doc/apt.conf.5.xml

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