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1 <?xml version="1.0" encoding="utf-8" standalone="no"?>
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
4 <!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
5 <!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
6 <!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
7 ]>
8
9 <refentry>
10
11 <refentryinfo>
12 &apt-author.jgunthorpe;
13 &apt-author.team;
14 <author>
15 &apt-name.dburrows;
16 <contrib>Initial documentation of Debug::*.</contrib>
17 <email>dburrows@debian.org</email>
18 </author>
19 &apt-email;
20 &apt-product;
21 <!-- The last update date -->
22 <date>2012-06-09T00:00:00Z</date>
23 </refentryinfo>
24
25 <refmeta>
26 <refentrytitle>apt.conf</refentrytitle>
27 <manvolnum>5</manvolnum>
28 <refmiscinfo class="manual">APT</refmiscinfo>
29 </refmeta>
30
31 <!-- Man page title -->
32 <refnamediv>
33 <refname>apt.conf</refname>
34 <refpurpose>Configuration file for APT</refpurpose>
35 </refnamediv>
36
37 <refsect1><title>Description</title>
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
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
49 alphanumeric ascending order which have either no or "<literal>conf</literal>"
50 as filename extension and which only contain alphanumeric,
51 hyphen (-), underscore (_) and period (.) characters.
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>
54 configuration list - in which case it will be silently ignored.</para></listitem>
55 <listitem><para>the main configuration file specified by
56 <literal>Dir::Etc::main</literal></para></listitem>
57 <listitem><para>the command line options are applied to override the
58 configuration directives or to load even more configuration files.</para></listitem>
59 </orderedlist>
60 </refsect1>
61 <refsect1><title>Syntax</title>
62 <para>The configuration file is organized in a tree with options organized into
63 functional groups. Option specification is given with a double colon
64 notation; for instance <literal>APT::Get::Assume-Yes</literal> is an option within
65 the APT tool group, for the Get tool. Options do not inherit from their
66 parent groups.</para>
67
68 <para>Syntactically the configuration language is modeled after what the ISC tools
69 such as bind and dhcp use. Lines starting with
70 <literal>//</literal> are treated as comments (ignored), as well as all text
71 between <literal>/*</literal> and <literal>*/</literal>, just like C/C++ comments.
72 Each line is of the form
73 <literal>APT::Get::Assume-Yes "true";</literal>.
74 The quotation marks and trailing semicolon are required.
75 The value must be on one line, and there is no kind of string concatenation.
76 Values must not include backslashes or extra quotation marks.
77 Option names are made up of alphanumeric characters and the characters "/-:._+".
78 A new scope can be opened with curly braces, like this:</para>
79
80 <informalexample><programlisting>
81 APT {
82 Get {
83 Assume-Yes "true";
84 Fix-Broken "true";
85 };
86 };
87 </programlisting></informalexample>
88
89 <para>with newlines placed to make it more readable. Lists can be created by
90 opening a scope and including a single string enclosed in quotes followed by a
91 semicolon. Multiple entries can be included, separated by a semicolon.</para>
92
93 <informalexample><programlisting>
94 DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
95 </programlisting></informalexample>
96
97 <para>In general the sample configuration file &configureindex;
98 is a good guide for how it should look.</para>
99
100 <para>Case is not significant in names of configuration items, so in the
101 previous example you could use <literal>dpkg::pre-install-pkgs</literal>.</para>
102
103 <para>Names for the configuration items are optional if a list is defined as can be seen in
104 the <literal>DPkg::Pre-Install-Pkgs</literal> example above. If you don't specify a name a
105 new entry will simply add a new option to the list. If you specify a name you can override
106 the option in the same way as any other option by reassigning a new value to the option.</para>
107
108 <para>Two special commands are defined: <literal>#include</literal> (which is
109 deprecated and not supported by alternative implementations) and
110 <literal>#clear</literal>. <literal>#include</literal> will include the
111 given file, unless the filename ends in a slash, in which case the whole
112 directory is included.
113 <literal>#clear</literal> is used to erase a part of the configuration tree. The
114 specified element and all its descendants are erased.
115 (Note that these lines also need to end with a semicolon.)</para>
116
117 <para>
118 The <literal>#clear</literal> command is the only way to delete a list or
119 a complete scope. Reopening a scope (or using the syntax described below
120 with an appended <literal>::</literal>) will <emphasis>not</emphasis>
121 override previously written entries. Options can only be overridden by
122 addressing a new value to them - lists and scopes can't be overridden,
123 only cleared.
124 </para>
125
126 <para>All of the APT tools take an -o option which allows an arbitrary configuration
127 directive to be specified on the command line. The syntax is a full option
128 name (<literal>APT::Get::Assume-Yes</literal> for instance) followed by an equals
129 sign then the new value of the option. To append a new element to a list, add a
130 trailing <literal>::</literal> to the name of the list.
131 (As you might suspect, the scope syntax can't be used on the command line.)</para>
132
133 <para>
134 Note that appending items to a list using <literal>::</literal> only works
135 for one item per line, and that you should not use it in combination with
136 the scope syntax (which adds <literal>::</literal> implicitly). Using both
137 syntaxes together will trigger a bug which some users unfortunately depend
138 on: an option with the unusual name "<literal>::</literal>" which acts
139 like every other option with a name. This introduces many problems; for
140 one thing, users who write multiple lines in this
141 <emphasis>wrong</emphasis> syntax in the hope of appending to a list will
142 achieve the opposite, as only the last assignment for this option
143 "<literal>::</literal>" will be used. Future versions of APT will raise
144 errors and stop working if they encounter this misuse, so please correct
145 such statements now while APT doesn't explicitly complain about them.
146 </para>
147 </refsect1>
148
149 <refsect1><title>The APT Group</title>
150 <para>This group of options controls general APT behavior as well as holding the
151 options for all of the tools.</para>
152
153 <variablelist>
154 <varlistentry><term><option>Architecture</option></term>
155 <listitem><para>System Architecture; sets the architecture to use when fetching files and
156 parsing package lists. The internal default is the architecture apt was
157 compiled for.</para></listitem>
158 </varlistentry>
159
160 <varlistentry><term><option>Architectures</option></term>
161 <listitem><para>
162 All Architectures the system supports. For instance, CPUs implementing
163 the <literal>amd64</literal> (also called <literal>x86-64</literal>)
164 instruction set are also able to execute binaries compiled for the
165 <literal>i386</literal> (<literal>x86</literal>) instruction set. This
166 list is used when fetching files and parsing package lists. The
167 initial default is always the system's native architecture
168 (<literal>APT::Architecture</literal>), and foreign architectures are
169 added to the default list when they are registered via
170 <command>dpkg --add-architecture</command>.
171 </para></listitem>
172 </varlistentry>
173
174 <varlistentry><term><option>Build-Profiles</option></term>
175 <listitem><para>
176 List of all build profiles enabled for build-dependency resolution,
177 without the "<literal>profile.</literal>" namespace prefix.
178 By default this list is empty. The <envar>DEB_BUILD_PROFILES</envar>
179 as used by &dpkg-buildpackage; overrides the list notation.
180 </para></listitem>
181 </varlistentry>
182
183 <varlistentry><term><option>Default-Release</option></term>
184 <listitem><para>Default release to install packages from if more than one
185 version is available. Contains release name, codename or release version. Examples: 'stable', 'testing',
186 'unstable', '&stable-codename;', '&testing-codename;', '4.0', '5.0*'. See also &apt-preferences;.</para></listitem>
187 </varlistentry>
188
189 <varlistentry><term><option>Ignore-Hold</option></term>
190 <listitem><para>Ignore held packages; this global option causes the problem resolver to
191 ignore held packages in its decision making.</para></listitem>
192 </varlistentry>
193
194 <varlistentry><term><option>Clean-Installed</option></term>
195 <listitem><para>Defaults to on. When turned on the autoclean feature will remove any packages
196 which can no longer be downloaded from the cache. If turned off then
197 packages that are locally installed are also excluded from cleaning - but
198 note that APT provides no direct means to reinstall them.</para></listitem>
199 </varlistentry>
200
201 <varlistentry><term><option>Immediate-Configure</option></term>
202 <listitem><para>
203 Defaults to on, which will cause APT to install essential and important
204 packages as soon as possible in an install/upgrade operation, in order
205 to limit the effect of a failing &dpkg; call. If this option is
206 disabled, APT treats an important package in the same way as an extra
207 package: between the unpacking of the package A and its configuration
208 there can be many other unpack or configuration calls for other
209 unrelated packages B, C etc. If these cause the &dpkg; call to fail
210 (e.g. because package B's maintainer scripts generate an error), this
211 results in a system state in which package A is unpacked but
212 unconfigured - so any package depending on A is now no longer
213 guaranteed to work, as its dependency on A is no longer satisfied.
214 </para><para>
215 The immediate configuration marker is also applied in the potentially
216 problematic case of circular dependencies, since a dependency with the
217 immediate flag is equivalent to a Pre-Dependency. In theory this allows
218 APT to recognise a situation in which it is unable to perform immediate
219 configuration, abort, and suggest to the user that the option should be
220 temporarily deactivated in order to allow the operation to proceed.
221 Note the use of the word "theory" here; in the real world this problem
222 has rarely been encountered, in non-stable distribution versions, and
223 was caused by wrong dependencies of the package in question or by a
224 system in an already broken state; so you should not blindly disable
225 this option, as the scenario mentioned above is not the only problem it
226 can help to prevent in the first place.
227 </para><para>
228 Before a big operation like <literal>dist-upgrade</literal> is run
229 with this option disabled you should try to explicitly
230 <literal>install</literal> the package APT is unable to configure
231 immediately; but please make sure you also report your problem to your
232 distribution and to the APT team with the buglink below, so they can
233 work on improving or correcting the upgrade process.
234 </para></listitem>
235 </varlistentry>
236
237 <varlistentry><term><option>Force-LoopBreak</option></term>
238 <listitem><para>
239 Never enable this option unless you <emphasis>really</emphasis> know
240 what you are doing. It permits APT to temporarily remove an essential
241 package to break a Conflicts/Conflicts or Conflicts/Pre-Depends loop
242 between two essential packages. <emphasis>Such a loop should never exist
243 and is a grave bug</emphasis>. This option will work if the essential
244 packages are not <command>tar</command>, <command>gzip</command>,
245 <command>libc</command>, <command>dpkg</command>, <command>dash</command>
246 or anything that those packages depend on.
247 </para></listitem>
248 </varlistentry>
249
250 <varlistentry><term><option>Cache-Start</option></term><term><option>Cache-Grow</option></term><term><option>Cache-Limit</option></term>
251 <listitem><para>APT uses since version 0.7.26 a resizable memory mapped cache file to store the available
252 information. <literal>Cache-Start</literal> acts as a hint of the size the cache will grow to,
253 and is therefore the amount of memory APT will request at startup. The default value is
254 20971520 bytes (~20 MB). Note that this amount of space needs to be available for APT;
255 otherwise it will likely fail ungracefully, so for memory restricted devices this value should
256 be lowered while on systems with a lot of configured sources it should be increased.
257 <literal>Cache-Grow</literal> defines in bytes with the default of 1048576 (~1 MB) how much
258 the cache size will be increased in the event the space defined by <literal>Cache-Start</literal>
259 is not enough. This value will be applied again and again until either the cache is big
260 enough to store all information or the size of the cache reaches the <literal>Cache-Limit</literal>.
261 The default of <literal>Cache-Limit</literal> is 0 which stands for no limit.
262 If <literal>Cache-Grow</literal> is set to 0 the automatic growth of the cache is disabled.
263 </para></listitem>
264 </varlistentry>
265
266 <varlistentry><term><option>Build-Essential</option></term>
267 <listitem><para>Defines which packages are considered essential build dependencies.</para></listitem>
268 </varlistentry>
269
270 <varlistentry><term><option>Get</option></term>
271 <listitem><para>The Get subsection controls the &apt-get; tool; please see its
272 documentation for more information about the options here.</para></listitem>
273 </varlistentry>
274
275 <varlistentry><term><option>Cache</option></term>
276 <listitem><para>The Cache subsection controls the &apt-cache; tool; please see its
277 documentation for more information about the options here.</para></listitem>
278 </varlistentry>
279
280 <varlistentry><term><option>CDROM</option></term>
281 <listitem><para>The CDROM subsection controls the &apt-cdrom; tool; please see its
282 documentation for more information about the options here.</para></listitem>
283 </varlistentry>
284 </variablelist>
285 </refsect1>
286
287 <refsect1><title>The Acquire Group</title>
288 <para>The <literal>Acquire</literal> group of options controls the
289 download of packages as well as the various "acquire methods" responsible
290 for the download itself (see also &sources-list;).</para>
291
292 <variablelist>
293 <varlistentry><term><option>Check-Valid-Until</option></term>
294 <listitem><para>
295 Security related option defaulting to true, as giving a Release file's
296 validation an expiration date prevents replay attacks over a long
297 timescale, and can also for example help users to identify mirrors
298 that are no longer updated - but the feature depends on the
299 correctness of the clock on the user system. Archive maintainers are
300 encouraged to create Release files with the
301 <literal>Valid-Until</literal> header, but if they don't or a
302 stricter value is desired the <literal>Max-ValidTime</literal>
303 option below can be used.
304 The <option>Check-Valid-Until</option> option of &sources-list; entries should be
305 preferred to disable the check selectively instead of using this global override.
306 </para></listitem>
307 </varlistentry>
308
309 <varlistentry><term><option>Max-ValidTime</option></term>
310 <listitem><para>Maximum time (in seconds) after its creation (as indicated
311 by the <literal>Date</literal> header) that the <filename>Release</filename>
312 file should be considered valid.
313 If the Release file itself includes a <literal>Valid-Until</literal> header
314 the earlier date of the two is used as the expiration date.
315 The default value is <literal>0</literal> which stands for "valid forever".
316 Archive specific settings can be made by appending the label of the archive
317 to the option name. Preferably, the same can be achieved for specific
318 &sources-list; entries by using the <option>Valid-Until-Max</option> option there.
319 </para></listitem>
320 </varlistentry>
321
322 <varlistentry><term><option>Min-ValidTime</option></term>
323 <listitem><para>Minimum time (in seconds) after its creation (as indicated
324 by the <literal>Date</literal> header) that the <filename>Release</filename>
325 file should be considered valid.
326 Use this if you need to use a seldom updated (local) mirror of a more
327 frequently updated archive with a <literal>Valid-Until</literal> header
328 instead of completely disabling the expiration date checking.
329 Archive specific settings can and should be used by appending the label of
330 the archive to the option name. Preferably, the same can be achieved for specific
331 &sources-list; entries by using the <option>Valid-Until-Min</option> option there.
332 </para></listitem>
333 </varlistentry>
334
335 <varlistentry><term><option>PDiffs</option></term>
336 <listitem><para>Try to download deltas called <literal>PDiffs</literal> for
337 indexes (like <filename>Packages</filename> files) instead of
338 downloading whole ones. True by default. Preferably, this can be set
339 for specific &sources-list; entries or index files by using the
340 <option>PDiffs</option> option there.</para>
341 <para>Two sub-options to limit the use of PDiffs are also available:
342 <literal>FileLimit</literal> can be used to specify a maximum number of
343 PDiff files should be downloaded to update a file. <literal>SizeLimit</literal>
344 on the other hand is the maximum percentage of the size of all patches
345 compared to the size of the targeted file. If one of these limits is
346 exceeded the complete file is downloaded instead of the patches.
347 </para></listitem>
348 </varlistentry>
349
350 <varlistentry><term><option>Queue-Mode</option></term>
351 <listitem><para>Queuing mode; <literal>Queue-Mode</literal> can be one of <literal>host</literal> or
352 <literal>access</literal> which determines how APT parallelizes outgoing
353 connections. <literal>host</literal> means that one connection per target host
354 will be opened, <literal>access</literal> means that one connection per URI type
355 will be opened.</para></listitem>
356 </varlistentry>
357
358 <varlistentry><term><option>Retries</option></term>
359 <listitem><para>Number of retries to perform. If this is non-zero APT will retry failed
360 files the given number of times.</para></listitem>
361 </varlistentry>
362
363 <varlistentry><term><option>Source-Symlinks</option></term>
364 <listitem><para>Use symlinks for source archives. If set to true then source archives will
365 be symlinked when possible instead of copying. True is the default.</para></listitem>
366 </varlistentry>
367
368 <varlistentry><term><option>http</option></term>
369 <listitem><para><literal>http::Proxy</literal> sets the default proxy to use for HTTP
370 URIs. It is in the standard form of <literal>http://[[user][:pass]@]host[:port]/</literal>.
371 Per host proxies can also be specified by using the form
372 <literal>http::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal>
373 meaning to use no proxies. If no one of the above settings is specified,
374 <envar>http_proxy</envar> environment variable
375 will be used.</para>
376
377 <para>Three settings are provided for cache control with HTTP/1.1 compliant
378 proxy caches.
379 <literal>No-Cache</literal> tells the proxy not to use its cached
380 response under any circumstances.
381 <literal>Max-Age</literal> sets the allowed maximum age (in seconds) of
382 an index file in the cache of the proxy.
383 <literal>No-Store</literal> specifies that the proxy should not store
384 the requested archive files in its cache, which can be used to prevent
385 the proxy from polluting its cache with (big) .deb files.</para>
386
387 <para>The option <literal>timeout</literal> sets the timeout timer used by the method;
388 this value applies to the connection as well as the data timeout.</para>
389
390 <para>The setting <literal>Acquire::http::Pipeline-Depth</literal> can be used to
391 enable HTTP pipelining (RFC 2616 section 8.1.2.2) which can be beneficial e.g. on
392 high-latency connections. It specifies how many requests are sent in a pipeline.
393 APT tries to detect and workaround misbehaving webservers and proxies at runtime, but
394 if you know that yours does not conform to the HTTP/1.1 specification pipelining can
395 be disabled by setting the value to 0. It is enabled by default with the value 10.</para>
396
397 <para><literal>Acquire::http::AllowRedirect</literal> controls whether APT will follow
398 redirects, which is enabled by default.</para>
399
400 <para>The used bandwidth can be limited with
401 <literal>Acquire::http::Dl-Limit</literal> which accepts integer
402 values in kilobytes per second. The default value is 0 which
403 deactivates the limit and tries to use all available bandwidth.
404 Note that this option implicitly disables downloading from
405 multiple servers at the same time.</para>
406
407 <para><literal>Acquire::http::User-Agent</literal> can be used to set a different
408 User-Agent for the http download method as some proxies allow access for clients
409 only if the client uses a known identifier.</para>
410
411 <para><literal>Acquire::http::Proxy-Auto-Detect</literal> can be used to
412 specify an external command to discover the http proxy to use. Apt expects
413 the command to output the proxy on stdout in the style
414 <literal>http://proxy:port/</literal>. This will override the
415 generic <literal>Acquire::http::Proxy</literal> but not any specific
416 host proxy configuration set via
417 <literal>Acquire::http::Proxy::$HOST</literal>.
418
419 See the &squid-deb-proxy-client; package for an example implementation that
420 uses avahi. This option takes precedence over the legacy option name
421 <literal>ProxyAutoDetect</literal>.
422 </para>
423
424 </listitem>
425 </varlistentry>
426
427 <varlistentry><term><option>https</option></term>
428 <listitem><para>
429 The <literal>Cache-control</literal>, <literal>Timeout</literal>,
430 <literal>AllowRedirect</literal>, <literal>Dl-Limit</literal> and
431 <literal>proxy</literal> options work for HTTPS URIs in the same way
432 as for the <literal>http</literal> method, and default to the same
433 values if they are not explicitly set. The
434 <literal>Pipeline-Depth</literal> option is not yet supported.
435 </para>
436
437 <para><literal>CaInfo</literal> suboption specifies place of file that
438 holds info about trusted certificates.
439 <literal>&lt;host&gt;::CaInfo</literal> is the corresponding per-host option.
440 <literal>Verify-Peer</literal> boolean suboption determines whether or not the
441 server's host certificate should be verified against trusted certificates.
442 <literal>&lt;host&gt;::Verify-Peer</literal> is the corresponding per-host option.
443 <literal>Verify-Host</literal> boolean suboption determines whether or not the
444 server's hostname should be verified.
445 <literal>&lt;host&gt;::Verify-Host</literal> is the corresponding per-host option.
446 <literal>SslCert</literal> determines what certificate to use for client
447 authentication. <literal>&lt;host&gt;::SslCert</literal> is the corresponding per-host option.
448 <literal>SslKey</literal> determines what private key to use for client
449 authentication. <literal>&lt;host&gt;::SslKey</literal> is the corresponding per-host option.
450 <literal>SslForceVersion</literal> overrides default SSL version to use.
451 It can contain either of the strings '<literal>TLSv1</literal>' or
452 '<literal>SSLv3</literal>'.
453 <literal>&lt;host&gt;::SslForceVersion</literal> is the corresponding per-host option.
454 </para></listitem></varlistentry>
455
456 <varlistentry><term><option>ftp</option></term>
457 <listitem><para>
458 <literal>ftp::Proxy</literal> sets the default proxy to use for FTP URIs.
459 It is in the standard form of <literal>ftp://[[user][:pass]@]host[:port]/</literal>.
460 Per host proxies can also be specified by using the form
461 <literal>ftp::Proxy::&lt;host&gt;</literal> with the special keyword <literal>DIRECT</literal>
462 meaning to use no proxies. If no one of the above settings is specified,
463 <envar>ftp_proxy</envar> environment variable
464 will be used. To use an FTP
465 proxy you will have to set the <literal>ftp::ProxyLogin</literal> script in the
466 configuration file. This entry specifies the commands to send to tell
467 the proxy server what to connect to. Please see
468 &configureindex; for an example of
469 how to do this. The substitution variables representing the corresponding
470 URI component are <literal>$(PROXY_USER)</literal>,
471 <literal>$(PROXY_PASS)</literal>, <literal>$(SITE_USER)</literal>,
472 <literal>$(SITE_PASS)</literal>, <literal>$(SITE)</literal> and
473 <literal>$(SITE_PORT)</literal>.</para>
474
475 <para>The option <literal>timeout</literal> sets the timeout timer used by the method;
476 this value applies to the connection as well as the data timeout.</para>
477
478 <para>Several settings are provided to control passive mode. Generally it is
479 safe to leave passive mode on; it works in nearly every environment.
480 However, some situations require that passive mode be disabled and port
481 mode FTP used instead. This can be done globally or for connections that
482 go through a proxy or for a specific host (see the sample config file
483 for examples).</para>
484
485 <para>It is possible to proxy FTP over HTTP by setting the <envar>ftp_proxy</envar>
486 environment variable to an HTTP URL - see the discussion of the http method
487 above for syntax. You cannot set this in the configuration file and it is
488 not recommended to use FTP over HTTP due to its low efficiency.</para>
489
490 <para>The setting <literal>ForceExtended</literal> controls the use of RFC2428
491 <literal>EPSV</literal> and <literal>EPRT</literal> commands. The default is false, which means
492 these commands are only used if the control connection is IPv6. Setting this
493 to true forces their use even on IPv4 connections. Note that most FTP servers
494 do not support RFC2428.</para></listitem>
495 </varlistentry>
496
497 <varlistentry><term><option>cdrom</option></term>
498 <listitem><para>
499 For URIs using the <literal>cdrom</literal> method, the only configurable
500 option is the mount point, <literal>cdrom::Mount</literal>, which must be
501 the mount point for the CD-ROM (or DVD, or whatever) drive as specified in
502 <filename>/etc/fstab</filename>. It is possible to provide alternate mount
503 and unmount commands if your mount point cannot be listed in the fstab.
504 The syntax is to put <literallayout>/cdrom/::Mount "foo";</literallayout> within
505 the <literal>cdrom</literal> block. It is important to have the trailing slash.
506 Unmount commands can be specified using UMount.
507 </para></listitem>
508 </varlistentry>
509
510 <varlistentry><term><option>gpgv</option></term>
511 <listitem><para>
512 For GPGV URIs the only configurable option is <literal>gpgv::Options</literal>,
513 which passes additional parameters to gpgv.
514 </para></listitem>
515 </varlistentry>
516
517 <varlistentry><term><option>CompressionTypes</option></term>
518 <listitem><para>List of compression types which are understood by the acquire methods.
519 Files like <filename>Packages</filename> can be available in various compression formats.
520 By default the acquire methods can decompress <command>bzip2</command>, <command>lzma</command>
521 and <command>gzip</command> compressed files; with this setting more formats can be added
522 on the fly or the used method can be changed. The syntax for this is:
523 <synopsis>Acquire::CompressionTypes::<replaceable>FileExtension</replaceable> "<replaceable>Methodname</replaceable>";</synopsis>
524 </para><para>Also, the <literal>Order</literal> subgroup can be used to define in which order
525 the acquire system will try to download the compressed files. The acquire system will try the first
526 and proceed with the next compression type in this list on error, so to prefer one over the other type
527 simply add the preferred type first - default types not already added will be implicitly appended
528 to the end of the list, so e.g. <synopsis>Acquire::CompressionTypes::Order:: "gz";</synopsis> can
529 be used to prefer <command>gzip</command> compressed files over <command>bzip2</command> and <command>lzma</command>.
530 If <command>lzma</command> should be preferred over <command>gzip</command> and <command>bzip2</command> the
531 configure setting should look like this: <synopsis>Acquire::CompressionTypes::Order { "lzma"; "gz"; };</synopsis>
532 It is not needed to add <literal>bz2</literal> to the list explicitly as it will be added automatically.</para>
533 <para>Note that the
534 <literal>Dir::Bin::<replaceable>Methodname</replaceable></literal>
535 will be checked at run time. If this option has been set, the
536 method will only be used if this file exists; e.g. for the
537 <literal>bzip2</literal> method (the inbuilt) setting is:
538 <literallayout>Dir::Bin::bzip2 "/bin/bzip2";</literallayout>
539 Note also that list entries specified on the command line will be added at the end of the list
540 specified in the configuration files, but before the default entries. To prefer a type in this case
541 over the ones specified in the configuration files you can set the option direct - not in list style.
542 This will not override the defined list; it will only prefix the list with this type.</para>
543 <para>The special type <literal>uncompressed</literal> can be used to give uncompressed files a
544 preference, but note that most archives don't provide uncompressed files so this is mostly only
545 useable for local mirrors.</para></listitem>
546 </varlistentry>
547
548 <varlistentry><term><option>GzipIndexes</option></term>
549 <listitem><para>
550 When downloading <literal>gzip</literal> compressed indexes (Packages, Sources, or
551 Translations), keep them gzip compressed locally instead of unpacking
552 them. This saves quite a lot of disk space at the expense of more CPU
553 requirements when building the local package caches. False by default.
554 </para></listitem>
555 </varlistentry>
556
557 <varlistentry><term><option>Languages</option></term>
558 <listitem><para>The Languages subsection controls which <filename>Translation</filename> files are downloaded
559 and in which order APT tries to display the description-translations. APT will try to display the first
560 available description in the language which is listed first. Languages can be defined with their
561 short or long language codes. Note that not all archives provide <filename>Translation</filename>
562 files for every language - the long language codes are especially rare.</para>
563 <para>The default list includes "environment" and "en". "<literal>environment</literal>" has a special meaning here:
564 it will be replaced at runtime with the language codes extracted from the <literal>LC_MESSAGES</literal> environment variable.
565 It will also ensure that these codes are not included twice in the list. If <literal>LC_MESSAGES</literal>
566 is set to "C" only the <filename>Translation-en</filename> file (if available) will be used.
567 To force APT to use no Translation file use the setting <literal>Acquire::Languages=none</literal>. "<literal>none</literal>"
568 is another special meaning code which will stop the search for a suitable <filename>Translation</filename> file.
569 This tells APT to download these translations too, without actually
570 using them unless the environment specifies the languages. So the
571 following example configuration will result in the order "en, de" in an
572 English locale or "de, en" in a German one. Note that "fr" is
573 downloaded, but not used unless APT is used in a French locale (where
574 the order would be "fr, de, en").
575 <programlisting>Acquire::Languages { "environment"; "de"; "en"; "none"; "fr"; };</programlisting></para>
576 <para>Note: To prevent problems resulting from APT being executed in different environments
577 (e.g. by different users or by other programs) all Translation files which are found in
578 <filename>/var/lib/apt/lists/</filename> will be added to the end of the list
579 (after an implicit "<literal>none</literal>").</para>
580 </listitem>
581 </varlistentry>
582
583 <varlistentry><term><option>ForceIPv4</option></term>
584 <listitem><para>
585 When downloading, force to use only the IPv4 protocol.
586 </para></listitem>
587 </varlistentry>
588
589 <varlistentry><term><option>ForceIPv6</option></term>
590 <listitem><para>
591 When downloading, force to use only the IPv6 protocol.
592 </para></listitem>
593 </varlistentry>
594
595 <varlistentry><term><option>MaxReleaseFileSize</option></term>
596 <listitem><para>
597 The maximum file size of Release/Release.gpg/InRelease files.
598 The default is 10MB.
599 </para></listitem>
600 </varlistentry>
601
602 <varlistentry><term><option>EnableSrvRecords</option></term>
603 <listitem><para>
604 This option controls if apt will use the DNS SRV server record
605 as specified in RFC 2782 to select an alternative server to
606 connect to.
607 The default is "true".
608 </para></listitem>
609 </varlistentry>
610
611 <varlistentry><term><option>AllowInsecureRepositories</option></term>
612 <listitem><para>
613 Allow the update operation to load data files from
614 a repository without a trusted signature. If enabled this
615 option no data files will be loaded and the update
616 operation fails with a error for this source. The default
617 is false for backward compatibility. This will be changed
618 in the future.
619 </para></listitem>
620 </varlistentry>
621
622 <varlistentry><term><option>AllowDowngradeToInsecureRepositories</option></term>
623 <listitem><para>
624 Allow that a repository that was previously gpg signed to become
625 unsigned durign a update operation. When there is no valid signature
626 of a perviously trusted repository apt will refuse the update. This
627 option can be used to override this protection. You almost certainly
628 never want to enable this. The default is false.
629
630 Note that apt will still consider packages from this source
631 untrusted and warn about them if you try to install
632 them.
633 </para></listitem>
634 </varlistentry>
635
636 <varlistentry><term><option>Changelogs::URI</option> scope</term>
637 <listitem><para>
638 Acquiring changelogs can only be done if an URI is known from where to get them.
639 Preferable the Release file indicates this in a 'Changelogs' field. If this isn't
640 available the Label/Origin field of the Release file is used to check if a
641 <literal>Acquire::Changelogs::URI::Label::<replaceable>LABEL</replaceable></literal> or
642 <literal>Acquire::Changelogs::URI::Origin::<replaceable>ORIGIN</replaceable></literal> option
643 exists and if so this value is taken. The value in the Release file can be overridden
644 with <literal>Acquire::Changelogs::URI::Override::Label::<replaceable>LABEL</replaceable></literal>
645 or <literal>Acquire::Changelogs::URI::Override::Origin::<replaceable>ORIGIN</replaceable></literal>.
646
647 The value should be a normal URI to a text file, expect that package specific data is
648 replaced with the placeholder <literal>CHANGEPATH</literal>. The
649 value for it is: 1. if the package is from a component (e.g. <literal>main</literal>)
650 this is the first part otherwise it is omitted, 2. the first letter of source package name,
651 expect if the source package name starts with '<literal>lib</literal>' in which case it will
652 be the first four letters. 3. The complete source package name. 4. the complete name again and
653 5. the source version.
654 The first (if present), second, third and fourth part are separated by a slash ('<literal>/</literal>')
655 and between the fourth and fifth part is an underscore ('<literal>_</literal>').
656
657 The special value '<literal>no</literal>' is available for this option indicating that
658 this source can't be used to acquire changelog files from. Another source will be tried
659 if available in this case.
660 </para></listitem>
661 </varlistentry>
662
663 </variablelist>
664 </refsect1>
665
666 <refsect1><title>Directories</title>
667
668 <para>The <literal>Dir::State</literal> section has directories that pertain to local
669 state information. <literal>lists</literal> is the directory to place downloaded
670 package lists in and <literal>status</literal> is the name of the &dpkg; status file.
671 <literal>preferences</literal> is the name of the APT <filename>preferences</filename> file.
672 <literal>Dir::State</literal> contains the default directory to prefix on all
673 sub-items if they do not start with <filename>/</filename> or <filename>./</filename>.</para>
674
675 <para><literal>Dir::Cache</literal> contains locations pertaining to local cache
676 information, such as the two package caches <literal>srcpkgcache</literal> and
677 <literal>pkgcache</literal> as well as the location to place downloaded archives,
678 <literal>Dir::Cache::archives</literal>. Generation of caches can be turned off
679 by setting <literal>pkgcache</literal> or <literal>srcpkgcache</literal> to
680 <literal>""</literal>. This will slow down startup but save disk space. It
681 is probably preferable to turn off the pkgcache rather than the srcpkgcache.
682 Like <literal>Dir::State</literal> the default directory is contained in
683 <literal>Dir::Cache</literal></para>
684
685 <para><literal>Dir::Etc</literal> contains the location of configuration files,
686 <literal>sourcelist</literal> gives the location of the sourcelist and
687 <literal>main</literal> is the default configuration file (setting has no effect,
688 unless it is done from the config file specified by
689 <envar>APT_CONFIG</envar>).</para>
690
691 <para>The <literal>Dir::Parts</literal> setting reads in all the config fragments in
692 lexical order from the directory specified. After this is done then the
693 main config file is loaded.</para>
694
695 <para>Binary programs are pointed to by <literal>Dir::Bin</literal>. <literal>Dir::Bin::Methods</literal>
696 specifies the location of the method handlers and <literal>gzip</literal>,
697 <literal>bzip2</literal>, <literal>lzma</literal>,
698 <literal>dpkg</literal>, <literal>apt-get</literal> <literal>dpkg-source</literal>
699 <literal>dpkg-buildpackage</literal> and <literal>apt-cache</literal> specify the location
700 of the respective programs.</para>
701
702 <para>
703 The configuration item <literal>RootDir</literal> has a special
704 meaning. If set, all paths will be
705 relative to <literal>RootDir</literal>, <emphasis>even paths that
706 are specified absolutely</emphasis>. So, for instance, if
707 <literal>RootDir</literal> is set to
708 <filename>/tmp/staging</filename> and
709 <literal>Dir::State::status</literal> is set to
710 <filename>/var/lib/dpkg/status</filename>, then the status file
711 will be looked up in
712 <filename>/tmp/staging/var/lib/dpkg/status</filename>.
713 If you want to prefix only relative paths, set <literal>Dir</literal> instead.
714 </para>
715
716 <para>
717 The <literal>Ignore-Files-Silently</literal> list can be used to specify
718 which files APT should silently ignore while parsing the files in the
719 fragment directories. Per default a file which end with <literal>.disabled</literal>,
720 <literal>~</literal>, <literal>.bak</literal> or <literal>.dpkg-[a-z]+</literal>
721 is silently ignored. As seen in the last default value these patterns can use regular
722 expression syntax.
723 </para>
724 </refsect1>
725
726 <refsect1><title>APT in DSelect</title>
727 <para>
728 When APT is used as a &dselect; method several configuration directives
729 control the default behavior. These are in the <literal>DSelect</literal> section.</para>
730
731 <variablelist>
732 <varlistentry><term><option>Clean</option></term>
733 <listitem><para>Cache Clean mode; this value may be one of
734 <literal>always</literal>, <literal>prompt</literal>,
735 <literal>auto</literal>, <literal>pre-auto</literal> and
736 <literal>never</literal>.
737 <literal>always</literal> and <literal>prompt</literal> will remove
738 all packages from the cache after upgrading, <literal>prompt</literal>
739 (the default) does so conditionally.
740 <literal>auto</literal> removes only those packages which are no longer
741 downloadable (replaced with a new version for instance).
742 <literal>pre-auto</literal> performs this action before downloading
743 new packages.</para></listitem>
744 </varlistentry>
745
746 <varlistentry><term><option>options</option></term>
747 <listitem><para>The contents of this variable are passed to &apt-get; as command line
748 options when it is run for the install phase.</para></listitem>
749 </varlistentry>
750
751 <varlistentry><term><option>Updateoptions</option></term>
752 <listitem><para>The contents of this variable are passed to &apt-get; as command line
753 options when it is run for the update phase.</para></listitem>
754 </varlistentry>
755
756 <varlistentry><term><option>PromptAfterUpdate</option></term>
757 <listitem><para>If true the [U]pdate operation in &dselect; will always prompt to continue.
758 The default is to prompt only on error.</para></listitem>
759 </varlistentry>
760 </variablelist>
761 </refsect1>
762
763 <refsect1><title>How APT calls &dpkg;</title>
764 <para>Several configuration directives control how APT invokes &dpkg;. These are
765 in the <literal>DPkg</literal> section.</para>
766
767 <variablelist>
768 <varlistentry><term><option>options</option></term>
769 <listitem><para>This is a list of options to pass to &dpkg;. The options must be specified
770 using the list notation and each list item is passed as a single argument
771 to &dpkg;.</para></listitem>
772 </varlistentry>
773
774 <varlistentry><term><option>Pre-Invoke</option></term><term><option>Post-Invoke</option></term>
775 <listitem><para>This is a list of shell commands to run before/after invoking &dpkg;.
776 Like <literal>options</literal> this must be specified in list notation. The
777 commands are invoked in order using <filename>/bin/sh</filename>; should any
778 fail APT will abort.</para></listitem>
779 </varlistentry>
780
781 <varlistentry><term><option>Pre-Install-Pkgs</option></term>
782 <listitem><para>This is a list of shell commands to run before invoking &dpkg;. Like
783 <literal>options</literal> this must be specified in list notation. The commands
784 are invoked in order using <filename>/bin/sh</filename>; should any fail APT
785 will abort. APT will pass the filenames of all .deb files it is going to
786 install to the commands, one per line on the requested file descriptor, defaulting
787 to standard input.</para>
788
789 <para>Version 2 of this protocol sends more information through the requested
790 file descriptor: a line with the text <literal>VERSION 2</literal>,
791 the APT configuration space, and a list of package actions with filename
792 and version information.</para>
793
794 <para>Each configuration directive line has the form
795 <literal>key=value</literal>. Special characters (equal signs, newlines,
796 nonprintable characters, quotation marks, and percent signs in
797 <literal>key</literal> and newlines, nonprintable characters, and percent
798 signs in <literal>value</literal>) are %-encoded. Lists are represented
799 by multiple <literal>key::=value</literal> lines with the same key. The
800 configuration section ends with a blank line.</para>
801
802 <para>Package action lines consist of five fields in Version 2: old version, direction
803 of version change (&lt; for upgrades, &gt; for downgrades, = for no
804 change), new version, action. The version fields are "-" for no version
805 at all (for example when installing a package for the first time; no
806 version is treated as earlier than any real version, so that is an
807 upgrade, indicated as <literal>- &lt; 1.23.4</literal>). The action field
808 is "**CONFIGURE**" if the package is being configured, "**REMOVE**" if it
809 is being removed, or the filename of a .deb file if it is being
810 unpacked.</para>
811
812 <para>In Version 3 after each version field follows the architecture
813 of this version, which is "-" if there is no version, and a field showing
814 the MultiArch type "same", foreign", "allowed" or "none". Note that "none"
815 is an incorrect typename which is just kept to remain compatible, it
816 should be read as "no" and users are encouraged to support both.</para>
817
818 <para>The version of the protocol to be used for the command
819 <literal><replaceable>cmd</replaceable></literal> can be chosen by setting
820 <literal>DPkg::Tools::options::<replaceable>cmd</replaceable>::Version</literal>
821 accordingly, the default being version 1. If APT isn't supporting the requested
822 version it will send the information in the highest version it has support for instead.
823 </para>
824
825 <para>The file descriptor to be used to send the information can be requested with
826 <literal>DPkg::Tools::options::<replaceable>cmd</replaceable>::InfoFD</literal>
827 which defaults to <literal>0</literal> for standard input and is available since
828 version 0.9.11. Support for the option can be detected by looking for the environment
829 variable <envar>APT_HOOK_INFO_FD</envar> which contains the number of the used
830 file descriptor as a confirmation.</para>
831 </listitem>
832 </varlistentry>
833
834 <varlistentry><term><option>Run-Directory</option></term>
835 <listitem><para>APT chdirs to this directory before invoking &dpkg;, the default is
836 <filename>/</filename>.</para></listitem>
837 </varlistentry>
838
839 <varlistentry><term><option>Build-options</option></term>
840 <listitem><para>These options are passed to &dpkg-buildpackage; when compiling packages;
841 the default is to disable signing and produce all binaries.</para></listitem>
842 </varlistentry>
843 </variablelist>
844
845 <refsect2><title>dpkg trigger usage (and related options)</title>
846 <para>APT can call &dpkg; in such a way as to let it make aggressive use of triggers over
847 multiple calls of &dpkg;. Without further options &dpkg; will use triggers once each time it runs.
848 Activating these options can therefore decrease the time needed to perform the
849 install or upgrade. Note that it is intended to activate these options per default in the
850 future, but as it drastically changes the way APT calls &dpkg; it needs a lot more testing.
851 <emphasis>These options are therefore currently experimental and should not be used in
852 production environments.</emphasis> It also breaks progress reporting such that all front-ends will
853 currently stay around half (or more) of the time in the 100% state while it actually configures
854 all packages.</para>
855 <para>Note that it is not guaranteed that APT will support these options or that these options will
856 not cause (big) trouble in the future. If you have understand the current risks and problems with
857 these options, but are brave enough to help testing them, create a new configuration file and test a
858 combination of options. Please report any bugs, problems and improvements you encounter and make sure
859 to note which options you have used in your reports. Asking &dpkg; for help could also be useful for
860 debugging proposes, see e.g. <command>dpkg --audit</command>. A defensive option combination would be
861 <literallayout>DPkg::NoTriggers "true";
862 PackageManager::Configure "smart";
863 DPkg::ConfigurePending "true";
864 DPkg::TriggersPending "true";</literallayout></para>
865
866 <variablelist>
867 <varlistentry><term><option>DPkg::NoTriggers</option></term>
868 <listitem><para>Add the no triggers flag to all &dpkg; calls (except the ConfigurePending call).
869 See &dpkg; if you are interested in what this actually means. In short: &dpkg; will not run the
870 triggers when this flag is present unless it is explicitly called to do so in an extra call.
871 Note that this option exists (undocumented) also in older APT versions with a slightly different
872 meaning: Previously these option only append --no-triggers to the configure calls to &dpkg; -
873 now APT will also add this flag to the unpack and remove calls.</para></listitem>
874 </varlistentry>
875 <varlistentry><term><option>PackageManager::Configure</option></term>
876 <listitem><para>Valid values are "<literal>all</literal>",
877 "<literal>smart</literal>" and "<literal>no</literal>".
878 The default value is "<literal>all</literal>", which causes APT to
879 configure all packages. The "<literal>smart</literal>" way is to
880 configure only packages which need to be configured before another
881 package can be unpacked (Pre-Depends), and let the rest be configured
882 by &dpkg; with a call generated by the ConfigurePending option (see
883 below). On the other hand, "<literal>no</literal>" will not configure
884 anything, and totally relies on &dpkg; for configuration (which at the
885 moment will fail if a Pre-Depends is encountered). Setting this option
886 to any value other than <literal>all</literal> will implicitly also
887 activate the next option by default, as otherwise the system could end
888 in an unconfigured and potentially unbootable state.</para></listitem>
889 </varlistentry>
890 <varlistentry><term><option>DPkg::ConfigurePending</option></term>
891 <listitem><para>If this option is set APT will call <command>dpkg --configure --pending</command>
892 to let &dpkg; handle all required configurations and triggers. This option is activated automatically
893 per default if the previous option is not set to <literal>all</literal>, but deactivating it could be useful
894 if you want to run APT multiple times in a row - e.g. in an installer. In these sceneries you could
895 deactivate this option in all but the last run.</para></listitem>
896 </varlistentry>
897 <varlistentry><term><option>DPkg::TriggersPending</option></term>
898 <listitem><para>Useful for the <literal>smart</literal> configuration as a package which has pending
899 triggers is not considered as <literal>installed</literal>, and &dpkg; treats them as <literal>unpacked</literal>
900 currently which is a showstopper for Pre-Dependencies (see debbugs #526774). Note that this will
901 process all triggers, not only the triggers needed to configure this package.</para></listitem>
902 </varlistentry>
903 <varlistentry><term><option>OrderList::Score::Immediate</option></term>
904 <listitem><para>Essential packages (and their dependencies) should be configured immediately
905 after unpacking. It is a good idea to do this quite early in the upgrade process as these
906 configure calls also currently require <literal>DPkg::TriggersPending</literal> which
907 will run quite a few triggers (which may not be needed). Essentials get per default a high score
908 but the immediate flag is relatively low (a package which has a Pre-Depends is rated higher).
909 These option and the others in the same group can be used to change the scoring. The following
910 example shows the settings with their default values.
911 <literallayout>OrderList::Score {
912 Delete 500;
913 Essential 200;
914 Immediate 10;
915 PreDepends 50;
916 };</literallayout>
917 </para></listitem>
918 </varlistentry>
919 </variablelist>
920 </refsect2>
921 </refsect1>
922
923 <refsect1>
924 <title>Periodic and Archives options</title>
925 <para><literal>APT::Periodic</literal> and <literal>APT::Archives</literal>
926 groups of options configure behavior of apt periodic updates, which is
927 done by the <literal>/etc/cron.daily/apt</literal> script. See the top of
928 this script for the brief documentation of these options.
929 </para>
930 </refsect1>
931
932 <refsect1>
933 <title>Debug options</title>
934 <para>
935 Enabling options in the <literal>Debug::</literal> section will
936 cause debugging information to be sent to the standard error
937 stream of the program utilizing the <literal>apt</literal>
938 libraries, or enable special program modes that are primarily
939 useful for debugging the behavior of <literal>apt</literal>.
940 Most of these options are not interesting to a normal user, but a
941 few may be:
942
943 <itemizedlist>
944 <listitem>
945 <para>
946 <literal>Debug::pkgProblemResolver</literal> enables output
947 about the decisions made by
948 <literal>dist-upgrade, upgrade, install, remove, purge</literal>.
949 </para>
950 </listitem>
951
952 <listitem>
953 <para>
954 <literal>Debug::NoLocking</literal> disables all file
955 locking. This can be used to run some operations (for
956 instance, <literal>apt-get -s install</literal>) as a
957 non-root user.
958 </para>
959 </listitem>
960
961 <listitem>
962 <para>
963 <literal>Debug::pkgDPkgPM</literal> prints out the actual
964 command line each time that <literal>apt</literal> invokes
965 &dpkg;.
966 </para>
967 </listitem>
968
969 <listitem>
970 <para>
971 <literal>Debug::IdentCdrom</literal> disables the inclusion
972 of statfs data in CD-ROM IDs. <!-- TODO: provide a
973 motivating example, except I haven't a clue why you'd want
974 to do this. -->
975 </para>
976 </listitem>
977 </itemizedlist>
978 </para>
979
980 <para>
981 A full list of debugging options to apt follows.
982 </para>
983
984 <variablelist>
985 <varlistentry>
986 <term><option>Debug::Acquire::cdrom</option></term>
987
988 <listitem>
989 <para>
990 Print information related to accessing
991 <literal>cdrom://</literal> sources.
992 </para>
993 </listitem>
994 </varlistentry>
995
996 <varlistentry>
997 <term><option>Debug::Acquire::ftp</option></term>
998
999 <listitem>
1000 <para>
1001 Print information related to downloading packages using
1002 FTP.
1003 </para>
1004 </listitem>
1005 </varlistentry>
1006
1007 <varlistentry>
1008 <term><option>Debug::Acquire::http</option></term>
1009
1010 <listitem>
1011 <para>
1012 Print information related to downloading packages using
1013 HTTP.
1014 </para>
1015 </listitem>
1016 </varlistentry>
1017
1018 <varlistentry>
1019 <term><option>Debug::Acquire::https</option></term>
1020
1021 <listitem>
1022 <para>
1023 Print information related to downloading packages using
1024 HTTPS.
1025 </para>
1026 </listitem>
1027 </varlistentry>
1028
1029 <varlistentry>
1030 <term><option>Debug::Acquire::gpgv</option></term>
1031
1032 <listitem>
1033 <para>
1034 Print information related to verifying cryptographic
1035 signatures using <literal>gpg</literal>.
1036 </para>
1037 </listitem>
1038 </varlistentry>
1039
1040 <varlistentry>
1041 <term><option>Debug::aptcdrom</option></term>
1042
1043 <listitem>
1044 <para>
1045 Output information about the process of accessing
1046 collections of packages stored on CD-ROMs.
1047 </para>
1048 </listitem>
1049 </varlistentry>
1050
1051 <varlistentry>
1052 <term><option>Debug::BuildDeps</option></term>
1053 <listitem>
1054 <para>
1055 Describes the process of resolving build-dependencies in
1056 &apt-get;.
1057 </para>
1058 </listitem>
1059 </varlistentry>
1060
1061 <varlistentry>
1062 <term><option>Debug::Hashes</option></term>
1063 <listitem>
1064 <para>
1065 Output each cryptographic hash that is generated by the
1066 <literal>apt</literal> libraries.
1067 </para>
1068 </listitem>
1069 </varlistentry>
1070
1071 <varlistentry>
1072 <term><option>Debug::IdentCDROM</option></term>
1073 <listitem>
1074 <para>
1075 Do not include information from <literal>statfs</literal>,
1076 namely the number of used and free blocks on the CD-ROM
1077 filesystem, when generating an ID for a CD-ROM.
1078 </para>
1079 </listitem>
1080 </varlistentry>
1081
1082 <varlistentry>
1083 <term><option>Debug::NoLocking</option></term>
1084 <listitem>
1085 <para>
1086 Disable all file locking. For instance, this will allow
1087 two instances of <quote><literal>apt-get
1088 update</literal></quote> to run at the same time.
1089 </para>
1090 </listitem>
1091 </varlistentry>
1092
1093 <varlistentry>
1094 <term><option>Debug::pkgAcquire</option></term>
1095
1096 <listitem>
1097 <para>
1098 Log when items are added to or removed from the global
1099 download queue.
1100 </para>
1101 </listitem>
1102 </varlistentry>
1103
1104 <varlistentry>
1105 <term><option>Debug::pkgAcquire::Auth</option></term>
1106 <listitem>
1107 <para>
1108 Output status messages and errors related to verifying
1109 checksums and cryptographic signatures of downloaded files.
1110 </para>
1111 </listitem>
1112 </varlistentry>
1113
1114 <varlistentry>
1115 <term><option>Debug::pkgAcquire::Diffs</option></term>
1116 <listitem>
1117 <para>
1118 Output information about downloading and applying package
1119 index list diffs, and errors relating to package index list
1120 diffs.
1121 </para>
1122 </listitem>
1123 </varlistentry>
1124
1125 <varlistentry>
1126 <term><option>Debug::pkgAcquire::RRed</option></term>
1127
1128 <listitem>
1129 <para>
1130 Output information related to patching apt package lists
1131 when downloading index diffs instead of full indices.
1132 </para>
1133 </listitem>
1134 </varlistentry>
1135
1136 <varlistentry>
1137 <term><option>Debug::pkgAcquire::Worker</option></term>
1138
1139 <listitem>
1140 <para>
1141 Log all interactions with the sub-processes that actually
1142 perform downloads.
1143 </para>
1144 </listitem>
1145 </varlistentry>
1146
1147 <varlistentry>
1148 <term><option>Debug::pkgAutoRemove</option></term>
1149
1150 <listitem>
1151 <para>
1152 Log events related to the automatically-installed status of
1153 packages and to the removal of unused packages.
1154 </para>
1155 </listitem>
1156 </varlistentry>
1157
1158 <varlistentry>
1159 <term><option>Debug::pkgDepCache::AutoInstall</option></term>
1160 <listitem>
1161 <para>
1162 Generate debug messages describing which packages are being
1163 automatically installed to resolve dependencies. This
1164 corresponds to the initial auto-install pass performed in,
1165 e.g., <literal>apt-get install</literal>, and not to the
1166 full <literal>apt</literal> dependency resolver; see
1167 <literal>Debug::pkgProblemResolver</literal> for that.
1168 </para>
1169 </listitem>
1170 </varlistentry>
1171
1172 <varlistentry>
1173 <term><option>Debug::pkgDepCache::Marker</option></term>
1174 <listitem>
1175 <para>
1176 Generate debug messages describing which packages are marked
1177 as keep/install/remove while the ProblemResolver does his work.
1178 Each addition or deletion may trigger additional actions;
1179 they are shown indented two additional spaces under the original entry.
1180 The format for each line is <literal>MarkKeep</literal>,
1181 <literal>MarkDelete</literal> or <literal>MarkInstall</literal> followed by
1182 <literal>package-name &lt;a.b.c -&gt; d.e.f | x.y.z&gt; (section)</literal>
1183 where <literal>a.b.c</literal> is the current version of the package,
1184 <literal>d.e.f</literal> is the version considered for installation and
1185 <literal>x.y.z</literal> is a newer version, but not considered for installation
1186 (because of a low pin score). The later two can be omitted if there is none or if
1187 it is the same as the installed version.
1188 <literal>section</literal> is the name of the section the package appears in.
1189 </para>
1190 </listitem>
1191 </varlistentry>
1192
1193 <varlistentry>
1194 <term><option>Debug::pkgDPkgPM</option></term>
1195 <listitem>
1196 <para>
1197 When invoking &dpkg;, output the precise command line with
1198 which it is being invoked, with arguments separated by a
1199 single space character.
1200 </para>
1201 </listitem>
1202 </varlistentry>
1203
1204 <varlistentry>
1205 <term><option>Debug::pkgDPkgProgressReporting</option></term>
1206 <listitem>
1207 <para>
1208 Output all the data received from &dpkg; on the status file
1209 descriptor and any errors encountered while parsing it.
1210 </para>
1211 </listitem>
1212 </varlistentry>
1213
1214 <varlistentry>
1215 <term><option>Debug::pkgOrderList</option></term>
1216
1217 <listitem>
1218 <para>
1219 Generate a trace of the algorithm that decides the order in
1220 which <literal>apt</literal> should pass packages to
1221 &dpkg;.
1222 </para>
1223 </listitem>
1224 </varlistentry>
1225
1226 <varlistentry>
1227 <term><option>Debug::pkgPackageManager</option></term>
1228
1229 <listitem>
1230 <para>
1231 Output status messages tracing the steps performed when
1232 invoking &dpkg;.
1233 </para>
1234 </listitem>
1235 </varlistentry>
1236
1237 <varlistentry>
1238 <term><option>Debug::pkgPolicy</option></term>
1239
1240 <listitem>
1241 <para>
1242 Output the priority of each package list on startup.
1243 </para>
1244 </listitem>
1245 </varlistentry>
1246
1247 <varlistentry>
1248 <term><option>Debug::pkgProblemResolver</option></term>
1249
1250 <listitem>
1251 <para>
1252 Trace the execution of the dependency resolver (this
1253 applies only to what happens when a complex dependency
1254 problem is encountered).
1255 </para>
1256 </listitem>
1257 </varlistentry>
1258
1259 <varlistentry>
1260 <term><option>Debug::pkgProblemResolver::ShowScores</option></term>
1261 <listitem>
1262 <para>
1263 Display a list of all installed packages with their calculated score
1264 used by the pkgProblemResolver. The description of the package
1265 is the same as described in <literal>Debug::pkgDepCache::Marker</literal>
1266 </para>
1267 </listitem>
1268 </varlistentry>
1269
1270 <varlistentry>
1271 <term><option>Debug::sourceList</option></term>
1272
1273 <listitem>
1274 <para>
1275 Print information about the vendors read from
1276 <filename>/etc/apt/vendors.list</filename>.
1277 </para>
1278 </listitem>
1279 </varlistentry>
1280
1281 <varlistentry>
1282 <term><option>Debug::RunScripts</option></term>
1283 <listitem>
1284 <para>
1285 Display the external commands that are called by apt hooks.
1286 This includes e.g. the config options
1287 <literal>DPkg::{Pre,Post}-Invoke</literal> or
1288 <literal>APT::Update::{Pre,Post}-Invoke</literal>.
1289 </para>
1290 </listitem>
1291 </varlistentry>
1292
1293 <!-- 2009/07/11 Currently used nowhere. The corresponding code
1294 is commented.
1295 <varlistentry>
1296 <term><literal>Debug::Vendor</literal></term>
1297
1298 <listitem>
1299 <para>
1300 Print information about each vendor.
1301 </para>
1302 </listitem>
1303 </varlistentry>
1304 -->
1305
1306 </variablelist>
1307 </refsect1>
1308
1309 <refsect1><title>Examples</title>
1310 <para>&configureindex; is a
1311 configuration file showing example values for all possible
1312 options.</para>
1313 </refsect1>
1314
1315 <refsect1><title>Files</title>
1316 <variablelist>
1317 &file-aptconf;
1318 </variablelist>
1319 </refsect1>
1320
1321 <refsect1><title>See Also</title>
1322 <para>&apt-cache;, &apt-config;<!-- ? reading apt.conf -->, &apt-preferences;.</para>
1323 </refsect1>
1324
1325 &manbugs;
1326
1327 </refentry>
1328