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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
<!ENTITY % aptent SYSTEM "apt.ent">
%aptent;
]>
<refentry>
<refentryinfo>
&apt-author.jgunthorpe;
&apt-author.team;
&apt-email;
&apt-product;
<!-- The last update date -->
<date>29 February 2004</date>
</refentryinfo>
<refmeta>
<refentrytitle>apt.conf</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<!-- Man page title -->
<refnamediv>
<refname>apt.conf</refname>
<refpurpose>Configuration file for APT</refpurpose>
</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>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).
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>
<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 word enclosed in quotes followed by a
semicolon. Multiple entries can be included, each 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 in
<filename>&docdir;examples/apt.conf</filename> &configureindex;
is a good guide for how it should look.</para>
<para>Two specials are allowed, <literal>#include</literal> and <literal>#clear</literal>
<literal>#include</literal> will include the given file, unless the filename
ends in a slash, then the whole directory is included.
<literal>#clear</literal> is used to erase a list of names.</para>
<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>
</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>Architecture</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>Default-Release</term>
<listitem><para>Default release to install packages from if more than one
version available. Contains release name or release version. Examples: 'stable', 'testing', 'unstable', '4.0', '5.0*'. Release codenames ('etch', 'lenny' etc.) are not allowed now. See also &apt-preferences;.</para></listitem>
</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>Clean-Installed</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>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>
</varlistentry>
<varlistentry><term>Force-LoopBreak</term>
<listitem><para>Never Enable this option unless you -really- know what you are doing. It
permits APT to temporarily remove an essential package to break a
Conflicts/Conflicts or Conflicts/Pre-Depend loop between two essential
packages. SUCH A LOOP SHOULD NEVER EXIST AND IS A GRAVE BUG. This option
will work if the essential packages are not tar, gzip, libc, dpkg, bash or
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>
<varlistentry><term>Build-Essential</term>
<listitem><para>Defines which package(s) are considered essential build dependencies.</para></listitem>
</varlistentry>
<varlistentry><term>Get</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>Cache</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>CDROM</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
and the URI handlers.
<variablelist>
<varlistentry><term>PDiffs</term>
<listitem><para>Try do download deltas called <literal>PDiffs</literal> for
Packages or Sources files instead of downloading whole ones. True
by default.</para></listitem>
</varlistentry>
<varlistentry><term>Queue-Mode</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>Retries</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>Source-Symlinks</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>http</term>
<listitem><para>HTTP URIs; http::Proxy is the default http proxy to use. It is in the
standard form of <literal>http://[[user][:pass]@]host[:port]/</literal>. Per
host proxies can also be specified by using the form
<literal>http::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal>
meaning to use no proxies. The <envar>http_proxy</envar> environment variable
will override all settings.</para>
<para>Three settings are provided for cache control with HTTP/1.1 compliant
proxy caches. <literal>No-Cache</literal> tells the proxy to not use its cached
response under any circumstances, <literal>Max-Age</literal> is sent only for
index files and tells the cache to refresh its object if it is older than
the given number of seconds. Debian updates its index files daily so the
default is 1 day. <literal>No-Store</literal> specifies that the cache should never
store this request, it is only set for archive files. This may be useful
to prevent polluting a proxy cache with very large .deb files. Note:
Squid 2.0.2 does not support any of these options.</para>
<para>The option <literal>timeout</literal> sets the timeout timer used by the method,
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)
<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>
</varlistentry>
<varlistentry><term>ftp</term>
<listitem><para>FTP URIs; ftp::Proxy is the default proxy server to use. It is in the
standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal> and is
overridden by the <envar>ftp_proxy</envar> environment variable. To use a ftp
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 available 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>
Each is taken from it's respective URI component.</para>
<para>The option <literal>timeout</literal> sets the timeout timer used by the method,
this applies to all things including connection timeout and 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, 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 a 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>cdrom</term>
<listitem><para>CDROM URIs; the only setting for CDROM URIs is the mount point,
<literal>cdrom::Mount</literal> which must be the mount point for the CDROM 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 (such as an SMB mount and old mount packages). The syntax
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>gpgv</term>
<listitem><para>GPGV URIs; the only option for GPGV URIs is the option to pass additional parameters to gpgv.
<literal>gpgv::Options</literal> Additional options passed to gpgv.
</para></listitem>
</varlistentry>
</variablelist>
</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 preferences 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 their names to be blank. This will slow down startup but
save disk space. It is probably preferred 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>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 in <literal>Dir::</literal> 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>.
</para>
</refsect1>
<refsect1><title>APT in DSelect</title>
<para>
When APT is used as a &dselect; method several configuration directives
control the default behaviour. These are in the <literal>DSelect</literal> section.</para>
<variablelist>
<varlistentry><term>Clean</term>
<listitem><para>Cache Clean mode; this value may be one of always, prompt, auto,
pre-auto and never. always and prompt will remove all packages from
the cache after upgrading, prompt (the default) does so conditionally.
auto removes only those packages which are no longer downloadable
(replaced with a new version for instance). pre-auto performs this
action before downloading new packages.</para></listitem>
</varlistentry>
<varlistentry><term>options</term>
<listitem><para>The contents of this variable is passed to &apt-get; as command line
options when it is run for the install phase.</para></listitem>
</varlistentry>
<varlistentry><term>Updateoptions</term>
<listitem><para>The contents of this variable is passed to &apt-get; as command line
options when it is run for the update phase.</para></listitem>
</varlistentry>
<varlistentry><term>PromptAfterUpdate</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>options</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>Pre-Invoke</term><term>Post-Invoke</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>Pre-Install-Pkgs</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 to the commands on standard input the
filenames of all .deb files it is going to install, one per line.</para>
<para>Version 2 of this protocol dumps more information, including the
protocol version, the APT configuration space and the packages, files
and versions being changed. Version 2 is enabled by setting
<literal>DPkg::Tools::options::cmd::Version</literal> to 2. <literal>cmd</literal> is a
command given to <literal>Pre-Install-Pkgs</literal>.</para></listitem>
</varlistentry>
<varlistentry><term>Run-Directory</term>
<listitem><para>APT chdirs to this directory before invoking dpkg, the default is
<filename>/</filename>.</para></listitem>
</varlistentry>
<varlistentry><term>Build-options</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>
</variablelist>
</refsect1>
<refsect1><title>Debug options</title>
<para>Most of the options in the <literal>debug</literal> section are not interesting to
the normal user, however <literal>Debug::pkgProblemResolver</literal> shows
interesting output about the decisions dist-upgrade makes.
<literal>Debug::NoLocking</literal> disables file locking so APT can do some
operations as non-root and <literal>Debug::pkgDPkgPM</literal> will print out the
command line for each dpkg invokation. <literal>Debug::IdentCdrom</literal> will
disable the inclusion of statfs data in CDROM IDs.
<literal>Debug::Acquire::gpgv</literal> Debugging of the gpgv method.
</para>
</refsect1>
<refsect1><title>Examples</title>
<para>&configureindex; is a
configuration file showing example values for all possible
options.</para>
</refsect1>
<refsect1><title>Files</title>
<para><filename>/etc/apt/apt.conf</filename></para>
</refsect1>
<refsect1><title>See Also</title>
<para>&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.</para>
</refsect1>
&manbugs;
</refentry>