merge from the mvo branch

1 files changed, 242 insertions, 32 deletions

diff --git a/doc/apt.conf.5.xml b/doc/apt.conf.5.xml
index 1835f2282..d7ad51cfb 100644
--- a/doc/apt.conf.5.xml
+++ b/doc/apt.conf.5.xml
@@ -21,12 +21,13 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>06 December 2008</date>
+   <date>18 September 2009</date>
  </refentryinfo>
  
  <refmeta>
    <refentrytitle>apt.conf</refentrytitle>
    <manvolnum>5</manvolnum>
+   <refmiscinfo class="manual">APT</refmiscinfo>
  </refmeta>
  
  <!-- Man page title -->
@@ -47,18 +48,23 @@
    loading even more config files.</para>
 
    <para>The configuration file is organized in a tree with options organized into
-   functional groups. option specification is given with a double colon
+   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 
+   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
-   such as bind and dhcp use.  Lines starting with
-   <literal>//</literal> are treated as comments (ignored).
+   such as bind and dhcp use. Lines starting with
+   <literal>//</literal> are treated as comments (ignored), as well as all text
+   between <literal>/*</literal> and <literal>*/</literal>, just like C/C++ comments.
    Each line is of the form
-   <literal>APT::Get::Assume-Yes "true";</literal> The trailing 
-   semicolon is required and the quotes are optional. A new scope can be
-   opened with curly braces, like:</para>
+   <literal>APT::Get::Assume-Yes "true";</literal>. The 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>
 
 <informalexample><programlisting>   
 APT {
@@ -70,7 +76,7 @@ APT {
 </programlisting></informalexample>
 
    <para>with newlines placed to make it more readable. Lists can be created by 
-   opening a scope and including a single word enclosed in quotes followed by a 
+   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>
 
 <informalexample><programlisting>   
@@ -84,16 +90,41 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
    <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>Two specials are allowed, <literal>#include</literal> and <literal>#clear</literal> 
+   <para>Names for the configuration items are optional if a list is defined as it can be see in
+   the <literal>DPkg::Pre-Install-Pkgs</literal> example above. If you don't specify a name a
+   new entry will simply add a new option to the list. If you specify a name you can override
+   the option as every other option by reassigning a new value to the option.</para>
+
+   <para>Two specials are allowed, <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, then the whole directory is included.  
-   <literal>#clear</literal> is used to erase a list of names.</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>All of the APT tools take a -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
    sign then the new value of the option. Lists can be appended too by adding 
-   a trailing :: to the list name.</para>
+   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>
  </refsect1>
 
  <refsect1><title>The APT Group</title>
@@ -109,7 +140,7 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      
      <varlistentry><term>Default-Release</term>
 	 <listitem><para>Default release to install packages from if more than one
-	 version available. Contains release name or release version. Examples: 'stable', 'testing', 'unstable', '4.0', '5.0*'. Release codenames ('etch', 'lenny' etc.) are not allowed now. See also &apt-preferences;.</para></listitem>
+	 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>
      
      <varlistentry><term>Ignore-Hold</term>
@@ -125,11 +156,26 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      </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>
+     <listitem><para>Defaults to on which will cause APT to install essential and important packages
+     as fast as possible in the install/upgrade operation. This is done to limit the effect of a failing
+     &dpkg; call: If this option is disabled APT does treat an important package in the same way as
+     an extra package: Between the unpacking of the important package A and his configuration can then
+     be many other unpack or configuration calls, e.g. for package B which has no relation to A, but
+     causes the dpkg call to fail (e.g. because maintainer script of package B generates an error) which results
+     in a system state in which package A is unpacked but unconfigured - each package depending on A is now no
+     longer guaranteed to work as their dependency on A is not longer satisfied. The immediate configuration marker
+     is also applied to all dependencies which can generate a problem if the dependencies e.g. form a circle
+     as a dependency with the immediate flag is comparable with a Pre-Dependency. So in theory it is possible
+     that APT encounters a situation in which it is unable to perform immediate configuration, error out and
+     refers to this option so the user can deactivate the immediate configuration temporary to be able to perform
+     an install/upgrade again. Note the use of the word "theory" here as this problem was only encountered by now
+     in real world a few times in non-stable distribution versions and 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 mentioned scenario above is not the only problem immediate configuration can help to prevent in the first place.
+     Before a big operation like <literal>dist-upgrade</literal> is run with this option disabled it should be tried to
+     explicitly <literal>install</literal> the package APT is unable to configure immediately, but please make sure to
+     report your problem also 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><term>Force-LoopBreak</term>
@@ -173,7 +219,7 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
 
    <variablelist>
      <varlistentry><term>PDiffs</term>
-	 <listitem><para>Try do 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>
      </varlistentry>
@@ -201,8 +247,9 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      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. The <envar>http_proxy</envar> environment variable
-     will override all settings.</para>
+	 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 
@@ -218,18 +265,30 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      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)
+     remote server is not RFC conforming or buggy (such as Squid 2.0.2).
      <literal>Acquire::http::Pipeline-Depth</literal> can be a value from 0 to 5 
      indicating how many outstanding requests APT should send. A value of
      zero MUST be specified if the remote host does not properly linger
      on TCP connections - otherwise data corruption will occur. Hosts which
-     require this are in violation of RFC 2068.</para></listitem>
+     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>
+
+     <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>
+     </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>
+	 <listitem><para>HTTPS URIs. Cache-control, Timeout, AllowRedirect, Dl-Limit and
+	 proxy options are the same as for <literal>http</literal> method and will also
+	 default to the options from the <literal>http</literal> method if they are not
+	 explicitly set for https. <literal>Pipeline-Depth</literal> option is not
+	 supported yet.</para>
 
 	 <para><literal>CaInfo</literal> suboption specifies place of file that
 	 holds info about trusted certificates.
@@ -250,9 +309,13 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
 	 </para></listitem></varlistentry>
 
      <varlistentry><term>ftp</term>
-     <listitem><para>FTP URIs; ftp::Proxy is the default proxy server to use. It is in the 
-     standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal> and is 
-     overridden by the <envar>ftp_proxy</envar> environment variable. To use a ftp 
+     <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 
+     <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 
      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 
@@ -290,7 +353,7 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      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 
+     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>
@@ -301,6 +364,34 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      </para></listitem>
      </varlistentry>
 
+     <varlistentry><term>CompressionTypes</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.
+     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
+     on the fly or the used method can be changed. The syntax for this is:
+     <synopsis>Acquire::CompressionTypes::<replaceable>FileExtension</replaceable> "<replaceable>Methodname</replaceable>";</synopsis>
+     </para><para>Also the <literal>Order</literal> subgroup can be used to define in which order
+     the acquire system will try to download the compressed files. The acquire system will try the first
+     and proceed with the next compression type in this list on error, so to prefer one over the other type
+     simple add the preferred type at first - not already added default types will be added at run time
+     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>
+     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>
+     </varlistentry>
    </variablelist>
   </para>
  </refsect1>
@@ -335,6 +426,7 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
 
    <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal> 
    specifies the location of the method handlers and <literal>gzip</literal>, 
+   <literal>bzip2</literal>, <literal>lzma</literal>,
    <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal> 
    <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
    of the respective programs.</para>
@@ -427,6 +519,87 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      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.
+     <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
+     currently stay around half (or more) of the time in the 100% state while it actually configures
+     all packages.</para>
+     <para>Note that it is not guaranteed that APT will support these options or that these options will
+     not cause (big) trouble in the future. If you have understand the current risks and problems with
+     these options, but are brave enough to help testing them create a new configuration file and test a
+     combination of options. Please report any bugs, problems and improvements you encounter and make sure
+     to note which options you have used in your reports. Asking dpkg for help could also be useful for
+     debugging proposes, see e.g. <command>dpkg --audit</command>. A defensive option combination would be
+<literallayout>DPkg::NoTriggers "true";
+PackageManager::Configure "smart";
+DPkg::ConfigurePending "true";
+DPkg::TriggersPending "true";</literallayout></para>
+
+     <variablelist>
+       <varlistentry><term>DPkg::NoTriggers</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 add these flag also to the unpack and remove calls.</para></listitem>
+       </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
+       rely 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 implicitly activate also the next option per
+       default as otherwise the system could end in an unconfigured status which could be unbootable!
+       </para></listitem>
+       </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 these sceneries you could
+       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
+       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).
+       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.
+       <literallayout>OrderList::Score {
+	Delete 500;
+	Essential 200;
+	Immediate 10;
+	PreDepends 50;
+};</literallayout>
+       </para></listitem>
+       </varlistentry>
+     </variablelist>
+   </refsect2>
  </refsect1>
 
  <refsect1>
@@ -678,12 +851,33 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
        </listitem>
      </varlistentry>
 
+     <varlistentry>
+       <term><literal>Debug::pkgDepCache::Marker</literal></term>
+       <listitem>
+        <para>
+           Generate debug messages describing which package is marked
+          as keep/install/remove while the ProblemResolver does his work.
+          Each addition or deletion may trigger additional actions;
+          they are shown indented two additional space under the original entry.
+          The format for each line is <literal>MarkKeep</literal>,
+          <literal>MarkDelete</literal> or <literal>MarkInstall</literal> followed by
+          <literal>package-name &lt;a.b.c -&gt; d.e.f | x.y.z&gt; (section)</literal>
+          where <literal>a.b.c</literal> is the current version of the package,
+          <literal>d.e.f</literal> is the version considered for installation and
+          <literal>x.y.z</literal> is a newer version, but not considered for installation
+          (because of a low pin score). The later two can be omitted if there is none or if
+          it is the same version as the installed.
+          <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>
        <term><literal>Debug::pkgInitConfig</literal></term>
        <listitem>
 	 <para>
-	   Dump the default configuration to standard output on
+	   Dump the default configuration to standard error on
 	   startup.
 	 </para>
        </listitem>
@@ -756,6 +950,17 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
      </varlistentry>
 
      <varlistentry>
+       <term><literal>Debug::pkgProblemResolver::ShowScores</literal></term>
+       <listitem>
+        <para>
+          Display a list of all installed packages with their calculated score
+          used by the pkgProblemResolver. The description of the package
+          is the same as described in <literal>Debug::pkgDepCache::Marker</literal>
+        </para>
+       </listitem>
+     </varlistentry>
+
+     <varlistentry>
        <term><literal>Debug::sourceList</literal></term>
 
        <listitem>
@@ -766,6 +971,8 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
        </listitem>
      </varlistentry>
 
+<!-- 2009/07/11 Currently used nowhere. The corresponding code
+is commented.
      <varlistentry>
        <term><literal>Debug::Vendor</literal></term>
 
@@ -775,6 +982,7 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
 	 </para>
        </listitem>
      </varlistentry>
+-->
    </variablelist>
  </refsect1>
  
@@ -785,7 +993,9 @@ DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
  </refsect1>
  
  <refsect1><title>Files</title>
-   <para><filename>/etc/apt/apt.conf</filename></para>
+   <variablelist>
+      &file-aptconf;
+   </variablelist>
  </refsect1>
  
  <refsect1><title>See Also</title>