Merge remote-tracking branch 'origin/bugfix/bts731738-fancy-progess' into bugfix...

[apt.git] / doc / apt.conf.5.xml

diff --git a/doc/apt.conf.5.xml b/doc/apt.conf.5.xml
index db8dfa7ce1ac4bcbf96b52ff80f0ee2b0874f7b6..bfc43ba29fa4c240b26b81a0e50e95301352e5f3 100644 (file)
--- a/doc/apt.conf.5.xml
+++ b/doc/apt.conf.5.xml
@@ -1,10 +1,15 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <?xml version="1.0" encoding="utf-8" standalone="no"?>

-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
-  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [

 
 <!ENTITY % aptent SYSTEM "apt.ent">
 %aptent;
 
 
 <!ENTITY % aptent SYSTEM "apt.ent">
 %aptent;
 

+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
+%aptverbatiment;
+
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent">
+%aptvendor;

 ]>
 
 <refentry>
 ]>
 
 <refentry>


@@ -12,15 +17,21 @@
  <refentryinfo>
    &apt-author.jgunthorpe;
    &apt-author.team;
  <refentryinfo>
    &apt-author.jgunthorpe;
    &apt-author.team;

+   <author>
+     &apt-name.dburrows;
+     <contrib>Initial documentation of Debug::*.</contrib>
+     <email>dburrows@debian.org</email>
+   </author>

    &apt-email;
    &apt-product;
    <!-- The last update date -->
    &apt-email;
    &apt-product;
    <!-- The last update date -->

-   <date>29 February 2004</date>
+   <date>2012-06-09T00:00:00Z</date>

  </refentryinfo>
  
  <refmeta>
    <refentrytitle>apt.conf</refentrytitle>
    <manvolnum>5</manvolnum>
  </refentryinfo>
  
  <refmeta>
    <refentrytitle>apt.conf</refentrytitle>
    <manvolnum>5</manvolnum>

+   <refmiscinfo class="manual">APT</refmiscinfo>

  </refmeta>
  
  <!-- Man page title -->
  </refmeta>
  
  <!-- Man page title -->


@@ -28,31 +39,49 @@
     <refname>apt.conf</refname>
     <refpurpose>Configuration file for APT</refpurpose>
  </refnamediv>
     <refname>apt.conf</refname>
     <refpurpose>Configuration file for APT</refpurpose>
  </refnamediv>

- 
+

  <refsect1><title>Description</title>
  <refsect1><title>Description</title>

-   <para><filename>apt.conf</filename> is the main configuration file for the APT suite of
-   tools, all tools make use of the configuration file and a common command line
-   parser to provide a uniform environment. When an APT tool starts up it will
-   read the configuration specified by the <envar>APT_CONFIG</envar> environment 
-   variable (if any) and then read the files in <literal>Dir::Etc::Parts</literal> 
-   then read the main configuration file specified by 
-   <literal>Dir::Etc::main</literal> then finally apply the
-   command line options to override the configuration directives, possibly 
-   loading even more config files.</para>
+   <para><filename>/etc/apt/apt.conf</filename> is the main configuration
+   file shared by all the tools in the APT suite of tools, though it is by
+   no means the only place options can be set. The suite also shares a common
+   command line parser to provide a uniform environment.</para>

 
 

+   <orderedlist>
+      <para>When an APT tool starts up it will read the configuration files
+      in the following order:</para>
+      <listitem><para>the file specified by the <envar>APT_CONFIG</envar>
+        environment variable (if any)</para></listitem>
+      <listitem><para>all files in <literal>Dir::Etc::Parts</literal> in
+        alphanumeric ascending order which have either no or "<literal>conf</literal>"
+        as filename extension and which only contain alphanumeric,
+        hyphen (-), underscore (_) and period (.) characters.
+        Otherwise APT will print a notice that it has ignored a file, unless that
+        file matches a pattern in the <literal>Dir::Ignore-Files-Silently</literal>
+        configuration list - in which case it will be silently ignored.</para></listitem>
+      <listitem><para>the main configuration file specified by
+        <literal>Dir::Etc::main</literal></para></listitem>
+      <listitem><para>the command line options are applied to override the
+        configuration directives or to load even more configuration files.</para></listitem>
+   </orderedlist>
+   </refsect1>
+   <refsect1><title>Syntax</title>

    <para>The configuration file is organized in a tree with options organized into
    <para>The configuration file is organized in a tree with options organized into

-   functional groups. option specification is given with a double colon
-   notation, for instance <literal>APT::Get::Assume-Yes</literal> is an option within 
-   the APT tool group, for the Get tool. options do not inherit from their 
+   functional groups. Option specification is given with a double colon
+   notation; for instance <literal>APT::Get::Assume-Yes</literal> is an option within 
+   the APT tool group, for the Get tool. Options do not inherit from their 

    parent groups.</para> 
 
    <para>Syntactically the configuration language is modeled after what the ISC tools
    parent groups.</para> 
 
    <para>Syntactically the configuration language is modeled after what the ISC tools

-   such as bind and dhcp use.  Lines starting with
-   <literal>//</literal> are treated as comments (ignored).
+   such as bind and dhcp use. Lines starting with
+   <literal>//</literal> are treated as comments (ignored), as well as all text
+   between <literal>/*</literal> and <literal>*/</literal>, just like C/C++ comments.

    Each line is of the form
    Each line is of the form

-   <literal>APT::Get::Assume-Yes "true";</literal> The trailing 
-   semicolon is required and the quotes are optional. A new scope can be
-   opened with curly braces, like:</para>
+   <literal>APT::Get::Assume-Yes "true";</literal>.
+   The quotation marks and trailing semicolon are required.
+   The value must be on one line, and there is no kind of string concatenation.
+   Values must not include backslashes or extra quotation marks.
+   Option names are made up of alphanumeric characters and the characters "/-:._+".
+   A new scope can be opened with curly braces, like this:</para>

 
 <informalexample><programlisting>   
 APT {
 
 <informalexample><programlisting>   
 APT {


@@ -64,30 +93,63 @@ APT {
 </programlisting></informalexample>
 
    <para>with newlines placed to make it more readable. Lists can be created by 
 </programlisting></informalexample>
 
    <para>with newlines placed to make it more readable. Lists can be created by 

-   opening a scope and including a single word enclosed in quotes followed by a 
-   semicolon. Multiple entries can be included, each separated by a semicolon.</para>
+   opening a scope and including a single string enclosed in quotes followed by a
+   semicolon. Multiple entries can be included, separated by a semicolon.</para>

 
 <informalexample><programlisting>   
 DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
 </programlisting></informalexample>
 
 
 <informalexample><programlisting>   
 DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
 </programlisting></informalexample>
 

-   <para>In general the sample configuration file in 
-   <filename>&docdir;examples/apt.conf</filename> &configureindex;
+   <para>In general the sample configuration file &configureindex;

    is a good guide for how it should look.</para>
 
    is a good guide for how it should look.</para>
 

-   <para>The names of the configuration items are not case-sensitive. So in the previous example
-   you could use <literal>dpkg::pre-install-pkgs</literal>.</para>
+   <para>Case is not significant in names of configuration items, so in the
+   previous example you could use <literal>dpkg::pre-install-pkgs</literal>.</para>
+
+   <para>Names for the configuration items are optional if a list is defined as can be seen in
+   the <literal>DPkg::Pre-Install-Pkgs</literal> example above. If you don't specify a name a
+   new entry will simply add a new option to the list. If you specify a name you can override
+   the option in the same way as any other option by reassigning a new value to the option.</para>
+
+   <para>Two special commands are defined: <literal>#include</literal> (which is
+   deprecated and not supported by alternative implementations) and
+   <literal>#clear</literal>. <literal>#include</literal> will include the
+   given file, unless the filename ends in a slash, in which case the whole
+   directory is included.
+   <literal>#clear</literal> is used to erase a part of the configuration tree. The
+   specified element and all its descendants are erased.
+   (Note that these lines also need to end with a semicolon.)</para>

 
 

-   <para>Two specials are allowed, <literal>#include</literal> and <literal>#clear</literal> 
-   <literal>#include</literal> will include the given file, unless the filename
-   ends in a slash, then the whole directory is included.  
-   <literal>#clear</literal> is used to erase a list of names.</para>
+   <para>
+   The <literal>#clear</literal> command is the only way to delete a list or
+   a complete scope. Reopening a scope (or using the syntax described below
+   with an appended <literal>::</literal>) will <emphasis>not</emphasis>
+   override previously written entries. Options can only be overridden by
+   addressing a new value to them - lists and scopes can't be overridden,
+   only cleared.
+   </para>

 
 

-   <para>All of the APT tools take a -o option which allows an arbitrary configuration 
+   <para>All of the APT tools take an -o option which allows an arbitrary configuration 

    directive to be specified on the command line. The syntax is a full option
    name (<literal>APT::Get::Assume-Yes</literal> for instance) followed by an equals
    directive to be specified on the command line. The syntax is a full option
    name (<literal>APT::Get::Assume-Yes</literal> for instance) followed by an equals

-   sign then the new value of the option. Lists can be appended too by adding 
-   a trailing :: to the list name.</para>
+   sign then the new value of the option. To append a new element to a list, add a
+   trailing <literal>::</literal> to the name of the list.
+   (As you might suspect, the scope syntax can't be used on the command line.)</para>
+
+   <para>
+   Note that appending items to a list using <literal>::</literal> only works
+   for one item per line, and that you should not use it in combination with
+   the scope syntax (which adds <literal>::</literal> implicitly). Using both
+   syntaxes together will trigger a bug which some users unfortunately depend
+   on: an option with the unusual name "<literal>::</literal>" which acts
+   like every other option with a name. This introduces many problems; for
+   one thing, users who write multiple lines in this
+   <emphasis>wrong</emphasis> syntax in the hope of appending to a list will
+   achieve the opposite, as only the last assignment for this option
+   "<literal>::</literal>" will be used. Future versions of APT will raise
+   errors and stop working if they encounter this misuse, so please correct
+   such statements now while APT doesn't explicitly complain about them.
+   </para>

  </refsect1>
 
  <refsect1><title>The APT Group</title>
  </refsect1>
 
  <refsect1><title>The APT Group</title>


@@ -95,73 +157,188 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
    options for all of the tools.</para>
 
    <variablelist>
    options for all of the tools.</para>
 
    <variablelist>

-     <varlistentry><term>Architecture</term>
+     <varlistentry><term><option>Architecture</option></term>

      <listitem><para>System Architecture; sets the architecture to use when fetching files and
      parsing package lists. The internal default is the architecture apt was 
      compiled for.</para></listitem>
      </varlistentry>
      <listitem><para>System Architecture; sets the architecture to use when fetching files and
      parsing package lists. The internal default is the architecture apt was 
      compiled for.</para></listitem>
      </varlistentry>

-     
-     <varlistentry><term>Ignore-Hold</term>
-     <listitem><para>Ignore Held packages; This global option causes the problem resolver to
+
+     <varlistentry><term><option>Architectures</option></term>
+     <listitem><para>
+     All Architectures the system supports. For instance, CPUs implementing
+     the <literal>amd64</literal> (also called <literal>x86-64</literal>)
+     instruction set are also able to execute binaries compiled for the
+     <literal>i386</literal> (<literal>x86</literal>) instruction set. This
+     list is used when fetching files and parsing package lists. The
+     initial default is always the system's native architecture
+     (<literal>APT::Architecture</literal>), and foreign architectures are
+     added to the default list when they are registered via
+     <command>dpkg --add-architecture</command>.
+     </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>Default-Release</option></term>
+     <listitem><para>Default release to install packages from if more than one
+     version is available. Contains release name, codename or release version. Examples: 'stable', 'testing',
+     'unstable', '&stable-codename;', '&testing-codename;', '4.0', '5.0*'. See also &apt-preferences;.</para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>Ignore-Hold</option></term>
+     <listitem><para>Ignore held packages; this global option causes the problem resolver to

      ignore held packages in its decision making.</para></listitem>
      </varlistentry>
 
      ignore held packages in its decision making.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>Clean-Installed</term>
+     <varlistentry><term><option>Clean-Installed</option></term>

      <listitem><para>Defaults to on. When turned on the autoclean feature will remove any packages
      which can no longer be downloaded from the cache. If turned off then
      packages that are locally installed are also excluded from cleaning - but
      note that APT provides no direct means to reinstall them.</para></listitem>
      </varlistentry>
 
      <listitem><para>Defaults to on. When turned on the autoclean feature will remove any packages
      which can no longer be downloaded from the cache. If turned off then
      packages that are locally installed are also excluded from cleaning - but
      note that APT provides no direct means to reinstall them.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>Immediate-Configure</term>
-     <listitem><para>Disable Immediate Configuration; This dangerous option disables some
-     of APT's ordering code to cause it to make fewer dpkg calls. Doing
-     so may be necessary on some extremely slow single user systems but 
-     is very dangerous and may cause package install scripts to fail or worse.
-     Use at your own risk.</para></listitem>
+     <varlistentry><term><option>Immediate-Configure</option></term>
+     <listitem><para>
+     Defaults to on, which will cause APT to install essential and important
+     packages as soon as possible in an install/upgrade operation, in order
+     to limit the effect of a failing &dpkg; call. If this option is
+     disabled, APT treats an important package in the same way as an extra
+     package: between the unpacking of the package A and its configuration
+     there can be many other unpack or configuration calls for other
+     unrelated packages B, C etc. If these cause the &dpkg; call to fail
+     (e.g. because package B's maintainer scripts generate an error), this
+     results in a system state in which package A is unpacked but
+     unconfigured - so any package depending on A is now no longer
+     guaranteed to work, as its dependency on A is no longer satisfied.
+     </para><para>
+     The immediate configuration marker is also applied in the potentially
+     problematic case of circular dependencies, since a dependency with the
+     immediate flag is equivalent to a Pre-Dependency. In theory this allows
+     APT to recognise a situation in which it is unable to perform immediate
+     configuration, abort, and suggest to the user that the option should be
+     temporarily deactivated in order to allow the operation to proceed.
+     Note the use of the word "theory" here; in the real world this problem
+     has rarely been encountered, in non-stable distribution versions, and
+     was caused by wrong dependencies of the package in question or by a
+     system in an already broken state; so you should not blindly disable
+     this option, as the scenario mentioned above is not the only problem it
+     can help to prevent in the first place.
+     </para><para>
+     Before a big operation like <literal>dist-upgrade</literal> is run
+     with this option disabled you should try to explicitly
+     <literal>install</literal> the package APT is unable to configure
+     immediately; but please make sure you also report your problem to your
+     distribution and to the APT team with the buglink below, so they can
+     work on improving or correcting the upgrade process.
+     </para></listitem>

      </varlistentry>
 
      </varlistentry>
 

-     <varlistentry><term>Force-LoopBreak</term>
-     <listitem><para>Never Enable this option unless you -really- know what you are doing. It
-     permits APT to temporarily remove an essential package to break a
-     Conflicts/Conflicts or Conflicts/Pre-Depend loop between two essential
-     packages. SUCH A LOOP SHOULD NEVER EXIST AND IS A GRAVE BUG. This option 
-     will work if the essential packages are not tar, gzip, libc, dpkg, bash or
-     anything that those packages depend on.</para></listitem>
+     <varlistentry><term><option>Force-LoopBreak</option></term>
+     <listitem><para>
+     Never enable this option unless you <emphasis>really</emphasis> know
+     what you are doing. It permits APT to temporarily remove an essential
+     package to break a Conflicts/Conflicts or Conflicts/Pre-Depends loop
+     between two essential packages. <emphasis>Such a loop should never exist
+     and is a grave bug</emphasis>. This option will work if the essential
+     packages are not <command>tar</command>, <command>gzip</command>,
+     <command>libc</command>, <command>dpkg</command>, <command>dash</command>
+     or anything that those packages depend on.
+     </para></listitem>

      </varlistentry>
 
      </varlistentry>
 

-     <varlistentry><term>Cache-Limit</term>
-     <listitem><para>APT uses a fixed size memory mapped cache file to store the 'available'
-     information. This sets the size of that cache (in bytes).</para></listitem>
+     <varlistentry><term><option>Cache-Start</option></term><term><option>Cache-Grow</option></term><term><option>Cache-Limit</option></term>
+     <listitem><para>APT uses since version 0.7.26 a resizable memory mapped cache file to store the available
+     information. <literal>Cache-Start</literal> acts as a hint of the size the cache will grow to,
+     and is therefore the amount of memory APT will request at startup. The default value is
+     20971520 bytes (~20 MB). Note that this amount of space needs to be available for APT;
+     otherwise it will likely fail ungracefully, so for memory restricted devices this value should
+     be lowered while on systems with a lot of configured sources it should be increased.
+     <literal>Cache-Grow</literal> defines in bytes with the default of 1048576 (~1 MB) how much
+     the cache size will be increased in the event the space defined by <literal>Cache-Start</literal>
+     is not enough. This value will be applied again and again until either the cache is big
+     enough to store all information or the size of the cache reaches the <literal>Cache-Limit</literal>.
+     The default of <literal>Cache-Limit</literal> is 0 which stands for no limit.
+     If <literal>Cache-Grow</literal> is set to 0 the automatic growth of the cache is disabled.
+     </para></listitem>

      </varlistentry>
 
      </varlistentry>
 

-     <varlistentry><term>Build-Essential</term>
-     <listitem><para>Defines which package(s) are considered essential build dependencies.</para></listitem>
+     <varlistentry><term><option>Build-Essential</option></term>
+     <listitem><para>Defines which packages are considered essential build dependencies.</para></listitem>

      </varlistentry>
 
      </varlistentry>
 

-     <varlistentry><term>Get</term>
-     <listitem><para>The Get subsection controls the &apt-get; tool, please see its
+     <varlistentry><term><option>Get</option></term>
+     <listitem><para>The Get subsection controls the &apt-get; tool; please see its

      documentation for more information about the options here.</para></listitem>
      </varlistentry>
 
      documentation for more information about the options here.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>Cache</term>
-     <listitem><para>The Cache subsection controls the &apt-cache; tool, please see its
+     <varlistentry><term><option>Cache</option></term>
+     <listitem><para>The Cache subsection controls the &apt-cache; tool; please see its

      documentation for more information about the options here.</para></listitem>
      </varlistentry>
 
      documentation for more information about the options here.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>CDROM</term>
-     <listitem><para>The CDROM subsection controls the &apt-cdrom; tool, please see its
+     <varlistentry><term><option>CDROM</option></term>
+     <listitem><para>The CDROM subsection controls the &apt-cdrom; tool; please see its

      documentation for more information about the options here.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
 
  <refsect1><title>The Acquire Group</title>
      documentation for more information about the options here.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
 
  <refsect1><title>The Acquire Group</title>

-   <para>The <literal>Acquire</literal> group of options controls the download of packages 
-   and the URI handlers. 
+   <para>The <literal>Acquire</literal> group of options controls the
+   download of packages as well as the various "acquire methods" responsible
+   for the download itself (see also &sources-list;).</para>

 
    <variablelist>
 
    <variablelist>

-     <varlistentry><term>Queue-Mode</term>
+     <varlistentry><term><option>Check-Valid-Until</option></term>
+     <listitem><para>
+     Security related option defaulting to true, as giving a Release file's
+     validation an expiration date prevents replay attacks over a long
+     timescale, and can also for example help users to identify mirrors
+     that are no longer updated - but the feature depends on the
+     correctness of the clock on the user system. Archive maintainers are
+     encouraged to create Release files with the
+     <literal>Valid-Until</literal> header, but if they don't or a
+     stricter value is desired the <literal>Max-ValidTime</literal>
+     option below can be used.
+     </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>Max-ValidTime</option></term>
+        <listitem><para>Maximum time (in seconds) after its creation (as indicated
+        by the <literal>Date</literal> header) that the <filename>Release</filename>
+        file should be considered valid.
+        If the Release file itself includes a <literal>Valid-Until</literal> header
+        the earlier date of the two is used as the expiration date.
+        The default value is <literal>0</literal> which stands for "valid forever".
+        Archive specific settings can be made by appending the label of the archive
+        to the option name.
+        </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>Min-ValidTime</option></term>
+        <listitem><para>Minimum time (in seconds) after its creation (as indicated
+        by the <literal>Date</literal> header) that the <filename>Release</filename>
+        file should be considered valid.
+        Use this if you need to use a seldom updated (local) mirror of a more
+        frequently updated archive with a <literal>Valid-Until</literal> header
+        instead of completely disabling the expiration date checking.
+        Archive specific settings can and should be used by appending the label of
+        the archive to the option name.
+        </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>PDiffs</option></term>
+        <listitem><para>Try to download deltas called <literal>PDiffs</literal> for
+        indexes (like <filename>Packages</filename> files) instead of downloading
+        whole ones. True by default.</para>
+        <para>Two sub-options to limit the use of PDiffs are also available:
+        <literal>FileLimit</literal> can be used to specify a maximum number of
+        PDiff files should be downloaded to update a file. <literal>SizeLimit</literal>
+        on the other hand is the maximum percentage of the size of all patches
+        compared to the size of the targeted file. If one of these limits is
+        exceeded the complete file is downloaded instead of the patches.
+        </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>Queue-Mode</option></term>

      <listitem><para>Queuing mode; <literal>Queue-Mode</literal> can be one of <literal>host</literal> or 
      <literal>access</literal> which determines how  APT parallelizes outgoing 
      connections. <literal>host</literal> means that one connection per target host 
      <listitem><para>Queuing mode; <literal>Queue-Mode</literal> can be one of <literal>host</literal> or 
      <literal>access</literal> which determines how  APT parallelizes outgoing 
      connections. <literal>host</literal> means that one connection per target host 


@@ -169,71 +346,135 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      will be opened.</para></listitem>
      </varlistentry>
 
      will be opened.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>Retries</term>
+     <varlistentry><term><option>Retries</option></term>

      <listitem><para>Number of retries to perform. If this is non-zero APT will retry failed 
      files the given number of times.</para></listitem>
      </varlistentry>
 
      <listitem><para>Number of retries to perform. If this is non-zero APT will retry failed 
      files the given number of times.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>Source-Symlinks</term>
+     <varlistentry><term><option>Source-Symlinks</option></term>

      <listitem><para>Use symlinks for source archives. If set to true then source archives will
      be symlinked when possible instead of copying. True is the default.</para></listitem>
      </varlistentry>
 
      <listitem><para>Use symlinks for source archives. If set to true then source archives will
      be symlinked when possible instead of copying. True is the default.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>http</term>
-     <listitem><para>HTTP URIs; http::Proxy is the default http proxy to use. It is in the 
-     standard form of <literal>http://[[user][:pass]@]host[:port]/</literal>. Per 
-     host proxies can also be specified by using the form 
+     <varlistentry><term><option>http</option></term>
+     <listitem><para><literal>http::Proxy</literal> sets the default proxy to use for HTTP
+     URIs. It is in the standard form of <literal>http://[[user][:pass]@]host[:port]/</literal>.
+     Per host proxies can also be specified by using the form

      <literal>http::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal> 
      <literal>http::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal> 

-     meaning to use no proxies. The <envar>http_proxy</envar> environment variable
-     will override all settings.</para>
-
-     <para>Three settings are provided for cache control with HTTP/1.1 compliant 
-     proxy caches. <literal>No-Cache</literal> tells the proxy to not use its cached 
-     response under any circumstances, <literal>Max-Age</literal> is sent only for 
-     index files and tells the cache to refresh its object if it is older than 
-     the given number of seconds. Debian updates its index files daily so the 
-     default is 1 day. <literal>No-Store</literal> specifies that the cache should never 
-     store this request, it is only set for archive files. This may be useful 
-     to prevent polluting a proxy cache with very large .deb files. Note: 
-     Squid 2.0.2 does not support any of these options.</para>
-
-     <para>The option <literal>timeout</literal> sets the timeout timer used by the method, 
-     this applies to all things including connection timeout and data timeout.</para>
-
-     <para>One setting is provided to control the pipeline depth in cases where the
-     remote server is not RFC conforming or buggy (such as Squid 2.0.2)
-     <literal>Acquire::http::Pipeline-Depth</literal> can be a value from 0 to 5 
-     indicating how many outstanding requests APT should send. A value of
-     zero MUST be specified if the remote host does not properly linger
-     on TCP connections - otherwise data corruption will occur. Hosts which
-     require this are in violation of RFC 2068.</para></listitem>
-     </varlistentry>
-
-     <varlistentry><term>ftp</term>
-     <listitem><para>FTP URIs; ftp::Proxy is the default proxy server to use. It is in the 
-     standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal> and is 
-     overridden by the <envar>ftp_proxy</envar> environment variable. To use a ftp 
+        meaning to use no proxies. If no one of the above settings is specified,
+        <envar>http_proxy</envar> environment variable
+        will be used.</para>
+
+     <para>Three settings are provided for cache control with HTTP/1.1 compliant
+     proxy caches.
+     <literal>No-Cache</literal> tells the proxy not to use its cached
+     response under any circumstances.
+     <literal>Max-Age</literal> sets the allowed maximum age (in seconds) of
+     an index file in the cache of the proxy.
+     <literal>No-Store</literal> specifies that the proxy should not store
+     the requested archive files in its cache, which can be used to prevent
+     the proxy from polluting its cache with (big) .deb files.</para>
+
+     <para>The option <literal>timeout</literal> sets the timeout timer used by the method;
+     this value applies to the connection as well as the data timeout.</para>
+
+     <para>The setting <literal>Acquire::http::Pipeline-Depth</literal> can be used to
+     enable HTTP pipelining (RFC 2616 section 8.1.2.2) which can be beneficial e.g. on
+     high-latency connections. It specifies how many requests are sent in a pipeline.
+     Previous APT versions had a default of 10 for this setting, but the default value
+     is now 0 (= disabled) to avoid problems with the ever-growing amount of webservers
+     and proxies which choose to not conform to the HTTP/1.1 specification.</para>
+
+     <para><literal>Acquire::http::AllowRedirect</literal> controls whether APT will follow
+     redirects, which is enabled by default.</para>
+
+     <para>The used bandwidth can be limited with
+     <literal>Acquire::http::Dl-Limit</literal> which accepts integer
+     values in kilobytes per second. The default value is 0 which
+     deactivates the limit and tries to use all available bandwidth.
+     Note that this option implicitly disables downloading from
+     multiple servers at the same time.</para>
+
+     <para><literal>Acquire::http::User-Agent</literal> can be used to set a different
+     User-Agent for the http download method as some proxies allow access for clients
+     only if the client uses a known identifier.</para>
+
+     <para><literal>Acquire::http::Proxy-Auto-Detect</literal> can be used to
+     specify an external command to discover the http proxy to use. Apt expects
+     the command to output the proxy on stdout in the style
+     <literal>http://proxy:port/</literal>. This will override the
+     generic <literal>Acquire::http::Proxy</literal> but not any specific
+     host proxy configuration set via 
+     <literal>Acquire::http::Proxy::$HOST</literal>.
+
+     See the &squid-deb-proxy-client; package for an example implementation that
+     uses avahi. This option takes precedence over the legacy option name 
+     <literal>ProxyAutoDetect</literal>.
+     </para>
+
+     </listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>https</option></term>
+        <listitem><para>
+        The <literal>Cache-control</literal>, <literal>Timeout</literal>,
+        <literal>AllowRedirect</literal>, <literal>Dl-Limit</literal> and
+        <literal>proxy</literal> options work for HTTPS URIs in the same way
+        as for the <literal>http</literal> method, and default to the same
+        values if they are not explicitly set. The
+        <literal>Pipeline-Depth</literal> option is not yet supported.
+        </para>
+
+        <para><literal>CaInfo</literal> suboption specifies place of file that
+        holds info about trusted certificates.
+        <literal>&lt;host&gt;::CaInfo</literal> is the corresponding per-host option.
+        <literal>Verify-Peer</literal> boolean suboption determines whether or not the
+        server's host certificate should be verified against trusted certificates.
+        <literal>&lt;host&gt;::Verify-Peer</literal> is the corresponding per-host option.
+        <literal>Verify-Host</literal> boolean suboption determines whether or not the
+        server's hostname should be verified.
+        <literal>&lt;host&gt;::Verify-Host</literal> is the corresponding per-host option.
+        <literal>SslCert</literal> determines what certificate to use for client
+        authentication. <literal>&lt;host&gt;::SslCert</literal> is the corresponding per-host option.
+        <literal>SslKey</literal> determines what private key to use for client
+        authentication. <literal>&lt;host&gt;::SslKey</literal> is the corresponding per-host option.
+        <literal>SslForceVersion</literal> overrides default SSL version to use.
+        It can contain either of the strings '<literal>TLSv1</literal>' or
+        '<literal>SSLv3</literal>'.
+        <literal>&lt;host&gt;::SslForceVersion</literal> is the corresponding per-host option.
+        </para></listitem></varlistentry>
+
+     <varlistentry><term><option>ftp</option></term>
+     <listitem><para>
+     <literal>ftp::Proxy</literal> sets the default proxy to use for FTP URIs.
+     It is in the standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal>.
+     Per host proxies can also be specified by using the form
+     <literal>ftp::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal> 
+        meaning to use no proxies. If no one of the above settings is specified,
+        <envar>ftp_proxy</envar> environment variable
+        will be used. To use an FTP

      proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the 
      configuration file. This entry specifies the commands to send to tell 
      the proxy server what to connect to. Please see 
      &configureindex; for an example of 
      proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the 
      configuration file. This entry specifies the commands to send to tell 
      the proxy server what to connect to. Please see 
      &configureindex; for an example of 

-     how to do this. The substitution variables available are 
-     <literal>$(PROXY_USER)</literal> <literal>$(PROXY_PASS)</literal> <literal>$(SITE_USER)</literal>
-     <literal>$(SITE_PASS)</literal> <literal>$(SITE)</literal> and <literal>$(SITE_PORT)</literal>
-     Each is taken from it's respective URI component.</para>
+     how to do this. The substitution variables representing the corresponding
+     URI component are <literal>$(PROXY_USER)</literal>,
+     <literal>$(PROXY_PASS)</literal>, <literal>$(SITE_USER)</literal>,
+     <literal>$(SITE_PASS)</literal>, <literal>$(SITE)</literal> and
+     <literal>$(SITE_PORT)</literal>.</para>

 
 

-     <para>The option <literal>timeout</literal> sets the timeout timer used by the method, 
-     this applies to all things including connection timeout and data timeout.</para>
+     <para>The option <literal>timeout</literal> sets the timeout timer used by the method;
+     this value applies to the connection as well as the data timeout.</para>

 
      <para>Several settings are provided to control passive mode. Generally it is 
 
      <para>Several settings are provided to control passive mode. Generally it is 

-     safe to leave passive mode on, it works in nearly every environment. 
-     However some situations require that passive mode be disabled and port 
-     mode ftp used instead. This can be done globally, for connections that 
-     go through a proxy or for a specific host (See the sample config file 
+     safe to leave passive mode on; it works in nearly every environment. 
+     However, some situations require that passive mode be disabled and port 
+     mode FTP used instead. This can be done globally or for connections that 
+     go through a proxy or for a specific host (see the sample config file 

      for examples).</para>
 
      <para>It is possible to proxy FTP over HTTP by setting the <envar>ftp_proxy</envar>
      for examples).</para>
 
      <para>It is possible to proxy FTP over HTTP by setting the <envar>ftp_proxy</envar>

-     environment variable to a http url - see the discussion of the http method
+     environment variable to an HTTP URL - see the discussion of the http method

      above for syntax. You cannot set this in the configuration file and it is
      not recommended to use FTP over HTTP due to its low efficiency.</para>
 
      above for syntax. You cannot set this in the configuration file and it is
      not recommended to use FTP over HTTP due to its low efficiency.</para>
 


@@ -244,42 +485,122 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      do not support RFC2428.</para></listitem>
      </varlistentry>
 
      do not support RFC2428.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>cdrom</term>
-     <listitem><para>CDROM URIs; the only setting for CDROM URIs is the mount point, 
-     <literal>cdrom::Mount</literal> which must be the mount point for the CDROM drive 
-     as specified in <filename>/etc/fstab</filename>. It is possible to provide 
-     alternate mount and unmount commands if your mount point cannot be listed 
-     in the fstab (such as an SMB mount and old mount packages). The syntax 
-     is to put <literallayout>"/cdrom/"::Mount "foo";</literallayout> within 
-     the cdrom block. It is important to have the trailing slash. Unmount 
-     commands can be specified using UMount.</para></listitem>
+     <varlistentry><term><option>cdrom</option></term>
+     <listitem><para>
+     For URIs using the <literal>cdrom</literal> method, the only configurable
+     option is the mount point, <literal>cdrom::Mount</literal>, which must be
+     the mount point for the CD-ROM (or DVD, or whatever) drive as specified in
+     <filename>/etc/fstab</filename>. It is possible to provide alternate mount
+     and unmount commands if your mount point cannot be listed in the fstab.
+     The syntax is to put <literallayout>/cdrom/::Mount "foo";</literallayout> within
+     the <literal>cdrom</literal> block. It is important to have the trailing slash.
+     Unmount commands can be specified using UMount.
+     </para></listitem>

      </varlistentry>
 
      </varlistentry>
 

-     <varlistentry><term>gpgv</term>
-     <listitem><para>GPGV URIs; the only option for GPGV URIs is the option to pass additional parameters to gpgv.
-     <literal>gpgv::Options</literal> Additional options passed to gpgv.
+     <varlistentry><term><option>gpgv</option></term>
+     <listitem><para>
+     For GPGV URIs the only configurable option is <literal>gpgv::Options</literal>,
+     which passes additional parameters to gpgv.

      </para></listitem>
      </varlistentry>
 
      </para></listitem>
      </varlistentry>
 

+     <varlistentry><term><option>CompressionTypes</option></term>
+     <listitem><para>List of compression types which are understood by the acquire methods.
+     Files like <filename>Packages</filename> can be available in various compression formats.
+     By default the acquire methods can decompress <command>bzip2</command>, <command>lzma</command>
+     and <command>gzip</command> compressed files; with this setting more formats can be added
+     on the fly or the used method can be changed. The syntax for this is:
+     <synopsis>Acquire::CompressionTypes::<replaceable>FileExtension</replaceable> "<replaceable>Methodname</replaceable>";</synopsis>
+     </para><para>Also, the <literal>Order</literal> subgroup can be used to define in which order
+     the acquire system will try to download the compressed files. The acquire system will try the first
+     and proceed with the next compression type in this list on error, so to prefer one over the other type
+     simply add the preferred type first - default types not already added will be implicitly appended
+     to the end of the list, so e.g. <synopsis>Acquire::CompressionTypes::Order:: "gz";</synopsis> can
+     be used to prefer <command>gzip</command> compressed files over <command>bzip2</command> and <command>lzma</command>.
+     If <command>lzma</command> should be preferred over <command>gzip</command> and <command>bzip2</command> the
+     configure setting should look like this: <synopsis>Acquire::CompressionTypes::Order { "lzma"; "gz"; };</synopsis>
+     It is not needed to add <literal>bz2</literal> to the list explicitly as it will be added automatically.</para>
+     <para>Note that the
+     <literal>Dir::Bin::<replaceable>Methodname</replaceable></literal>
+     will be checked at run time. If this option has been set, the
+     method will only be used if this file exists; e.g. for the
+     <literal>bzip2</literal> method (the inbuilt) setting is:
+     <literallayout>Dir::Bin::bzip2 "/bin/bzip2";</literallayout>
+     Note also that list entries specified on the command line will be added at the end of the list
+     specified in the configuration files, but before the default entries. To prefer a type in this case
+     over the ones specified in the configuration files you can set the option direct - not in list style.
+     This will not override the defined list; it will only prefix the list with this type.</para>
+     <para>The special type <literal>uncompressed</literal> can be used to give uncompressed files a
+     preference, but note that most archives don't provide uncompressed files so this is mostly only
+     useable for local mirrors.</para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>GzipIndexes</option></term>
+        <listitem><para>
+        When downloading <literal>gzip</literal> compressed indexes (Packages, Sources, or
+        Translations), keep them gzip compressed locally instead of unpacking
+        them. This saves quite a lot of disk space at the expense of more CPU
+        requirements when building the local package caches. False by default.
+        </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>Languages</option></term>
+     <listitem><para>The Languages subsection controls which <filename>Translation</filename> files are downloaded
+     and in which order APT tries to display the description-translations. APT will try to display the first
+     available description in the language which is listed first. Languages can be defined with their
+     short or long language codes. Note that not all archives provide <filename>Translation</filename>
+     files for every language - the long language codes are especially rare.</para>
+     <para>The default list includes "environment" and "en". "<literal>environment</literal>" has a special meaning here:
+     it will be replaced at runtime with the language codes extracted from the <literal>LC_MESSAGES</literal> environment variable.
+     It will also ensure that these codes are not included twice in the list. If <literal>LC_MESSAGES</literal>
+     is set to "C" only the <filename>Translation-en</filename> file (if available) will be used.
+     To force APT to use no Translation file use the setting <literal>Acquire::Languages=none</literal>. "<literal>none</literal>"
+     is another special meaning code which will stop the search for a suitable <filename>Translation</filename> file.
+     This tells APT to download these translations too, without actually
+     using them unless the environment specifies the languages. So the
+     following example configuration will result in the order "en, de" in an
+     English locale or "de, en" in a German one. Note that "fr" is
+     downloaded, but not used unless APT is used in a French locale (where
+     the order would be "fr, de, en").
+     <programlisting>Acquire::Languages { "environment"; "de"; "en"; "none"; "fr"; };</programlisting></para>
+     <para>Note: To prevent problems resulting from APT being executed in different environments
+     (e.g. by different users or by other programs) all Translation files which are found in
+     <filename>/var/lib/apt/lists/</filename> will be added to the end of the list
+     (after an implicit "<literal>none</literal>").</para>
+     </listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>ForceIPv4</option></term>
+        <listitem><para>
+         When downloading, force to use only the IPv4 protocol.
+        </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>ForceIPv6</option></term>
+        <listitem><para>
+         When downloading, force to use only the IPv6 protocol.
+        </para></listitem>
+     </varlistentry>
+

    </variablelist>
    </variablelist>

-  </para>

  </refsect1>
 
  <refsect1><title>Directories</title>
 
    <para>The <literal>Dir::State</literal> section has directories that pertain to local 
    state information. <literal>lists</literal> is the directory to place downloaded 
  </refsect1>
 
  <refsect1><title>Directories</title>
 
    <para>The <literal>Dir::State</literal> section has directories that pertain to local 
    state information. <literal>lists</literal> is the directory to place downloaded 

-   package lists in and <literal>status</literal> is the name of the dpkg status file.
-   <literal>preferences</literal> is the name of the APT preferences file.
-   <literal>Dir::State</literal> contains the default directory to prefix on all sub 
-   items if they do not start with <filename>/</filename> or <filename>./</filename>.</para>
+   package lists in and <literal>status</literal> is the name of the &dpkg; status file.
+   <literal>preferences</literal> is the name of the APT <filename>preferences</filename> file.
+   <literal>Dir::State</literal> contains the default directory to prefix on all
+   sub-items if they do not start with <filename>/</filename> or <filename>./</filename>.</para>

 
    <para><literal>Dir::Cache</literal> contains locations pertaining to local cache 
    information, such as the two package caches <literal>srcpkgcache</literal> and 
    <literal>pkgcache</literal> as well as the location to place downloaded archives, 
    <literal>Dir::Cache::archives</literal>. Generation of caches can be turned off
 
    <para><literal>Dir::Cache</literal> contains locations pertaining to local cache 
    information, such as the two package caches <literal>srcpkgcache</literal> and 
    <literal>pkgcache</literal> as well as the location to place downloaded archives, 
    <literal>Dir::Cache::archives</literal>. Generation of caches can be turned off

-   by setting their names to be blank. This will slow down startup but
-   save disk space. It is probably preferred to turn off the pkgcache rather
+   by setting their names to the empty string. This will slow down startup but
+   save disk space. It is probably preferable to turn off the pkgcache rather

    than the srcpkgcache. Like <literal>Dir::State</literal> the default
    directory is contained in <literal>Dir::Cache</literal></para>
 
    than the srcpkgcache. Like <literal>Dir::State</literal> the default
    directory is contained in <literal>Dir::Cache</literal></para>
 


@@ -295,6 +616,7 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
 
    <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal> 
    specifies the location of the method handlers and <literal>gzip</literal>, 
 
    <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal> 
    specifies the location of the method handlers and <literal>gzip</literal>, 

+   <literal>bzip2</literal>, <literal>lzma</literal>,

    <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal> 
    <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
    of the respective programs.</para>
    <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal> 
    <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
    of the respective programs.</para>


@@ -311,94 +633,562 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      will be looked up in
      <filename>/tmp/staging/var/lib/dpkg/status</filename>.
    </para>
      will be looked up in
      <filename>/tmp/staging/var/lib/dpkg/status</filename>.
    </para>

+
+   <para>
+      The <literal>Ignore-Files-Silently</literal> list can be used to specify
+      which files APT should silently ignore while parsing the files in the
+      fragment directories. Per default a file which end with <literal>.disabled</literal>,
+      <literal>~</literal>, <literal>.bak</literal> or <literal>.dpkg-[a-z]+</literal>
+      is silently ignored. As seen in the last default value these patterns can use regular
+      expression syntax.
+   </para>

  </refsect1>
  
  <refsect1><title>APT in DSelect</title>
    <para>   
    When APT is used as a &dselect; method several configuration directives
  </refsect1>
  
  <refsect1><title>APT in DSelect</title>
    <para>   
    When APT is used as a &dselect; method several configuration directives

-   control the default behaviour. These are in the <literal>DSelect</literal> section.</para>
+   control the default behavior. These are in the <literal>DSelect</literal> section.</para>

    
    <variablelist>
    
    <variablelist>

-     <varlistentry><term>Clean</term>
-     <listitem><para>Cache Clean mode; this value may be one of always, prompt, auto,
-     pre-auto and never.  always and prompt will remove all packages from
-     the cache after upgrading, prompt (the default) does so conditionally. 
-     auto removes only those packages which are no longer downloadable
-     (replaced with a new version for instance).  pre-auto performs this
-     action before downloading new packages.</para></listitem>
+     <varlistentry><term><option>Clean</option></term>
+     <listitem><para>Cache Clean mode; this value may be one of
+     <literal>always</literal>, <literal>prompt</literal>,
+     <literal>auto</literal>, <literal>pre-auto</literal> and
+     <literal>never</literal>.
+     <literal>always</literal> and <literal>prompt</literal> will remove
+     all packages from the cache after upgrading, <literal>prompt</literal>
+     (the default) does so conditionally.
+     <literal>auto</literal> removes only those packages which are no longer
+     downloadable (replaced with a new version for instance).
+     <literal>pre-auto</literal> performs this action before downloading
+     new packages.</para></listitem>

      </varlistentry>
 
      </varlistentry>
 

-     <varlistentry><term>options</term>
-     <listitem><para>The contents of this variable is passed to &apt-get; as command line
+     <varlistentry><term><option>options</option></term>
+     <listitem><para>The contents of this variable are passed to &apt-get; as command line

      options when it is run for the install phase.</para></listitem>
      </varlistentry>
 
      options when it is run for the install phase.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>Updateoptions</term>
-     <listitem><para>The contents of this variable is passed to &apt-get; as command line
+     <varlistentry><term><option>Updateoptions</option></term>
+     <listitem><para>The contents of this variable are passed to &apt-get; as command line

      options when it is run for the update phase.</para></listitem>
      </varlistentry>
 
      options when it is run for the update phase.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>PromptAfterUpdate</term>
+     <varlistentry><term><option>PromptAfterUpdate</option></term>

      <listitem><para>If true the [U]pdate operation in &dselect; will always prompt to continue. 
      The default is to prompt only on error.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
  
      <listitem><para>If true the [U]pdate operation in &dselect; will always prompt to continue. 
      The default is to prompt only on error.</para></listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
  

- <refsect1><title>How APT calls dpkg</title>
+ <refsect1><title>How APT calls &dpkg;</title>

    <para>Several configuration directives control how APT invokes &dpkg;. These are 
    in the <literal>DPkg</literal> section.</para>
 
    <variablelist>
    <para>Several configuration directives control how APT invokes &dpkg;. These are 
    in the <literal>DPkg</literal> section.</para>
 
    <variablelist>

-     <varlistentry><term>options</term>
-     <listitem><para>This is a list of options to pass to dpkg. The options must be specified
+     <varlistentry><term><option>options</option></term>
+     <listitem><para>This is a list of options to pass to &dpkg;. The options must be specified

      using the list notation and each list item is passed as a single argument
      to &dpkg;.</para></listitem>
      </varlistentry>
      
      using the list notation and each list item is passed as a single argument
      to &dpkg;.</para></listitem>
      </varlistentry>
      

-     <varlistentry><term>Pre-Invoke</term><term>Post-Invoke</term>
+     <varlistentry><term><option>Pre-Invoke</option></term><term><option>Post-Invoke</option></term>

      <listitem><para>This is a list of shell commands to run before/after invoking &dpkg;. 
      Like <literal>options</literal> this must be specified in list notation. The 
      <listitem><para>This is a list of shell commands to run before/after invoking &dpkg;. 
      Like <literal>options</literal> this must be specified in list notation. The 

-     commands are invoked in order using <filename>/bin/sh</filename>, should any 
+     commands are invoked in order using <filename>/bin/sh</filename>; should any 

      fail APT will abort.</para></listitem>
      </varlistentry>
 
      fail APT will abort.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>Pre-Install-Pkgs</term>
-     <listitem><para>This is a list of shell commands to run before invoking dpkg. Like
+     <varlistentry><term><option>Pre-Install-Pkgs</option></term>
+     <listitem><para>This is a list of shell commands to run before invoking &dpkg;. Like

      <literal>options</literal> this must be specified in list notation. The commands
      <literal>options</literal> this must be specified in list notation. The commands

-     are invoked in order using <filename>/bin/sh</filename>, should any fail APT 
-     will abort. APT will pass to the commands on standard input the 
-     filenames of all .deb files it is going to install, one per line.</para>
+     are invoked in order using <filename>/bin/sh</filename>; should any fail APT 
+     will abort. APT will pass the filenames of all .deb files it is going to
+     install to the commands, one per line on the requested file descriptor, defaulting
+     to standard input.</para>

 
 

-     <para>Version 2 of this protocol dumps more information, including the 
+     <para>Version 2 of this protocol dumps more information, including the

      protocol version, the APT configuration space and the packages, files
      protocol version, the APT configuration space and the packages, files

-     and versions being changed. Version 2 is enabled by setting 
-     <literal>DPkg::Tools::options::cmd::Version</literal> to 2. <literal>cmd</literal> is a
-     command given to <literal>Pre-Install-Pkgs</literal>.</para></listitem>
+     and versions being changed. Version 3 adds the architecture and <literal>MultiArch</literal>
+     flag to each version being dumped.</para>
+
+     <para>The version of the protocol to be used for the command
+     <literal><replaceable>cmd</replaceable></literal> can be chosen by setting
+     <literal>DPkg::Tools::options::<replaceable>cmd</replaceable>::Version</literal>
+     accordingly, the default being version 1. If APT isn't supporting the requested
+     version it will send the information in the highest version it has support for instead.
+     </para>
+
+     <para>The file descriptor to be used to send the information can be requested with
+     <literal>DPkg::Tools::options::<replaceable>cmd</replaceable>::InfoFD</literal>
+     which defaults to <literal>0</literal> for standard input and is available since
+     version 0.9.11. Support for the option can be detected by looking for the environment
+     variable <envar>APT_HOOK_INFO_FD</envar> which contains the number of the used
+     file descriptor as a confirmation.</para>
+     </listitem>

      </varlistentry>
 
      </varlistentry>
 

-     <varlistentry><term>Run-Directory</term>
-     <listitem><para>APT chdirs to this directory before invoking dpkg, the default is 
+     <varlistentry><term><option>Run-Directory</option></term>
+     <listitem><para>APT chdirs to this directory before invoking &dpkg;, the default is 

      <filename>/</filename>.</para></listitem>
      </varlistentry>
 
      <filename>/</filename>.</para></listitem>
      </varlistentry>
 

-     <varlistentry><term>Build-options</term>
-     <listitem><para>These options are passed to &dpkg-buildpackage; when compiling packages,
+     <varlistentry><term><option>Build-options</option></term>
+     <listitem><para>These options are passed to &dpkg-buildpackage; when compiling packages;

      the default is to disable signing and produce all binaries.</para></listitem>
      </varlistentry>
    </variablelist>
      the default is to disable signing and produce all binaries.</para></listitem>
      </varlistentry>
    </variablelist>

+
+   <refsect2><title>dpkg trigger usage (and related options)</title>
+     <para>APT can call &dpkg; in such a way as to let it make aggressive use of triggers over
+     multiple calls of &dpkg;. Without further options &dpkg; will use triggers once each time it runs.
+     Activating these options can therefore decrease the time needed to perform the
+     install or upgrade. Note that it is intended to activate these options per default in the
+     future, but as it drastically changes the way APT calls &dpkg; it needs a lot more testing.
+     <emphasis>These options are therefore currently experimental and should not be used in
+     production environments.</emphasis> It also breaks progress reporting such that all front-ends will
+     currently stay around half (or more) of the time in the 100% state while it actually configures
+     all packages.</para>
+     <para>Note that it is not guaranteed that APT will support these options or that these options will
+     not cause (big) trouble in the future. If you have understand the current risks and problems with
+     these options, but are brave enough to help testing them, create a new configuration file and test a
+     combination of options. Please report any bugs, problems and improvements you encounter and make sure
+     to note which options you have used in your reports. Asking &dpkg; for help could also be useful for
+     debugging proposes, see e.g. <command>dpkg --audit</command>. A defensive option combination would be
+<literallayout>DPkg::NoTriggers "true";
+PackageManager::Configure "smart";
+DPkg::ConfigurePending "true";
+DPkg::TriggersPending "true";</literallayout></para>
+
+     <variablelist>
+       <varlistentry><term><option>DPkg::NoTriggers</option></term>
+       <listitem><para>Add the no triggers flag to all &dpkg; calls (except the ConfigurePending call).
+       See &dpkg; if you are interested in what this actually means. In short: &dpkg; will not run the
+       triggers when this flag is present unless it is explicitly called to do so in an extra call.
+       Note that this option exists (undocumented) also in older APT versions with a slightly different
+       meaning: Previously these option only append --no-triggers to the configure calls to &dpkg; -
+       now APT will also add this flag to the unpack and remove calls.</para></listitem>
+       </varlistentry>
+       <varlistentry><term><option>PackageManager::Configure</option></term>
+       <listitem><para>Valid values are "<literal>all</literal>",
+       "<literal>smart</literal>" and "<literal>no</literal>".
+       The default value is "<literal>all</literal>", which causes APT to
+       configure all packages. The "<literal>smart</literal>" way is to
+       configure only packages which need to be configured before another
+       package can be unpacked (Pre-Depends), and let the rest be configured
+       by &dpkg; with a call generated by the ConfigurePending option (see
+       below). On the other hand, "<literal>no</literal>" will not configure
+       anything, and totally relies on &dpkg; for configuration (which at the
+       moment will fail if a Pre-Depends is encountered). Setting this option
+       to any value other than <literal>all</literal> will implicitly also
+       activate the next option by default, as otherwise the system could end
+       in an unconfigured and potentially unbootable state.</para></listitem>
+       </varlistentry>
+       <varlistentry><term><option>DPkg::ConfigurePending</option></term>
+       <listitem><para>If this option is set APT will call <command>dpkg --configure --pending</command>
+       to let &dpkg; handle all required configurations and triggers. This option is activated automatically
+       per default if the previous option is not set to <literal>all</literal>, but deactivating it could be useful
+       if you want to run APT multiple times in a row - e.g. in an installer. In these sceneries you could
+       deactivate this option in all but the last run.</para></listitem>
+       </varlistentry>
+       <varlistentry><term><option>DPkg::TriggersPending</option></term>
+       <listitem><para>Useful for the <literal>smart</literal> configuration as a package which has pending
+       triggers is not considered as <literal>installed</literal>, and &dpkg; treats them as <literal>unpacked</literal>
+       currently which is a showstopper for Pre-Dependencies (see debbugs #526774). Note that this will
+       process all triggers, not only the triggers needed to configure this package.</para></listitem>
+       </varlistentry>
+       <varlistentry><term><option>OrderList::Score::Immediate</option></term>
+       <listitem><para>Essential packages (and their dependencies) should be configured immediately
+       after unpacking. It is a good idea to do this quite early in the upgrade process as these
+       configure calls also currently require <literal>DPkg::TriggersPending</literal> which
+       will run quite a few triggers (which may not be needed). Essentials get per default a high score
+       but the immediate flag is relatively low (a package which has a Pre-Depends is rated higher).
+       These option and the others in the same group can be used to change the scoring. The following
+       example shows the settings with their default values.
+       <literallayout>OrderList::Score {
+       Delete 500;
+       Essential 200;
+       Immediate 10;
+       PreDepends 50;
+};</literallayout>
+       </para></listitem>
+       </varlistentry>
+     </variablelist>
+   </refsect2>

  </refsect1>
 
  </refsect1>
 

- <refsect1><title>Debug options</title>
-   <para>Most of the options in the <literal>debug</literal> section are not interesting to 
-   the normal user, however <literal>Debug::pkgProblemResolver</literal> shows 
-   interesting output about the decisions dist-upgrade makes. 
-   <literal>Debug::NoLocking</literal> disables file locking so APT can do some 
-   operations as non-root and <literal>Debug::pkgDPkgPM</literal> will print out the 
-   command line for each dpkg invokation. <literal>Debug::IdentCdrom</literal> will 
-   disable the inclusion of statfs data in CDROM IDs.
-   <literal>Debug::Acquire::gpgv</literal> Debugging of the gpgv method.
+ <refsect1>
+   <title>Periodic and Archives options</title>
+   <para><literal>APT::Periodic</literal> and <literal>APT::Archives</literal>
+   groups of options configure behavior of apt periodic updates, which is
+   done by the <literal>/etc/cron.daily/apt</literal> script. See the top of
+   this script for the brief documentation of these options.
+   </para>
+ </refsect1>
+
+ <refsect1>
+   <title>Debug options</title>
+   <para>
+     Enabling options in the <literal>Debug::</literal> section will
+     cause debugging information to be sent to the standard error
+     stream of the program utilizing the <literal>apt</literal>
+     libraries, or enable special program modes that are primarily
+     useful for debugging the behavior of <literal>apt</literal>.
+     Most of these options are not interesting to a normal user, but a
+     few may be:
+
+     <itemizedlist>
+       <listitem>
+        <para>
+          <literal>Debug::pkgProblemResolver</literal> enables output
+          about the decisions made by
+          <literal>dist-upgrade, upgrade, install, remove, purge</literal>.
+        </para>
+       </listitem>
+
+       <listitem>
+        <para>
+          <literal>Debug::NoLocking</literal> disables all file
+          locking.  This can be used to run some operations (for
+          instance, <literal>apt-get -s install</literal>) as a
+          non-root user.
+        </para>
+       </listitem>
+
+       <listitem>
+        <para>
+          <literal>Debug::pkgDPkgPM</literal> prints out the actual
+          command line each time that <literal>apt</literal> invokes
+          &dpkg;.
+        </para>
+       </listitem>
+
+       <listitem>
+        <para>
+          <literal>Debug::IdentCdrom</literal> disables the inclusion
+          of statfs data in CD-ROM IDs.  <!-- TODO: provide a
+          motivating example, except I haven't a clue why you'd want
+          to do this. -->
+        </para>
+       </listitem>
+     </itemizedlist>

    </para>
    </para>

+
+   <para>
+     A full list of debugging options to apt follows.
+   </para>
+
+   <variablelist>
+     <varlistentry>
+       <term><option>Debug::Acquire::cdrom</option></term>
+
+       <listitem>
+        <para>
+          Print information related to accessing
+          <literal>cdrom://</literal> sources.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::Acquire::ftp</option></term>
+
+       <listitem>
+        <para>
+          Print information related to downloading packages using
+          FTP.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::Acquire::http</option></term>
+
+       <listitem>
+        <para>
+          Print information related to downloading packages using
+          HTTP.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::Acquire::https</option></term>
+
+       <listitem>
+        <para>
+          Print information related to downloading packages using
+          HTTPS.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::Acquire::gpgv</option></term>
+
+       <listitem>
+        <para>
+          Print information related to verifying cryptographic
+          signatures using <literal>gpg</literal>.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::aptcdrom</option></term>
+
+       <listitem>
+        <para>
+          Output information about the process of accessing
+          collections of packages stored on CD-ROMs.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::BuildDeps</option></term>
+       <listitem>
+        <para>
+          Describes the process of resolving build-dependencies in
+          &apt-get;.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::Hashes</option></term>
+       <listitem>
+        <para>
+          Output each cryptographic hash that is generated by the
+          <literal>apt</literal> libraries.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::IdentCDROM</option></term>
+       <listitem>
+        <para>
+          Do not include information from <literal>statfs</literal>,
+          namely the number of used and free blocks on the CD-ROM
+          filesystem, when generating an ID for a CD-ROM.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::NoLocking</option></term>
+       <listitem>
+        <para>
+          Disable all file locking.  For instance, this will allow
+          two instances of <quote><literal>apt-get
+          update</literal></quote> to run at the same time.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgAcquire</option></term>
+
+       <listitem>
+        <para>
+          Log when items are added to or removed from the global
+          download queue.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgAcquire::Auth</option></term>
+       <listitem>
+        <para>
+          Output status messages and errors related to verifying
+          checksums and cryptographic signatures of downloaded files.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgAcquire::Diffs</option></term>
+       <listitem>
+        <para>
+          Output information about downloading and applying package
+          index list diffs, and errors relating to package index list
+          diffs.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgAcquire::RRed</option></term>
+
+       <listitem>
+        <para>
+          Output information related to patching apt package lists
+          when downloading index diffs instead of full indices.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgAcquire::Worker</option></term>
+
+       <listitem>
+        <para>
+          Log all interactions with the sub-processes that actually
+          perform downloads.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgAutoRemove</option></term>
+
+       <listitem>
+        <para>
+          Log events related to the automatically-installed status of
+          packages and to the removal of unused packages.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgDepCache::AutoInstall</option></term>
+       <listitem>
+        <para>
+          Generate debug messages describing which packages are being
+          automatically installed to resolve dependencies.  This
+          corresponds to the initial auto-install pass performed in,
+          e.g., <literal>apt-get install</literal>, and not to the
+          full <literal>apt</literal> dependency resolver; see
+          <literal>Debug::pkgProblemResolver</literal> for that.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgDepCache::Marker</option></term>
+       <listitem>
+        <para>
+           Generate debug messages describing which packages are marked
+          as keep/install/remove while the ProblemResolver does his work.
+          Each addition or deletion may trigger additional actions;
+          they are shown indented two additional spaces under the original entry.
+          The format for each line is <literal>MarkKeep</literal>,
+          <literal>MarkDelete</literal> or <literal>MarkInstall</literal> followed by
+          <literal>package-name &lt;a.b.c -&gt; d.e.f | x.y.z&gt; (section)</literal>
+          where <literal>a.b.c</literal> is the current version of the package,
+          <literal>d.e.f</literal> is the version considered for installation and
+          <literal>x.y.z</literal> is a newer version, but not considered for installation
+          (because of a low pin score). The later two can be omitted if there is none or if
+          it is the same as the installed version.
+          <literal>section</literal> is the name of the section the package appears in.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgDPkgPM</option></term>
+       <listitem>
+        <para>
+          When invoking &dpkg;, output the precise command line with
+          which it is being invoked, with arguments separated by a
+          single space character.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgDPkgProgressReporting</option></term>
+       <listitem>
+        <para>
+          Output all the data received from &dpkg; on the status file
+          descriptor and any errors encountered while parsing it.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgOrderList</option></term>
+
+       <listitem>
+        <para>
+          Generate a trace of the algorithm that decides the order in
+          which <literal>apt</literal> should pass packages to
+          &dpkg;.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgPackageManager</option></term>
+
+       <listitem>
+        <para>
+          Output status messages tracing the steps performed when
+          invoking &dpkg;.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgPolicy</option></term>
+
+       <listitem>
+        <para>
+          Output the priority of each package list on startup.
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgProblemResolver</option></term>
+
+       <listitem>
+        <para>
+          Trace the execution of the dependency resolver (this
+          applies only to what happens when a complex dependency
+          problem is encountered).
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::pkgProblemResolver::ShowScores</option></term>
+       <listitem>
+        <para>
+          Display a list of all installed packages with their calculated score
+          used by the pkgProblemResolver. The description of the package
+          is the same as described in <literal>Debug::pkgDepCache::Marker</literal>
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
+       <term><option>Debug::sourceList</option></term>
+
+       <listitem>
+        <para>
+          Print information about the vendors read from
+          <filename>/etc/apt/vendors.list</filename>.
+        </para>
+       </listitem>
+     </varlistentry>
+
+<!-- 2009/07/11 Currently used nowhere. The corresponding code
+is commented.
+     <varlistentry>
+       <term><literal>Debug::Vendor</literal></term>
+
+       <listitem>
+        <para>
+          Print information about each vendor.
+        </para>
+       </listitem>
+     </varlistentry>
+-->
+
+   </variablelist>

  </refsect1>
  
  <refsect1><title>Examples</title>
  </refsect1>
  
  <refsect1><title>Examples</title>


@@ -408,7 +1198,9 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
  </refsect1>
  
  <refsect1><title>Files</title>
  </refsect1>
  
  <refsect1><title>Files</title>

-   <para><filename>/etc/apt/apt.conf</filename></para>
+   <variablelist>
+      &file-aptconf;
+   </variablelist>

  </refsect1>
  
  <refsect1><title>See Also</title>
  </refsect1>
  
  <refsect1><title>See Also</title>