&apt-email;
&apt-product;
<!-- The last update date -->
- <date>10 December 2008</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 no or "<literal>conf</literal>"
+ as filename extension and which only contain alphanumeric,
+ hyphen (-), underscore (_) and period (.) characters -
+ otherwise they 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
+ 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
<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 {
<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 part of the configuration tree. The
- specified element and all its descendents are erased.</para>
+ 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>
</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>
<listitem><para>Ignore Held packages; This global option causes the problem resolver to
ignore held packages in its decision making.</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>
+ <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, 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 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
+ 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>
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>
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.
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>
<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.
- This list defines in which order the acquire methods will try to download these files.
- Per default <command>bzip2</command> compressed files will be prefered over
- <command>lzma</command>, <command>gzip</command> and uncompressed files. The syntax for
- the configuration fileentry is
+ 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>
- e.g. <synopsis>Acquire::CompressionTypes::bz2 "bzip2";</synopsis>
- Note that at runtime the <literal>Dir::Bin::<replaceable>Methodname</replaceable></literal> will
+ </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 above (the inbuilt) setting is <literallayout>Dir::Bin::bzip2 "/bin/bzip2";</literallayout>
- </para></listitem>
+ 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>
+
+ <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 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> 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 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>
+ </varlistentry>
+
</variablelist>
</para>
</refsect1>
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>
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>
</listitem>
</varlistentry>
-->
+
</variablelist>
</refsect1>
<refsect1><title>Files</title>
<variablelist>
- <varlistentry><term><filename>/etc/apt/apt.conf</filename></term>
- <listitem><para>APT configuration file.
- Configuration Item: <literal>Dir::Etc::Main</literal>.</para></listitem>
- </varlistentry>
-
- <varlistentry><term><filename>/etc/apt/apt.conf.d/</filename></term>
- <listitem><para>APT configuration file fragments.
- Configuration Item: <literal>Dir::Etc::Parts</literal>.</para></listitem>
- </varlistentry>
+ &file-aptconf;
</variablelist>
</refsect1>
projects / apt.git / blobdiff