(SITE_PASS)</literal> <literal>$(SITE)</literal> and <literal>$(SITE_PORT)</literal>
 257      Each is taken from it's respective URI component.</para>
 258
 259      <para>The option <literal>timeout</literal> sets the timeout timer used by the method,
 260      this applies to all things including connection timeout and data timeout.</para>
 261
 262      <para>Several settings are provided to control passive mode. Generally it is
 263      safe to leave passive mode on, it works in nearly every environment.
 264      However some situations require that passive mode be disabled and port
 265      mode ftp used instead. This can be done globally, for connections that
 266      go through a proxy or for a specific host (See the sample config file
 267      for examples).</para>
 268
 269      <para>It is possible to proxy FTP over HTTP by setting the <envar>ftp_proxy</envar>
 270      environment variable to a http url - see the discussion of the http method
 271      above for syntax. You cannot set this in the configuration file and it is
 272      not recommended to use FTP over HTTP due to its low efficiency.</para>
 273
 274      <para>The setting <literal>ForceExtended</literal> controls the use of RFC2428
 275      <literal>EPSV</literal> and <literal>EPRT</literal> commands. The default is false, which means
 276      these commands are only used if the control connection is IPv6. Setting this
 277      to true forces their use even on IPv4 connections. Note that most FTP servers
 278      do not support RFC2428.</para></listitem>
 279      </varlistentry>
 280
 281      <varlistentry><term>cdrom</term>
 282      <listitem><para>CDROM URIs; the only setting for CDROM URIs is the mount point,
 283      <literal>cdrom::Mount</literal> which must be the mount point for the CDROM drive
 284      as specified in <filename>/etc/fstab</filename>. It is possible to provide
 285      alternate mount and unmount commands if your mount point cannot be listed
 286      in the fstab (such as an SMB mount and old mount packages). The syntax
 287      is to put <literallayout>"/cdrom/"::Mount "foo";</literallayout> within
 288      the cdrom block. It is important to have the trailing slash. Unmount
 289      commands can be specified using UMount.</para></listitem>
 290      </varlistentry>
 291
 292      <varlistentry><term>gpgv</term>
 293      <listitem><para>GPGV URIs; the only option for GPGV URIs is the option to pass additional parameters to gpgv.
 294      <literal>gpgv::Options</literal> Additional options passed to gpgv.
 295      </para></listitem>
 296      </varlistentry>
 297
 298    </variablelist>
 299   </para>
 300  </refsect1>
 301
 302  <refsect1><title>Directories</title>
 303
 304    <para>The <literal>Dir::State</literal> section has directories that pertain to local
 305    state information. <literal>lists</literal> is the directory to place downloaded
 306    package lists in and <literal>status</literal> is the name of the dpkg status file.
 307    <literal>preferences</literal> is the name of the APT preferences file.
 308    <literal>Dir::State</literal> contains the default directory to prefix on all sub
 309    items if they do not start with <filename>/</filename> or <filename>./</filename>.</para>
 310
 311    <para><literal>Dir::Cache</literal> contains locations pertaining to local cache
 312    information, such as the two package caches <literal>srcpkgcache</literal> and
 313    <literal>pkgcache</literal> as well as the location to place downloaded archives,
 314    <literal>Dir::Cache::archives</literal>. Generation of caches can be turned off
 315    by setting their names to be blank. This will slow down startup but
 316    save disk space. It is probably preferred to turn off the pkgcache rather
 317    than the srcpkgcache. Like <literal>Dir::State</literal> the default
 318    directory is contained in <literal>Dir::Cache</literal></para>
 319
 320    <para><literal>Dir::Etc</literal> contains the location of configuration files,
 321    <literal>sourcelist</literal> gives the location of the sourcelist and
 322    <literal>main</literal> is the default configuration file (setting has no effect,
 323    unless it is done from the config file specified by
 324    <envar>APT_CONFIG</envar>).</para>
 325
 326    <para>The <literal>Dir::Parts</literal> setting reads in all the config fragments in
 327    lexical order from the directory specified. After this is done then the
 328    main config file is loaded.</para>
 329
 330    <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal>
 331    specifies the location of the method handlers and <literal>gzip</literal>,
 332    <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal>
 333    <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
 334    of the respective programs.</para>
 335
 336    <para>
 337      The configuration item <literal>RootDir</literal> has a special
 338      meaning.  If set, all paths in <literal>Dir::</literal> will be
 339      relative to <literal>RootDir</literal>, <emphasis>even paths that
 340      are specified absolutely</emphasis>.  So, for instance, if
 341      <literal>RootDir</literal> is set to
 342      <filename>/tmp/staging</filename> and
 343      <literal>Dir::State::status</literal> is set to
 344      <filename>/var/lib/dpkg/status</filename>, then the status file
 345      will be looked up in
 346      <filename>/tmp/staging/var/lib/dpkg/status</filename>.
 347    </para>
 348  </refsect1>
 349
 350  <refsect1><title>APT in DSelect</title>
 351    <para>
 352    When APT is used as a &dselect; method several configuration directives
 353    control the default behaviour. These are in the <literal>DSelect</literal> section.</para>
 354
 355    <variablelist>
 356      <varlistentry><term>Clean</term>
 357      <listitem><para>Cache Clean mode; this value may be one of always, prompt, auto,
 358      pre-auto and never.  always and prompt will remove all packages from
 359      the cache after upgrading, prompt (the default) does so conditionally.
 360      auto removes only those packages which are no longer downloadable
 361      (replaced with a new version for instance).  pre-auto performs this
 362      action before downloading new packages.</para></listitem>
 363      </varlistentry>
 364
 365      <varlistentry><term>options</term>
 366      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 367      options when it is run for the install phase.</para></listitem>
 368      </varlistentry>
 369
 370      <varlistentry><term>Updateoptions</term>
 371      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 372      options when it is run for the update phase.</para></listitem>
 373      </varlistentry>
 374
 375      <varlistentry><term>PromptAfterUpdate</term>
 376      <listitem><para>If true the [U]pdate operation in &dselect; will always prompt to continue.
 377      The default is to prompt only on error.</para></listitem>
 378      </varlistentry>
 379    </variablelist>
 380  </refsect1>
 381
 382  <refsect1><title>How APT calls dpkg</title>
 383    <para>Several configuration directives control how APT invokes &dpkg;. These are
 384    in the <literal>DPkg</literal> section.</para>
 385
 386    <variablelist>
 387      <varlistentry><term>options</term>
 388      <listitem><para>This is a list of options to pass to dpkg. The options must be specified
 389      using the list notation and each list item is passed as a single argument
 390      to &dpkg;.</para></listitem>
 391      </varlistentry>
 392
 393      <varlistentry><term>Pre-Invoke</term><term>Post-Invoke</term>
 394      <listitem><para>This is a list of shell commands to run before/after invoking &dpkg;.
 395      Like <literal>options</literal> this must be specified in list notation. The
 396      commands are invoked in order using <filename>/bin/sh</filename>, should any
 397      fail APT will abort.</para></listitem>
 398      </varlistentry>
 399
 400      <varlistentry><term>Pre-Install-Pkgs</term>
 401      <listitem><para>This is a list of shell commands to run before invoking dpkg. Like
 402      <literal>options</literal> this must be specified in list notation. The commands
 403      are invoked in order using <filename>/bin/sh</filename>, should any fail APT
 404      will abort. APT will pass to the commands on standard input the
 405      filenames of all .deb files it is going to install, one per line.</para>
 406
 407      <para>Version 2 of this protocol dumps more information, including the
 408      protocol version, the APT configuration space and the packages, files
 409      and versions being changed. Version 2 is enabled by setting
 410      <literal>DPkg::Tools::options::cmd::Version</literal> to 2. <literal>cmd</literal> is a
 411      command given to <literal>Pre-Install-Pkgs</literal>.</para></listitem>
 412      </varlistentry>
 413
 414      <varlistentry><term>Run-Directory</term>
 415      <listitem><para>APT chdirs to this directory before invoking dpkg, the default is
 416      <filename>/</filename>.</para></listitem>
 417      </varlistentry>
 418
 419      <varlistentry><term>Build-options</term>
 420      <listitem><para>These options are passed to &dpkg-buildpackage; when compiling packages,
 421      the default is to disable signing and produce all binaries.</para></listitem>
 422      </varlistentry>
 423    </variablelist>
 424  </refsect1>
 425
 426  <refsect1><title>Debug options</title>
 427    <para>Most of the options in the <literal>debug</literal> section are not interesting to
 428    the normal user, however <literal>Debug::pkgProblemResolver</literal> shows
 429    interesting output about the decisions dist-upgrade makes.
 430    <literal>Debug::NoLocking</literal> disables file locking so APT can do some
 431    operations as non-root and <literal>Debug::pkgDPkgPM</literal> will print out the
 432    command line for each dpkg invokation. <literal>Debug::IdentCdrom</literal> will
 433    disable the inclusion of statfs data in CDROM IDs.
 434    <literal>Debug::Acquire::gpgv</literal> Debugging of the gpgv method.
 435    </para>
 436  </refsect1>
 437
 438  <refsect1><title>Examples</title>
 439    <para>&configureindex; is a
 440    configuration file showing example values for all possible
 441    options.</para>
 442  </refsect1>
 443
 444  <refsect1><title>Files</title>
 445    <para><filename>/etc/apt/apt.conf</filename></para>
 446  </refsect1>
 447
 448  <refsect1><title>See Also</title>
 449    <para>&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.</para>
 450  </refsect1>
 451
 452  &manbugs;
 453
 454 </refentry>
 455