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39
<refsect1><title>Description</title>
39
<para><filename>apt.conf</filename> is the main configuration file for the APT suite of
40
tools, all tools make use of the configuration file and a common command line
41
parser to provide a uniform environment. When an APT tool starts up it will
42
read the configuration specified by the <envar>APT_CONFIG</envar> environment
43
variable (if any) and then read the files in <literal>Dir::Etc::Parts</literal>
44
then read the main configuration file specified by
45
<literal>Dir::Etc::main</literal> then finally apply the
46
command line options to override the configuration directives, possibly
47
loading even more config files.</para>
40
<para><filename>apt.conf</filename> is the main configuration file for
41
the APT suite of tools, but by far not the only place changes to options
42
can be made. All tools therefore share the configuration files and also
43
use a common command line parser to provide a uniform environment.</para>
45
<para>When an APT tool starts up it will read the configuration files
46
in the following order:</para>
47
<listitem><para>the file specified by the <envar>APT_CONFIG</envar>
48
environment variable (if any)</para></listitem>
49
<listitem><para>all files in <literal>Dir::Etc::Parts</literal> in
50
alphanumeric ascending order which have no or "<literal>conf</literal>"
51
as filename extension and which only contain alphanumeric,
52
hyphen (-), underscore (_) and period (.) characters -
53
otherwise they will be silently ignored.</para></listitem>
54
<listitem><para>the main configuration file specified by
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<literal>Dir::Etc::main</literal></para></listitem>
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<listitem><para>the command line options are applied to override the
57
configuration directives or to load even more configuration files.</para></listitem>
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<refsect1><title>Syntax</title>
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61
<para>The configuration file is organized in a tree with options organized into
50
functional groups. option specification is given with a double colon
62
functional groups. Option specification is given with a double colon
51
63
notation, for instance <literal>APT::Get::Assume-Yes</literal> is an option within
52
the APT tool group, for the Get tool. options do not inherit from their
64
the APT tool group, for the Get tool. Options do not inherit from their
53
65
parent groups.</para>
55
67
<para>Syntactically the configuration language is modeled after what the ISC tools
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69
<literal>//</literal> are treated as comments (ignored), as well as all text
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between <literal>/*</literal> and <literal>*/</literal>, just like C/C++ comments.
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Each line is of the form
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<literal>APT::Get::Assume-Yes "true";</literal> The trailing
61
semicolon is required and the quotes are optional. A new scope can be
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opened with curly braces, like:</para>
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<literal>APT::Get::Assume-Yes "true";</literal>. The trailing
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semicolon and the quotes are required. The value must be on one line, and
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there is no kind of string concatenation. It must not include inside quotes.
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The behavior of the backslash "\" and escaped characters inside a value is
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undefined and it should not be used. An option name may include
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alphanumerical characters and the "/-:._+" characters. A new scope can
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be opened with curly braces, like:</para>
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<informalexample><programlisting>
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<para>The names of the configuration items are not case-sensitive. So in the previous example
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you could use <literal>dpkg::pre-install-pkgs</literal>.</para>
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<para>Two specials are allowed, <literal>#include</literal> and <literal>#clear</literal>
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<para>Names for the configuration items are optional if a list is defined as it can be see in
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the <literal>DPkg::Pre-Install-Pkgs</literal> example above. If you don't specify a name a
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new entry will simply add a new option to the list. If you specify a name you can override
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the option as every other option by reassigning a new value to the option.</para>
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<para>Two specials are allowed, <literal>#include</literal> (which is deprecated
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and not supported by alternative implementations) and <literal>#clear</literal>:
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<literal>#include</literal> will include the given file, unless the filename
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ends in a slash, then the whole directory is included.
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<literal>#clear</literal> is used to erase a list of names.</para>
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<literal>#clear</literal> is used to erase a part of the configuration tree. The
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specified element and all its descendants are erased.
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(Note that these lines also need to end with a semicolon.)</para>
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<para>The #clear command is the only way to delete a list or a complete scope.
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Reopening a scope or the ::-style described below will <emphasis>not</emphasis>
119
override previously written entries. Only options can be overridden by addressing a new
120
value to it - lists and scopes can't be overridden, only cleared.</para>
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<para>All of the APT tools take a -o option which allows an arbitrary configuration
94
123
directive to be specified on the command line. The syntax is a full option
95
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name (<literal>APT::Get::Assume-Yes</literal> for instance) followed by an equals
96
125
sign then the new value of the option. Lists can be appended too by adding
97
a trailing :: to the list name.</para>
126
a trailing :: to the list name. (As you might suspect: The scope syntax can't be used
127
on the command line.)</para>
129
<para>Note that you can use :: only for appending one item per line to a list and
130
that you should not use it in combination with the scope syntax.
131
(The scope syntax implicit insert ::) Using both syntaxes together will trigger a bug
132
which some users unfortunately relay on: An option with the unusual name "<literal>::</literal>"
133
which acts like every other option with a name. These introduces many problems
134
including that a user who writes multiple lines in this <emphasis>wrong</emphasis> syntax in
135
the hope to append to a list will gain the opposite as only the last assignment for this option
136
"<literal>::</literal>" will be used. Upcoming APT versions will raise errors and
137
will stop working if they encounter this misuse, so please correct such statements now
138
as long as APT doesn't complain explicit about them.</para>
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<refsect1><title>The APT Group</title>
111
152
<varlistentry><term>Default-Release</term>
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153
<listitem><para>Default release to install packages from if more than one
113
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>
154
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>
116
157
<varlistentry><term>Ignore-Hold</term>
117
158
<listitem><para>Ignore Held packages; This global option causes the problem resolver to
118
159
ignore held packages in its decision making.</para></listitem>
128
169
<varlistentry><term>Immediate-Configure</term>
129
<listitem><para>Disable Immediate Configuration; This dangerous option disables some
130
of APT's ordering code to cause it to make fewer dpkg calls. Doing
131
so may be necessary on some extremely slow single user systems but
132
is very dangerous and may cause package install scripts to fail or worse.
133
Use at your own risk.</para></listitem>
170
<listitem><para>Defaults to on which will cause APT to install essential and important packages
171
as fast as possible in the install/upgrade operation. This is done to limit the effect of a failing
172
&dpkg; call: If this option is disabled APT does treat an important package in the same way as
173
an extra package: Between the unpacking of the important package A and his configuration can then
174
be many other unpack or configuration calls, e.g. for package B which has no relation to A, but
175
causes the dpkg call to fail (e.g. because maintainer script of package B generates an error) which results
176
in a system state in which package A is unpacked but unconfigured - each package depending on A is now no
177
longer guaranteed to work as their dependency on A is not longer satisfied. The immediate configuration marker
178
is also applied to all dependencies which can generate a problem if the dependencies e.g. form a circle
179
as a dependency with the immediate flag is comparable with a Pre-Dependency. So in theory it is possible
180
that APT encounters a situation in which it is unable to perform immediate configuration, errors out and
181
refers to this option so the user can deactivate the immediate configuration temporarily to be able to perform
182
an install/upgrade again. Note the use of the word "theory" here as this problem was only encountered by now
183
in real world a few times in non-stable distribution versions and was caused by wrong dependencies of the package
184
in question or by a system in an already broken state, so you should not blindly disable this option as
185
the mentioned scenario above is not the only problem immediate configuration can help to prevent in the first place.
186
Before a big operation like <literal>dist-upgrade</literal> is run with this option disabled it should be tried to
187
explicitly <literal>install</literal> the package APT is unable to configure immediately, but please make sure to
188
report your problem also to your distribution and to the APT team with the buglink below so they can work on
189
improving or correcting the upgrade process.</para></listitem>
136
192
<varlistentry><term>Force-LoopBreak</term>
176
232
<varlistentry><term>PDiffs</term>
177
<listitem><para>Try do download deltas called <literal>PDiffs</literal> for
233
<listitem><para>Try to download deltas called <literal>PDiffs</literal> for
178
234
Packages or Sources files instead of downloading whole ones. True
179
by default.</para></listitem>
236
<para>Two sub-options to limit the use of PDiffs are also available:
237
With <literal>FileLimit</literal> can be specified how many PDiff files
238
are downloaded at most to patch a file. <literal>SizeLimit</literal>
239
on the other hand is the maximum precentage of the size of all patches
240
compared to the size of the targeted file. If one of these limits is
241
exceeded the complete file is downloaded instead of the patches.
182
245
<varlistentry><term>Queue-Mode</term>
220
283
this applies to all things including connection timeout and data timeout.</para>
222
285
<para>One setting is provided to control the pipeline depth in cases where the
223
remote server is not RFC conforming or buggy (such as Squid 2.0.2)
286
remote server is not RFC conforming or buggy (such as Squid 2.0.2).
224
287
<literal>Acquire::http::Pipeline-Depth</literal> can be a value from 0 to 5
225
288
indicating how many outstanding requests APT should send. A value of
226
289
zero MUST be specified if the remote host does not properly linger
227
290
on TCP connections - otherwise data corruption will occur. Hosts which
228
require this are in violation of RFC 2068.</para></listitem>
291
require this are in violation of RFC 2068.</para>
293
<para>The used bandwidth can be limited with <literal>Acquire::http::Dl-Limit</literal>
294
which accepts integer values in kilobyte. The default value is 0 which deactivates
295
the limit and tries uses as much as possible of the bandwidth (Note that this option implicit
296
deactivates the download from multiple servers at the same time.)</para>
298
<para><literal>Acquire::http::User-Agent</literal> can be used to set a different
299
User-Agent for the http download method as some proxies allow access for clients
300
only if the client uses a known identifier.</para>
231
304
<varlistentry><term>https</term>
232
<listitem><para>HTTPS URIs. Cache-control and proxy options are the same as for
233
<literal>http</literal> method.
234
<literal>Pipeline-Depth</literal> option is not supported yet.</para>
305
<listitem><para>HTTPS URIs. Cache-control, Timeout, AllowRedirect, Dl-Limit and
306
proxy options are the same as for <literal>http</literal> method and will also
307
default to the options from the <literal>http</literal> method if they are not
308
explicitly set for https. <literal>Pipeline-Depth</literal> option is not
309
supported yet.</para>
236
311
<para><literal>CaInfo</literal> suboption specifies place of file that
237
312
holds info about trusted certificates.
307
382
</para></listitem>
385
<varlistentry><term>CompressionTypes</term>
386
<listitem><para>List of compression types which are understood by the acquire methods.
387
Files like <filename>Packages</filename> can be available in various compression formats.
388
Per default the acquire methods can decompress <command>bzip2</command>, <command>lzma</command>
389
and <command>gzip</command> compressed files, with this setting more formats can be added
390
on the fly or the used method can be changed. The syntax for this is:
391
<synopsis>Acquire::CompressionTypes::<replaceable>FileExtension</replaceable> "<replaceable>Methodname</replaceable>";</synopsis>
392
</para><para>Also the <literal>Order</literal> subgroup can be used to define in which order
393
the acquire system will try to download the compressed files. The acquire system will try the first
394
and proceed with the next compression type in this list on error, so to prefer one over the other type
395
simple add the preferred type at first - not already added default types will be added at run time
396
to the end of the list, so e.g. <synopsis>Acquire::CompressionTypes::Order:: "gz";</synopsis> can
397
be used to prefer <command>gzip</command> compressed files over <command>bzip2</command> and <command>lzma</command>.
398
If <command>lzma</command> should be preferred over <command>gzip</command> and <command>bzip2</command> the
399
configure setting should look like this <synopsis>Acquire::CompressionTypes::Order { "lzma"; "gz"; };</synopsis>
400
It is not needed to add <literal>bz2</literal> explicit to the list as it will be added automatic.</para>
401
<para>Note that at run time the <literal>Dir::Bin::<replaceable>Methodname</replaceable></literal> will
402
be checked: If this setting exists the method will only be used if this file exists, e.g. for
403
the bzip2 method (the inbuilt) setting is <literallayout>Dir::Bin::bzip2 "/bin/bzip2";</literallayout>
404
Note also that list entries specified on the command line will be added at the end of the list
405
specified in the configuration files, but before the default entries. To prefer a type in this case
406
over the ones specified in in the configuration files you can set the option direct - not in list style.
407
This will not override the defined list, it will only prefix the list with this type.</para>
408
<para>While it is possible to add an empty compression type to the order list, but APT in its current
409
version doesn't understand it correctly and will display many warnings about not downloaded files -
410
these warnings are most of the time false negatives. Future versions will maybe include a way to
411
really prefer uncompressed files to support the usage of local mirrors.</para></listitem>
414
<varlistentry><term>Languages</term>
415
<listitem><para>The Languages subsection controls which <filename>Translation</filename> files are downloaded
416
and in which order APT tries to display the Description-Translations. APT will try to display the first
417
available Description in the Language which is listed at first. Languages can be defined with their
418
short or long Languagecodes. Note that not all archives provide <filename>Translation</filename>
419
files for every Language - especially the long Languagecodes are rare, so please
420
inform you which ones are available before you set here impossible values.</para>
421
<para>The default list includes "environment" and "en". "<literal>environment</literal>" has a special meaning here:
422
It will be replaced at runtime with the languagecodes extracted from the <literal>LC_MESSAGES</literal> environment variable.
423
It will also ensure that these codes are not included twice in the list. If <literal>LC_MESSAGES</literal>
424
is set to "C" only the <filename>Translation-en</filename> file (if available) will be used.
425
To force apt to use no Translation file use the setting <literal>Acquire::Languages=none</literal>. "<literal>none</literal>"
426
is another special meaning code which will stop the search for a fitting <filename>Translation</filename> file.
427
This can be used by the system administrator to let APT know that it should download also this files without
428
actually use them if the environment doesn't specify this languages. So the following example configuration will
429
result in the order "en, de" in an english and in "de, en" in a german localization. Note that "fr" is downloaded,
430
but not used if APT is not used in a french localization, in such an environment the order would be "fr, de, en".
431
<programlisting>Acquire::Languages { "environment"; "de"; "en"; "none"; "fr"; };</programlisting></para></listitem>
433
558
the default is to disable signing and produce all binaries.</para></listitem>
562
<refsect2><title>dpkg trigger usage (and related options)</title>
563
<para>APT can call dpkg in a way so it can make aggressive use of triggers over
564
multiply calls of dpkg. Without further options dpkg will use triggers only in between his
565
own run. Activating these options can therefore decrease the time needed to perform the
566
install / upgrade. Note that it is intended to activate these options per default in the
567
future, but as it changes the way APT calling dpkg drastically it needs a lot more testing.
568
<emphasis>These options are therefore currently experimental and should not be used in
569
productive environments.</emphasis> Also it breaks the progress reporting so all frontends will
570
currently stay around half (or more) of the time in the 100% state while it actually configures
572
<para>Note that it is not guaranteed that APT will support these options or that these options will
573
not cause (big) trouble in the future. If you have understand the current risks and problems with
574
these options, but are brave enough to help testing them create a new configuration file and test a
575
combination of options. Please report any bugs, problems and improvements you encounter and make sure
576
to note which options you have used in your reports. Asking dpkg for help could also be useful for
577
debugging proposes, see e.g. <command>dpkg --audit</command>. A defensive option combination would be
578
<literallayout>DPkg::NoTriggers "true";
579
PackageManager::Configure "smart";
580
DPkg::ConfigurePending "true";
581
DPkg::TriggersPending "true";</literallayout></para>
584
<varlistentry><term>DPkg::NoTriggers</term>
585
<listitem><para>Add the no triggers flag to all dpkg calls (except the ConfigurePending call).
586
See &dpkg; if you are interested in what this actually means. In short: dpkg will not run the
587
triggers when this flag is present unless it is explicitly called to do so in an extra call.
588
Note that this option exists (undocumented) also in older apt versions with a slightly different
589
meaning: Previously these option only append --no-triggers to the configure calls to dpkg -
590
now apt will add these flag also to the unpack and remove calls.</para></listitem>
592
<varlistentry><term>PackageManager::Configure</term>
593
<listitem><para>Valid values are "<literal>all</literal>", "<literal>smart</literal>" and "<literal>no</literal>".
594
"<literal>all</literal>" is the default value and causes APT to configure all packages explicit.
595
The "<literal>smart</literal>" way is it to configure only packages which need to be configured before
596
another package can be unpacked (Pre-Depends) and let the rest configure by dpkg with a call generated
597
by the next option. "<literal>no</literal>" on the other hand will not configure anything and totally
598
rely on dpkg for configuration (which will at the moment fail if a Pre-Depends is encountered).
599
Setting this option to another than the all value will implicitly activate also the next option per
600
default as otherwise the system could end in an unconfigured status which could be unbootable!
603
<varlistentry><term>DPkg::ConfigurePending</term>
604
<listitem><para>If this option is set apt will call <command>dpkg --configure --pending</command>
605
to let dpkg handle all required configurations and triggers. This option is activated automatic
606
per default if the previous option is not set to <literal>all</literal>, but deactivating could be useful
607
if you want to run APT multiple times in a row - e.g. in an installer. In these sceneries you could
608
deactivate this option in all but the last run.</para></listitem>
610
<varlistentry><term>DPkg::TriggersPending</term>
611
<listitem><para>Useful for <literal>smart</literal> configuration as a package which has pending
612
triggers is not considered as <literal>installed</literal> and dpkg treats them as <literal>unpacked</literal>
613
currently which is a dealbreaker for Pre-Dependencies (see debbugs #526774). Note that this will
614
process all triggers, not only the triggers needed to configure this package.</para></listitem>
616
<varlistentry><term>PackageManager::UnpackAll</term>
617
<listitem><para>As the configuration can be deferred to be done at the end by dpkg it can be
618
tried to order the unpack series only by critical needs, e.g. by Pre-Depends. Default is true
619
and therefore the "old" method of ordering in various steps by everything. While both method
620
were present in earlier APT versions the <literal>OrderCritical</literal> method was unused, so
621
this method is very experimental and needs further improvements before becoming really useful.
624
<varlistentry><term>OrderList::Score::Immediate</term>
625
<listitem><para>Essential packages (and there dependencies) should be configured immediately
626
after unpacking. It will be a good idea to do this quite early in the upgrade process as these
627
these configure calls require currently also <literal>DPkg::TriggersPending</literal> which
628
will run quite a few triggers (which maybe not needed). Essentials get per default a high score
629
but the immediate flag is relatively low (a package which has a Pre-Depends is higher rated).
630
These option and the others in the same group can be used to change the scoring. The following
631
example shows the settings with there default values.
632
<literallayout>OrderList::Score {
894
<term><literal>Debug::pkgDepCache::Marker</literal></term>
897
Generate debug messages describing which package is marked
898
as keep/install/remove while the ProblemResolver does his work.
899
Each addition or deletion may trigger additional actions;
900
they are shown indented two additional space under the original entry.
901
The format for each line is <literal>MarkKeep</literal>,
902
<literal>MarkDelete</literal> or <literal>MarkInstall</literal> followed by
903
<literal>package-name <a.b.c -> d.e.f | x.y.z> (section)</literal>
904
where <literal>a.b.c</literal> is the current version of the package,
905
<literal>d.e.f</literal> is the version considered for installation and
906
<literal>x.y.z</literal> is a newer version, but not considered for installation
907
(because of a low pin score). The later two can be omitted if there is none or if
908
it is the same version as the installed.
909
<literal>section</literal> is the name of the section the package appears in.
687
914
<!-- Question: why doesn't this do anything? The code says it should. -->
689
916
<term><literal>Debug::pkgInitConfig</literal></term>
692
Dump the default configuration to standard output on
919
Dump the default configuration to standard error on
added
removed
doc/apt.conf.5.xml
