&apt-email;
&apt-product;
<!-- The last update date -->
- <date>18 September 2009</date>
+ <date>16 January 2010</date>
</refentryinfo>
<refmeta>
</refnamediv>
<refsect1><title>Description</title>
- <para><filename>apt.conf</filename> is the main configuration file for the APT suite of
- tools, all tools make use of the configuration file and a common command line
- parser to provide a uniform environment. When an APT tool starts up it will
- read the configuration specified by the <envar>APT_CONFIG</envar> environment
- variable (if any) and then read the files in <literal>Dir::Etc::Parts</literal>
- then read the main configuration file specified by
- <literal>Dir::Etc::main</literal> then finally apply the
- command line options to override the configuration directives, possibly
- loading even more config files.</para>
-
+ <para><filename>apt.conf</filename> is the main configuration file for
+ the APT suite of tools, but by far not the only place changes to options
+ can be made. All tools therefore share the configuration files and also
+ use a common command line parser to provide a uniform environment.</para>
+ <orderedlist>
+ <para>When an APT tool starts up it will read the configuration files
+ in the following order:</para>
+ <listitem><para>the file specified by the <envar>APT_CONFIG</envar>
+ environment variable (if any)</para></listitem>
+ <listitem><para>all files in <literal>Dir::Etc::Parts</literal> in
+ alphanumeric ascending order which have no or "<literal>conf</literal>"
+ as filename extension and which only contain alphanumeric,
+ hyphen (-), underscore (_) and period (.) characters -
+ otherwise they will be silently ignored.</para></listitem>
+ <listitem><para>the main configuration file specified by
+ <literal>Dir::Etc::main</literal></para></listitem>
+ <listitem><para>the command line options are applied to override the
+ configuration directives or to load even more configuration files.</para></listitem>
+ </orderedlist>
+ </refsect1>
+ <refsect1><title>Syntax</title>
<para>The configuration file is organized in a tree with options organized into
functional groups. Option specification is given with a double colon
notation, for instance <literal>APT::Get::Assume-Yes</literal> is an option within
</varlistentry>
<varlistentry><term>Default-Release</term>
- <listitem><para>Default release to install packages from if more than one
- version available. Contains release name, codename or release version. Examples: 'stable', 'testing', 'unstable', 'lenny', 'squeeze', '4.0', '5.0*'. See also &apt-preferences;.</para></listitem>
+ <listitem><para>Default release to install packages from if more than one
+ version available. Contains release name, codename or release version. Examples: 'stable', 'testing',
+ 'unstable', '&stable-codename;', '&testing-codename;', '4.0', '5.0*'. See also &apt-preferences;.</para></listitem>
</varlistentry>
<varlistentry><term>Ignore-Hold</term>
and the URI handlers.
<variablelist>
+ <varlistentry><term>Check-Valid-Until</term>
+ <listitem><para>Security related option defaulting to true as an
+ expiring validation for a Release file prevents longtime replay attacks
+ and can e.g. also help users to identify no longer updated mirrors -
+ but the feature depends on the correctness of the time on the user system.
+ Archive maintainers are encouraged to create Release files with the
+ <literal>Valid-Until</literal> header, but if they don't or a stricter value
+ is volitional the following <literal>Max-ValidTime</literal> option can be used.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry><term>Max-ValidTime</term>
+ <listitem><para>Seconds the Release file should be considered valid after
+ it was created. The default is "for ever" (0) if the Release file of the
+ archive doesn't include a <literal>Valid-Until</literal> header.
+ If it does then this date is the default. The date from the Release file or
+ the date specified by the creation time of the Release file
+ (<literal>Date</literal> header) plus the seconds specified with this
+ options are used to check if the validation of a file has expired by using
+ the earlier date of the two. Archive specific settings can be made by
+ appending the label of the archive to the option name.
+ </para></listitem>
+ </varlistentry>
+
<varlistentry><term>PDiffs</term>
<listitem><para>Try to download deltas called <literal>PDiffs</literal> for
Packages or Sources files instead of downloading whole ones. True