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diff --git a/doc/apt.conf.5.xml b/doc/apt.conf.5.xml new file mode 100644 index 0000000..1573495 --- /dev/null +++ b/doc/apt.conf.5.xml @@ -0,0 +1,1272 @@ +<?xml version="1.0" encoding="utf-8" standalone="no"?> +<!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> + + <refentryinfo> + &apt-author.jgunthorpe; + &apt-author.team; + <author> + &apt-name.dburrows; + <contrib>Initial documentation of Debug::*.</contrib> + <email>dburrows@debian.org</email> + </author> + &apt-email; + &apt-product; + <!-- The last update date --> + <date>2019-04-04T00:00:00Z</date> + </refentryinfo> + + <refmeta> + <refentrytitle>apt.conf</refentrytitle> + <manvolnum>5</manvolnum> + <refmiscinfo class="manual">APT</refmiscinfo> + </refmeta> + + <!-- Man page title --> + <refnamediv> + <refname>apt.conf</refname> + <refpurpose>Configuration file for APT</refpurpose> + </refnamediv> + + <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 + 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 + 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 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 { + Get { + Assume-Yes "true"; + Fix-Broken "true"; + }; +}; +</programlisting></informalexample> + + <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, separated by a semicolon.</para> + +<informalexample><programlisting> +DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";}; +</programlisting></informalexample> + + <para>In general the sample configuration file &configureindex; + is a good guide for how it should look.</para> + + <para>Case is not significant in names of configuration items, so in the + previous example you could use <literal>dpkg::pre-install-pkgs</literal>.</para> + + <para>Names for the configuration items are optional if a list is defined as can be seen in + the <literal>DPkg::Pre-Install-Pkgs</literal> example above. If you don't specify a name a + new entry will simply add a new option to the list. If you specify a name you can override + the option in the same way as any other option by reassigning a new value to the option.</para> + + <para>Two special commands are defined: <literal>#include</literal> (which is + deprecated and not supported by alternative implementations) and + <literal>#clear</literal>. <literal>#include</literal> will include the + given file, unless the filename ends in a slash, in which case the whole + directory is included. + <literal>#clear</literal> is used to erase a part of the configuration tree. The + specified element and all its descendants are erased. + (Note that these lines also need to end with a semicolon.)</para> + + <para> + 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 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 + 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> + <para>This group of options controls general APT behavior as well as holding the + options for all of the tools.</para> + + <variablelist> + <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> + + <varlistentry><term><option>Architectures</option></term> + <listitem><para> + All Architectures the system supports. For instance, CPUs implementing + the <literal>amd64</literal> (also called <literal>x86-64</literal>) + instruction set are also able to execute binaries compiled for the + <literal>i386</literal> (<literal>x86</literal>) instruction set. This + list is used when fetching files and parsing package lists. The + initial default is always the system's native architecture + (<literal>APT::Architecture</literal>), and foreign architectures are + added to the default list when they are registered via + <command>dpkg --add-architecture</command>. + </para></listitem> + </varlistentry> + + <varlistentry><term><option>Compressor</option></term> + <listitem><para> + This scope defines which compression formats are supported, how compression + and decompression can be performed if support for this format isn't built + into apt directly and a cost-value indicating how costly it is to compress + something in this format. As an example the following configuration stanza + would allow apt to download and uncompress as well as create and store + files with the low-cost <literal>.reversed</literal> file extension which + it will pass to the command <command>rev</command> without additional + commandline parameters for compression and uncompression:</para> +<informalexample><programlisting> +APT::Compressor::rev { + Name "rev"; + Extension ".reversed"; + Binary "rev"; + CompressArg {}; + UncompressArg {}; + Cost "10"; +}; +</programlisting></informalexample> + </listitem> + </varlistentry> + + <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', '&debian-stable-codename;', '&debian-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> + + <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> + + <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 bug link below, so they can + work on improving or correcting the upgrade process. + </para></listitem> + </varlistentry> + + <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><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><term><option>Build-Essential</option></term> + <listitem><para>Defines which packages are considered essential build dependencies.</para></listitem> + </varlistentry> + + <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> + + <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> + + <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> + <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> + <varlistentry><term><option>Check-Date</option></term> + <listitem><para> + Security related option defaulting to true, enabling time-related + checks. Disabling it means that the machine's time cannot be + trusted, and APT will hence disable all time-related checks, + such as <option>Check-Valid-Until</option> and verifying that + the Date field of a release file is not in the future. + </para></listitem> + </varlistentry> + + <varlistentry><term><option>Max-FutureTime</option></term> + <listitem><para>Maximum time (in seconds) before its creation (as indicated + by the <literal>Date</literal> header) that the <filename>Release</filename> + file should be considered valid. + + The default value is <literal>10</literal>. + 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>Date-Max-Future</option> option there. + </para></listitem> + </varlistentry> + <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>AllowTLS</option></term> + <listitem><para> + Allow use of the internal TLS support in the http method. If set to false, + this completely disables support for TLS in apt's own methods (excluding + the curl-based https method). No TLS-related functions will be called + anymore. + </para></listitem> + </varlistentry> + + <varlistentry><term><option>PDiffs</option></term> + <listitem><para>Try to download deltas called <literal>PDiffs</literal> for + indexes (like <filename>Packages</filename> files) instead of + downloading whole ones. True by default. 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><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 + will be opened, <literal>access</literal> means that one connection per URI type + will be opened.</para></listitem> + </varlistentry> + + <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> + + <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> + + <varlistentry><term><option>http</option> <option>https</option></term> + <listitem><para>The options in these scopes configure APT's acquire transports for the protocols + HTTP and HTTPS and are documented in the &apt-transport-http; and &apt-transport-https; + manpages respectively.</para></listitem> + </varlistentry> + + <varlistentry><term><option>ftp</option></term> + <listitem><para> + <literal>ftp::Proxy</literal> sets the default proxy to use for FTP URIs. + It is in the standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal>. + Per host proxies can also be specified by using the form + <literal>ftp::Proxy::<host></literal> with the special keyword <literal>DIRECT</literal> + meaning to use no proxies. If no one of the above settings is specified, + <envar>ftp_proxy</envar> environment variable + will be used. To use an FTP + proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the + configuration file. This entry specifies the commands to send to tell + the proxy server what to connect to. Please see + &configureindex; for an example of + 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 value applies to the connection as well as the data timeout.</para> + + <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 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> + 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> + + <para>The setting <literal>ForceExtended</literal> controls the use of RFC2428 + <literal>EPSV</literal> and <literal>EPRT</literal> commands. The default is false, which means + these commands are only used if the control connection is IPv6. Setting this + to true forces their use even on IPv4 connections. Note that most FTP servers + do not support RFC2428.</para></listitem> + </varlistentry> + + <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><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> + + <varlistentry><term><option>CompressionTypes</option></term> + <listitem><para>List of compression types which are understood by the acquire methods. + Files like <filename>Packages</filename> can be available in various compression formats. + By default the acquire methods can decompress and recompress many common formats like <command>xz</command> and + <command>gzip</command>; with this scope the supported formats can be queried, modified + as well as support for more formats added (see also <option>APT::Compressor</option>). The syntax for this is: + <synopsis>Acquire::CompressionTypes::<replaceable>FileExtension</replaceable> "<replaceable>Methodname</replaceable>";</synopsis> + </para><para>Also, the <literal>Order</literal> subgroup can be used to define in which order + the acquire system will try to download the compressed files. The acquire system will try the first + and proceed with the next compression type in this list on error, so to prefer one over the other type + simply add the preferred type first - 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 all other compression formats. + If <command>xz</command> should be preferred over <command>gzip</command> and <command>bzip2</command> the + configure setting should look like this: <synopsis>Acquire::CompressionTypes::Order { "xz"; "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 and support for + this format isn't directly built into apt, the method will only be used if + this file exists; e.g. for the <literal>bzip2</literal> method (the + inbuilt) setting is: <literallayout>Dir::Bin::bzip2 "/bin/bzip2";</literallayout> + Note also that list entries specified on the command line will be added at the end of the list + specified in the configuration files, but before the default entries. To prefer a type in this case + over the ones specified in the configuration files you can set the option direct - not in list style. + This will not override the defined list; it will only prefix the list with this type.</para> + <para>The special type <literal>uncompressed</literal> can be used to give uncompressed files a + preference, but note that most archives don't provide uncompressed files so this is mostly only + usable 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 update operations to load data files from + repositories without sufficient security information. + The default value is "<literal>false</literal>". + Concept, implications as well as alternatives are detailed in &apt-secure;. + </para></listitem> + </varlistentry> + + <varlistentry><term><option>AllowWeakRepositories</option></term> + <listitem><para> + Allow update operations to load data files from + repositories which provide security information, but these + are deemed no longer cryptographically strong enough. + The default value is "<literal>false</literal>". + Concept, implications as well as alternatives are detailed in &apt-secure;. + </para></listitem> + </varlistentry> + + <varlistentry><term><option>AllowDowngradeToInsecureRepositories</option></term> + <listitem><para> + Allow that a repository that was previously gpg signed to become + unsigned during an update operation. When there is no valid signature + for a previously 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 <literal>false</literal>. + Concept, implications as well as alternatives are detailed in &apt-secure;. + </para></listitem> + </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, except 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, + except 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> + </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 + 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 + 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 + <literal>main</literal> is the default configuration file (setting has no effect, + unless it is done from the config file specified by + <envar>APT_CONFIG</envar>).</para> + + <para>The <literal>Dir::Parts</literal> setting reads in all the config fragments in + lexical order from the directory specified. After this is done then the + main config file is loaded.</para> + + <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> + + <para> + The configuration item <literal>RootDir</literal> has a special + 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 + <filename>/tmp/staging</filename> and + <literal>Dir::State::status</literal> is set to + <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 ends 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 + control the default behavior. These are in the <literal>DSelect</literal> section.</para> + + <variablelist> + <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><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> + + <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> + + <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> + + <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> + <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> + + <varlistentry><term><option>Path</option></term> + <listitem><para>This is a string that defines the <envar>PATH</envar> + environment variable used when running dpkg. It may be set to any + valid value of that environment variable; or the empty string, in + which case the variable is not changed.</para></listitem> + </varlistentry> + + <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 + commands are invoked in order using <filename>/bin/sh</filename>; should any + fail APT will abort.</para></listitem> + </varlistentry> + + <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 + 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: package + name (without architecture qualification even if foreign), old version, + direction of version change (< for upgrades, > 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>- < 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><term><option>Run-Directory</option></term> + <listitem><para>APT chdirs to this directory before invoking &dpkg;, the default is + <filename>/</filename>.</para></listitem> + </varlistentry> + + <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> + + <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 by default, + but deactivating it could be useful if you want to run APT multiple times in a row - e.g. in an installer. + In this scenario you could deactivate this option in all but the last run.</para></listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Periodic and Archives options</title> + <para><literal>APT::Periodic</literal> and <literal>APT::Archives</literal> + groups of options configure behavior of apt periodic updates, which is + done by the <literal>/usr/lib/apt/apt.systemd.daily</literal> script. See the top of + this script for the brief documentation of these options. + </para> + </refsect1> + + <refsect1> + <title>Debug options</title> + <para> + Enabling options in the <literal>Debug::</literal> section will + cause debugging information to be sent to the standard error + stream of the program utilizing the <literal>apt</literal> + libraries, or enable special program modes that are primarily + useful for debugging the behavior of <literal>apt</literal>. + Most of these options are not interesting to a normal user, but a + few may be: + + <itemizedlist> + <listitem> + <para> + <literal>Debug::pkgProblemResolver</literal> enables output + about the decisions made by + <literal>dist-upgrade, upgrade, install, remove, purge</literal>. + </para> + </listitem> + + <listitem> + <para> + <literal>Debug::NoLocking</literal> disables all file + locking. This can be used to run some operations (for + instance, <literal>apt-get -s install</literal>) as a + non-root user. + </para> + </listitem> + + <listitem> + <para> + <literal>Debug::pkgDPkgPM</literal> prints out the actual + command line each time that <literal>apt</literal> invokes + &dpkg;. + </para> + </listitem> + + <listitem> + <para> + <literal>Debug::IdentCdrom</literal> disables the inclusion + of statfs data in CD-ROM IDs. <!-- TODO: provide a + motivating example, except I haven't a clue why you'd want + to do this. --> + </para> + </listitem> + </itemizedlist> + </para> + + <para> + A full list of debugging options to apt follows. + </para> + + <variablelist> + <varlistentry> + <term><option>Debug::Acquire::cdrom</option></term> + + <listitem> + <para> + Print information related to accessing + <literal>cdrom://</literal> sources. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::Acquire::ftp</option></term> + + <listitem> + <para> + Print information related to downloading packages using + FTP. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::Acquire::http</option></term> + + <listitem> + <para> + Print information related to downloading packages using + HTTP. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::Acquire::https</option></term> + + <listitem> + <para> + Print information related to downloading packages using + HTTPS. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::Acquire::gpgv</option></term> + + <listitem> + <para> + Print information related to verifying cryptographic + signatures using <literal>gpg</literal>. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::aptcdrom</option></term> + + <listitem> + <para> + Output information about the process of accessing + collections of packages stored on CD-ROMs. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::BuildDeps</option></term> + <listitem> + <para> + Describes the process of resolving build-dependencies in + &apt-get;. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::Hashes</option></term> + <listitem> + <para> + Output each cryptographic hash that is generated by the + <literal>apt</literal> libraries. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::IdentCDROM</option></term> + <listitem> + <para> + Do not include information from <literal>statfs</literal>, + namely the number of used and free blocks on the CD-ROM + filesystem, when generating an ID for a CD-ROM. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::NoLocking</option></term> + <listitem> + <para> + Disable all file locking. For instance, this will allow + two instances of <quote><literal>apt-get + update</literal></quote> to run at the same time. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgAcquire</option></term> + + <listitem> + <para> + Log when items are added to or removed from the global + download queue. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgAcquire::Auth</option></term> + <listitem> + <para> + Output status messages and errors related to verifying + checksums and cryptographic signatures of downloaded files. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgAcquire::Diffs</option></term> + <listitem> + <para> + Output information about downloading and applying package + index list diffs, and errors relating to package index list + diffs. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgAcquire::RRed</option></term> + + <listitem> + <para> + Output information related to patching apt package lists + when downloading index diffs instead of full indices. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgAcquire::Worker</option></term> + + <listitem> + <para> + Log all interactions with the sub-processes that actually + perform downloads. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgAutoRemove</option></term> + + <listitem> + <para> + Log events related to the automatically-installed status of + packages and to the removal of unused packages. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgDepCache::AutoInstall</option></term> + <listitem> + <para> + Generate debug messages describing which packages are being + automatically installed to resolve dependencies. This + corresponds to the initial auto-install pass performed in, + e.g., <literal>apt-get install</literal>, and not to the + full <literal>apt</literal> dependency resolver; see + <literal>Debug::pkgProblemResolver</literal> for that. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgDepCache::Marker</option></term> + <listitem> + <para> + Generate debug messages describing which packages are marked + as keep/install/remove while the ProblemResolver does his work. + Each addition or deletion may trigger additional actions; + they are shown indented two additional spaces under the original entry. + The format for each line is <literal>MarkKeep</literal>, + <literal>MarkDelete</literal> or <literal>MarkInstall</literal> followed by + <literal>package-name <a.b.c -> d.e.f | x.y.z> (section)</literal> + where <literal>a.b.c</literal> is the current version of the package, + <literal>d.e.f</literal> is the version considered for installation and + <literal>x.y.z</literal> is a newer version, but not considered for installation + (because of a low pin score). The later two can be omitted if there is none or if + it is the same as the installed version. + <literal>section</literal> is the name of the section the package appears in. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgDPkgPM</option></term> + <listitem> + <para> + When invoking &dpkg;, output the precise command line with + which it is being invoked, with arguments separated by a + single space character. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgDPkgProgressReporting</option></term> + <listitem> + <para> + Output all the data received from &dpkg; on the status file + descriptor and any errors encountered while parsing it. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgOrderList</option></term> + + <listitem> + <para> + Generate a trace of the algorithm that decides the order in + which <literal>apt</literal> should pass packages to + &dpkg;. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgPackageManager</option></term> + + <listitem> + <para> + Output status messages tracing the steps performed when + invoking &dpkg;. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgPolicy</option></term> + + <listitem> + <para> + Output the priority of each package list on startup. + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgProblemResolver</option></term> + + <listitem> + <para> + Trace the execution of the dependency resolver (this + applies only to what happens when a complex dependency + problem is encountered). + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::pkgProblemResolver::ShowScores</option></term> + <listitem> + <para> + Display a list of all installed packages with their calculated score + used by the pkgProblemResolver. The description of the package + is the same as described in <literal>Debug::pkgDepCache::Marker</literal> + </para> + </listitem> + </varlistentry> + + <varlistentry> + <term><option>Debug::sourceList</option></term> + + <listitem> + <para> + Print information about the vendors read from + <filename>/etc/apt/vendors.list</filename>. + </para> + </listitem> + </varlistentry> + + <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> + <term><literal>Debug::Vendor</literal></term> + + <listitem> + <para> + Print information about each vendor. + </para> + </listitem> + </varlistentry> +--> + + </variablelist> + </refsect1> + + <refsect1><title>Examples</title> + <para>&configureindex; is a + configuration file showing example values for all possible + options.</para> + </refsect1> + + <refsect1><title>Files</title> + <variablelist> + &file-aptconf; + </variablelist> + </refsect1> + + <refsect1><title>See Also</title> + <para>&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.</para> + </refsect1> + + &manbugs; + +</refentry> + |