&apt-email;
&apt-product;
<!-- The last update date -->
- <date>10 December 2008</date>
+ <date>18 September 2009</date>
</refentryinfo>
<refmeta>
<refentrytitle>apt.conf</refentrytitle>
<manvolnum>5</manvolnum>
+ <refmiscinfo class="manual">APT</refmiscinfo>
</refmeta>
<!-- Man page title -->
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
+ 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
+ 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
<literal>//</literal> are treated as comments (ignored), as well as all text
between <literal>/*</literal> and <literal>*/</literal>, just like C/C++ comments.
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>
+ <literal>APT::Get::Assume-Yes "true";</literal>. The trailing
+ semicolon and the quotes are required. The value must be on one line, and
+ there is no kind of string concatenation. It must not include inside quotes.
+ The behavior of the backslash "\" and escaped characters inside a value is
+ undefined and it should not be used. An option name may include
+ alphanumerical characters and the "/-:._+" characters. A new scope can
+ be opened with curly braces, like:</para>
<informalexample><programlisting>
APT {
<para>The names of the configuration items are not case-sensitive. So in the previous example
you could use <literal>dpkg::pre-install-pkgs</literal>.</para>
- <para>Two specials are allowed, <literal>#include</literal> and <literal>#clear</literal>
+ <para>Names for the configuration items are optional if a list is defined as it can be see in
+ the <literal>DPkg::Pre-Install-Pkgs</literal> example above. If you don't specify a name a
+ new entry will simply add a new option to the list. If you specify a name you can override
+ the option as every other option by reassigning a new value to the option.</para>
+
+ <para>Two specials are allowed, <literal>#include</literal> (which is deprecated
+ and not supported by alternative implementations) 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 part of the configuration tree. The
- specified element and all its descendents are erased.</para>
+ specified element and all its descendants are erased.
+ (Note that these lines also need to end with a semicolon.)</para>
+
+ <para>The #clear command is the only way to delete a list or a complete scope.
+ Reopening a scope or the ::-style described below will <emphasis>not</emphasis>
+ override previously written entries. Only options can be overridden by addressing a new
+ value to it - lists and scopes can't be overridden, only cleared.</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>
+ a trailing :: to the list name. (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 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
+ "<literal>::</literal>" will be used. Upcoming APT versions will raise errors and
+ will stop working if they encounter this misuse, so please correct such statements now
+ as long as APT doesn't complain explicit about them.</para>
</refsect1>
<refsect1><title>The APT Group</title>
</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>
+ <listitem><para>Defaults to on which will cause APT to install essential and important packages
+ as fast as possible in the install/upgrade operation. This is done to limit the effect of a failing
+ &dpkg; call: If this option is disabled APT does treat an important package in the same way as
+ an extra package: Between the unpacking of the important package A and his configuration can then
+ be many other unpack or configuration calls, e.g. for package B which has no relation to A, but
+ causes the dpkg call to fail (e.g. because maintainer script of package B generates an error) which results
+ in a system state in which package A is unpacked but unconfigured - each package depending on A is now no
+ longer guaranteed to work as their dependency on A is not longer satisfied. The immediate configuration marker
+ is also applied to all dependencies which can generate a problem if the dependencies e.g. form a circle
+ as a dependency with the immediate flag is comparable with a Pre-Dependency. So in theory it is possible
+ that APT encounters a situation in which it is unable to perform immediate configuration, error out and
+ refers to this option so the user can deactivate the immediate configuration temporary to be able to perform
+ an install/upgrade again. Note the use of the word "theory" here as this problem was only encountered by now
+ in real world a few times in non-stable distribution versions and caused by wrong dependencies of the package
+ in question or by a system in an already broken state, so you should not blindly disable this option as
+ the mentioned scenario above is not the only problem immediate configuration can help to prevent in the first place.
+ Before a big operation like <literal>dist-upgrade</literal> is run with this option disabled it should be tried to
+ explicitly <literal>install</literal> the package APT is unable to configure immediately, but please make sure to
+ report your problem also to your distribution and to the APT team with the buglink below so they can work on
+ improving or correcting the upgrade process.</para></listitem>
</varlistentry>
<varlistentry><term>Force-LoopBreak</term>
standard form of <literal>http://[[user][:pass]@]host[:port]/</literal>. Per
host proxies can also be specified by using the form
<literal>http::Proxy::<host></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>
+ meaning to use no proxies. If no one of the above settings is specified,
+ <envar>http_proxy</envar> environment variable
+ will be used.</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
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)
+ 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>
+ require this are in violation of RFC 2068.</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
+ the limit and tries uses as much as possible of the bandwidth (Note that this option implicit
+ deactivates the download from multiple servers at the same time.)</para></listitem>
</varlistentry>
<varlistentry><term>https</term>
</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
+ <listitem><para>FTP URIs; ftp::Proxy is the default ftp proxy to use. It is in the
+ standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal>. Per
+ host proxies can also be specified by using the form
+ <literal>ftp::Proxy::<host></literal> with the special keyword <literal>DIRECT</literal>
+ meaning to use no proxies. If no one of the above settings is specified,
+ <envar>ftp_proxy</envar> environment variable
+ will be used. 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
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
+ 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>
</para></listitem>
</varlistentry>
+ <varlistentry><term>CompressionTypes</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.
+ Per 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
+ simple add the preferred type at first - not already added default types will be added at run time
+ 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> explicit to the list as it will be added automatic.</para>
+ <para>Note that at run time the <literal>Dir::Bin::<replaceable>Methodname</replaceable></literal> will
+ be checked: If this setting exists the method will only be used if this file exists, e.g. for
+ the bzip2 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 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>While it is possible to add an empty compression type to the order list, but APT in its current
+ version doesn't understand it correctly and will display many warnings about not downloaded files -
+ these warnings are most of the time false negatives. Future versions will maybe include a way to
+ really prefer uncompressed files to support the usage of local mirrors.</para></listitem>
+ </varlistentry>
</variablelist>
</para>
</refsect1>
<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>bzip2</literal>, <literal>lzma</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>
the default is to disable signing and produce all binaries.</para></listitem>
</varlistentry>
</variablelist>
+
+ <refsect2><title>dpkg trigger usage (and related options)</title>
+ <para>APT can call dpkg in a way so it can make aggressive use of triggers over
+ multiply calls of dpkg. Without further options dpkg will use triggers only in between his
+ own run. Activating these options can therefore decrease the time needed to perform the
+ install / upgrade. Note that it is intended to activate these options per default in the
+ future, but as it changes the way APT calling dpkg drastically it needs a lot more testing.
+ <emphasis>These options are therefore currently experimental and should not be used in
+ productive environments.</emphasis> Also it breaks the progress reporting so all frontends will
+ currently stay around half (or more) of the time in the 100% state while it actually configures
+ all packages.</para>
+ <para>Note that it is not guaranteed that APT will support these options or that these options will
+ not cause (big) trouble in the future. If you have understand the current risks and problems with
+ these options, but are brave enough to help testing them create a new configuration file and test a
+ combination of options. Please report any bugs, problems and improvements you encounter and make sure
+ to note which options you have used in your reports. Asking dpkg for help could also be useful for
+ debugging proposes, see e.g. <command>dpkg --audit</command>. A defensive option combination would be
+<literallayout>DPkg::NoTriggers "true";
+PackageManager::Configure "smart";
+DPkg::ConfigurePending "true";
+DPkg::TriggersPending "true";</literallayout></para>
+
+ <variablelist>
+ <varlistentry><term>DPkg::NoTriggers</term>
+ <listitem><para>Add the no triggers flag to all dpkg calls (except the ConfigurePending call).
+ See &dpkg; if you are interested in what this actually means. In short: dpkg will not run the
+ triggers when this flag is present unless it is explicitly called to do so in an extra call.
+ Note that this option exists (undocumented) also in older apt versions with a slightly different
+ meaning: Previously these option only append --no-triggers to the configure calls to dpkg -
+ now apt will add these flag also to the unpack and remove calls.</para></listitem>
+ </varlistentry>
+ <varlistentry><term>PackageManager::Configure</term>
+ <listitem><para>Valid values are "<literal>all</literal>", "<literal>smart</literal>" and "<literal>no</literal>".
+ "<literal>all</literal>" is the default value and causes APT to configure all packages explicit.
+ The "<literal>smart</literal>" way is it to configure only packages which need to be configured before
+ another package can be unpacked (Pre-Depends) and let the rest configure by dpkg with a call generated
+ by the next option. "<literal>no</literal>" on the other hand will not configure anything and totally
+ rely on dpkg for configuration (which will at the moment fail if a Pre-Depends is encountered).
+ Setting this option to another than the all value will implicitly activate also the next option per
+ default as otherwise the system could end in an unconfigured status which could be unbootable!
+ </para></listitem>
+ </varlistentry>
+ <varlistentry><term>DPkg::ConfigurePending</term>
+ <listitem><para>If this option is set apt will call <command>dpkg --configure --pending</command>
+ to let dpkg handle all required configurations and triggers. This option is activated automatic
+ per default if the previous option is not set to <literal>all</literal>, but deactivating could be useful
+ if you want to run APT multiple times in a row - e.g. in an installer. In these sceneries you could
+ deactivate this option in all but the last run.</para></listitem>
+ </varlistentry>
+ <varlistentry><term>DPkg::TriggersPending</term>
+ <listitem><para>Useful for <literal>smart</literal> configuration as a package which has pending
+ triggers is not considered as <literal>installed</literal> and dpkg treats them as <literal>unpacked</literal>
+ currently which is a dealbreaker for Pre-Dependencies (see debbugs #526774). Note that this will
+ process all triggers, not only the triggers needed to configure this package.</para></listitem>
+ </varlistentry>
+ <varlistentry><term>PackageManager::UnpackAll</term>
+ <listitem><para>As the configuration can be deferred to be done at the end by dpkg it can be
+ tried to order the unpack series only by critical needs, e.g. by Pre-Depends. Default is true
+ and therefore the "old" method of ordering in various steps by everything. While both method
+ were present in earlier APT versions the <literal>OrderCritical</literal> method was unused, so
+ this method is very experimental and needs further improvements before becoming really useful.
+ </para></listitem>
+ </varlistentry>
+ <varlistentry><term>OrderList::Score::Immediate</term>
+ <listitem><para>Essential packages (and there dependencies) should be configured immediately
+ after unpacking. It will be a good idea to do this quite early in the upgrade process as these
+ these configure calls require currently also <literal>DPkg::TriggersPending</literal> which
+ will run quite a few triggers (which maybe not needed). Essentials get per default a high score
+ but the immediate flag is relatively low (a package which has a Pre-Depends is higher rated).
+ These option and the others in the same group can be used to change the scoring. The following
+ example shows the settings with there default values.
+ <literallayout>OrderList::Score {
+ Delete 500;
+ Essential 200;
+ Immediate 10;
+ PreDepends 50;
+};</literallayout>
+ </para></listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect2>
</refsect1>
<refsect1>
</refsect1>
<refsect1><title>Files</title>
- <para><filename>/etc/apt/apt.conf</filename></para>
+ <variablelist>
+ &file-aptconf;
+ </variablelist>
</refsect1>
<refsect1><title>See Also</title>
projects / apt.git / blobdiff