<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. (As you might suspect: The scope syntax can't be used
- on the command line.)</para>
+ sign then the new value of the option. To append a new element to a list, add a
+ trailing :: 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 you can use :: only for appending one item per line to a list and
that you should not use it in combination with the scope syntax.
(The scope syntax implicit insert ::) Using both syntaxes together will trigger a bug
- which some users unfortunately relay on: An option with the unusual name "<literal>::</literal>"
+ which some users unfortunately depend on: An option with the unusual name "<literal>::</literal>"
which acts like every other option with a name. These introduces many problems
including that a user who writes multiple lines in this <emphasis>wrong</emphasis> syntax in
the hope to append to a list will gain the opposite as only the last assignment for this option
</varlistentry>
<varlistentry><term>Architectures</term>
- <listitem><para>All Architectures the system supports. Processors implementing the <literal>amd64</literal>
- are e.g. also able to execute binaries compiled for <literal>i386</literal>; This list is use when fetching files and
+ <listitem><para>All Architectures the system supports. Processors implementing the
+ <literal>amd64</literal> (also called <literal>x86-64</literal>) instruction set are
+ e.g. also able to execute binaries compiled for the <literal>i386</literal>
+ (<literal>x86</literal>) instruction set; This list is use when fetching files and
parsing package lists. The internal default is always the native architecture (<literal>APT::Architecture</literal>)
and all foreign architectures it can retrieve by calling <command>dpkg --print-foreign-architectures</command>.
</para></listitem>
<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 to which size the Cache will grow
and is therefore the amount of memory APT will request at startup. The default value is
- 20971520 bytes (~20 MB). Note that these amount of space need to be available for APT
- otherwise it will likely fail ungracefully, so for memory restricted devices these value should
- be lowered while on systems with a lot of configured sources this might be increased.
- <literal>Cache-Grow</literal> defines in byte with the default of 1048576 (~1 MB) how much
+ 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. These 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>.
<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.
+ it was created (indicated by the <literal>Date</literal> header).
+ 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 "for ever valid".
+ Archive specific settings can be made by appending the label of the archive
+ to the option name.
+ </para></listitem>
+ </varlistentry>
+
+ <varlistentry><term>Min-ValidTime</term>
+ <listitem><para>Minimum of seconds the Release file should be considered
+ valid after it was created (indicated by the <literal>Date</literal> header).
+ Use this if you need to use a seldomly updated (local) mirror of a more
+ regular 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.
</para></listitem>
</varlistentry>
by default.</para>
<para>Two sub-options to limit the use of PDiffs are also available:
With <literal>FileLimit</literal> can be specified how many PDiff files
- are downloaded at most to patch a file. <literal>SizeLimit</literal>
- on the other hand is the maximum precentage of the size of all patches
+ are downloaded at most 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>
<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>
+ <para>The setting <literal>Acquire::http::Pipeline-Depth</literal> can be used to
+ enabled HTTP pipeling (RFC 2616 section 8.1.2.2) which can be beneficial e.g. on
+ high-latency connections. It specifies how many requests are send in a pipeline.
+ Previous APT versions had a default of 10 for this setting, but the default value
+ is now 0 (= disabled) to avoid problems with the ever-growing amount of webservers
+ and proxies which choose to not conform to the HTTP/1.1 specification.</para>
+
+ <para><literal>Acquire::http::AllowRedirect</literal> controls if APT will follow
+ redirects, which is enabled by default.</para>
<para>The used bandwidth can be limited with <literal>Acquire::http::Dl-Limit</literal>
which accepts integer values in kilobyte. The default value is 0 which deactivates
actually use them if the environment doesn't specify this languages. So the following example configuration will
result in the order "en, de" in an english and in "de, en" in a german localization. Note that "fr" is downloaded,
but not used if APT is not used in a french localization, in such an environment the order would be "fr, de, en".
- <programlisting>Acquire::Languages { "environment"; "de"; "en"; "none"; "fr"; };</programlisting></para></listitem>
+ <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>
</variablelist>
<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>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>
projects / apt.git / blobdiff