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24f6490f 1<?xml version="1.0" encoding="utf-8" standalone="no"?>
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2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
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4<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
5<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
6<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
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7]>
8
9<refentry>
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10
11 <refentryinfo>
12 &apt-author.jgunthorpe;
13 &apt-author.team;
be1b8568 14 <author>
d5aa88bf 15 &apt-name.dburrows;
be1b8568 16 <contrib>Initial documentation of Debug::*.</contrib>
4920c8c7 17 <email>dburrows@debian.org</email>
be1b8568 18 </author>
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19 &apt-email;
20 &apt-product;
21 <!-- The last update date -->
317bb39f 22 <date>2016-08-17T00:00:00Z</date>
5e80de29 23 </refentryinfo>
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24
25 <refmeta>
26 <refentrytitle>apt.conf</refentrytitle>
27 <manvolnum>5</manvolnum>
f0599b9c 28 <refmiscinfo class="manual">APT</refmiscinfo>
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29 </refmeta>
30
31 <!-- Man page title -->
32 <refnamediv>
33 <refname>apt.conf</refname>
34 <refpurpose>Configuration file for APT</refpurpose>
35 </refnamediv>
5723791e 36
24f6490f 37 <refsect1><title>Description</title>
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38 <para><filename>/etc/apt/apt.conf</filename> is the main configuration
39 file shared by all the tools in the APT suite of tools, though it is by
40 no means the only place options can be set. The suite also shares a common
41 command line parser to provide a uniform environment.</para>
42
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43 <orderedlist>
44 <para>When an APT tool starts up it will read the configuration files
45 in the following order:</para>
46 <listitem><para>the file specified by the <envar>APT_CONFIG</envar>
47 environment variable (if any)</para></listitem>
48 <listitem><para>all files in <literal>Dir::Etc::Parts</literal> in
1fc8c922 49 alphanumeric ascending order which have either no or "<literal>conf</literal>"
e29a6bb1 50 as filename extension and which only contain alphanumeric,
7376837d 51 hyphen (-), underscore (_) and period (.) characters.
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52 Otherwise APT will print a notice that it has ignored a file, unless that
53 file matches a pattern in the <literal>Dir::Ignore-Files-Silently</literal>
5723791e 54 configuration list - in which case it will be silently ignored.</para></listitem>
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55 <listitem><para>the main configuration file specified by
56 <literal>Dir::Etc::main</literal></para></listitem>
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57 <listitem><para>all options set in the binary specific configuration
58 subtree are moved into the root of the tree.</para></listitem>
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59 <listitem><para>the command line options are applied to override the
60 configuration directives or to load even more configuration files.</para></listitem>
61 </orderedlist>
62 </refsect1>
63 <refsect1><title>Syntax</title>
24f6490f 64 <para>The configuration file is organized in a tree with options organized into
5f4331c4 65 functional groups. Option specification is given with a double colon
5723791e 66 notation; for instance <literal>APT::Get::Assume-Yes</literal> is an option within
5f4331c4 67 the APT tool group, for the Get tool. Options do not inherit from their
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68 parent groups.</para>
69
e3a1f08d 70 <para>Syntactically the configuration language is modeled after what the ISC tools
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71 such as bind and dhcp use. Lines starting with
72 <literal>//</literal> are treated as comments (ignored), as well as all text
73 between <literal>/*</literal> and <literal>*/</literal>, just like C/C++ comments.
24f6490f 74 Each line is of the form
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75 <literal>APT::Get::Assume-Yes "true";</literal>.
76 The quotation marks and trailing semicolon are required.
77 The value must be on one line, and there is no kind of string concatenation.
78 Values must not include backslashes or extra quotation marks.
79 Option names are made up of alphanumeric characters and the characters "/-:._+".
80 A new scope can be opened with curly braces, like this:</para>
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81
82<informalexample><programlisting>
83APT {
84 Get {
85 Assume-Yes "true";
86 Fix-Broken "true";
87 };
88};
89</programlisting></informalexample>
90
91 <para>with newlines placed to make it more readable. Lists can be created by
d82cdf73 92 opening a scope and including a single string enclosed in quotes followed by a
5723791e 93 semicolon. Multiple entries can be included, separated by a semicolon.</para>
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94
95<informalexample><programlisting>
96DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
97</programlisting></informalexample>
98
00612a8c 99 <para>In general the sample configuration file &configureindex;
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100 is a good guide for how it should look.</para>
101
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102 <para>Case is not significant in names of configuration items, so in the
103 previous example you could use <literal>dpkg::pre-install-pkgs</literal>.</para>
fb3b7ef0 104
5723791e 105 <para>Names for the configuration items are optional if a list is defined as can be seen in
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106 the <literal>DPkg::Pre-Install-Pkgs</literal> example above. If you don't specify a name a
107 new entry will simply add a new option to the list. If you specify a name you can override
5723791e 108 the option in the same way as any other option by reassigning a new value to the option.</para>
63fc5550 109
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110 <para>Two special commands are defined: <literal>#include</literal> (which is
111 deprecated and not supported by alternative implementations) and
112 <literal>#clear</literal>. <literal>#include</literal> will include the
113 given file, unless the filename ends in a slash, in which case the whole
114 directory is included.
d82cdf73 115 <literal>#clear</literal> is used to erase a part of the configuration tree. The
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116 specified element and all its descendants are erased.
117 (Note that these lines also need to end with a semicolon.)</para>
118
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119 <para>
120 The <literal>#clear</literal> command is the only way to delete a list or
121 a complete scope. Reopening a scope (or using the syntax described below
122 with an appended <literal>::</literal>) will <emphasis>not</emphasis>
123 override previously written entries. Options can only be overridden by
124 addressing a new value to them - lists and scopes can't be overridden,
125 only cleared.
126 </para>
24f6490f 127
5723791e 128 <para>All of the APT tools take an -o option which allows an arbitrary configuration
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129 directive to be specified on the command line. The syntax is a full option
130 name (<literal>APT::Get::Assume-Yes</literal> for instance) followed by an equals
c086ac18 131 sign then the new value of the option. To append a new element to a list, add a
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132 trailing <literal>::</literal> to the name of the list.
133 (As you might suspect, the scope syntax can't be used on the command line.)</para>
134
135 <para>
136 Note that appending items to a list using <literal>::</literal> only works
137 for one item per line, and that you should not use it in combination with
138 the scope syntax (which adds <literal>::</literal> implicitly). Using both
139 syntaxes together will trigger a bug which some users unfortunately depend
140 on: an option with the unusual name "<literal>::</literal>" which acts
141 like every other option with a name. This introduces many problems; for
142 one thing, users who write multiple lines in this
143 <emphasis>wrong</emphasis> syntax in the hope of appending to a list will
144 achieve the opposite, as only the last assignment for this option
145 "<literal>::</literal>" will be used. Future versions of APT will raise
146 errors and stop working if they encounter this misuse, so please correct
147 such statements now while APT doesn't explicitly complain about them.
148 </para>
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149 </refsect1>
150
151 <refsect1><title>The APT Group</title>
152 <para>This group of options controls general APT behavior as well as holding the
153 options for all of the tools.</para>
154
155 <variablelist>
2b9b27c3 156 <varlistentry><term><option>Architecture</option></term>
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157 <listitem><para>System Architecture; sets the architecture to use when fetching files and
158 parsing package lists. The internal default is the architecture apt was
159 compiled for.</para></listitem>
160 </varlistentry>
58014adc 161
2b9b27c3 162 <varlistentry><term><option>Architectures</option></term>
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163 <listitem><para>
164 All Architectures the system supports. For instance, CPUs implementing
165 the <literal>amd64</literal> (also called <literal>x86-64</literal>)
166 instruction set are also able to execute binaries compiled for the
167 <literal>i386</literal> (<literal>x86</literal>) instruction set. This
168 list is used when fetching files and parsing package lists. The
169 initial default is always the system's native architecture
170 (<literal>APT::Architecture</literal>), and foreign architectures are
171 added to the default list when they are registered via
172 <command>dpkg --add-architecture</command>.
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173 </para></listitem>
174 </varlistentry>
175
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176 <varlistentry><term><option>Compressor</option></term>
177 <listitem><para>
178 This scope defines which compression formats are supported, how compression
179 and decompression can be performed if support for this format isn't built
180 into apt directly and a cost-value indicating how costly it is to compress
181 something in this format. As an example the following configuration stanza
182 would allow apt to download and uncompress as well as create and store
183 files with the low-cost <literal>.reversed</literal> file extension which
184 it will pass to the command <command>rev</command> without additional
185 commandline parameters for compression and uncompression:
186<informalexample><programlisting>
187APT::Compressor::rev {
188 Name "rev";
189 Extension ".reversed";
190 Binary "rev";
191 CompressArg {};
192 UncompressArg {};
193 Cost "10";
194};
195</programlisting></informalexample>
196 </para></listitem>
197 </varlistentry>
198
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199 <varlistentry><term><option>Build-Profiles</option></term>
200 <listitem><para>
201 List of all build profiles enabled for build-dependency resolution,
202 without the "<literal>profile.</literal>" namespace prefix.
203 By default this list is empty. The <envar>DEB_BUILD_PROFILES</envar>
204 as used by &dpkg-buildpackage; overrides the list notation.
205 </para></listitem>
206 </varlistentry>
207
2b9b27c3 208 <varlistentry><term><option>Default-Release</option></term>
e1dd65c9 209 <listitem><para>Default release to install packages from if more than one
5723791e 210 version is available. Contains release name, codename or release version. Examples: 'stable', 'testing',
9feb98eb 211 'unstable', '&debian-stable-codename;', '&debian-testing-codename;', '4.0', '5.0*'. See also &apt-preferences;.</para></listitem>
60a8f9c0 212 </varlistentry>
45df0ad2 213
2b9b27c3 214 <varlistentry><term><option>Ignore-Hold</option></term>
5723791e 215 <listitem><para>Ignore held packages; this global option causes the problem resolver to
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216 ignore held packages in its decision making.</para></listitem>
217 </varlistentry>
218
2b9b27c3 219 <varlistentry><term><option>Clean-Installed</option></term>
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220 <listitem><para>Defaults to on. When turned on the autoclean feature will remove any packages
221 which can no longer be downloaded from the cache. If turned off then
222 packages that are locally installed are also excluded from cleaning - but
223 note that APT provides no direct means to reinstall them.</para></listitem>
224 </varlistentry>
225
2b9b27c3 226 <varlistentry><term><option>Immediate-Configure</option></term>
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227 <listitem><para>
228 Defaults to on, which will cause APT to install essential and important
229 packages as soon as possible in an install/upgrade operation, in order
230 to limit the effect of a failing &dpkg; call. If this option is
231 disabled, APT treats an important package in the same way as an extra
232 package: between the unpacking of the package A and its configuration
233 there can be many other unpack or configuration calls for other
234 unrelated packages B, C etc. If these cause the &dpkg; call to fail
235 (e.g. because package B's maintainer scripts generate an error), this
236 results in a system state in which package A is unpacked but
237 unconfigured - so any package depending on A is now no longer
238 guaranteed to work, as its dependency on A is no longer satisfied.
239 </para><para>
240 The immediate configuration marker is also applied in the potentially
241 problematic case of circular dependencies, since a dependency with the
242 immediate flag is equivalent to a Pre-Dependency. In theory this allows
243 APT to recognise a situation in which it is unable to perform immediate
244 configuration, abort, and suggest to the user that the option should be
245 temporarily deactivated in order to allow the operation to proceed.
246 Note the use of the word "theory" here; in the real world this problem
247 has rarely been encountered, in non-stable distribution versions, and
248 was caused by wrong dependencies of the package in question or by a
249 system in an already broken state; so you should not blindly disable
250 this option, as the scenario mentioned above is not the only problem it
251 can help to prevent in the first place.
252 </para><para>
253 Before a big operation like <literal>dist-upgrade</literal> is run
254 with this option disabled you should try to explicitly
255 <literal>install</literal> the package APT is unable to configure
256 immediately; but please make sure you also report your problem to your
257 distribution and to the APT team with the buglink below, so they can
258 work on improving or correcting the upgrade process.
259 </para></listitem>
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260 </varlistentry>
261
2b9b27c3 262 <varlistentry><term><option>Force-LoopBreak</option></term>
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263 <listitem><para>
264 Never enable this option unless you <emphasis>really</emphasis> know
265 what you are doing. It permits APT to temporarily remove an essential
266 package to break a Conflicts/Conflicts or Conflicts/Pre-Depends loop
267 between two essential packages. <emphasis>Such a loop should never exist
268 and is a grave bug</emphasis>. This option will work if the essential
269 packages are not <command>tar</command>, <command>gzip</command>,
270 <command>libc</command>, <command>dpkg</command>, <command>dash</command>
271 or anything that those packages depend on.
272 </para></listitem>
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273 </varlistentry>
274
2b9b27c3 275 <varlistentry><term><option>Cache-Start</option></term><term><option>Cache-Grow</option></term><term><option>Cache-Limit</option></term>
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276 <listitem><para>APT uses since version 0.7.26 a resizable memory mapped cache file to store the available
277 information. <literal>Cache-Start</literal> acts as a hint of the size the cache will grow to,
dcdf1ef1 278 and is therefore the amount of memory APT will request at startup. The default value is
5723791e 279 20971520 bytes (~20 MB). Note that this amount of space needs to be available for APT;
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280 otherwise it will likely fail ungracefully, so for memory restricted devices this value should
281 be lowered while on systems with a lot of configured sources it should be increased.
282 <literal>Cache-Grow</literal> defines in bytes with the default of 1048576 (~1 MB) how much
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283 the cache size will be increased in the event the space defined by <literal>Cache-Start</literal>
284 is not enough. This value will be applied again and again until either the cache is big
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285 enough to store all information or the size of the cache reaches the <literal>Cache-Limit</literal>.
286 The default of <literal>Cache-Limit</literal> is 0 which stands for no limit.
5723791e 287 If <literal>Cache-Grow</literal> is set to 0 the automatic growth of the cache is disabled.
dcdf1ef1 288 </para></listitem>
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289 </varlistentry>
290
2b9b27c3 291 <varlistentry><term><option>Build-Essential</option></term>
5723791e 292 <listitem><para>Defines which packages are considered essential build dependencies.</para></listitem>
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293 </varlistentry>
294
2b9b27c3 295 <varlistentry><term><option>Get</option></term>
5723791e 296 <listitem><para>The Get subsection controls the &apt-get; tool; please see its
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297 documentation for more information about the options here.</para></listitem>
298 </varlistentry>
299
2b9b27c3 300 <varlistentry><term><option>Cache</option></term>
5723791e 301 <listitem><para>The Cache subsection controls the &apt-cache; tool; please see its
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302 documentation for more information about the options here.</para></listitem>
303 </varlistentry>
304
2b9b27c3 305 <varlistentry><term><option>CDROM</option></term>
5723791e 306 <listitem><para>The CDROM subsection controls the &apt-cdrom; tool; please see its
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307 documentation for more information about the options here.</para></listitem>
308 </varlistentry>
309 </variablelist>
310 </refsect1>
311
312 <refsect1><title>The Acquire Group</title>
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313 <para>The <literal>Acquire</literal> group of options controls the
314 download of packages as well as the various "acquire methods" responsible
315 for the download itself (see also &sources-list;).</para>
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316
317 <variablelist>
2b9b27c3 318 <varlistentry><term><option>Check-Valid-Until</option></term>
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319 <listitem><para>
320 Security related option defaulting to true, as giving a Release file's
321 validation an expiration date prevents replay attacks over a long
322 timescale, and can also for example help users to identify mirrors
323 that are no longer updated - but the feature depends on the
324 correctness of the clock on the user system. Archive maintainers are
325 encouraged to create Release files with the
326 <literal>Valid-Until</literal> header, but if they don't or a
327 stricter value is desired the <literal>Max-ValidTime</literal>
328 option below can be used.
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329 The <option>Check-Valid-Until</option> option of &sources-list; entries should be
330 preferred to disable the check selectively instead of using this global override.
5723791e 331 </para></listitem>
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332 </varlistentry>
333
2b9b27c3 334 <varlistentry><term><option>Max-ValidTime</option></term>
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335 <listitem><para>Maximum time (in seconds) after its creation (as indicated
336 by the <literal>Date</literal> header) that the <filename>Release</filename>
337 file should be considered valid.
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338 If the Release file itself includes a <literal>Valid-Until</literal> header
339 the earlier date of the two is used as the expiration date.
5723791e 340 The default value is <literal>0</literal> which stands for "valid forever".
89500a25 341 Archive specific settings can be made by appending the label of the archive
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342 to the option name. Preferably, the same can be achieved for specific
343 &sources-list; entries by using the <option>Valid-Until-Max</option> option there.
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344 </para></listitem>
345 </varlistentry>
346
2b9b27c3 347 <varlistentry><term><option>Min-ValidTime</option></term>
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348 <listitem><para>Minimum time (in seconds) after its creation (as indicated
349 by the <literal>Date</literal> header) that the <filename>Release</filename>
350 file should be considered valid.
351 Use this if you need to use a seldom updated (local) mirror of a more
352 frequently updated archive with a <literal>Valid-Until</literal> header
2130caa8 353 instead of completely disabling the expiration date checking.
89500a25 354 Archive specific settings can and should be used by appending the label of
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355 the archive to the option name. Preferably, the same can be achieved for specific
356 &sources-list; entries by using the <option>Valid-Until-Min</option> option there.
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357 </para></listitem>
358 </varlistentry>
359
2b9b27c3 360 <varlistentry><term><option>PDiffs</option></term>
d82cdf73 361 <listitem><para>Try to download deltas called <literal>PDiffs</literal> for
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362 indexes (like <filename>Packages</filename> files) instead of
363 downloading whole ones. True by default. Preferably, this can be set
364 for specific &sources-list; entries or index files by using the
365 <option>PDiffs</option> option there.</para>
02dceb31 366 <para>Two sub-options to limit the use of PDiffs are also available:
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367 <literal>FileLimit</literal> can be used to specify a maximum number of
368 PDiff files should be downloaded to update a file. <literal>SizeLimit</literal>
f3b8d857 369 on the other hand is the maximum percentage of the size of all patches
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370 compared to the size of the targeted file. If one of these limits is
371 exceeded the complete file is downloaded instead of the patches.
372 </para></listitem>
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373 </varlistentry>
374
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375 <varlistentry><term><option>By-Hash</option></term>
376 <listitem><para>Try to download indexes via an URI constructed from a
377 hashsum of the expected file rather than downloaded via a well-known
378 stable filename. True by default, but automatically disabled if the
379 source indicates no support for it. Usage can be forced with the special
380 value "force". Preferably, this can be set for specific &sources-list; entries
381 or index files by using the <option>By-Hash</option> option there.
382 </para></listitem>
383 </varlistentry>
384
2b9b27c3 385 <varlistentry><term><option>Queue-Mode</option></term>
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386 <listitem><para>Queuing mode; <literal>Queue-Mode</literal> can be one of <literal>host</literal> or
387 <literal>access</literal> which determines how APT parallelizes outgoing
388 connections. <literal>host</literal> means that one connection per target host
389 will be opened, <literal>access</literal> means that one connection per URI type
390 will be opened.</para></listitem>
391 </varlistentry>
392
2b9b27c3 393 <varlistentry><term><option>Retries</option></term>
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394 <listitem><para>Number of retries to perform. If this is non-zero APT will retry failed
395 files the given number of times.</para></listitem>
396 </varlistentry>
397
2b9b27c3 398 <varlistentry><term><option>Source-Symlinks</option></term>
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399 <listitem><para>Use symlinks for source archives. If set to true then source archives will
400 be symlinked when possible instead of copying. True is the default.</para></listitem>
401 </varlistentry>
402
2b9b27c3 403 <varlistentry><term><option>http</option></term>
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404 <listitem><para><literal>http::Proxy</literal> sets the default proxy to use for HTTP
405 URIs. It is in the standard form of <literal>http://[[user][:pass]@]host[:port]/</literal>.
406 Per host proxies can also be specified by using the form
24f6490f 407 <literal>http::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal>
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408 meaning to use no proxies. If no one of the above settings is specified,
409 <envar>http_proxy</envar> environment variable
410 will be used.</para>
24f6490f 411
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412 <para>Three settings are provided for cache control with HTTP/1.1 compliant
413 proxy caches.
414 <literal>No-Cache</literal> tells the proxy not to use its cached
415 response under any circumstances.
416 <literal>Max-Age</literal> sets the allowed maximum age (in seconds) of
417 an index file in the cache of the proxy.
418 <literal>No-Store</literal> specifies that the proxy should not store
419 the requested archive files in its cache, which can be used to prevent
420 the proxy from polluting its cache with (big) .deb files.</para>
24f6490f 421
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422 <para>The option <literal>timeout</literal> sets the timeout timer used by the method;
423 this value applies to the connection as well as the data timeout.</para>
24f6490f 424
82214317 425 <para>The setting <literal>Acquire::http::Pipeline-Depth</literal> can be used to
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426 enable HTTP pipelining (RFC 2616 section 8.1.2.2) which can be beneficial e.g. on
427 high-latency connections. It specifies how many requests are sent in a pipeline.
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428 APT tries to detect and workaround misbehaving webservers and proxies at runtime, but
429 if you know that yours does not conform to the HTTP/1.1 specification pipelining can
430 be disabled by setting the value to 0. It is enabled by default with the value 10.</para>
5900bd8d 431
5723791e 432 <para><literal>Acquire::http::AllowRedirect</literal> controls whether APT will follow
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433 redirects, which is enabled by default.</para>
434
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435 <para>The used bandwidth can be limited with
436 <literal>Acquire::http::Dl-Limit</literal> which accepts integer
437 values in kilobytes per second. The default value is 0 which
438 deactivates the limit and tries to use all available bandwidth.
439 Note that this option implicitly disables downloading from
440 multiple servers at the same time.</para>
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441
442 <para><literal>Acquire::http::User-Agent</literal> can be used to set a different
443 User-Agent for the http download method as some proxies allow access for clients
444 only if the client uses a known identifier.</para>
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445
446 <para><literal>Acquire::http::Proxy-Auto-Detect</literal> can be used to
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447 specify an external command to discover the http proxy to use. The first
448 and only parameter is an URI denoting the host to be contacted to allow
449 for host-specific configuration. APT expects the command to output the
450 proxy on stdout as a single line in the style <literal>http://proxy:port/</literal>
451 or the word <literal>DIRECT</literal> if no proxy should be used. No output
452 indicates that the generic proxy settings should be used.
453
454 Note that auto-detection will not be used for a host if a host-specific proxy
455 configuration is already set via <literal>Acquire::http::Proxy::<replaceable>HOST</replaceable></literal>.
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456
457 See the &squid-deb-proxy-client; package for an example implementation that
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458 uses avahi.
459
460 This option takes precedence over the legacy option name
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461 <literal>ProxyAutoDetect</literal>.
462 </para>
c08cf1dc 463
4494239c 464 </listitem>
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465 </varlistentry>
466
2b9b27c3 467 <varlistentry><term><option>https</option></term>
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468 <listitem><para>
469 The <literal>Cache-control</literal>, <literal>Timeout</literal>,
470 <literal>AllowRedirect</literal>, <literal>Dl-Limit</literal> and
471 <literal>proxy</literal> options work for HTTPS URIs in the same way
472 as for the <literal>http</literal> method, and default to the same
473 values if they are not explicitly set. The
474 <literal>Pipeline-Depth</literal> option is not yet supported.
475 </para>
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476
477 <para><literal>CaInfo</literal> suboption specifies place of file that
478 holds info about trusted certificates.
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479 <literal>&lt;host&gt;::CaInfo</literal> is the corresponding per-host option.
480 <literal>Verify-Peer</literal> boolean suboption determines whether or not the
481 server's host certificate should be verified against trusted certificates.
482 <literal>&lt;host&gt;::Verify-Peer</literal> is the corresponding per-host option.
483 <literal>Verify-Host</literal> boolean suboption determines whether or not the
484 server's hostname should be verified.
485 <literal>&lt;host&gt;::Verify-Host</literal> is the corresponding per-host option.
370ad5e1 486 <literal>SslCert</literal> determines what certificate to use for client
5723791e 487 authentication. <literal>&lt;host&gt;::SslCert</literal> is the corresponding per-host option.
370ad5e1 488 <literal>SslKey</literal> determines what private key to use for client
5723791e 489 authentication. <literal>&lt;host&gt;::SslKey</literal> is the corresponding per-host option.
370ad5e1 490 <literal>SslForceVersion</literal> overrides default SSL version to use.
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491 It can contain either of the strings '<literal>TLSv1</literal>' or
492 '<literal>SSLv3</literal>'.
493 <literal>&lt;host&gt;::SslForceVersion</literal> is the corresponding per-host option.
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494 </para></listitem></varlistentry>
495
2b9b27c3 496 <varlistentry><term><option>ftp</option></term>
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497 <listitem><para>
498 <literal>ftp::Proxy</literal> sets the default proxy to use for FTP URIs.
499 It is in the standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal>.
500 Per host proxies can also be specified by using the form
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501 <literal>ftp::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal>
502 meaning to use no proxies. If no one of the above settings is specified,
503 <envar>ftp_proxy</envar> environment variable
5723791e 504 will be used. To use an FTP
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505 proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the
506 configuration file. This entry specifies the commands to send to tell
507 the proxy server what to connect to. Please see
508 &configureindex; for an example of
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509 how to do this. The substitution variables representing the corresponding
510 URI component are <literal>$(PROXY_USER)</literal>,
511 <literal>$(PROXY_PASS)</literal>, <literal>$(SITE_USER)</literal>,
512 <literal>$(SITE_PASS)</literal>, <literal>$(SITE)</literal> and
513 <literal>$(SITE_PORT)</literal>.</para>
24f6490f 514
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515 <para>The option <literal>timeout</literal> sets the timeout timer used by the method;
516 this value applies to the connection as well as the data timeout.</para>
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517
518 <para>Several settings are provided to control passive mode. Generally it is
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519 safe to leave passive mode on; it works in nearly every environment.
520 However, some situations require that passive mode be disabled and port
521 mode FTP used instead. This can be done globally or for connections that
522 go through a proxy or for a specific host (see the sample config file
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523 for examples).</para>
524
525 <para>It is possible to proxy FTP over HTTP by setting the <envar>ftp_proxy</envar>
5723791e 526 environment variable to an HTTP URL - see the discussion of the http method
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527 above for syntax. You cannot set this in the configuration file and it is
528 not recommended to use FTP over HTTP due to its low efficiency.</para>
529
530 <para>The setting <literal>ForceExtended</literal> controls the use of RFC2428
e3a1f08d 531 <literal>EPSV</literal> and <literal>EPRT</literal> commands. The default is false, which means
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532 these commands are only used if the control connection is IPv6. Setting this
533 to true forces their use even on IPv4 connections. Note that most FTP servers
534 do not support RFC2428.</para></listitem>
535 </varlistentry>
536
2b9b27c3 537 <varlistentry><term><option>cdrom</option></term>
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538 <listitem><para>
539 For URIs using the <literal>cdrom</literal> method, the only configurable
540 option is the mount point, <literal>cdrom::Mount</literal>, which must be
541 the mount point for the CD-ROM (or DVD, or whatever) drive as specified in
542 <filename>/etc/fstab</filename>. It is possible to provide alternate mount
543 and unmount commands if your mount point cannot be listed in the fstab.
544 The syntax is to put <literallayout>/cdrom/::Mount "foo";</literallayout> within
545 the <literal>cdrom</literal> block. It is important to have the trailing slash.
546 Unmount commands can be specified using UMount.
547 </para></listitem>
24f6490f 548 </varlistentry>
8a3642bd 549
2b9b27c3 550 <varlistentry><term><option>gpgv</option></term>
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551 <listitem><para>
552 For GPGV URIs the only configurable option is <literal>gpgv::Options</literal>,
553 which passes additional parameters to gpgv.
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554 </para></listitem>
555 </varlistentry>
556
2b9b27c3 557 <varlistentry><term><option>CompressionTypes</option></term>
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558 <listitem><para>List of compression types which are understood by the acquire methods.
559 Files like <filename>Packages</filename> can be available in various compression formats.
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560 By default the acquire methods can decompress and recompress many common formats like <command>xz</command> and
561 <command>gzip</command>; with this scope the supported formats can be queried, modified
562 as well as support for more formats added (see also <option>APT::Compressor</option>). The syntax for this is:
e85b4cd5 563 <synopsis>Acquire::CompressionTypes::<replaceable>FileExtension</replaceable> "<replaceable>Methodname</replaceable>";</synopsis>
5723791e 564 </para><para>Also, the <literal>Order</literal> subgroup can be used to define in which order
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565 the acquire system will try to download the compressed files. The acquire system will try the first
566 and proceed with the next compression type in this list on error, so to prefer one over the other type
124e6916 567 simply add the preferred type first - types not already added will be implicitly appended
8bd02d8b 568 to the end of the list, so e.g. <synopsis>Acquire::CompressionTypes::Order:: "gz";</synopsis> can
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569 be used to prefer <command>gzip</command> compressed files over all other compression formats.
570 If <command>xz</command> should be preferred over <command>gzip</command> and <command>bzip2</command> the
571 configure setting should look like this: <synopsis>Acquire::CompressionTypes::Order { "xz"; "gz"; };</synopsis>
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572 It is not needed to add <literal>bz2</literal> to the list explicitly as it will be added automatically.</para>
573 <para>Note that the
574 <literal>Dir::Bin::<replaceable>Methodname</replaceable></literal>
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575 will be checked at run time. If this option has been set and support for
576 this format isn't directly built into apt, the method will only be used if
577 this file exists; e.g. for the <literal>bzip2</literal> method (the
578 inbuilt) setting is: <literallayout>Dir::Bin::bzip2 "/bin/bzip2";</literallayout>
a9564741 579 Note also that list entries specified on the command line will be added at the end of the list
8bd02d8b 580 specified in the configuration files, but before the default entries. To prefer a type in this case
5d885723 581 over the ones specified in the configuration files you can set the option direct - not in list style.
5723791e 582 This will not override the defined list; it will only prefix the list with this type.</para>
5d885723 583 <para>The special type <literal>uncompressed</literal> can be used to give uncompressed files a
1fc8c922 584 preference, but note that most archives don't provide uncompressed files so this is mostly only
5d885723 585 useable for local mirrors.</para></listitem>
e85b4cd5 586 </varlistentry>
45df0ad2 587
2b9b27c3 588 <varlistentry><term><option>GzipIndexes</option></term>
c8c6e61b 589 <listitem><para>
590 When downloading <literal>gzip</literal> compressed indexes (Packages, Sources, or
591 Translations), keep them gzip compressed locally instead of unpacking
592 them. This saves quite a lot of disk space at the expense of more CPU
593 requirements when building the local package caches. False by default.
594 </para></listitem>
595 </varlistentry>
596
2b9b27c3 597 <varlistentry><term><option>Languages</option></term>
45df0ad2 598 <listitem><para>The Languages subsection controls which <filename>Translation</filename> files are downloaded
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599 and in which order APT tries to display the description-translations. APT will try to display the first
600 available description in the language which is listed first. Languages can be defined with their
601 short or long language codes. Note that not all archives provide <filename>Translation</filename>
602 files for every language - the long language codes are especially rare.</para>
45df0ad2 603 <para>The default list includes "environment" and "en". "<literal>environment</literal>" has a special meaning here:
5723791e 604 it will be replaced at runtime with the language codes extracted from the <literal>LC_MESSAGES</literal> environment variable.
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605 It will also ensure that these codes are not included twice in the list. If <literal>LC_MESSAGES</literal>
606 is set to "C" only the <filename>Translation-en</filename> file (if available) will be used.
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607 To force APT to use no Translation file use the setting <literal>Acquire::Languages=none</literal>. "<literal>none</literal>"
608 is another special meaning code which will stop the search for a suitable <filename>Translation</filename> file.
609 This tells APT to download these translations too, without actually
610 using them unless the environment specifies the languages. So the
611 following example configuration will result in the order "en, de" in an
612 English locale or "de, en" in a German one. Note that "fr" is
613 downloaded, but not used unless APT is used in a French locale (where
614 the order would be "fr, de, en").
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615 <programlisting>Acquire::Languages { "environment"; "de"; "en"; "none"; "fr"; };</programlisting></para>
616 <para>Note: To prevent problems resulting from APT being executed in different environments
617 (e.g. by different users or by other programs) all Translation files which are found in
618 <filename>/var/lib/apt/lists/</filename> will be added to the end of the list
619 (after an implicit "<literal>none</literal>").</para>
620 </listitem>
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621 </varlistentry>
622
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623 <varlistentry><term><option>ForceIPv4</option></term>
624 <listitem><para>
625 When downloading, force to use only the IPv4 protocol.
626 </para></listitem>
627 </varlistentry>
628
629 <varlistentry><term><option>ForceIPv6</option></term>
630 <listitem><para>
631 When downloading, force to use only the IPv6 protocol.
632 </para></listitem>
633 </varlistentry>
634
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635 <varlistentry><term><option>MaxReleaseFileSize</option></term>
636 <listitem><para>
637 The maximum file size of Release/Release.gpg/InRelease files.
638 The default is 10MB.
639 </para></listitem>
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640 </varlistentry>
641
c8ec5ab7 642 <varlistentry><term><option>EnableSrvRecords</option></term>
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643 <listitem><para>
644 This option controls if apt will use the DNS SRV server record
645 as specified in RFC 2782 to select an alternative server to
646 connect to.
647 The default is "true".
648 </para></listitem>
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649 </varlistentry>
650
651 <varlistentry><term><option>AllowInsecureRepositories</option></term>
652 <listitem><para>
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653 Allow update operations to load data files from
654 repositories without sufficient security information.
655 The default value is "<literal>false</literal>".
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656 Concept, implications as well as alternatives are detailed in &apt-secure;.
657 </para></listitem>
658 </varlistentry>
659
660 <varlistentry><term><option>AllowWeakRepositories</option></term>
661 <listitem><para>
662 Allow update operations to load data files from
663 repositories which provide security information, but these
664 are deemed no longer cryptographically strong enough.
665 The default value is "<literal>false</literal>".
666 Concept, implications as well as alternatives are detailed in &apt-secure;.
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667 </para></listitem>
668 </varlistentry>
669
670 <varlistentry><term><option>AllowDowngradeToInsecureRepositories</option></term>
671 <listitem><para>
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672 Allow that a repository that was previously gpg signed to become
673 unsigned during an update operation. When there is no valid signature
674 for a previously trusted repository apt will refuse the update. This
675 option can be used to override this protection. You almost certainly
676 never want to enable this. The default is <literal>false</literal>.
d03b947b 677 Concept, implications as well as alternatives are detailed in &apt-secure;.
952ee63b 678 </para></listitem>
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679 </varlistentry>
680
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681 <varlistentry><term><option>Changelogs::URI</option> scope</term>
682 <listitem><para>
683 Acquiring changelogs can only be done if an URI is known from where to get them.
684 Preferable the Release file indicates this in a 'Changelogs' field. If this isn't
685 available the Label/Origin field of the Release file is used to check if a
686 <literal>Acquire::Changelogs::URI::Label::<replaceable>LABEL</replaceable></literal> or
687 <literal>Acquire::Changelogs::URI::Origin::<replaceable>ORIGIN</replaceable></literal> option
688 exists and if so this value is taken. The value in the Release file can be overridden
689 with <literal>Acquire::Changelogs::URI::Override::Label::<replaceable>LABEL</replaceable></literal>
690 or <literal>Acquire::Changelogs::URI::Override::Origin::<replaceable>ORIGIN</replaceable></literal>.
691
2ffd3535 692 The value should be a normal URI to a text file, except that package specific data is
430481e7 693 replaced with the placeholder <literal>@CHANGEPATH@</literal>. The
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694 value for it is: 1. if the package is from a component (e.g. <literal>main</literal>)
695 this is the first part otherwise it is omitted, 2. the first letter of source package name,
2ffd3535 696 except if the source package name starts with '<literal>lib</literal>' in which case it will
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697 be the first four letters. 3. The complete source package name. 4. the complete name again and
698 5. the source version.
699 The first (if present), second, third and fourth part are separated by a slash ('<literal>/</literal>')
700 and between the fourth and fifth part is an underscore ('<literal>_</literal>').
701
702 The special value '<literal>no</literal>' is available for this option indicating that
703 this source can't be used to acquire changelog files from. Another source will be tried
704 if available in this case.
705 </para></listitem>
706 </varlistentry>
707
24f6490f 708 </variablelist>
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709 </refsect1>
710
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711 <refsect1><title>Binary specific configuration</title>
712 <para>Especially with the introduction of the <command>apt</command> binary
713 it can be useful to set certain options only for a specific binary as
714 even options which look like they would effect only a certain binary like
715 <option>APT::Get::Show-Versions</option> effect
716 <command>apt-get</command> as well as <command>apt</command>.
717 </para>
718 <para>Setting an option for a specific binary only can be achieved by
719 setting the option inside the
720 <option>Binary::<replaceable>specific-binary</replaceable></option>
721 scope. Setting the option <option>APT::Get::Show-Versions</option> for
722 the <command>apt</command> only can e.g. by done by setting
723 <option>Binary::apt::APT::Get::Show-Versions</option> instead.</para>
724 <para>Note that as seen in the DESCRIPTION section further above you can't
725 set binary-specific options on the commandline itself nor in
726 configuration files loaded via the commandline.</para>
727 </refsect1>
728
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729 <refsect1><title>Directories</title>
730
731 <para>The <literal>Dir::State</literal> section has directories that pertain to local
732 state information. <literal>lists</literal> is the directory to place downloaded
5723791e 733 package lists in and <literal>status</literal> is the name of the &dpkg; status file.
c086ac18 734 <literal>preferences</literal> is the name of the APT <filename>preferences</filename> file.
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735 <literal>Dir::State</literal> contains the default directory to prefix on all
736 sub-items if they do not start with <filename>/</filename> or <filename>./</filename>.</para>
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737
738 <para><literal>Dir::Cache</literal> contains locations pertaining to local cache
739 information, such as the two package caches <literal>srcpkgcache</literal> and
740 <literal>pkgcache</literal> as well as the location to place downloaded archives,
741 <literal>Dir::Cache::archives</literal>. Generation of caches can be turned off
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742 by setting <literal>pkgcache</literal> or <literal>srcpkgcache</literal> to
743 <literal>""</literal>. This will slow down startup but save disk space. It
744 is probably preferable to turn off the pkgcache rather than the srcpkgcache.
745 Like <literal>Dir::State</literal> the default directory is contained in
746 <literal>Dir::Cache</literal></para>
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747
748 <para><literal>Dir::Etc</literal> contains the location of configuration files,
749 <literal>sourcelist</literal> gives the location of the sourcelist and
750 <literal>main</literal> is the default configuration file (setting has no effect,
751 unless it is done from the config file specified by
13e8426f 752 <envar>APT_CONFIG</envar>).</para>
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753
754 <para>The <literal>Dir::Parts</literal> setting reads in all the config fragments in
755 lexical order from the directory specified. After this is done then the
756 main config file is loaded.</para>
757
758 <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal>
759 specifies the location of the method handlers and <literal>gzip</literal>,
e85b4cd5 760 <literal>bzip2</literal>, <literal>lzma</literal>,
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761 <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal>
762 <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
763 of the respective programs.</para>
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764
765 <para>
766 The configuration item <literal>RootDir</literal> has a special
35bf76cf 767 meaning. If set, all paths will be
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768 relative to <literal>RootDir</literal>, <emphasis>even paths that
769 are specified absolutely</emphasis>. So, for instance, if
770 <literal>RootDir</literal> is set to
771 <filename>/tmp/staging</filename> and
772 <literal>Dir::State::status</literal> is set to
773 <filename>/var/lib/dpkg/status</filename>, then the status file
774 will be looked up in
775 <filename>/tmp/staging/var/lib/dpkg/status</filename>.
35bf76cf 776 If you want to prefix only relative paths, set <literal>Dir</literal> instead.
db2cca11 777 </para>
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778
779 <para>
780 The <literal>Ignore-Files-Silently</literal> list can be used to specify
781 which files APT should silently ignore while parsing the files in the
782 fragment directories. Per default a file which end with <literal>.disabled</literal>,
783 <literal>~</literal>, <literal>.bak</literal> or <literal>.dpkg-[a-z]+</literal>
784 is silently ignored. As seen in the last default value these patterns can use regular
785 expression syntax.
786 </para>
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787 </refsect1>
788
789 <refsect1><title>APT in DSelect</title>
790 <para>
791 When APT is used as a &dselect; method several configuration directives
5723791e 792 control the default behavior. These are in the <literal>DSelect</literal> section.</para>
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793
794 <variablelist>
2b9b27c3 795 <varlistentry><term><option>Clean</option></term>
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796 <listitem><para>Cache Clean mode; this value may be one of
797 <literal>always</literal>, <literal>prompt</literal>,
798 <literal>auto</literal>, <literal>pre-auto</literal> and
799 <literal>never</literal>.
800 <literal>always</literal> and <literal>prompt</literal> will remove
801 all packages from the cache after upgrading, <literal>prompt</literal>
802 (the default) does so conditionally.
803 <literal>auto</literal> removes only those packages which are no longer
804 downloadable (replaced with a new version for instance).
805 <literal>pre-auto</literal> performs this action before downloading
806 new packages.</para></listitem>
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807 </varlistentry>
808
2b9b27c3 809 <varlistentry><term><option>options</option></term>
5723791e 810 <listitem><para>The contents of this variable are passed to &apt-get; as command line
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811 options when it is run for the install phase.</para></listitem>
812 </varlistentry>
813
2b9b27c3 814 <varlistentry><term><option>Updateoptions</option></term>
5723791e 815 <listitem><para>The contents of this variable are passed to &apt-get; as command line
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816 options when it is run for the update phase.</para></listitem>
817 </varlistentry>
818
2b9b27c3 819 <varlistentry><term><option>PromptAfterUpdate</option></term>
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820 <listitem><para>If true the [U]pdate operation in &dselect; will always prompt to continue.
821 The default is to prompt only on error.</para></listitem>
822 </varlistentry>
823 </variablelist>
824 </refsect1>
825
5723791e 826 <refsect1><title>How APT calls &dpkg;</title>
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827 <para>Several configuration directives control how APT invokes &dpkg;. These are
828 in the <literal>DPkg</literal> section.</para>
829
830 <variablelist>
2b9b27c3 831 <varlistentry><term><option>options</option></term>
5723791e 832 <listitem><para>This is a list of options to pass to &dpkg;. The options must be specified
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833 using the list notation and each list item is passed as a single argument
834 to &dpkg;.</para></listitem>
835 </varlistentry>
836
2b9b27c3 837 <varlistentry><term><option>Pre-Invoke</option></term><term><option>Post-Invoke</option></term>
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838 <listitem><para>This is a list of shell commands to run before/after invoking &dpkg;.
839 Like <literal>options</literal> this must be specified in list notation. The
5723791e 840 commands are invoked in order using <filename>/bin/sh</filename>; should any
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841 fail APT will abort.</para></listitem>
842 </varlistentry>
843
2b9b27c3 844 <varlistentry><term><option>Pre-Install-Pkgs</option></term>
5723791e 845 <listitem><para>This is a list of shell commands to run before invoking &dpkg;. Like
24f6490f 846 <literal>options</literal> this must be specified in list notation. The commands
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847 are invoked in order using <filename>/bin/sh</filename>; should any fail APT
848 will abort. APT will pass the filenames of all .deb files it is going to
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849 install to the commands, one per line on the requested file descriptor, defaulting
850 to standard input.</para>
24f6490f 851
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852 <para>Version 2 of this protocol sends more information through the requested
853 file descriptor: a line with the text <literal>VERSION 2</literal>,
854 the APT configuration space, and a list of package actions with filename
855 and version information.</para>
856
857 <para>Each configuration directive line has the form
858 <literal>key=value</literal>. Special characters (equal signs, newlines,
859 nonprintable characters, quotation marks, and percent signs in
860 <literal>key</literal> and newlines, nonprintable characters, and percent
861 signs in <literal>value</literal>) are %-encoded. Lists are represented
862 by multiple <literal>key::=value</literal> lines with the same key. The
863 configuration section ends with a blank line.</para>
864
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865 <para>Package action lines consist of five fields in Version 2: package
866 name (without architecture qualification even if foreign), old version,
867 direction of version change (&lt; for upgrades, &gt; for downgrades, = for
868 no change), new version, action. The version fields are "-" for no version
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869 at all (for example when installing a package for the first time; no
870 version is treated as earlier than any real version, so that is an
871 upgrade, indicated as <literal>- &lt; 1.23.4</literal>). The action field
872 is "**CONFIGURE**" if the package is being configured, "**REMOVE**" if it
873 is being removed, or the filename of a .deb file if it is being
874 unpacked.</para>
875
876 <para>In Version 3 after each version field follows the architecture
877 of this version, which is "-" if there is no version, and a field showing
2ffd3535 878 the MultiArch type "same", "foreign", "allowed" or "none". Note that "none"
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879 is an incorrect typename which is just kept to remain compatible, it
880 should be read as "no" and users are encouraged to support both.</para>
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881
882 <para>The version of the protocol to be used for the command
883 <literal><replaceable>cmd</replaceable></literal> can be chosen by setting
884 <literal>DPkg::Tools::options::<replaceable>cmd</replaceable>::Version</literal>
885 accordingly, the default being version 1. If APT isn't supporting the requested
886 version it will send the information in the highest version it has support for instead.
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887 </para>
888
889 <para>The file descriptor to be used to send the information can be requested with
890 <literal>DPkg::Tools::options::<replaceable>cmd</replaceable>::InfoFD</literal>
891 which defaults to <literal>0</literal> for standard input and is available since
892 version 0.9.11. Support for the option can be detected by looking for the environment
893 variable <envar>APT_HOOK_INFO_FD</envar> which contains the number of the used
894 file descriptor as a confirmation.</para>
895 </listitem>
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896 </varlistentry>
897
2b9b27c3 898 <varlistentry><term><option>Run-Directory</option></term>
5723791e 899 <listitem><para>APT chdirs to this directory before invoking &dpkg;, the default is
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900 <filename>/</filename>.</para></listitem>
901 </varlistentry>
902
2b9b27c3 903 <varlistentry><term><option>Build-options</option></term>
5723791e 904 <listitem><para>These options are passed to &dpkg-buildpackage; when compiling packages;
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905 the default is to disable signing and produce all binaries.</para></listitem>
906 </varlistentry>
3e9c4f70 907
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908 <varlistentry><term><option>DPkg::ConfigurePending</option></term>
909 <listitem><para>If this option is set APT will call <command>dpkg --configure --pending</command>
910 to let &dpkg; handle all required configurations and triggers. This option is activated by default,
911 but deactivating it could be useful if you want to run APT multiple times in a row - e.g. in an installer.
912 In this scenario you could deactivate this option in all but the last run.</para></listitem>
913 </varlistentry>
914 </variablelist>
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915 </refsect1>
916
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917 <refsect1>
918 <title>Periodic and Archives options</title>
919 <para><literal>APT::Periodic</literal> and <literal>APT::Archives</literal>
920 groups of options configure behavior of apt periodic updates, which is
6289f5d7 921 done by the <literal>/usr/lib/apt/apt.systemd.daily</literal> script. See the top of
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922 this script for the brief documentation of these options.
923 </para>
924 </refsect1>
925
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926 <refsect1>
927 <title>Debug options</title>
928 <para>
929 Enabling options in the <literal>Debug::</literal> section will
930 cause debugging information to be sent to the standard error
931 stream of the program utilizing the <literal>apt</literal>
932 libraries, or enable special program modes that are primarily
933 useful for debugging the behavior of <literal>apt</literal>.
934 Most of these options are not interesting to a normal user, but a
935 few may be:
936
937 <itemizedlist>
938 <listitem>
939 <para>
940 <literal>Debug::pkgProblemResolver</literal> enables output
941 about the decisions made by
942 <literal>dist-upgrade, upgrade, install, remove, purge</literal>.
943 </para>
944 </listitem>
945
946 <listitem>
947 <para>
948 <literal>Debug::NoLocking</literal> disables all file
949 locking. This can be used to run some operations (for
950 instance, <literal>apt-get -s install</literal>) as a
951 non-root user.
952 </para>
953 </listitem>
954
955 <listitem>
956 <para>
957 <literal>Debug::pkgDPkgPM</literal> prints out the actual
958 command line each time that <literal>apt</literal> invokes
959 &dpkg;.
960 </para>
961 </listitem>
962
963 <listitem>
964 <para>
965 <literal>Debug::IdentCdrom</literal> disables the inclusion
25838be6 966 of statfs data in CD-ROM IDs. <!-- TODO: provide a
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967 motivating example, except I haven't a clue why you'd want
968 to do this. -->
969 </para>
970 </listitem>
971 </itemizedlist>
8a3642bd 972 </para>
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973
974 <para>
975 A full list of debugging options to apt follows.
976 </para>
977
978 <variablelist>
979 <varlistentry>
2b9b27c3 980 <term><option>Debug::Acquire::cdrom</option></term>
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981
982 <listitem>
983 <para>
984 Print information related to accessing
985 <literal>cdrom://</literal> sources.
986 </para>
987 </listitem>
988 </varlistentry>
989
990 <varlistentry>
2b9b27c3 991 <term><option>Debug::Acquire::ftp</option></term>
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992
993 <listitem>
994 <para>
995 Print information related to downloading packages using
996 FTP.
997 </para>
998 </listitem>
999 </varlistentry>
1000
1001 <varlistentry>
2b9b27c3 1002 <term><option>Debug::Acquire::http</option></term>
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1003
1004 <listitem>
1005 <para>
1006 Print information related to downloading packages using
1007 HTTP.
1008 </para>
1009 </listitem>
1010 </varlistentry>
1011
1012 <varlistentry>
2b9b27c3 1013 <term><option>Debug::Acquire::https</option></term>
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1014
1015 <listitem>
1016 <para>
1017 Print information related to downloading packages using
1018 HTTPS.
1019 </para>
1020 </listitem>
1021 </varlistentry>
1022
1023 <varlistentry>
2b9b27c3 1024 <term><option>Debug::Acquire::gpgv</option></term>
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1025
1026 <listitem>
1027 <para>
1028 Print information related to verifying cryptographic
1029 signatures using <literal>gpg</literal>.
1030 </para>
1031 </listitem>
1032 </varlistentry>
1033
1034 <varlistentry>
2b9b27c3 1035 <term><option>Debug::aptcdrom</option></term>
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1036
1037 <listitem>
1038 <para>
1039 Output information about the process of accessing
1040 collections of packages stored on CD-ROMs.
1041 </para>
1042 </listitem>
1043 </varlistentry>
1044
1045 <varlistentry>
2b9b27c3 1046 <term><option>Debug::BuildDeps</option></term>
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1047 <listitem>
1048 <para>
1049 Describes the process of resolving build-dependencies in
1050 &apt-get;.
1051 </para>
1052 </listitem>
1053 </varlistentry>
1054
1055 <varlistentry>
2b9b27c3 1056 <term><option>Debug::Hashes</option></term>
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1057 <listitem>
1058 <para>
1059 Output each cryptographic hash that is generated by the
1060 <literal>apt</literal> libraries.
1061 </para>
1062 </listitem>
1063 </varlistentry>
1064
1065 <varlistentry>
2b9b27c3 1066 <term><option>Debug::IdentCDROM</option></term>
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1067 <listitem>
1068 <para>
1069 Do not include information from <literal>statfs</literal>,
1070 namely the number of used and free blocks on the CD-ROM
1071 filesystem, when generating an ID for a CD-ROM.
1072 </para>
1073 </listitem>
1074 </varlistentry>
1075
1076 <varlistentry>
2b9b27c3 1077 <term><option>Debug::NoLocking</option></term>
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1078 <listitem>
1079 <para>
1080 Disable all file locking. For instance, this will allow
1081 two instances of <quote><literal>apt-get
1082 update</literal></quote> to run at the same time.
1083 </para>
1084 </listitem>
1085 </varlistentry>
1086
1087 <varlistentry>
2b9b27c3 1088 <term><option>Debug::pkgAcquire</option></term>
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1089
1090 <listitem>
1091 <para>
1092 Log when items are added to or removed from the global
1093 download queue.
1094 </para>
1095 </listitem>
1096 </varlistentry>
1097
1098 <varlistentry>
2b9b27c3 1099 <term><option>Debug::pkgAcquire::Auth</option></term>
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1100 <listitem>
1101 <para>
1102 Output status messages and errors related to verifying
1103 checksums and cryptographic signatures of downloaded files.
1104 </para>
1105 </listitem>
1106 </varlistentry>
1107
1108 <varlistentry>
2b9b27c3 1109 <term><option>Debug::pkgAcquire::Diffs</option></term>
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1110 <listitem>
1111 <para>
1112 Output information about downloading and applying package
1113 index list diffs, and errors relating to package index list
1114 diffs.
1115 </para>
1116 </listitem>
1117 </varlistentry>
1118
1119 <varlistentry>
2b9b27c3 1120 <term><option>Debug::pkgAcquire::RRed</option></term>
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1121
1122 <listitem>
1123 <para>
1124 Output information related to patching apt package lists
1125 when downloading index diffs instead of full indices.
1126 </para>
1127 </listitem>
1128 </varlistentry>
1129
1130 <varlistentry>
2b9b27c3 1131 <term><option>Debug::pkgAcquire::Worker</option></term>
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1132
1133 <listitem>
1134 <para>
1135 Log all interactions with the sub-processes that actually
1136 perform downloads.
1137 </para>
1138 </listitem>
1139 </varlistentry>
1140
1141 <varlistentry>
2b9b27c3 1142 <term><option>Debug::pkgAutoRemove</option></term>
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1143
1144 <listitem>
1145 <para>
1146 Log events related to the automatically-installed status of
1147 packages and to the removal of unused packages.
1148 </para>
1149 </listitem>
1150 </varlistentry>
1151
1152 <varlistentry>
2b9b27c3 1153 <term><option>Debug::pkgDepCache::AutoInstall</option></term>
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1154 <listitem>
1155 <para>
1156 Generate debug messages describing which packages are being
1157 automatically installed to resolve dependencies. This
1158 corresponds to the initial auto-install pass performed in,
1159 e.g., <literal>apt-get install</literal>, and not to the
1160 full <literal>apt</literal> dependency resolver; see
1161 <literal>Debug::pkgProblemResolver</literal> for that.
1162 </para>
1163 </listitem>
1164 </varlistentry>
1165
af29ffb4 1166 <varlistentry>
2b9b27c3 1167 <term><option>Debug::pkgDepCache::Marker</option></term>
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1168 <listitem>
1169 <para>
5723791e 1170 Generate debug messages describing which packages are marked
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1171 as keep/install/remove while the ProblemResolver does his work.
1172 Each addition or deletion may trigger additional actions;
5723791e 1173 they are shown indented two additional spaces under the original entry.
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1174 The format for each line is <literal>MarkKeep</literal>,
1175 <literal>MarkDelete</literal> or <literal>MarkInstall</literal> followed by
1176 <literal>package-name &lt;a.b.c -&gt; d.e.f | x.y.z&gt; (section)</literal>
1177 where <literal>a.b.c</literal> is the current version of the package,
1178 <literal>d.e.f</literal> is the version considered for installation and
1179 <literal>x.y.z</literal> is a newer version, but not considered for installation
1180 (because of a low pin score). The later two can be omitted if there is none or if
5723791e 1181 it is the same as the installed version.
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1182 <literal>section</literal> is the name of the section the package appears in.
1183 </para>
1184 </listitem>
1185 </varlistentry>
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1186
1187 <varlistentry>
2b9b27c3 1188 <term><option>Debug::pkgDPkgPM</option></term>
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1189 <listitem>
1190 <para>
1191 When invoking &dpkg;, output the precise command line with
1192 which it is being invoked, with arguments separated by a
1193 single space character.
1194 </para>
1195 </listitem>
1196 </varlistentry>
1197
1198 <varlistentry>
2b9b27c3 1199 <term><option>Debug::pkgDPkgProgressReporting</option></term>
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1200 <listitem>
1201 <para>
1202 Output all the data received from &dpkg; on the status file
1203 descriptor and any errors encountered while parsing it.
1204 </para>
1205 </listitem>
1206 </varlistentry>
1207
1208 <varlistentry>
2b9b27c3 1209 <term><option>Debug::pkgOrderList</option></term>
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1210
1211 <listitem>
1212 <para>
1213 Generate a trace of the algorithm that decides the order in
1214 which <literal>apt</literal> should pass packages to
1215 &dpkg;.
1216 </para>
1217 </listitem>
1218 </varlistentry>
1219
1220 <varlistentry>
2b9b27c3 1221 <term><option>Debug::pkgPackageManager</option></term>
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1222
1223 <listitem>
1224 <para>
1225 Output status messages tracing the steps performed when
1226 invoking &dpkg;.
1227 </para>
1228 </listitem>
1229 </varlistentry>
1230
1231 <varlistentry>
2b9b27c3 1232 <term><option>Debug::pkgPolicy</option></term>
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1233
1234 <listitem>
1235 <para>
1236 Output the priority of each package list on startup.
1237 </para>
1238 </listitem>
1239 </varlistentry>
1240
1241 <varlistentry>
2b9b27c3 1242 <term><option>Debug::pkgProblemResolver</option></term>
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1243
1244 <listitem>
1245 <para>
1246 Trace the execution of the dependency resolver (this
1247 applies only to what happens when a complex dependency
1248 problem is encountered).
1249 </para>
1250 </listitem>
1251 </varlistentry>
1252
8b4894fe 1253 <varlistentry>
2b9b27c3 1254 <term><option>Debug::pkgProblemResolver::ShowScores</option></term>
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1255 <listitem>
1256 <para>
1257 Display a list of all installed packages with their calculated score
1258 used by the pkgProblemResolver. The description of the package
1259 is the same as described in <literal>Debug::pkgDepCache::Marker</literal>
1260 </para>
1261 </listitem>
1262 </varlistentry>
1263
be1b8568 1264 <varlistentry>
2b9b27c3 1265 <term><option>Debug::sourceList</option></term>
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1266
1267 <listitem>
1268 <para>
1269 Print information about the vendors read from
1270 <filename>/etc/apt/vendors.list</filename>.
1271 </para>
1272 </listitem>
1273 </varlistentry>
1274
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1275 <varlistentry>
1276 <term><option>Debug::RunScripts</option></term>
1277 <listitem>
1278 <para>
1279 Display the external commands that are called by apt hooks.
1280 This includes e.g. the config options
1281 <literal>DPkg::{Pre,Post}-Invoke</literal> or
1282 <literal>APT::Update::{Pre,Post}-Invoke</literal>.
1283 </para>
1284 </listitem>
1285 </varlistentry>
1286
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1287<!-- 2009/07/11 Currently used nowhere. The corresponding code
1288is commented.
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1289 <varlistentry>
1290 <term><literal>Debug::Vendor</literal></term>
1291
1292 <listitem>
1293 <para>
1294 Print information about each vendor.
1295 </para>
1296 </listitem>
1297 </varlistentry>
d82cdf73 1298-->
45df0ad2 1299
be1b8568 1300 </variablelist>
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1301 </refsect1>
1302
1303 <refsect1><title>Examples</title>
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1304 <para>&configureindex; is a
1305 configuration file showing example values for all possible
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1306 options.</para>
1307 </refsect1>
1308
1309 <refsect1><title>Files</title>
6e2525a1 1310 <variablelist>
1221c3a3 1311 &file-aptconf;
6e2525a1 1312 </variablelist>
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1313 </refsect1>
1314
1315 <refsect1><title>See Also</title>
1316 <para>&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.</para>
1317 </refsect1>
1318
1319 &manbugs;
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1320
1321</refentry>
1322