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. The <envar>http_proxy</envar> environment variable
 208      will override all settings.</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 proxy server to use. It is in the
 257      standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal> and is
 258      overridden by the <envar>ftp_proxy</envar> environment variable. To use a ftp
 259      proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the
 260      configuration file. This entry specifies the commands to send to tell
 261      the proxy server what to connect to. Please see
 262      &configureindex; for an example of
 263      how to do this. The substitution variables available are
 264      <literal>$(PROXY_USER)</literal> <literal>$(PROXY_PASS)</literal> <literal>$(SITE_USER)</literal>
 265      <literal>$(SITE_PASS)</literal> <literal>$(SITE)</literal> and <literal>$(SITE_PORT)</literal>
 266      Each is taken from it's respective URI component.</para>
 267
 268      <para>The option <literal>timeout</literal> sets the timeout timer used by the method,
 269      this applies to all things including connection timeout and data timeout.</para>
 270
 271      <para>Several settings are provided to control passive mode. Generally it is
 272      safe to leave passive mode on, it works in nearly every environment.
 273      However some situations require that passive mode be disabled and port
 274      mode ftp used instead. This can be done globally, for connections that
 275      go through a proxy or for a specific host (See the sample config file
 276      for examples).</para>
 277
 278      <para>It is possible to proxy FTP over HTTP by setting the <envar>ftp_proxy</envar>
 279      environment variable to a http url - see the discussion of the http method
 280      above for syntax. You cannot set this in the configuration file and it is
 281      not recommended to use FTP over HTTP due to its low efficiency.</para>
 282
 283      <para>The setting <literal>ForceExtended</literal> controls the use of RFC2428
 284      <literal>EPSV</literal> and <literal>EPRT</literal> commands. The default is false, which means
 285      these commands are only used if the control connection is IPv6. Setting this
 286      to true forces their use even on IPv4 connections. Note that most FTP servers
 287      do not support RFC2428.</para></listitem>
 288      </varlistentry>
 289
 290      <varlistentry><term>cdrom</term>
 291      <listitem><para>CDROM URIs; the only setting for CDROM URIs is the mount point,
 292      <literal>cdrom::Mount</literal> which must be the mount point for the CDROM drive
 293      as specified in <filename>/etc/fstab</filename>. It is possible to provide
 294      alternate mount and unmount commands if your mount point cannot be listed
 295      in the fstab (such as an SMB mount and old mount packages). The syntax
 296      is to put <literallayout>"/cdrom/"::Mount "foo";</literallayout> within
 297      the cdrom block. It is important to have the trailing slash. Unmount
 298      commands can be specified using UMount.</para></listitem>
 299      </varlistentry>
 300
 301      <varlistentry><term>gpgv</term>
 302      <listitem><para>GPGV URIs; the only option for GPGV URIs is the option to pass additional parameters to gpgv.
 303      <literal>gpgv::Options</literal> Additional options passed to gpgv.
 304      </para></listitem>
 305      </varlistentry>
 306
 307      <varlistentry><term>CompressionTypes</term>
 308      <listitem><para>List of compression types which are understood by the acquire methods.
 309      Files like <filename>Packages</filename> can be available in various compression formats.
 310      This list defines in which order the acquire methods will try to download these files.
 311      Per default <command>bzip2</command> compressed files will be prefered over
 312      <command>lzma</command>, <command>gzip</command> and uncompressed files. The syntax for
 313      the configuration fileentry is
 314      <synopsis>Acquire::CompressionTypes::<replaceable>FileExtension</replaceable> "<replaceable>Methodname</replaceable>";</synopsis>
 315      e.g. <synopsis>Acquire::CompressionTypes::bz2 "bzip2";</synopsis>
 316      Note that at runtime the <literal>Dir::Bin::<replaceable>Methodname</replaceable></literal> will
 317      be checked: If this setting exists the method will only be used if this file exists, e.g. for
 318      the bzip2 method above (the inbuilt) setting is <literallayout>Dir::Bin::bzip2 "/bin/bzip2";</literallayout>
 319      </para></listitem>
 320      </varlistentry>
 321    </variablelist>
 322   </para>
 323  </refsect1>
 324
 325  <refsect1><title>Directories</title>
 326
 327    <para>The <literal>Dir::State</literal> section has directories that pertain to local
 328    state information. <literal>lists</literal> is the directory to place downloaded
 329    package lists in and <literal>status</literal> is the name of the dpkg status file.
 330    <literal>preferences</literal> is the name of the APT preferences file.
 331    <literal>Dir::State</literal> contains the default directory to prefix on all sub
 332    items if they do not start with <filename>/</filename> or <filename>./</filename>.</para>
 333
 334    <para><literal>Dir::Cache</literal> contains locations pertaining to local cache
 335    information, such as the two package caches <literal>srcpkgcache</literal> and
 336    <literal>pkgcache</literal> as well as the location to place downloaded archives,
 337    <literal>Dir::Cache::archives</literal>. Generation of caches can be turned off
 338    by setting their names to be blank. This will slow down startup but
 339    save disk space. It is probably preferred to turn off the pkgcache rather
 340    than the srcpkgcache. Like <literal>Dir::State</literal> the default
 341    directory is contained in <literal>Dir::Cache</literal></para>
 342
 343    <para><literal>Dir::Etc</literal> contains the location of configuration files,
 344    <literal>sourcelist</literal> gives the location of the sourcelist and
 345    <literal>main</literal> is the default configuration file (setting has no effect,
 346    unless it is done from the config file specified by
 347    <envar>APT_CONFIG</envar>).</para>
 348
 349    <para>The <literal>Dir::Parts</literal> setting reads in all the config fragments in
 350    lexical order from the directory specified. After this is done then the
 351    main config file is loaded.</para>
 352
 353    <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal>
 354    specifies the location of the method handlers and <literal>gzip</literal>,
 355    <literal>bzip2</literal>, <literal>lzma</literal>,
 356    <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal>
 357    <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
 358    of the respective programs.</para>
 359
 360    <para>
 361      The configuration item <literal>RootDir</literal> has a special
 362      meaning.  If set, all paths in <literal>Dir::</literal> will be
 363      relative to <literal>RootDir</literal>, <emphasis>even paths that
 364      are specified absolutely</emphasis>.  So, for instance, if
 365      <literal>RootDir</literal> is set to
 366      <filename>/tmp/staging</filename> and
 367      <literal>Dir::State::status</literal> is set to
 368      <filename>/var/lib/dpkg/status</filename>, then the status file
 369      will be looked up in
 370      <filename>/tmp/staging/var/lib/dpkg/status</filename>.
 371    </para>
 372  </refsect1>
 373
 374  <refsect1><title>APT in DSelect</title>
 375    <para>
 376    When APT is used as a &dselect; method several configuration directives
 377    control the default behaviour. These are in the <literal>DSelect</literal> section.</para>
 378
 379    <variablelist>
 380      <varlistentry><term>Clean</term>
 381      <listitem><para>Cache Clean mode; this value may be one of always, prompt, auto,
 382      pre-auto and never.  always and prompt will remove all packages from
 383      the cache after upgrading, prompt (the default) does so conditionally.
 384      auto removes only those packages which are no longer downloadable
 385      (replaced with a new version for instance).  pre-auto performs this
 386      action before downloading new packages.</para></listitem>
 387      </varlistentry>
 388
 389      <varlistentry><term>options</term>
 390      <listitem><para>The contents of this variable is passed to &apt-get; as command line
 391      options when it is run for the install phase.</para></listitem>
 392      </varlistentry>
 393
 394      <varlistentry><term>Updateoptions</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 update phase.</para></listitem>
 397      </varlistentry>
 398
 399      <varlistentry><term>PromptAfterUpdate</term>
 400      <listitem><para>If true the [U]pdate operation in &dselect; will always prompt to continue.
 401      The default is to prompt only on error.</para></listitem>
 402      </varlistentry>
 403    </variablelist>
 404  </refsect1>
 405
 406  <refsect1><title>How APT calls dpkg</title>
 407    <para>Several configuration directives control how APT invokes &dpkg;. These are
 408    in the <literal>DPkg</literal> section.</para>
 409
 410    <variablelist>
 411      <varlistentry><term>options</term>
 412      <listitem><para>This is a list of options to pass to dpkg. The options must be specified
 413      using the list notation and each list item is passed as a single argument
 414      to &dpkg;.</para></listitem>
 415      </varlistentry>
 416
 417      <varlistentry><term>Pre-Invoke</term><term>Post-Invoke</term>
 418      <listitem><para>This is a list of shell commands to run before/after invoking &dpkg;.
 419      Like <literal>options</literal> this must be specified in list notation. The
 420      commands are invoked in order using <filename>/bin/sh</filename>, should any
 421      fail APT will abort.</para></listitem>
 422      </varlistentry>
 423
 424      <varlistentry><term>Pre-Install-Pkgs</term>
 425      <listitem><para>This is a list of shell commands to run before invoking dpkg. Like
 426      <literal>options</literal> this must be specified in list notation. The commands
 427      are invoked in order using <filename>/bin/sh</filename>, should any fail APT
 428      will abort. APT will pass to the commands on standard input the
 429      filenames of all .deb files it is going to install, one per line.</para>
 430
 431      <para>Version 2 of this protocol dumps more information, including the
 432      protocol version, the APT configuration space and the packages, files
 433      and versions being changed. Version 2 is enabled by setting
 434      <literal>DPkg::Tools::options::cmd::Version</literal> to 2. <literal>cmd</literal> is a
 435      command given to <literal>Pre-Install-Pkgs</literal>.</para></listitem>
 436      </varlistentry>
 437
 438      <varlistentry><term>Run-Directory</term>
 439      <listitem><para>APT chdirs to this directory before invoking dpkg, the default is
 440      <filename>/</filename>.</para></listitem>
 441      </varlistentry>
 442
 443      <varlistentry><term>Build-options</term>
 444      <listitem><para>These options are passed to &dpkg-buildpackage; when compiling packages,
 445      the default is to disable signing and produce all binaries.</para></listitem>
 446      </varlistentry>
 447    </variablelist>
 448  </refsect1>
 449
 450  <refsect1>
 451    <title>Periodic and Archives options</title>
 452    <para><literal>APT::Periodic</literal> and <literal>APT::Archives</literal>
 453    groups of options configure behavior of apt periodic updates, which is
 454    done by <literal>/etc/cron.daily/apt</literal> script. See header of
 455    this script for the brief documentation of these options.
 456    </para>
 457  </refsect1>
 458
 459  <refsect1>
 460    <title>Debug options</title>
 461    <para>
 462      Enabling options in the <literal>Debug::</literal> section will
 463      cause debugging information to be sent to the standard error
 464      stream of the program utilizing the <literal>apt</literal>
 465      libraries, or enable special program modes that are primarily
 466      useful for debugging the behavior of <literal>apt</literal>.
 467      Most of these options are not interesting to a normal user, but a
 468      few may be:
 469
 470      <itemizedlist>
 471        <listitem>
 472          <para>
 473            <literal>Debug::pkgProblemResolver</literal> enables output
 474            about the decisions made by
 475            <literal>dist-upgrade, upgrade, install, remove, purge</literal>.
 476          </para>
 477        </listitem>
 478
 479        <listitem>
 480          <para>
 481            <literal>Debug::NoLocking</literal> disables all file
 482            locking.  This can be used to run some operations (for
 483            instance, <literal>apt-get -s install</literal>) as a
 484            non-root user.
 485          </para>
 486        </listitem>
 487
 488        <listitem>
 489          <para>
 490            <literal>Debug::pkgDPkgPM</literal> prints out the actual
 491            command line each time that <literal>apt</literal> invokes
 492            &dpkg;.
 493          </para>
 494        </listitem>
 495
 496        <listitem>
 497          <para>
 498            <literal>Debug::IdentCdrom</literal> disables the inclusion
 499            of statfs data in CDROM IDs.  <!-- TODO: provide a
 500            motivating example, except I haven't a clue why you'd want
 501            to do this. -->
 502          </para>
 503        </listitem>
 504      </itemizedlist>
 505    </para>
 506
 507    <para>
 508      A full list of debugging options to apt follows.
 509    </para>
 510
 511    <variablelist>
 512      <varlistentry>
 513        <term><literal>Debug::Acquire::cdrom</literal></term>
 514
 515        <listitem>
 516          <para>
 517            Print information related to accessing
 518            <literal>cdrom://</literal> sources.
 519          </para>
 520        </listitem>
 521      </varlistentry>
 522
 523      <varlistentry>
 524        <term><literal>Debug::Acquire::ftp</literal></term>
 525
 526        <listitem>
 527          <para>
 528            Print information related to downloading packages using
 529            FTP.
 530          </para>
 531        </listitem>
 532      </varlistentry>
 533
 534      <varlistentry>
 535        <term><literal>Debug::Acquire::http</literal></term>
 536
 537        <listitem>
 538          <para>
 539            Print information related to downloading packages using
 540            HTTP.
 541          </para>
 542        </listitem>
 543      </varlistentry>
 544
 545      <varlistentry>
 546        <term><literal>Debug::Acquire::https</literal></term>
 547
 548        <listitem>
 549          <para>
 550            Print information related to downloading packages using
 551            HTTPS.
 552          </para>
 553        </listitem>
 554      </varlistentry>
 555
 556      <varlistentry>
 557        <term><literal>Debug::Acquire::gpgv</literal></term>
 558
 559        <listitem>
 560          <para>
 561            Print information related to verifying cryptographic
 562            signatures using <literal>gpg</literal>.
 563          </para>
 564        </listitem>
 565      </varlistentry>
 566
 567      <varlistentry>
 568        <term><literal>Debug::aptcdrom</literal></term>
 569
 570        <listitem>
 571          <para>
 572            Output information about the process of accessing
 573            collections of packages stored on CD-ROMs.
 574          </para>
 575        </listitem>
 576      </varlistentry>
 577
 578      <varlistentry>
 579        <term><literal>Debug::BuildDeps</literal></term>
 580        <listitem>
 581          <para>
 582            Describes the process of resolving build-dependencies in
 583            &apt-get;.
 584          </para>
 585        </listitem>
 586      </varlistentry>
 587
 588      <varlistentry>
 589        <term><literal>Debug::Hashes</literal></term>
 590        <listitem>
 591          <para>
 592            Output each cryptographic hash that is generated by the
 593            <literal>apt</literal> libraries.
 594          </para>
 595        </listitem>
 596      </varlistentry>
 597
 598      <varlistentry>
 599        <term><literal>Debug::IdentCDROM</literal></term>
 600        <listitem>
 601          <para>
 602            Do not include information from <literal>statfs</literal>,
 603            namely the number of used and free blocks on the CD-ROM
 604            filesystem, when generating an ID for a CD-ROM.
 605          </para>
 606        </listitem>
 607      </varlistentry>
 608
 609      <varlistentry>
 610        <term><literal>Debug::NoLocking</literal></term>
 611        <listitem>
 612          <para>
 613            Disable all file locking.  For instance, this will allow
 614            two instances of <quote><literal>apt-get
 615            update</literal></quote> to run at the same time.
 616          </para>
 617        </listitem>
 618      </varlistentry>
 619
 620      <varlistentry>
 621        <term><literal>Debug::pkgAcquire</literal></term>
 622
 623        <listitem>
 624          <para>
 625            Log when items are added to or removed from the global
 626            download queue.
 627          </para>
 628        </listitem>
 629      </varlistentry>
 630
 631      <varlistentry>
 632        <term><literal>Debug::pkgAcquire::Auth</literal></term>
 633        <listitem>
 634          <para>
 635            Output status messages and errors related to verifying
 636            checksums and cryptographic signatures of downloaded files.
 637          </para>
 638        </listitem>
 639      </varlistentry>
 640
 641      <varlistentry>
 642        <term><literal>Debug::pkgAcquire::Diffs</literal></term>
 643        <listitem>
 644          <para>
 645            Output information about downloading and applying package
 646            index list diffs, and errors relating to package index list
 647            diffs.
 648          </para>
 649        </listitem>
 650      </varlistentry>
 651
 652      <varlistentry>
 653        <term><literal>Debug::pkgAcquire::RRed</literal></term>
 654
 655        <listitem>
 656          <para>
 657            Output information related to patching apt package lists
 658            when downloading index diffs instead of full indices.
 659          </para>
 660        </listitem>
 661      </varlistentry>
 662
 663      <varlistentry>
 664        <term><literal>Debug::pkgAcquire::Worker</literal></term>
 665
 666        <listitem>
 667          <para>
 668            Log all interactions with the sub-processes that actually
 669            perform downloads.
 670          </para>
 671        </listitem>
 672      </varlistentry>
 673
 674      <varlistentry>
 675        <term><literal>Debug::pkgAutoRemove</literal></term>
 676
 677        <listitem>
 678          <para>
 679            Log events related to the automatically-installed status of
 680            packages and to the removal of unused packages.
 681          </para>
 682        </listitem>
 683      </varlistentry>
 684
 685      <varlistentry>
 686        <term><literal>Debug::pkgDepCache::AutoInstall</literal></term>
 687        <listitem>
 688          <para>
 689            Generate debug messages describing which packages are being
 690            automatically installed to resolve dependencies.  This
 691            corresponds to the initial auto-install pass performed in,
 692            e.g., <literal>apt-get install</literal>, and not to the
 693            full <literal>apt</literal> dependency resolver; see
 694            <literal>Debug::pkgProblemResolver</literal> for that.
 695          </para>
 696        </listitem>
 697      </varlistentry>
 698
 699      <varlistentry>
 700        <term><literal>Debug::pkgDepCache::Marker</literal></term>
 701        <listitem>
 702         <para>
 703            Generate debug messages describing which package is marked
 704           as keep/install/remove while the ProblemResolver does his work.
 705           Each addition or deletion may trigger additional actions;
 706           they are shown indented two additional space under the original entry.
 707           The format for each line is <literal>MarkKeep</literal>,
 708           <literal>MarkDelete</literal> or <literal>MarkInstall</literal> followed by
 709           <literal>package-name &lt;a.b.c -&gt; d.e.f | x.y.z&gt; (section)</literal>
 710           where <literal>a.b.c</literal> is the current version of the package,
 711           <literal>d.e.f</literal> is the version considered for installation and
 712           <literal>x.y.z</literal> is a newer version, but not considered for installation
 713           (because of a low pin score). The later two can be omitted if there is none or if
 714           it is the same version as the installed.
 715           <literal>section</literal> is the name of the section the package appears in.
 716         </para>
 717        </listitem>
 718      </varlistentry>
 719
 720      <!-- Question: why doesn't this do anything?  The code says it should. -->
 721      <varlistentry>
 722        <term><literal>Debug::pkgInitConfig</literal></term>
 723        <listitem>
 724          <para>
 725            Dump the default configuration to standard error on
 726            startup.
 727          </para>
 728        </listitem>
 729      </varlistentry>
 730
 731      <varlistentry>
 732        <term><literal>Debug::pkgDPkgPM</literal></term>
 733        <listitem>
 734          <para>
 735            When invoking &dpkg;, output the precise command line with
 736            which it is being invoked, with arguments separated by a
 737            single space character.
 738          </para>
 739        </listitem>
 740      </varlistentry>
 741
 742      <varlistentry>
 743        <term><literal>Debug::pkgDPkgProgressReporting</literal></term>
 744        <listitem>
 745          <para>
 746            Output all the data received from &dpkg; on the status file
 747            descriptor and any errors encountered while parsing it.
 748          </para>
 749        </listitem>
 750      </varlistentry>
 751
 752      <varlistentry>
 753        <term><literal>Debug::pkgOrderList</literal></term>
 754
 755        <listitem>
 756          <para>
 757            Generate a trace of the algorithm that decides the order in
 758            which <literal>apt</literal> should pass packages to
 759            &dpkg;.
 760          </para>
 761        </listitem>
 762      </varlistentry>
 763
 764      <varlistentry>
 765        <term><literal>Debug::pkgPackageManager</literal></term>
 766
 767        <listitem>
 768          <para>
 769            Output status messages tracing the steps performed when
 770            invoking &dpkg;.
 771          </para>
 772        </listitem>
 773      </varlistentry>
 774
 775      <varlistentry>
 776        <term><literal>Debug::pkgPolicy</literal></term>
 777
 778        <listitem>
 779          <para>
 780            Output the priority of each package list on startup.
 781          </para>
 782        </listitem>
 783      </varlistentry>
 784
 785      <varlistentry>
 786        <term><literal>Debug::pkgProblemResolver</literal></term>
 787
 788        <listitem>
 789          <para>
 790            Trace the execution of the dependency resolver (this
 791            applies only to what happens when a complex dependency
 792            problem is encountered).
 793          </para>
 794        </listitem>
 795      </varlistentry>
 796
 797      <varlistentry>
 798        <term><literal>Debug::pkgProblemResolver::ShowScores</literal></term>
 799        <listitem>
 800         <para>
 801           Display a list of all installed packages with their calculated score
 802           used by the pkgProblemResolver. The description of the package
 803           is the same as described in <literal>Debug::pkgDepCache::Marker</literal>
 804         </para>
 805        </listitem>
 806      </varlistentry>
 807
 808      <varlistentry>
 809        <term><literal>Debug::sourceList</literal></term>
 810
 811        <listitem>
 812          <para>
 813            Print information about the vendors read from
 814            <filename>/etc/apt/vendors.list</filename>.
 815          </para>
 816        </listitem>
 817      </varlistentry>
 818
 819 <!-- 2009/07/11 Currently used nowhere. The corresponding code
 820 is commented.
 821      <varlistentry>
 822        <term><literal>Debug::Vendor</literal></term>
 823
 824        <listitem>
 825          <para>
 826            Print information about each vendor.
 827          </para>
 828        </listitem>
 829      </varlistentry>
 830 -->
 831    </variablelist>
 832  </refsect1>
 833
 834  <refsect1><title>Examples</title>
 835    <para>&configureindex; is a
 836    configuration file showing example values for all possible
 837    options.</para>
 838  </refsect1>
 839
 840  <refsect1><title>Files</title>
 841    <variablelist>
 842       <varlistentry><term><filename>/etc/apt/apt.conf</filename></term>
 843       <listitem><para>APT configuration file.
 844       Configuration Item: <literal>Dir::Etc::Main</literal>.</para></listitem>
 845       </varlistentry>
 846
 847       <varlistentry><term><filename>/etc/apt/apt.conf.d/</filename></term>
 848       <listitem><para>APT configuration file fragments.
 849       Configuration Item: <literal>Dir::Etc::Parts</literal>.</para></listitem>
 850       </varlistentry>
 851    </variablelist>
 852  </refsect1>
 853
 854  <refsect1><title>See Also</title>
 855    <para>&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.</para>
 856  </refsect1>
 857
 858  &manbugs;
 859
 860 </refentry>
 861