doc/apt.conf.5.xml

   1 <?xml version="1.0" encoding="utf-8" standalone="no"?>
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
   4
   5 <!ENTITY % aptent SYSTEM "apt.ent">
   6 %aptent;
   7
   8 ]>
   9
  10 <refentry>
  11
  12  <refentryinfo>
  13    &apt-author.jgunthorpe;
  14    &apt-author.team;
  15    <author>
  16      <firstname>Daniel</firstname>
  17      <surname>Burrows</surname>
  18      <contrib>Initial documentation of Debug::*.</contrib>
  19      <email>dburrows@debian.org</email>
  20    </author>
  21    &apt-email;
  22    &apt-product;
  23    <!-- The last update date -->
  24    <date>10 December 2008</date>
  25  </refentryinfo>
  26
  27  <refmeta>
  28    <refentrytitle>apt.conf</refentrytitle>
  29    <manvolnum>5</manvolnum>
  30    <refmiscinfo class="manual">APT</refmiscinfo>
  31  </refmeta>
  32
  33  <!-- Man page title -->
  34  <refnamediv>
  35     <refname>apt.conf</refname>
  36     <refpurpose>Configuration file for APT</refpurpose>
  37  </refnamediv>
  38
  39  <refsect1><title>Description</title>
  40    <para><filename>apt.conf</filename> is the main configuration file for the APT suite of
  41    tools, all tools make use of the configuration file and a common command line
  42    parser to provide a uniform environment. When an APT tool starts up it will
  43    read the configuration specified by the <envar>APT_CONFIG</envar> environment
  44    variable (if any) and then read the files in <literal>Dir::Etc::Parts</literal>
  45    then read the main configuration file specified by
  46    <literal>Dir::Etc::main</literal> then finally apply the
  47    command line options to override the configuration directives, possibly
  48    loading even more config files.</para>
  49
  50    <para>The configuration file is organized in a tree with options organized into
  51    functional groups. option specification is given with a double colon
  52    notation, for instance <literal>APT::Get::Assume-Yes</literal> is an option within
  53    the APT tool group, for the Get tool. options do not inherit from their
  54    parent groups.</para>
  55
  56    <para>Syntactically the configuration language is modeled after what the ISC tools
  57    such as bind and dhcp use. Lines starting with
  58    <literal>//</literal> are treated as comments (ignored), as well as all text
  59    between <literal>/*</literal> and <literal>*/</literal>, just like C/C++ comments.
  60    Each line is of the form
  61    <literal>APT::Get::Assume-Yes "true";</literal> The trailing
  62    semicolon is required and the quotes are optional. A new scope can be
  63    opened with curly braces, like:</para>
  64
  65 <informalexample><programlisting>
  66 APT {
  67   Get {
  68     Assume-Yes "true";
  69     Fix-Broken "true";
  70   };
  71 };
  72 </programlisting></informalexample>
  73
  74    <para>with newlines placed to make it more readable. Lists can be created by
  75    opening a scope and including a single string enclosed in quotes followed by a
  76    semicolon. Multiple entries can be included, each separated by a semicolon.</para>
  77
  78 <informalexample><programlisting>
  79 DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
  80 </programlisting></informalexample>
  81
  82    <para>In general the sample configuration file in
  83    <filename>&docdir;examples/apt.conf</filename> &configureindex;
  84    is a good guide for how it should look.</para>
  85
  86    <para>The names of the configuration items are not case-sensitive. So in the previous example
  87    you could use <literal>dpkg::pre-install-pkgs</literal>.</para>
  88
  89    <para>Two specials are allowed, <literal>#include</literal> and <literal>#clear</literal>
  90    <literal>#include</literal> will include the given file, unless the filename
  91    ends in a slash, then the whole directory is included.
  92    <literal>#clear</literal> is used to erase a part of the configuration tree. The
  93    specified element and all its descendents are erased.</para>
  94
  95    <para>All of the APT tools take a -o option which allows an arbitrary configuration
  96    directive to be specified on the command line. The syntax is a full option
  97    name (<literal>APT::Get::Assume-Yes</literal> for instance) followed by an equals
  98    sign then the new value of the option. Lists can be appended too by adding
  99    a trailing :: to the list name.</para>
 100  </refsect1>
 101
 102  <refsect1><title>The APT Group</title>
 103    <para>This group of options controls general APT behavior as well as holding the
 104    options for all of the tools.</para>
 105
 106    <variablelist>
 107      <varlistentry><term>Architecture</term>
 108      <listitem><para>System Architecture; sets the architecture to use when fetching files and
 109      parsing package lists. The internal default is the architecture apt was
 110      compiled for.</para></listitem>
 111      </varlistentry>
 112
 113      <varlistentry><term>Default-Release</term>
 114          <listitem><para>Default release to install packages from if more than one
 115          version available. Contains release name, codename or release version. Examples: 'stable', 'testing', 'unstable', 'lenny', 'squeeze', '4.0', '5.0*'. See also &apt-preferences;.</para></listitem>
 116      </varlistentry>
 117
 118      <varlistentry><term>Ignore-Hold</term>
 119      <listitem><para>Ignore Held packages; This global option causes the problem resolver to
 120      ignore held packages in its decision making.</para></listitem>
 121      </varlistentry>
 122
 123      <varlistentry><term>Clean-Installed</term>
 124      <listitem><para>Defaults to on. When turned on the autoclean feature will remove any packages
 125      which can no longer be downloaded from the cache. If turned off then
 126      packages that are locally installed are also excluded from cleaning - but
 127      note that APT provides no direct means to reinstall them.</para></listitem>
 128      </varlistentry>
 129
 130      <varlistentry><term>Immediate-Configure</term>
 131      <listitem><para>Disable Immediate Configuration; This dangerous option disables some
 132      of APT's ordering code to cause it to make fewer dpkg calls. Doing
 133      so may be necessary on some extremely slow single user systems but
 134      is very dangerous and may cause package install scripts to fail or worse.
 135      Use at your own risk.</para></listitem>
 136      </varlistentry>
 137
 138      <varlistentry><term>Force-LoopBreak</term>
 139      <listitem><para>Never Enable this option unless you -really- know what you are doing. It
 140      permits APT to temporarily remove an essential package to break a
 141      Conflicts/Conflicts or Conflicts/Pre-Depend loop between two essential
 142      packages. SUCH A LOOP SHOULD NEVER EXIST AND IS A GRAVE BUG. This option
 143      will work if the essential packages are not tar, gzip, libc, dpkg, bash or
 144      anything that those packages depend on.</para></listitem>
 145      </varlistentry>
 146
 147      <varlistentry><term>Cache-Limit</term>
 148      <listitem><para>APT uses a fixed size memory mapped cache file to store the 'available'
 149      information. This sets the size of that cache (in bytes).</para></listitem>
 150      </varlistentry>
 151
 152      <varlistentry><term>Build-Essential</term>
 153      <listitem><para>Defines which package(s) are considered essential build dependencies.</para></listitem>
 154      </varlistentry>
 155
 156      <varlistentry><term>Get</term>
 157      <listitem><para>The Get subsection controls the &apt-get; tool, please see its
 158      documentation for more information about the options here.</para></listitem>
 159      </varlistentry>
 160
 161      <varlistentry><term>Cache</term>
 162      <listitem><para>The Cache subsection controls the &apt-cache; tool, please see its
 163      documentation for more information about the options here.</para></listitem>
 164      </varlistentry>
 165
 166      <varlistentry><term>CDROM</term>
 167      <listitem><para>The CDROM subsection controls the &apt-cdrom; tool, please see its
 168      documentation for more information about the options here.</para></listitem>
 169      </varlistentry>
 170    </variablelist>
 171  </refsect1>
 172
 173  <refsect1><title>The Acquire Group</title>
 174    <para>The <literal>Acquire</literal> group of options controls the download of packages
 175    and the URI handlers.
 176
 177    <variablelist>
 178      <varlistentry><term>PDiffs</term>
 179          <listitem><para>Try to download deltas called <literal>PDiffs</literal> for
 180          Packages or Sources files instead of downloading whole ones. True
 181          by default.</para></listitem>
 182      </varlistentry>
 183
 184      <varlistentry><term>Queue-Mode</term>
 185      <listitem><para>Queuing mode; <literal>Queue-Mode</literal> can be one of <literal>host</literal> or
 186      <literal>access</literal> which determines how  APT parallelizes outgoing
 187      connections. <literal>host</literal> means that one connection per target host
 188      will be opened, <literal>access</literal> means that one connection per URI type
 189      will be opened.</para></listitem>
 190      </varlistentry>
 191
 192      <varlistentry><term>Retries</term>
 193      <listitem><para>Number of retries to perform. If this is non-zero APT will retry failed
 194      files the given number of times.</para></listitem>
 195      </varlistentry>
 196
 197      <varlistentry><term>Source-Symlinks</term>
 198      <listitem><para>Use symlinks for source archives. If set to true then source archives will
 199      be symlinked when possible instead of copying. True is the default.</para></listitem>
 200      </varlistentry>
 201
 202      <varlistentry><term>http</term>
 203      <listitem><para>HTTP URIs; http::Proxy is the default http proxy to use. It is in the
 204      standard form of <literal>http://[[user][:pass]@]host[:port]/</literal>. Per
 205      host proxies can also be specified by using the form
 206      <literal>http::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal>
 207          meaning to use no proxies. If no one of the above settings is specified,
 208          <envar>http_proxy</envar> environment variable
 209          will be used.</para>
 210
 211      <para>Three settings are provided for cache control with HTTP/1.1 compliant
 212      proxy caches. <literal>No-Cache</literal> tells the proxy to not use its cached
 213      response under any circumstances, <literal>Max-Age</literal> is sent only for
 214      index files and tells the cache to refresh its object if it is older than
 215      the given number of seconds. Debian updates its index files daily so the
 216      default is 1 day. <literal>No-Store</literal> specifies that the cache should never
 217      store this request, it is only set for archive files. This may be useful
 218      to prevent polluting a proxy cache with very large .deb files. Note:
 219      Squid 2.0.2 does not support any of these options.</para>
 220
 221      <para>The option <literal>timeout</literal> sets the timeout timer used by the method,
 222      this applies to all things including connection timeout and data timeout.</para>
 223
 224      <para>One setting is provided to control the pipeline depth in cases where the
 225      remote server is not RFC conforming or buggy (such as Squid 2.0.2)
 226      <literal>Acquire::http::Pipeline-Depth</literal> can be a value from 0 to 5
 227      indicating how many outstanding requests APT should send. A value of
 228      zero MUST be specified if the remote host does not properly linger
 229      on TCP connections - otherwise data corruption will occur. Hosts which
 230      require this are in violation of RFC 2068.</para></listitem>
 231      </varlistentry>
 232
 233      <varlistentry><term>https</term>
 234          <listitem><para>HTTPS URIs. Cache-control and proxy options are the same as for
 235          <literal>http</literal> method.
 236          <literal>Pipeline-Depth</literal> option is not supported yet.</para>
 237
 238          <para><literal>CaInfo</literal> suboption specifies place of file that
 239          holds info about trusted certificates.
 240          <literal>&lt;host&gt;::CaInfo</literal> is corresponding per-host option.
 241          <literal>Verify-Peer</literal> boolean suboption determines whether verify
 242          server's host certificate against trusted certificates or not.
 243          <literal>&lt;host&gt;::Verify-Peer</literal> is corresponding per-host option.
 244          <literal>Verify-Host</literal> boolean suboption determines whether verify
 245          server's hostname or not.
 246          <literal>&lt;host&gt;::Verify-Host</literal> is corresponding per-host option.
 247          <literal>SslCert</literal> determines what certificate to use for client
 248          authentication. <literal>&lt;host&gt;::SslCert</literal> is corresponding per-host option.
 249          <literal>SslKey</literal> determines what private key to use for client
 250          authentication. <literal>&lt;host&gt;::SslKey</literal> is corresponding per-host option.
 251          <literal>SslForceVersion</literal> overrides default SSL version to use.
 252          Can contain 'TLSv1' or 'SSLv3' string.
 253          <literal>&lt;host&gt;::SslForceVersion</literal> is corresponding per-host option.
 254          </para></listitem></varlistentry>
 255
 256      <varlistentry><term>ftp</term>
 257      <listitem><para>FTP URIs; ftp::Proxy is the default ftp proxy to use. It is in the
 258      standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal>. Per
 259      host proxies can also be specified by using the form
 260      <literal>ftp::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal>
 261          meaning to use no proxies. If no one of the above settings is specified,
 262          <envar>ftp_proxy</envar> environment variable
 263          will be used. To use a ftp
 264      proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the
 265      configuration file. This entry specifies the commands to send to tell
 266      the proxy server what to connect to. Please see
 267      &configureindex; for an example of
 268      how to do this. The substitution variables available are
 269      <literal>$(PROXY_USER)</literal> <literal>$(PROXY_PASS)</literal> <literal>$(SITE_USER)</literal>
 270      <literal>$(SITE_PASS)</literal> <literal>$(SITE)</literal> and <literal>$(SITE_PORT)</literal>
 271      Each is taken from it's respective URI component.</para>
 272
 273      <para>The option <literal>timeout</literal> sets the timeout timer used by the method,
 274      this applies to all things including connection timeout and data timeout.</para>
 275
 276      <para>Several settings are provided to control passive mode. Generally it is
 277      safe to leave passive mode on, it works in nearly every environment.
 278      However some situations require that passive mode be disabled and port
 279      mode ftp used instead. This can be done globally, for connections that
 280      go through a proxy or for a specific host (See the sample config file
 281      for examples).</para>
 282
 283      <para>It is possible to proxy FTP over HTTP by setting the <envar>ftp_proxy</envar>
 284      environment variable to a http url - see the discussion of the http method
 285      above for syntax. You cannot set this in the configuration file and it is
 286      not recommended to use FTP over HTTP due to its low efficiency.</para>
 287
 288      <para>The setting <literal>ForceExtended</literal> controls the use of RFC2428
 289      <literal>EPSV</literal> and <literal>EPRT</literal> commands. The default is false, which means
 290      these commands are only used if the control connection is IPv6. Setting this
 291      to true forces their use even on IPv4 connections. Note that most FTP servers
 292      do not support RFC2428.</para></listitem>
 293      </varlistentry>
 294
 295      <varlistentry><term>cdrom</term>
 296      <listitem><para>CDROM URIs; the only setting for CDROM URIs is the mount point,
 297      <literal>cdrom::Mount</literal> which must be the mount point for the CDROM drive
 298      as specified in <filename>/etc/fstab</filename>. It is possible to provide
 299      alternate mount and unmount commands if your mount point cannot be listed
 300      in the fstab (such as an SMB mount and old mount packages). The syntax
 301      is to put <literallayout>"/cdrom/"::Mount "foo";</literallayout> within
 302      the cdrom block. It is important to have the trailing slash. Unmount
 303      commands can be specified using UMount.</para></listitem>
 304      </varlistentry>
 305
 306      <varlistentry><term>gpgv</term>
 307      <listitem><para>GPGV URIs; the only option for GPGV URIs is the option to pass additional parameters to gpgv.
 308      <literal>gpgv::Options</literal> Additional options passed to gpgv.
 309      </para></listitem>
 310      </varlistentry>
 311
 312      <varlistentry><term>CompressionTypes</term>
 313      <listitem><para>List of compression types which are understood by the acquire methods.
 314      Files like <filename>Packages</filename> can be available in various compression formats.
 315      This list defines in which order the acquire methods will try to download these files.
 316      Per default <command>bzip2</command> compressed files will be prefered over
 317      <command>lzma</command>, <command>gzip</command> and uncompressed files. The syntax for
 318      the configuration fileentry is
 319      <synopsis>Acquire::CompressionTypes::<replaceable>FileExtension</replaceable> "<replaceable>Methodname</replaceable>";</synopsis>
 320      e.g. <synopsis>Acquire::CompressionTypes::bz2 "bzip2";</synopsis>
 321      Note that at runtime the <literal>Dir::Bin::<replaceable>Methodname</replaceable></literal> will
 322      be checked: If this setting exists the method will only be used if this file exists, e.g. for
 323      the bzip2 method above (the inbuilt) setting is <literallayout>Dir::Bin::bzip2 "/bin/bzip2";</literallayout>
 324      </para></listitem>
 325      </varlistentry>
 326    </variablelist>
 327   </para>
 328  </refsect1>
 329
 330  <refsect1><title>Directories</title>
 331
 332    <para>The <literal>Dir::State</literal> section has directories that pertain to local
 333    state information. <literal>lists</literal> is the directory to place downloaded
 334    package lists in and <literal>status</literal> is the name of the dpkg status file.
 335    <literal>preferences</literal> is the name of the APT preferences file.
 336    <literal>Dir::State</literal> contains the default directory to prefix on all sub
 337    items if they do not start with <filename>/</filename> or <filename>./</filename>.</para>
 338
 339    <para><literal>Dir::Cache</literal> contains locations pertaining to local cache
 340    information, such as the two package caches <literal>srcpkgcache</literal> and
 341    <literal>pkgcache</literal> as well as the location to place downloaded archives,
 342    <literal>Dir::Cache::archives</literal>. Generation of caches can be turned off
 343    by setting their names to be blank. This will slow down startup but
 344    save disk space. It is probably preferred to turn off the pkgcache rather
 345    than the srcpkgcache. Like <literal>Dir::State</literal> the default
 346    directory is contained in <literal>Dir::Cache</literal></para>
 347
 348    <para><literal>Dir::Etc</literal> contains the location of configuration files,
 349    <literal>sourcelist</literal> gives the location of the sourcelist and
 350    <literal>main</literal> is the default configuration file (setting has no effect,
 351    unless it is done from the config file specified by
 352    <envar>APT_CONFIG</envar>).</para>
 353
 354    <para>The <literal>Dir::Parts</literal> setting reads in all the config fragments in
 355    lexical order from the directory specified. After this is done then the
 356    main config file is loaded.</para>
 357
 358    <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal>
 359    specifies the location of the method handlers and <literal>gzip</literal>,
 360    <literal>bzip2</literal>, <literal>lzma</literal>,
 361    <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal>
 362    <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
 363    of the respective programs.</para>
 364
 365    <para>
 366      The configuration item <literal>RootDir</literal> has a special
 367      meaning.  If set, all paths in <literal>Dir::</literal> will be
 368      relative to <literal>RootDir</literal>, <emphasis>even paths that
 369      are specified absolutely</emphasis>.  So, for instance, if
 370      <literal>RootDir</literal> is set to
 371      <filename>/tmp/staging</filename> and
 372      <literal>Dir::State::status</literal> is set to
 373      <filename>/var/lib/dpkg/status</filename>, then the status file
 374      will be looked up in
 375      <filename>/tmp/staging/var/lib/dpkg/status</filename>.
 376    </para>
 377  </refsect1>
 378
 379  <refsect1><title>APT in DSelect</title>
 380    <para>
 381    When APT is used as a &dselect; method several configuration directives
 382    control the default behaviour. These are in the <literal>DSelect</literal> section.</para>
 383
 384    <variablelist>
 385      <varlistentry><term>Clean</term>
 386      <listitem><para>Cache Clean mode; this value may be one of always, prompt, auto,
 387      pre-auto and never.  always and prompt will remove all packages from
 388      the cache after upgrading, prompt (the default) does so conditionally.
 389      auto removes only those packages which are no longer downloadable
 390      (replaced with a new version for instance).  pre-auto performs this
 391      action before downloading new packages.</para></listitem>
 392      </varlistentry>
 393
 394      <varlistentry><term>options</term>
 395      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 396      options when it is run for the install phase.</para></listitem>
 397      </varlistentry>
 398
 399      <varlistentry><term>Updateoptions</term>
 400      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 401      options when it is run for the update phase.</para></listitem>
 402      </varlistentry>
 403
 404      <varlistentry><term>PromptAfterUpdate</term>
 405      <listitem><para>If true the [U]pdate operation in &dselect; will always prompt to continue.
 406      The default is to prompt only on error.</para></listitem>
 407      </varlistentry>
 408    </variablelist>
 409  </refsect1>
 410
 411  <refsect1><title>How APT calls dpkg</title>
 412    <para>Several configuration directives control how APT invokes &dpkg;. These are
 413    in the <literal>DPkg</literal> section.</para>
 414
 415    <variablelist>
 416      <varlistentry><term>options</term>
 417      <listitem><para>This is a list of options to pass to dpkg. The options must be specified
 418      using the list notation and each list item is passed as a single argument
 419      to &dpkg;.</para></listitem>
 420      </varlistentry>
 421
 422      <varlistentry><term>Pre-Invoke</term><term>Post-Invoke</term>
 423      <listitem><para>This is a list of shell commands to run before/after invoking &dpkg;.
 424      Like <literal>options</literal> this must be specified in list notation. The
 425      commands are invoked in order using <filename>/bin/sh</filename>, should any
 426      fail APT will abort.</para></listitem>
 427      </varlistentry>
 428
 429      <varlistentry><term>Pre-Install-Pkgs</term>
 430      <listitem><para>This is a list of shell commands to run before invoking dpkg. Like
 431      <literal>options</literal> this must be specified in list notation. The commands
 432      are invoked in order using <filename>/bin/sh</filename>, should any fail APT
 433      will abort. APT will pass to the commands on standard input the
 434      filenames of all .deb files it is going to install, one per line.</para>
 435
 436      <para>Version 2 of this protocol dumps more information, including the
 437      protocol version, the APT configuration space and the packages, files
 438      and versions being changed. Version 2 is enabled by setting
 439      <literal>DPkg::Tools::options::cmd::Version</literal> to 2. <literal>cmd</literal> is a
 440      command given to <literal>Pre-Install-Pkgs</literal>.</para></listitem>
 441      </varlistentry>
 442
 443      <varlistentry><term>Run-Directory</term>
 444      <listitem><para>APT chdirs to this directory before invoking dpkg, the default is
 445      <filename>/</filename>.</para></listitem>
 446      </varlistentry>
 447
 448      <varlistentry><term>Build-options</term>
 449      <listitem><para>These options are passed to &dpkg-buildpackage; when compiling packages,
 450      the default is to disable signing and produce all binaries.</para></listitem>
 451      </varlistentry>
 452    </variablelist>
 453  </refsect1>
 454
 455  <refsect1>
 456    <title>Periodic and Archives options</title>
 457    <para><literal>APT::Periodic</literal> and <literal>APT::Archives</literal>
 458    groups of options configure behavior of apt periodic updates, which is
 459    done by <literal>/etc/cron.daily/apt</literal> script. See header of
 460    this script for the brief documentation of these options.
 461    </para>
 462  </refsect1>
 463
 464  <refsect1>
 465    <title>Debug options</title>
 466    <para>
 467      Enabling options in the <literal>Debug::</literal> section will
 468      cause debugging information to be sent to the standard error
 469      stream of the program utilizing the <literal>apt</literal>
 470      libraries, or enable special program modes that are primarily
 471      useful for debugging the behavior of <literal>apt</literal>.
 472      Most of these options are not interesting to a normal user, but a
 473      few may be:
 474
 475      <itemizedlist>
 476        <listitem>
 477          <para>
 478            <literal>Debug::pkgProblemResolver</literal> enables output
 479            about the decisions made by
 480            <literal>dist-upgrade, upgrade, install, remove, purge</literal>.
 481          </para>
 482        </listitem>
 483
 484        <listitem>
 485          <para>
 486            <literal>Debug::NoLocking</literal> disables all file
 487            locking.  This can be used to run some operations (for
 488            instance, <literal>apt-get -s install</literal>) as a
 489            non-root user.
 490          </para>
 491        </listitem>
 492
 493        <listitem>
 494          <para>
 495            <literal>Debug::pkgDPkgPM</literal> prints out the actual
 496            command line each time that <literal>apt</literal> invokes
 497            &dpkg;.
 498          </para>
 499        </listitem>
 500
 501        <listitem>
 502          <para>
 503            <literal>Debug::IdentCdrom</literal> disables the inclusion
 504            of statfs data in CDROM IDs.  <!-- TODO: provide a
 505            motivating example, except I haven't a clue why you'd want
 506            to do this. -->
 507          </para>
 508        </listitem>
 509      </itemizedlist>
 510    </para>
 511
 512    <para>
 513      A full list of debugging options to apt follows.
 514    </para>
 515
 516    <variablelist>
 517      <varlistentry>
 518        <term><literal>Debug::Acquire::cdrom</literal></term>
 519
 520        <listitem>
 521          <para>
 522            Print information related to accessing
 523            <literal>cdrom://</literal> sources.
 524          </para>
 525        </listitem>
 526      </varlistentry>
 527
 528      <varlistentry>
 529        <term><literal>Debug::Acquire::ftp</literal></term>
 530
 531        <listitem>
 532          <para>
 533            Print information related to downloading packages using
 534            FTP.
 535          </para>
 536        </listitem>
 537      </varlistentry>
 538
 539      <varlistentry>
 540        <term><literal>Debug::Acquire::http</literal></term>
 541
 542        <listitem>
 543          <para>
 544            Print information related to downloading packages using
 545            HTTP.
 546          </para>
 547        </listitem>
 548      </varlistentry>
 549
 550      <varlistentry>
 551        <term><literal>Debug::Acquire::https</literal></term>
 552
 553        <listitem>
 554          <para>
 555            Print information related to downloading packages using
 556            HTTPS.
 557          </para>
 558        </listitem>
 559      </varlistentry>
 560
 561      <varlistentry>
 562        <term><literal>Debug::Acquire::gpgv</literal></term>
 563
 564        <listitem>
 565          <para>
 566            Print information related to verifying cryptographic
 567            signatures using <literal>gpg</literal>.
 568          </para>
 569        </listitem>
 570      </varlistentry>
 571
 572      <varlistentry>
 573        <term><literal>Debug::aptcdrom</literal></term>
 574
 575        <listitem>
 576          <para>
 577            Output information about the process of accessing
 578            collections of packages stored on CD-ROMs.
 579          </para>
 580        </listitem>
 581      </varlistentry>
 582
 583      <varlistentry>
 584        <term><literal>Debug::BuildDeps</literal></term>
 585        <listitem>
 586          <para>
 587            Describes the process of resolving build-dependencies in
 588            &apt-get;.
 589          </para>
 590        </listitem>
 591      </varlistentry>
 592
 593      <varlistentry>
 594        <term><literal>Debug::Hashes</literal></term>
 595        <listitem>
 596          <para>
 597            Output each cryptographic hash that is generated by the
 598            <literal>apt</literal> libraries.
 599          </para>
 600        </listitem>
 601      </varlistentry>
 602
 603      <varlistentry>
 604        <term><literal>Debug::IdentCDROM</literal></term>
 605        <listitem>
 606          <para>
 607            Do not include information from <literal>statfs</literal>,
 608            namely the number of used and free blocks on the CD-ROM
 609            filesystem, when generating an ID for a CD-ROM.
 610          </para>
 611        </listitem>
 612      </varlistentry>
 613
 614      <varlistentry>
 615        <term><literal>Debug::NoLocking</literal></term>
 616        <listitem>
 617          <para>
 618            Disable all file locking.  For instance, this will allow
 619            two instances of <quote><literal>apt-get
 620            update</literal></quote> to run at the same time.
 621          </para>
 622        </listitem>
 623      </varlistentry>
 624
 625      <varlistentry>
 626        <term><literal>Debug::pkgAcquire</literal></term>
 627
 628        <listitem>
 629          <para>
 630            Log when items are added to or removed from the global
 631            download queue.
 632          </para>
 633        </listitem>
 634      </varlistentry>
 635
 636      <varlistentry>
 637        <term><literal>Debug::pkgAcquire::Auth</literal></term>
 638        <listitem>
 639          <para>
 640            Output status messages and errors related to verifying
 641            checksums and cryptographic signatures of downloaded files.
 642          </para>
 643        </listitem>
 644      </varlistentry>
 645
 646      <varlistentry>
 647        <term><literal>Debug::pkgAcquire::Diffs</literal></term>
 648        <listitem>
 649          <para>
 650            Output information about downloading and applying package
 651            index list diffs, and errors relating to package index list
 652            diffs.
 653          </para>
 654        </listitem>
 655      </varlistentry>
 656
 657      <varlistentry>
 658        <term><literal>Debug::pkgAcquire::RRed</literal></term>
 659
 660        <listitem>
 661          <para>
 662            Output information related to patching apt package lists
 663            when downloading index diffs instead of full indices.
 664          </para>
 665        </listitem>
 666      </varlistentry>
 667
 668      <varlistentry>
 669        <term><literal>Debug::pkgAcquire::Worker</literal></term>
 670
 671        <listitem>
 672          <para>
 673            Log all interactions with the sub-processes that actually
 674            perform downloads.
 675          </para>
 676        </listitem>
 677      </varlistentry>
 678
 679      <varlistentry>
 680        <term><literal>Debug::pkgAutoRemove</literal></term>
 681
 682        <listitem>
 683          <para>
 684            Log events related to the automatically-installed status of
 685            packages and to the removal of unused packages.
 686          </para>
 687        </listitem>
 688      </varlistentry>
 689
 690      <varlistentry>
 691        <term><literal>Debug::pkgDepCache::AutoInstall</literal></term>
 692        <listitem>
 693          <para>
 694            Generate debug messages describing which packages are being
 695            automatically installed to resolve dependencies.  This
 696            corresponds to the initial auto-install pass performed in,
 697            e.g., <literal>apt-get install</literal>, and not to the
 698            full <literal>apt</literal> dependency resolver; see
 699            <literal>Debug::pkgProblemResolver</literal> for that.
 700          </para>
 701        </listitem>
 702      </varlistentry>
 703
 704      <varlistentry>
 705        <term><literal>Debug::pkgDepCache::Marker</literal></term>
 706        <listitem>
 707         <para>
 708            Generate debug messages describing which package is marked
 709           as keep/install/remove while the ProblemResolver does his work.
 710           Each addition or deletion may trigger additional actions;
 711           they are shown indented two additional space under the original entry.
 712           The format for each line is <literal>MarkKeep</literal>,
 713           <literal>MarkDelete</literal> or <literal>MarkInstall</literal> followed by
 714           <literal>package-name &lt;a.b.c -&gt; d.e.f | x.y.z&gt; (section)</literal>
 715           where <literal>a.b.c</literal> is the current version of the package,
 716           <literal>d.e.f</literal> is the version considered for installation and
 717           <literal>x.y.z</literal> is a newer version, but not considered for installation
 718           (because of a low pin score). The later two can be omitted if there is none or if
 719           it is the same version as the installed.
 720           <literal>section</literal> is the name of the section the package appears in.
 721         </para>
 722        </listitem>
 723      </varlistentry>
 724
 725      <!-- Question: why doesn't this do anything?  The code says it should. -->
 726      <varlistentry>
 727        <term><literal>Debug::pkgInitConfig</literal></term>
 728        <listitem>
 729          <para>
 730            Dump the default configuration to standard error on
 731            startup.
 732          </para>
 733        </listitem>
 734      </varlistentry>
 735
 736      <varlistentry>
 737        <term><literal>Debug::pkgDPkgPM</literal></term>
 738        <listitem>
 739          <para>
 740            When invoking &dpkg;, output the precise command line with
 741            which it is being invoked, with arguments separated by a
 742            single space character.
 743          </para>
 744        </listitem>
 745      </varlistentry>
 746
 747      <varlistentry>
 748        <term><literal>Debug::pkgDPkgProgressReporting</literal></term>
 749        <listitem>
 750          <para>
 751            Output all the data received from &dpkg; on the status file
 752            descriptor and any errors encountered while parsing it.
 753          </para>
 754        </listitem>
 755      </varlistentry>
 756
 757      <varlistentry>
 758        <term><literal>Debug::pkgOrderList</literal></term>
 759
 760        <listitem>
 761          <para>
 762            Generate a trace of the algorithm that decides the order in
 763            which <literal>apt</literal> should pass packages to
 764            &dpkg;.
 765          </para>
 766        </listitem>
 767      </varlistentry>
 768
 769      <varlistentry>
 770        <term><literal>Debug::pkgPackageManager</literal></term>
 771
 772        <listitem>
 773          <para>
 774            Output status messages tracing the steps performed when
 775            invoking &dpkg;.
 776          </para>
 777        </listitem>
 778      </varlistentry>
 779
 780      <varlistentry>
 781        <term><literal>Debug::pkgPolicy</literal></term>
 782
 783        <listitem>
 784          <para>
 785            Output the priority of each package list on startup.
 786          </para>
 787        </listitem>
 788      </varlistentry>
 789
 790      <varlistentry>
 791        <term><literal>Debug::pkgProblemResolver</literal></term>
 792
 793        <listitem>
 794          <para>
 795            Trace the execution of the dependency resolver (this
 796            applies only to what happens when a complex dependency
 797            problem is encountered).
 798          </para>
 799        </listitem>
 800      </varlistentry>
 801
 802      <varlistentry>
 803        <term><literal>Debug::pkgProblemResolver::ShowScores</literal></term>
 804        <listitem>
 805         <para>
 806           Display a list of all installed packages with their calculated score
 807           used by the pkgProblemResolver. The description of the package
 808           is the same as described in <literal>Debug::pkgDepCache::Marker</literal>
 809         </para>
 810        </listitem>
 811      </varlistentry>
 812
 813      <varlistentry>
 814        <term><literal>Debug::sourceList</literal></term>
 815
 816        <listitem>
 817          <para>
 818            Print information about the vendors read from
 819            <filename>/etc/apt/vendors.list</filename>.
 820          </para>
 821        </listitem>
 822      </varlistentry>
 823
 824 <!-- 2009/07/11 Currently used nowhere. The corresponding code
 825 is commented.
 826      <varlistentry>
 827        <term><literal>Debug::Vendor</literal></term>
 828
 829        <listitem>
 830          <para>
 831            Print information about each vendor.
 832          </para>
 833        </listitem>
 834      </varlistentry>
 835 -->
 836    </variablelist>
 837  </refsect1>
 838
 839  <refsect1><title>Examples</title>
 840    <para>&configureindex; is a
 841    configuration file showing example values for all possible
 842    options.</para>
 843  </refsect1>
 844
 845  <refsect1><title>Files</title>
 846    <variablelist>
 847       <varlistentry><term><filename>/etc/apt/apt.conf</filename></term>
 848       <listitem><para>APT configuration file.
 849       Configuration Item: <literal>Dir::Etc::Main</literal>.</para></listitem>
 850       </varlistentry>
 851
 852       <varlistentry><term><filename>/etc/apt/apt.conf.d/</filename></term>
 853       <listitem><para>APT configuration file fragments.
 854       Configuration Item: <literal>Dir::Etc::Parts</literal>.</para></listitem>
 855       </varlistentry>
 856    </variablelist>
 857  </refsect1>
 858
 859  <refsect1><title>See Also</title>
 860    <para>&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.</para>
 861  </refsect1>
 862
 863  &manbugs;
 864
 865 </refentry>
 866