FildFd: Introduce a Flush() function and call it from Close()

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

diff --git a/doc/apt.conf.5.xml b/doc/apt.conf.5.xml
index 661f97ab1ca5ea30be265f2cb916c3c798eed093..18896066b271c3480b67bc128b3b3c020ef2c228 100644 (file)
--- a/doc/apt.conf.5.xml
+++ b/doc/apt.conf.5.xml
@@ -1,10 +1,9 @@
 <?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" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
+<!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 % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;

 ]>
 
 <refentry>
 ]>
 
 <refentry>


@@ -13,15 +12,14 @@
    &apt-author.jgunthorpe;
    &apt-author.team;
    <author>
    &apt-author.jgunthorpe;
    &apt-author.team;
    <author>

-     <firstname>Daniel</firstname>
-     <surname>Burrows</surname>
+     &apt-name.dburrows;

      <contrib>Initial documentation of Debug::*.</contrib>
      <email>dburrows@debian.org</email>
    </author>
    &apt-email;
    &apt-product;
    <!-- The last update date -->
      <contrib>Initial documentation of Debug::*.</contrib>
      <email>dburrows@debian.org</email>
    </author>
    &apt-email;
    &apt-product;
    <!-- The last update date -->

-   <date>18 September 2009</date>
+   <date>2015-12-14T00:00:00Z</date>

  </refentryinfo>
  
  <refmeta>
  </refentryinfo>
  
  <refmeta>


@@ -35,22 +33,38 @@
     <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>
-   <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>

 
 

+ <refsect1><title>Description</title>
+   <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>all options set in the binary specific configuration
+           subtree are moved into the root of the tree.</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


@@ -58,13 +72,12 @@
    <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
    <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

-   <literal>APT::Get::Assume-Yes "true";</literal> The trailing 
-   semicolon and the quotes are required. The value must be on one line, and
-   there is no kind of string concatenation. It must not include inside quotes.
-   The behavior of the backslash "\" and escaped characters inside a value is
-   undefined and it should not be used. An option name may include
-   alphanumerical characters and the "/-:._+" characters. 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 {


@@ -77,53 +90,62 @@ APT {
 
    <para>with newlines placed to make it more readable. Lists can be created by 
    opening a scope and including a single string enclosed in quotes followed by a
 
    <para>with newlines placed to make it more readable. Lists can be created by 
    opening a scope and including a single string enclosed in quotes followed by a

-   semicolon. Multiple entries can be included, each separated by a semicolon.</para>
+   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 it can be see in
+   <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 <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 as every other option by reassigning a new value to the option.</para>
+   the option in the same way as any other option by reassigning a new value to the option.</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.  
+   <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>
 
    <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>The #clear command is the only way to delete a list or a complete scope.
-   Reopening a scope or the ::-style described below will <emphasis>not</emphasis>
-   override previously written entries. Only options can be overridden by addressing a new
-   value to it - lists and scopes can't be overridden, only cleared.</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. (As you might suspect: The scope syntax can't be used
-   on the command line.)</para>
-
-   <para>Note that you can use :: only for appending one item per line to a list and
-   that you should not use it in combination with the scope syntax.
-   (The scope syntax implicit insert ::) Using both syntaxes together will trigger a bug
-   which some users unfortunately relay on: An option with the unusual name "<literal>::</literal>"
-   which acts like every other option with a name. These introduces many problems
-   including that a user who writes multiple lines in this <emphasis>wrong</emphasis> syntax in
-   the hope to append to a list will gain the opposite as only the last assignment for this option
-   "<literal>::</literal>" will be used. Upcoming APT versions will raise errors and
-   will stop working if they encounter this misuse, so please correct such statements now
-   as long as APT doesn't complain explicit about them.</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>


@@ -131,84 +153,213 @@ 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>Default-Release</term>
-        <listitem><para>Default release to install packages from if more than one
-        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>
+
+     <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>

-     
-     <varlistentry><term>Ignore-Hold</term>
-     <listitem><para>Ignore Held packages; This global option causes the problem resolver to
+
+     <varlistentry><term><option>Build-Profiles</option></term>
+     <listitem><para>
+     List of all build profiles enabled for build-dependency resolution,
+     without the "<literal>profile.</literal>" namespace prefix.
+     By default this list is empty. The <envar>DEB_BUILD_PROFILES</envar>
+     as used by &dpkg-buildpackage; overrides the list notation.
+     </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>PDiffs</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.
+     The <option>Check-Valid-Until</option> option of &sources-list; entries should be
+     preferred to disable the check selectively instead of using this global override.
+     </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. Preferably, the same can be achieved for specific
+        &sources-list; entries by using the <option>Valid-Until-Max</option> option there.
+        </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. Preferably, the same can be achieved for specific
+        &sources-list; entries by using the <option>Valid-Until-Min</option> option there.
+        </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>PDiffs</option></term>

         <listitem><para>Try to download deltas called <literal>PDiffs</literal> for
         <listitem><para>Try to download deltas called <literal>PDiffs</literal> for

-        Packages or Sources files instead of downloading whole ones. True
-        by default.</para></listitem>
+        indexes (like <filename>Packages</filename> files) instead of
+        downloading whole ones. True by default. Preferably, this can be set
+        for specific &sources-list; entries or index files by using the
+        <option>PDiffs</option> option there.</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>
 

-     <varlistentry><term>Queue-Mode</term>
+     <varlistentry><term><option>By-Hash</option></term>
+        <listitem><para>Try to download indexes via an URI constructed from a
+        hashsum of the expected file rather than downloaded via a well-known
+        stable filename. True by default, but automatically disabled if the
+        source indicates no support for it. Usage can be forced with the special
+        value "force". Preferably, this can be set for specific &sources-list; entries
+        or index files by using the <option>By-Hash</option> option there.
+        </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 


@@ -216,104 +367,135 @@ 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> 
         meaning to use no proxies. If no one of the above settings is specified,
         <envar>http_proxy</envar> environment variable
         will be used.</para>
 
      <literal>http::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>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 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>
-
-     <para>The used bandwidth can be limited with <literal>Acquire::http::Dl-Limit</literal>
-     which accepts integer values in kilobyte. The default value is 0 which deactivates
-     the limit and tries uses as much as possible of the bandwidth (Note that this option implicit
-     deactivates the download from multiple servers at the same time.)</para></listitem>
-     </varlistentry>
-
-     <varlistentry><term>https</term>
-        <listitem><para>HTTPS URIs. Cache-control and proxy options are the same as for
-        <literal>http</literal> method.
-        <literal>Pipeline-Depth</literal> option is not supported yet.</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.
+     APT tries to detect and workaround misbehaving webservers and proxies at runtime, but
+     if you know that yours does not conform to the HTTP/1.1 specification pipelining can
+     be disabled by setting the value to 0. It is enabled by default with the value 10.</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.
 
         <para><literal>CaInfo</literal> suboption specifies place of file that
         holds info about trusted certificates.

-        <literal>&lt;host&gt;::CaInfo</literal> is corresponding per-host option.
-        <literal>Verify-Peer</literal> boolean suboption determines whether verify
-        server's host certificate against trusted certificates or not.
-        <literal>&lt;host&gt;::Verify-Peer</literal> is corresponding per-host option.
-        <literal>Verify-Host</literal> boolean suboption determines whether verify
-        server's hostname or not.
-        <literal>&lt;host&gt;::Verify-Host</literal> is corresponding per-host option.
+        <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
         <literal>SslCert</literal> determines what certificate to use for client

-        authentication. <literal>&lt;host&gt;::SslCert</literal> is corresponding per-host option.
+        authentication. <literal>&lt;host&gt;::SslCert</literal> is the corresponding per-host option.

         <literal>SslKey</literal> determines what private key to use for client
         <literal>SslKey</literal> determines what private key to use for client

-        authentication. <literal>&lt;host&gt;::SslKey</literal> is corresponding per-host option.
+        authentication. <literal>&lt;host&gt;::SslKey</literal> is the corresponding per-host option.

         <literal>SslForceVersion</literal> overrides default SSL version to use.
         <literal>SslForceVersion</literal> overrides default SSL version to use.

-        Can contain 'TLSv1' or 'SSLv3' string.
-        <literal>&lt;host&gt;::SslForceVersion</literal> is corresponding per-host option.
+        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>
 
         </para></listitem></varlistentry>
 

-     <varlistentry><term>ftp</term>
-     <listitem><para>FTP URIs; ftp::Proxy is the default ftp proxy to use. 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 
+     <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
      <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 a ftp 
+        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>
 


@@ -324,72 +506,211 @@ 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>CompressionTypes</term>
+     <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.
      <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.

-     Per 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
+     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>
      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
+     </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
      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

-     simple add the preferred type at first - not already added default types will be added at run time
+     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
      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> explicit to the list as it will be added automatic.</para>
-     <para>Note that at run time the <literal>Dir::Bin::<replaceable>Methodname</replaceable></literal> will
-     be checked: If this setting exists the method will only be used if this file exists, e.g. for
-     the bzip2 method (the inbuilt) setting is <literallayout>Dir::Bin::bzip2 "/bin/bzip2";</literallayout>
+     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
      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 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>While it is possible to add an empty compression type to the order list, but APT in its current
-     version doesn't understand it correctly and will display many warnings about not downloaded files -
-     these warnings are most of the time false negatives. Future versions will maybe include a way to
-     really prefer uncompressed files to support the usage of local mirrors.</para></listitem>
+     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>
+
+     <varlistentry><term><option>MaxReleaseFileSize</option></term>
+        <listitem><para>
+           The maximum file size of Release/Release.gpg/InRelease files.
+           The default is 10MB.
+        </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>EnableSrvRecords</option></term>
+        <listitem><para>
+           This option controls if apt will use the DNS SRV server record
+           as specified in RFC 2782 to select an alternative server to
+           connect to.
+           The default is "true".
+        </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>AllowInsecureRepositories</option></term>
+        <listitem><para>
+           Allow the update operation to load data files from
+           a repository without a trusted signature. If enabled this
+           option no data files will be loaded and the update
+           operation fails with a error for this source. The default
+           is false for backward compatibility. This will be changed
+           in the future.
+        </para></listitem>
+     </varlistentry>
+
+     <varlistentry><term><option>AllowDowngradeToInsecureRepositories</option></term>
+        <listitem><para>
+           Allow that a repository that was previously gpg signed to become
+           unsigned durign a update operation. When there is no valid signature
+           of a perviously trusted repository apt will refuse the update. This
+           option can be used to override this protection. You almost certainly
+           never want to enable this. The default is false.
+
+           Note that apt will still consider packages from this source
+           untrusted and warn about them if you try to install
+           them.
+         </para></listitem>

      </varlistentry>
      </varlistentry>

+
+     <varlistentry><term><option>Changelogs::URI</option> scope</term>
+       <listitem><para>
+         Acquiring changelogs can only be done if an URI is known from where to get them.
+         Preferable the Release file indicates this in a 'Changelogs' field. If this isn't
+         available the Label/Origin field of the Release file is used to check if a
+         <literal>Acquire::Changelogs::URI::Label::<replaceable>LABEL</replaceable></literal> or
+         <literal>Acquire::Changelogs::URI::Origin::<replaceable>ORIGIN</replaceable></literal> option
+         exists and if so this value is taken. The value in the Release file can be overridden
+         with <literal>Acquire::Changelogs::URI::Override::Label::<replaceable>LABEL</replaceable></literal>
+         or <literal>Acquire::Changelogs::URI::Override::Origin::<replaceable>ORIGIN</replaceable></literal>.
+
+         The value should be a normal URI to a text file, expect that package specific data is
+         replaced with the placeholder <literal>@CHANGEPATH@</literal>. The
+         value for it is: 1. if the package is from a component (e.g. <literal>main</literal>)
+         this is the first part otherwise it is omitted, 2. the first letter of source package name,
+         expect if the source package name starts with '<literal>lib</literal>' in which case it will
+         be the first four letters. 3. The complete source package name. 4. the complete name again and
+         5. the source version.
+         The first (if present), second, third and fourth part are separated by a slash ('<literal>/</literal>')
+         and between the fourth and fifth part is an underscore ('<literal>_</literal>').
+
+         The special value '<literal>no</literal>' is available for this option indicating that
+         this source can't be used to acquire changelog files from. Another source will be tried
+         if available in this case.
+       </para></listitem>
+    </varlistentry>
+

    </variablelist>
    </variablelist>

-  </para>
+ </refsect1>
+
+ <refsect1><title>Binary specific configuration</title>
+    <para>Especially with the introduction of the <command>apt</command> binary
+       it can be useful to set certain options only for a specific binary as
+       even options which look like they would effect only a certain binary like
+       <option>APT::Get::Show-Versions</option> effect
+       <command>apt-get</command> as well as <command>apt</command>.
+    </para>
+    <para>Setting an option for a specific binary only can be achieved by
+       setting the option inside the
+       <option>Binary::<replaceable>specific-binary</replaceable></option>
+       scope. Setting the option <option>APT::Get::Show-Versions</option> for
+       the <command>apt</command> only can e.g. by done by setting
+       <option>Binary::apt::APT::Get::Show-Versions</option> instead.</para>
+    <para>Note that as seen in the DESCRIPTION section further above you can't
+       set binary-specific options on the commandline itself nor in
+       configuration files loaded via the commandline.</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
-   than the srcpkgcache. Like <literal>Dir::State</literal> the default
-   directory is contained in <literal>Dir::Cache</literal></para>
+   by setting <literal>pkgcache</literal> or <literal>srcpkgcache</literal> to
+   <literal>""</literal>.  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>

 
    <para><literal>Dir::Etc</literal> contains the location of configuration files, 
    <literal>sourcelist</literal> gives the location of the sourcelist and 
 
    <para><literal>Dir::Etc</literal> contains the location of configuration files, 
    <literal>sourcelist</literal> gives the location of the sourcelist and 


@@ -410,7 +731,7 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
 
    <para>
      The configuration item <literal>RootDir</literal> has a special
 
    <para>
      The configuration item <literal>RootDir</literal> has a special

-     meaning.  If set, all paths in <literal>Dir::</literal> will be
+     meaning.  If set, all paths will be

      relative to <literal>RootDir</literal>, <emphasis>even paths that
      are specified absolutely</emphasis>.  So, for instance, if
      <literal>RootDir</literal> is set to
      relative to <literal>RootDir</literal>, <emphasis>even paths that
      are specified absolutely</emphasis>.  So, for instance, if
      <literal>RootDir</literal> is set to


@@ -419,99 +740,153 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      <filename>/var/lib/dpkg/status</filename>, then the status file
      will be looked up in
      <filename>/tmp/staging/var/lib/dpkg/status</filename>.
      <filename>/var/lib/dpkg/status</filename>, then the status file
      will be looked up in
      <filename>/tmp/staging/var/lib/dpkg/status</filename>.

+     If you want to prefix only relative paths, set <literal>Dir</literal> instead.
+   </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
    </para>
  </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>
-
-     <para>Version 2 of this protocol dumps more information, including the 
-     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>
+     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 sends more information through the requested
+     file descriptor: a line with the text <literal>VERSION 2</literal>,
+     the APT configuration space, and a list of package actions with filename
+     and version information.</para>
+
+     <para>Each configuration directive line has the form
+     <literal>key=value</literal>.  Special characters (equal signs, newlines,
+     nonprintable characters, quotation marks, and percent signs in
+     <literal>key</literal> and newlines, nonprintable characters, and percent
+     signs in <literal>value</literal>) are %-encoded. Lists are represented
+     by multiple <literal>key::=value</literal> lines with the same key. The
+     configuration section ends with a blank line.</para>
+
+     <para>Package action lines consist of five fields in Version 2: old version, direction
+     of version change (&lt; for upgrades, &gt; for downgrades, = for no
+     change), new version, action. The version fields are "-" for no version
+     at all (for example when installing a package for the first time; no
+     version is treated as earlier than any real version, so that is an
+     upgrade, indicated as <literal>- &lt; 1.23.4</literal>). The action field
+     is "**CONFIGURE**" if the package is being configured, "**REMOVE**" if it
+     is being removed, or the filename of a .deb file if it is being
+     unpacked.</para>
+
+     <para>In Version 3 after each version field follows the architecture
+     of this version, which is "-" if there is no version, and a field showing
+     the MultiArch type "same", foreign", "allowed" or "none". Note that "none"
+     is an incorrect typename which is just kept to remain compatible, it
+     should be read as "no" and users are encouraged to support both.</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>
 
    <refsect2><title>dpkg trigger usage (and related options)</title>
      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 a way so it can make aggressive use of triggers over
-     multiply calls of dpkg. Without further options dpkg will use triggers only in between his
-     own run. Activating these options can therefore decrease the time needed to perform the
-     install / upgrade. Note that it is intended to activate these options per default in the
-     future, but as it changes the way APT calling dpkg drastically it needs a lot more testing.
+     <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
      <emphasis>These options are therefore currently experimental and should not be used in

-     productive environments.</emphasis> Also it breaks the progress reporting so all frontends will
+     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
      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
+     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
      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
+     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";
      debugging proposes, see e.g. <command>dpkg --audit</command>. A defensive option combination would be
 <literallayout>DPkg::NoTriggers "true";
 PackageManager::Configure "smart";


@@ -519,54 +894,50 @@ DPkg::ConfigurePending "true";
 DPkg::TriggersPending "true";</literallayout></para>
 
      <variablelist>
 DPkg::TriggersPending "true";</literallayout></para>
 
      <variablelist>

-       <varlistentry><term>DPkg::NoTriggers</term>
-       <listitem><para>Add the no triggers flag to all dpkg calls (expect the ConfigurePending call).
-       See &dpkg; if you are interested in what this actually means. In short: dpkg will not run the
-       triggers then this flag is present unless it is explicit 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 add these flag also to the unpack and remove calls.</para></listitem>
+       <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>

-       <varlistentry><term>PackageManager::Configure</term>
-       <listitem><para>Valid values are "<literal>all</literal>", "<literal>smart</literal>" and "<literal>no</literal>".
-       "<literal>all</literal>" is the default value and causes APT to configure all packages explicit.
-       The "<literal>smart</literal>" way is it to configure only packages which need to be configured before
-       another package can be unpacked (Pre-Depends) and let the rest configure by dpkg with a call generated
-       by the next option. "<literal>no</literal>" on the other hand will not configure anything and totally
-       relay on dpkg for configuration (which will at the moment fail if a Pre-Depends is encountered).
-       Setting this option to another than the all value will implicit activate also the next option per
-       default as otherwise the system could end in an unconfigured status which could be unbootable!
-       </para></listitem>
+       <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>

-       <varlistentry><term>DPkg::ConfigurePending</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 automatic
-       per default if the previous option is not set to <literal>all</literal>, but deactivating could be useful
-       if you want to run APT multiple times in a row - e.g. in an installer. In this sceneries you could
+       <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>
        deactivate this option in all but the last run.</para></listitem>
        </varlistentry>

-       <varlistentry><term>DPkg::TriggersPending</term>
-       <listitem><para>Useful for <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 dealbreaker for Pre-Dependencies (see debbugs #526774). Note that this will
+       <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>
        process all triggers, not only the triggers needed to configure this package.</para></listitem>
        </varlistentry>

-       <varlistentry><term>PackageManager::UnpackAll</term>
-       <listitem><para>As the configuration can be deferred to be done at the end by dpkg it can be
-       tried to order the unpack series only by critical needs, e.g. by Pre-Depends. Default is true
-       and therefore the "old" method of ordering in various steps by everything. While both method
-       were present in earlier APT versions the <literal>OrderCritical</literal> method was unused, so
-       this method is very experimental and needs further improvements before becoming really useful.
-       </para></listitem>
-       </varlistentry>
-       <varlistentry><term>OrderList::Score::Immediate</term>
-       <listitem><para>Essential packages (and there dependencies) should be configured immediately
-       after unpacking. It will be a good idea to do this quite early in the upgrade process as these
-       these configure calls require currently also <literal>DPkg::TriggersPending</literal> which
-       will run quite a few triggers (which maybe not needed). Essentials get per default a high score
-       but the immediate flag is relatively low (a package which has a Pre-Depends is higher rated).
+       <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
        These option and the others in the same group can be used to change the scoring. The following

-       example shows the settings with there default values.
+       example shows the settings with their default values.

        <literallayout>OrderList::Score {
        Delete 500;
        Essential 200;
        <literallayout>OrderList::Score {
        Delete 500;
        Essential 200;


@@ -583,7 +954,7 @@ DPkg::TriggersPending "true";</literallayout></para>
    <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
    <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 <literal>/etc/cron.daily/apt</literal> script. See header of
+   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>
    this script for the brief documentation of these options.
    </para>
  </refsect1>


@@ -628,7 +999,7 @@ DPkg::TriggersPending "true";</literallayout></para>
        <listitem>
         <para>
           <literal>Debug::IdentCdrom</literal> disables the inclusion
        <listitem>
         <para>
           <literal>Debug::IdentCdrom</literal> disables the inclusion

-          of statfs data in CDROM IDs.  <!-- TODO: provide a
+          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>
           motivating example, except I haven't a clue why you'd want
           to do this. -->
         </para>


@@ -642,7 +1013,7 @@ DPkg::TriggersPending "true";</literallayout></para>
 
    <variablelist>
      <varlistentry>
 
    <variablelist>
      <varlistentry>

-       <term><literal>Debug::Acquire::cdrom</literal></term>
+       <term><option>Debug::Acquire::cdrom</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -653,7 +1024,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::Acquire::ftp</literal></term>
+       <term><option>Debug::Acquire::ftp</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -664,7 +1035,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::Acquire::http</literal></term>
+       <term><option>Debug::Acquire::http</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -675,7 +1046,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::Acquire::https</literal></term>
+       <term><option>Debug::Acquire::https</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -686,7 +1057,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::Acquire::gpgv</literal></term>
+       <term><option>Debug::Acquire::gpgv</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -697,7 +1068,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::aptcdrom</literal></term>
+       <term><option>Debug::aptcdrom</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -708,7 +1079,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::BuildDeps</literal></term>
+       <term><option>Debug::BuildDeps</option></term>

        <listitem>
         <para>
           Describes the process of resolving build-dependencies in
        <listitem>
         <para>
           Describes the process of resolving build-dependencies in


@@ -718,7 +1089,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::Hashes</literal></term>
+       <term><option>Debug::Hashes</option></term>

        <listitem>
         <para>
           Output each cryptographic hash that is generated by the
        <listitem>
         <para>
           Output each cryptographic hash that is generated by the


@@ -728,7 +1099,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::IdentCDROM</literal></term>
+       <term><option>Debug::IdentCDROM</option></term>

        <listitem>
         <para>
           Do not include information from <literal>statfs</literal>,
        <listitem>
         <para>
           Do not include information from <literal>statfs</literal>,


@@ -739,7 +1110,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::NoLocking</literal></term>
+       <term><option>Debug::NoLocking</option></term>

        <listitem>
         <para>
           Disable all file locking.  For instance, this will allow
        <listitem>
         <para>
           Disable all file locking.  For instance, this will allow


@@ -750,7 +1121,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgAcquire</literal></term>
+       <term><option>Debug::pkgAcquire</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -761,7 +1132,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgAcquire::Auth</literal></term>
+       <term><option>Debug::pkgAcquire::Auth</option></term>

        <listitem>
         <para>
           Output status messages and errors related to verifying
        <listitem>
         <para>
           Output status messages and errors related to verifying


@@ -771,7 +1142,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgAcquire::Diffs</literal></term>
+       <term><option>Debug::pkgAcquire::Diffs</option></term>

        <listitem>
         <para>
           Output information about downloading and applying package
        <listitem>
         <para>
           Output information about downloading and applying package


@@ -782,7 +1153,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgAcquire::RRed</literal></term>
+       <term><option>Debug::pkgAcquire::RRed</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -793,7 +1164,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgAcquire::Worker</literal></term>
+       <term><option>Debug::pkgAcquire::Worker</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -804,7 +1175,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgAutoRemove</literal></term>
+       <term><option>Debug::pkgAutoRemove</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -815,7 +1186,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgDepCache::AutoInstall</literal></term>
+       <term><option>Debug::pkgDepCache::AutoInstall</option></term>

        <listitem>
         <para>
           Generate debug messages describing which packages are being
        <listitem>
         <para>
           Generate debug messages describing which packages are being


@@ -829,13 +1200,13 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgDepCache::Marker</literal></term>
+       <term><option>Debug::pkgDepCache::Marker</option></term>

        <listitem>
         <para>
        <listitem>
         <para>

-           Generate debug messages describing which package is marked
+           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;
           as keep/install/remove while the ProblemResolver does his work.
           Each addition or deletion may trigger additional actions;

-          they are shown indented two additional space under the original entry.
+          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>
           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>


@@ -843,25 +1214,14 @@ DPkg::TriggersPending "true";</literallayout></para>
           <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
           <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 version as the installed.
+          it is the same as the installed version.

           <literal>section</literal> is the name of the section the package appears in.
         </para>
        </listitem>
      </varlistentry>
 
           <literal>section</literal> is the name of the section the package appears in.
         </para>
        </listitem>
      </varlistentry>
 

-     <!-- Question: why doesn't this do anything?  The code says it should. -->

      <varlistentry>
      <varlistentry>

-       <term><literal>Debug::pkgInitConfig</literal></term>
-       <listitem>
-        <para>
-          Dump the default configuration to standard error on
-          startup.
-        </para>
-       </listitem>
-     </varlistentry>
-
-     <varlistentry>
-       <term><literal>Debug::pkgDPkgPM</literal></term>
+       <term><option>Debug::pkgDPkgPM</option></term>

        <listitem>
         <para>
           When invoking &dpkg;, output the precise command line with
        <listitem>
         <para>
           When invoking &dpkg;, output the precise command line with


@@ -872,7 +1232,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgDPkgProgressReporting</literal></term>
+       <term><option>Debug::pkgDPkgProgressReporting</option></term>

        <listitem>
         <para>
           Output all the data received from &dpkg; on the status file
        <listitem>
         <para>
           Output all the data received from &dpkg; on the status file


@@ -882,7 +1242,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgOrderList</literal></term>
+       <term><option>Debug::pkgOrderList</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -894,7 +1254,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgPackageManager</literal></term>
+       <term><option>Debug::pkgPackageManager</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -905,7 +1265,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgPolicy</literal></term>
+       <term><option>Debug::pkgPolicy</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -915,7 +1275,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgProblemResolver</literal></term>
+       <term><option>Debug::pkgProblemResolver</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -927,7 +1287,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::pkgProblemResolver::ShowScores</literal></term>
+       <term><option>Debug::pkgProblemResolver::ShowScores</option></term>

        <listitem>
         <para>
           Display a list of all installed packages with their calculated score
        <listitem>
         <para>
           Display a list of all installed packages with their calculated score


@@ -938,7 +1298,7 @@ DPkg::TriggersPending "true";</literallayout></para>
      </varlistentry>
 
      <varlistentry>
      </varlistentry>
 
      <varlistentry>

-       <term><literal>Debug::sourceList</literal></term>
+       <term><option>Debug::sourceList</option></term>

 
        <listitem>
         <para>
 
        <listitem>
         <para>


@@ -948,6 +1308,18 @@ DPkg::TriggersPending "true";</literallayout></para>
        </listitem>
      </varlistentry>
 
        </listitem>
      </varlistentry>
 

+     <varlistentry>
+       <term><option>Debug::RunScripts</option></term>
+       <listitem>
+        <para>
+          Display the external commands that are called by apt hooks.
+          This includes e.g. the config options
+          <literal>DPkg::{Pre,Post}-Invoke</literal> or
+          <literal>APT::Update::{Pre,Post}-Invoke</literal>.
+        </para>
+       </listitem>
+     </varlistentry>
+

 <!-- 2009/07/11 Currently used nowhere. The corresponding code
 is commented.
      <varlistentry>
 <!-- 2009/07/11 Currently used nowhere. The corresponding code
 is commented.
      <varlistentry>


@@ -960,6 +1332,7 @@ is commented.
        </listitem>
      </varlistentry>
 -->
        </listitem>
      </varlistentry>
 -->

+

    </variablelist>
  </refsect1>
  
    </variablelist>
  </refsect1>