+ <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 <command>bzip2</command>, <command>lzma</command>
+ and <command>gzip</command> compressed files; with this setting more formats can be added
+ on the fly or the used method can be changed. The syntax for this is:
+ <synopsis>Acquire::CompressionTypes::<replaceable>FileExtension</replaceable> "<replaceable>Methodname</replaceable>";</synopsis>
+ </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 - default 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 <command>bzip2</command> and <command>lzma</command>.
+ If <command>lzma</command> should be preferred over <command>gzip</command> and <command>bzip2</command> the
+ configure setting should look like this: <synopsis>Acquire::CompressionTypes::Order { "lzma"; "gz"; };</synopsis>
+ It is not needed to add <literal>bz2</literal> 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, 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
+ useable 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>
+