<!ENTITY % aptent SYSTEM "apt.ent">
%aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent">
+%aptverbatiment;
+
]>
<refentry>
&apt-email;
&apt-product;
<!-- The last update date -->
- <date>18 September 2009</date>
+ <date>16 January 2010</date>
</refentryinfo>
<refmeta>
</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>
-
+ <para><filename>apt.conf</filename> is the main configuration file for
+ the APT suite of tools, but by far not the only place changes to options
+ can be made. All tools therefore share the configuration files and also
+ use 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 if the file
+ doesn't match a pattern in the <literal>Dir::Ignore-Files-Silently</literal>
+ configuration list - in this case it will be silently ignored.</para></listitem>
+ <listitem><para>the main configuration file specified by
+ <literal>Dir::Etc::main</literal></para></listitem>
+ <listitem><para>the command line options are applied to override the
+ configuration directives or to load even more configuration files.</para></listitem>
+ </orderedlist>
+ </refsect1>
+ <refsect1><title>Syntax</title>
<para>The configuration file is organized in a tree with options organized into
functional groups. Option specification is given with a double colon
notation, for instance <literal>APT::Get::Assume-Yes</literal> is an option within
parsing package lists. The internal default is the architecture apt was
compiled for.</para></listitem>
</varlistentry>
-
+
+ <varlistentry><term>Architectures</term>
+ <listitem><para>All Architectures the system supports. Processors implementing the <literal>amd64</literal>
+ are e.g. also able to execute binaries compiled for <literal>i386</literal>; This list is use when fetching files and
+ parsing package lists. The internal default is always the native architecture (<literal>APT::Architecture</literal>)
+ and all foreign architectures it can retrieve by calling <command>dpkg --print-foreign-architectures</command>.
+ </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>
+ <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', '&stable-codename;', '&testing-codename;', '4.0', '5.0*'. See also &apt-preferences;.</para></listitem>
</varlistentry>
<varlistentry><term>Ignore-Hold</term>
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
+ that APT encounters a situation in which it is unable to perform immediate configuration, errors out and
+ refers to this option so the user can deactivate the immediate configuration temporarily 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 real world a few times 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 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
anything that those packages depend on.</para></listitem>
</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>Cache-Start, Cache-Grow and Cache-Limit</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 to which size the Cache will grow
+ and is therefore the amount of memory APT will request at startup. The default value is
+ 20971520 bytes (~20 MB). Note that these amount of space need to be available for APT
+ otherwise it will likely fail ungracefully, so for memory restricted devices these value should
+ be lowered while on systems with a lot of configured sources this might be increased.
+ <literal>Cache-Grow</literal> defines in byte 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. These 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 grow of the cache is disabled.
+ </para></listitem>
</varlistentry>
<varlistentry><term>Build-Essential</term>
and the URI handlers.
<variablelist>
+ <varlistentry><term>Check-Valid-Until</term>
+ <listitem><para>Security related option defaulting to true as an
+ expiring validation for a Release file prevents longtime replay attacks
+ and can e.g. also help users to identify no longer updated mirrors -
+ but the feature depends on the correctness of the time 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 volitional the following <literal>Max-ValidTime</literal> option can be used.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry><term>Max-ValidTime</term>
+ <listitem><para>Seconds the Release file should be considered valid after
+ it was created. The default is "for ever" (0) if the Release file of the
+ archive doesn't include a <literal>Valid-Until</literal> header.
+ If it does then this date is the default. The date from the Release file or
+ the date specified by the creation time of the Release file
+ (<literal>Date</literal> header) plus the seconds specified with this
+ options are used to check if the validation of a file has expired by using
+ the earlier date of the two. Archive specific settings can be made by
+ appending the label of the archive to the option name.
+ </para></listitem>
+ </varlistentry>
+
<varlistentry><term>PDiffs</term>
<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>
+ by default.</para>
+ <para>Two sub-options to limit the use of PDiffs are also available:
+ With <literal>FileLimit</literal> can be specified how many PDiff files
+ are downloaded at most to patch a file. <literal>SizeLimit</literal>
+ on the other hand is the maximum precentage of the size of all patches
+ compared to the size of the targeted file. If one of these limits is
+ exceeded the complete file is downloaded instead of the patches.
+ </para></listitem>
</varlistentry>
<varlistentry><term>Queue-Mode</term>
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>
+ 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.
+ 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>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>
+ <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>GzipIndexes</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>Languages</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 for the Language which is listed at first. Languages can be defined with their
+ available Description in the Language which is listed at first. Languages can be defined with their
short or long Languagecodes. Note that not all archives provide <filename>Translation</filename>
files for every Language - especially the long Languagecodes are rare, so please
inform you which ones are available before you set here impossible values.</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 languagecodes extracted from the <literal>LC_MESSAGES</literal> enviroment variable.
+ It will be replaced at runtime with the languagecodes 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 fitting <filename>Translation</filename> file.
This can be used by the system administrator to let APT know that it should download also this files without
- actually use them if not the environment specifies this languages. So the following example configuration will
+ actually use them if the environment doesn't specify this languages. So the following example configuration will
result in the order "en, de" in an english and in "de, en" in a german localization. Note that "fr" is downloaded,
but not used if APT is not used in a french localization, in such an environment the order would be "fr, de, en".
<programlisting>Acquire::Languages { "environment"; "de"; "en"; "none"; "fr"; };</programlisting></para></listitem>
will be looked up in
<filename>/tmp/staging/var/lib/dpkg/status</filename>.
</para>
+
+ <para>
+ The <literal>Ignore-Files-Silently</literal> list can be used to specify
+ which files APT should silently ignore while parsing the files in the
+ fragment directories. Per default a file which end with <literal>.disabled</literal>,
+ <literal>~</literal>, <literal>.bak</literal> or <literal>.dpkg-[a-z]+</literal>
+ is silently ignored. As seen in the last default value these patterns can use regular
+ expression syntax.
+ </para>
</refsect1>
<refsect1><title>APT in DSelect</title>
<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
+ multiple 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.
projects / apt.git / blobdiff