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<!-- -*- mode: sgml; mode: fold -*- -->
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<!doctype refentry PUBLIC "-//OASIS//DTD DocBook V3.1//EN" [
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<!ENTITY % aptent SYSTEM "apt.ent">
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<refentrytitle>apt.conf</>
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<!-- Man page title -->
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<refpurpose>Configuration file for APT</>
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<RefSect1><Title>Description</>
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<filename/apt.conf/ is the main configuration file for the APT suite of
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tools, all tools make use of the configuration file and a common command line
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parser to provide a uniform environment. When an APT tool starts up it will
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read the configuration specified by the <envar/APT_CONFIG/ environment
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variable (if any) and then read the files in <literal/Dir::Etc::Parts/
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then read the main configuration file specified by
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<literal/Dir::Etc::main/ then finally apply the
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command line options to override the configuration directives, possibly
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loading even more config files.
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The configuration file is organized in a tree with options organized into
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functional groups. Option specification is given with a double colon
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notation, for instance <literal/APT::Get::Assume-Yes/ is an option within
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the APT tool group, for the Get tool. Options do not inherit from their
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Syntacticly the configuration language is modeled after what the ISC tools
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such as bind and dhcp use. Each line is of the form
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<literallayout>APT::Get::Assume-Yes "true";</literallayout> The trailing
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semicolon is required and the quotes are optional. A new scope can be
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opened with curly braces, like:
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<informalexample><programlisting>
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</programlisting></informalexample>
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with newlines placed to make it more readable. Lists can be created by
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opening a scope and including a single word enclosed in quotes followed by a
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semicolon. Multiple entries can be included, each seperated by a semicolon.
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<informalexample><programlisting>
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DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
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</programlisting></informalexample>
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In general the sample configuration file in
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<filename>&docdir;/examples/apt.conf</> &configureindex;
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is a good guide for how it should look.
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Two specials are allowed, <literal/#include/ and <literal/#clear/.
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<literal/#include/ will include the given file, unless the filename
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ends in a slash, then the whole directory is included.
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<literal/#clear/ is used to erase a list of names.
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All of the APT tools take a -o option which allows an arbitary configuration
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directive to be specified on the command line. The syntax is a full option
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name (<literal/APT::Get::Assume-Yes/ for instance) followed by an equals
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sign then the new value of the option. Lists can be appended too by adding
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a trailing :: to the list name.
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<RefSect1><Title>The APT Group</>
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This group of options controls general APT behavoir as well as holding the
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options for all of the tools.
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<VarListEntry><Term>Architecture</Term>
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System Architecture; sets the architecture to use when fetching files and
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parsing package lists. The internal default is the architecture apt was
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<VarListEntry><Term>Ignore-Hold</Term>
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Ignore Held packages; This global option causes the problem resolver to
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ignore held packages in its decision making.
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<VarListEntry><Term>Clean-Installed</Term>
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Defaults to on. When turned on the autoclean feature will remove any pacakge
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which can no longer be downloaded from the cache. If turned off then
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packages that are locally installed are also excluded from cleaning - but
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note that APT provides no direct means to reinstall them.
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<VarListEntry><Term>Immediate-Configure</Term>
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Disable Immedate Configuration; This dangerous option disables some
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of APT's ordering code to cause it to make fewer dpkg calls. Doing
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so may be necessary on some extremely slow single user systems but
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is very dangerous and may cause package install scripts to fail or worse.
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Use at your own risk.
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<VarListEntry><Term>Force-LoopBreak</Term>
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Never Enable this option unless you -really- know what you are doing. It
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permits APT to temporarily remove an essential package to break a
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Conflicts/Conflicts or Conflicts/Pre-Depend loop between two essential
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packages. SUCH A LOOP SHOULD NEVER EXIST AND IS A GRAVE BUG. This option
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will work if the essential packages are not tar, gzip, libc, dpkg, bash or
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anything that those packages depend on.
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<VarListEntry><Term>Cache-Limit</Term>
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APT uses a fixed size memory mapped cache file to store the 'available'
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information. This sets the size of that cache.
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<VarListEntry><Term>Get</Term>
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The Get subsection controls the &apt-get; tool, please see its
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documentation for more information about the options here.
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<VarListEntry><Term>Cache</Term>
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The Cache subsection controls the &apt-cache; tool, please see its
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documentation for more information about the options here.
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<VarListEntry><Term>CDROM</Term>
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The CDROM subsection controls the &apt-cdrom; tool, please see its
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documentation for more information about the options here.
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<RefSect1><Title>The Acquire Group</>
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The <literal/Acquire/ group of options controls the download of packages
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and the URI handlers.
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<VarListEntry><Term>Queue-Mode</Term>
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Queuing mode; <literal/Queue-Mode/ can be one of <literal/host/ or
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<literal/access/ which determines how APT parallelizes outgoing
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connections. <literal/host/ means that one connection per target host
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will be opened, <literal/access/ means that one connection per URI type
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<VarListEntry><Term>Retries</Term>
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Number of retries to perform. If this is non-zero APT will retry failed
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files the given number of times.
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<VarListEntry><Term>Source-Symlinks</Term>
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Use symlinks for source archives. If set to true then source archives will
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be symlinked when possible instead of copying. True is the default
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<VarListEntry><Term>http</Term>
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HTTP URIs; http::Proxy is the default http proxy to use. It is in the
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standard form of <literal>http://[[user][:pass]@]host[:port]/</>. Per
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host proxies can also be specified by using the form
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<literal/http::Proxy::<host>/ with the special keyword <literal/DIRECT/
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meaning to use no proxies. The <envar/http_proxy/ environment variable
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will override all settings.
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Three settings are provided for cache control with HTTP/1.1 complient
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proxy caches. <literal/No-Cache/ tells the proxy to not used its cached
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response under any circumstances, <literal/Max-Age/ is sent only for
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index files and tells the cache to refresh its object if it is older than
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the given number of seconds. Debian updates its index files daily so the
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default is 1 day. <literal/No-Store/ specifies that the cache should never
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store this request, it is only set for archive files. This may be useful
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to prevent polluting a proxy cache with very large .deb files. Note:
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Squid 2.0.2 does not support any of these options.
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The option <literal/timeout/ sets the timeout timer used by the method,
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this applies to all things including connection timeout and data timeout.
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One setting is provided to control the pipeline depth in cases where the
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remote server is not RFC conforming or buggy (such as Squid 2.0.2)
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<literal/Acquire::http::Pipeline-Depth/ can be a value from 0 to 5
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indicating how many outstanding requests APT should send. A value of
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zero MUST be specified if the remote host does not properly linger
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on TCP connections - otherwise data corruption will occur. Hosts which
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require this are in violation of RFC 2068.
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<VarListEntry><Term>ftp</Term>
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FTP URIs; ftp::Proxy is the default proxy server to use. It is in the
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standard form of <literal>ftp://[[user][:pass]@]host[:port]/</> and is
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overriden by the <envar/ftp_proxy/ environment variable. To use a ftp
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proxy you will have to set the <literal/ftp::ProxyLogin/ script in the
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configuration file. This entry specifies the commands to send to tell
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the proxy server what to connect to. Please see
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&configureindex; for an example of
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how to do this. The subsitution variables available are
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<literal/$(PROXY_USER)/, <literal/$(PROXY_PASS)/, <literal/$(SITE_USER)/,
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<literal/$(SITE_PASS)/, <literal/$(SITE)/, and <literal/$(SITE_PORT)/.
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Each is taken from it's respective URI component.
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The option <literal/timeout/ sets the timeout timer used by the method,
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this applies to all things including connection timeout and data timeout.
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Several settings are provided to control passive mode. Generally it is
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safe to leave passive mode on, it works in nearly every environment.
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However some situations require that passive mode be disabled and port
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mode ftp used instead. This can be done globally, for connections that
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go through a proxy or for a specific host (See the sample config file
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It is possible to proxy FTP over HTTP by setting the <envar/ftp_proxy/
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environment variable to a http url - see the discussion of the http method
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above for syntax. You cannot set this in the configuration file and it is
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not recommended to use FTP over HTTP due to its low efficiency.
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The setting <literal/ForceExtended/ controls the use of RFC2428
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<literal/EPSV/ and <literal/EPRT/ commands. The defaut is false, which means
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these commands are only used if the control connection is IPv6. Setting this
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to true forces their use even on IPv4 connections. Note that most FTP servers
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do not support RFC2428.
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<VarListEntry><Term>cdrom</Term>
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CDROM URIs; the only setting for CDROM URIs is the mount point,
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<literal/cdrom::Mount/ which must be the mount point for the CDROM drive
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as specified in <filename>/etc/fstab</>. It is possible to provide
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alternate mount and unmount commands if your mount point cannot be listed
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in the fstab (such as an SMB mount and old mount packages). The syntax
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is to put <literallayout>"/cdrom/"::Mount "foo";</literallayout> within
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the cdrom block. It is important to have the trailing slash. Unmount
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commands can be specified using UMount.
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<RefSect1><Title>Directories</>
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The <literal/Dir::State/ section has directories that pertain to local
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state information. <literal/lists/ is the directory to place downloaded
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package lists in and <literal/status/ is the name of the dpkg status file.
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<literal/preferences/ is the name of the APT preferences file.
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<literal/Dir::State/ contains the default directory to prefix on all sub
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items if they do not start with <filename>/</> or <filename>./</>.
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<literal/Dir::Cache/ contains locations pertaining to local cache
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information, such as the two package caches <literal/srcpkgcache/ and
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<literal/pkgcache/ as well as the location to place downloaded archives,
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<literal/Dir::Cache::archives/. Generation of caches can be turned off
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by setting their names to be blank. This will slow down startup but
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save disk space. It is probably prefered to turn off the pkgcache rather
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than the srcpkgcache. Like <literal/Dir::State/ the default
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directory is contained in <literal/Dir::Cache/
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<literal/Dir::Etc/ contains the location of configuration files,
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<literal/sourcelist/ gives the location of the sourcelist and
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<literal/main/ is the default configuration file (setting has no effect,
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unless it is done from the config file specified by
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The <literal/Dir::Parts/ setting reads in all the config fragments in
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lexical order from the directory specified. After this is done then the
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main config file is loaded.
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Binary programs are pointed to by <literal/Dir::Bin/. <literal/methods/
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specifies the location of the method handlers and <literal/gzip/,
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<literal/dpkg/, <literal/apt-get/, <literal/dpkg-source/,
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<literal/dpkg-buildpackage/ and <literal/apt-cache/ specify the location
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of the respective programs.
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<RefSect1><Title>APT in DSelect</>
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When APT is used as a &dselect; method several configuration directives
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control the default behaviour. These are in the <literal/DSelect/ section.
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<VarListEntry><Term>Clean</Term>
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Cache Clean mode; this value may be one of always, prompt, auto,
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pre-auto and never. always and prompt will remove all packages from
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the cache after upgrading, prompt (the default) does so conditionally.
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auto removes only those packages which are no longer downloadable
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(replaced with a new version for instance). pre-auto performs this
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action before downloading new packages.
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<VarListEntry><Term>Options</Term>
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The contents of this variable is passed to &apt-get; as command line
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options when it is run for the install phase.
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<VarListEntry><Term>UpdateOptions</Term>
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The contents of this variable is passed to &apt-get; as command line
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options when it is run for the update phase.
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<VarListEntry><Term>PromptAfterUpdate</Term>
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If true the [U]pdate operation in &dselect; will always prompt to continue.
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The default is to prompt only on error.
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<RefSect1><Title>How APT calls dpkg</>
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Several configuration directives control how APT invokes &dpkg;. These are
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in the <literal/DPkg/ section.
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<VarListEntry><Term>Options</Term>
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This is a list of options to pass to dpkg. The options must be specified
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using the list notation and each list item is passed as a single argument
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<VarListEntry><Term>Pre-Invoke</Term><Term>Post-Invoke</Term>
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This is a list of shell commands to run before/after invoking &dpkg;.
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Like <literal/Options/ this must be specified in list notation. The
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commands are invoked in order using <filename>/bin/sh</>, should any
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<VarListEntry><Term>Pre-Install-Pkgs</Term>
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This is a list of shell commands to run before invoking dpkg. Like
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<literal/Options/ this must be specified in list notation. The commands
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are invoked in order using <filename>/bin/sh</>, should any fail APT
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will abort. APT will pass to the commands on standard input the
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filenames of all .deb files it is going to install, one per line.
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Version 2 of this protocol dumps more information, including the
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protocol version, the APT configuration space and the packages, files
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and versions being changed. Version 2 is enabled by setting
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<literal/DPkg::Tools::Options::cmd::Version/ to 2. <literal/cmd/ is a
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command given to <literal/Pre-Install-Pkgs/.
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<VarListEntry><Term>Run-Directory</Term>
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APT chdirs to this directory before invoking dpkg, the default is
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<VarListEntry><Term>Build-Options</Term>
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These options are passed to &dpkg-buildpackage; when compiling packages,
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the default is to disable signing and produce all binaries.
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<RefSect1><Title>Debug Options</>
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Most of the options in the <literal/debug/ section are not interesting to
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the normal user, however <literal/Debug::pkgProblemResolver/ shows
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interesting output about the decisions dist-upgrade makes.
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<literal/Debug::NoLocking/ disables file locking so APT can do some
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operations as non-root and <literal/Debug::pkgDPkgPM/ will print out the
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command line for each dpkg invokation. <literal/Debug::IdentCdrom/ will
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disable the inclusion of statfs data in CDROM IDs.
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<RefSect1><Title>Examples</>
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&configureindex; contains a
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sample configuration file showing the default values for all possible
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<RefSect1><Title>Files</>
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<filename>/etc/apt/apt.conf</>
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<RefSect1><Title>See Also</>
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&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.
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doc/apt.conf.5.sgml
