1APT.CONF(5)                           APT                          APT.CONF(5)
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3
4

NAME

6       apt.conf - Configuration file for APT
7

DESCRIPTION

9       /etc/apt/apt.conf is the main configuration file shared by all the
10       tools in the APT suite of tools, though it is by no means the only
11       place options can be set. The suite also shares a common command line
12       parser to provide a uniform environment.
13
14       When an APT tool starts up it will read the configuration files in the
15       following order:
16
17        1. the file specified by the APT_CONFIG environment variable (if any)
18
19        2. all files in Dir::Etc::Parts in alphanumeric ascending order which
20           have either no or "conf" as filename extension and which only
21           contain alphanumeric, hyphen (-), underscore (_) and period (.)
22           characters. Otherwise APT will print a notice that it has ignored a
23           file, unless that file matches a pattern in the
24           Dir::Ignore-Files-Silently configuration list - in which case it
25           will be silently ignored.
26
27        3. the main configuration file specified by Dir::Etc::main
28
29        4. all options set in the binary specific configuration subtree are
30           moved into the root of the tree.
31
32        5. the command line options are applied to override the configuration
33           directives or to load even more configuration files.
34

SYNTAX

36       The configuration file is organized in a tree with options organized
37       into functional groups. Option specification is given with a double
38       colon notation; for instance APT::Get::Assume-Yes is an option within
39       the APT tool group, for the Get tool. Options do not inherit from their
40       parent groups.
41
42       Syntactically the configuration language is modeled after what the ISC
43       tools such as bind and dhcp use. Lines starting with // are treated as
44       comments (ignored), as well as all text between /* and */, just like
45       C/C++ comments. Each line is of the form APT::Get::Assume-Yes "true";.
46       The quotation marks and trailing semicolon are required. The value must
47       be on one line, and there is no kind of string concatenation. Values
48       must not include backslashes or extra quotation marks. Option names are
49       made up of alphanumeric characters and the characters "/-:._+". A new
50       scope can be opened with curly braces, like this:
51
52
53           APT {
54             Get {
55               Assume-Yes "true";
56               Fix-Broken "true";
57             };
58           };
59
60       with newlines placed to make it more readable. Lists can be created by
61       opening a scope and including a single string enclosed in quotes
62       followed by a semicolon. Multiple entries can be included, separated by
63       a semicolon.
64
65
66           DPkg::Pre-Install-Pkgs {"/usr/sbin/dpkg-preconfigure --apt";};
67
68       In general the sample configuration file
69       /usr/share/doc/apt/examples/configure-index.gz is a good guide for how
70       it should look.
71
72       Case is not significant in names of configuration items, so in the
73       previous example you could use dpkg::pre-install-pkgs.
74
75       Names for the configuration items are optional if a list is defined as
76       can be seen in the DPkg::Pre-Install-Pkgs example above. If you don't
77       specify a name a new entry will simply add a new option to the list. If
78       you specify a name you can override the option in the same way as any
79       other option by reassigning a new value to the option.
80
81       Two special commands are defined: #include (which is deprecated and not
82       supported by alternative implementations) and #clear.  #include will
83       include the given file, unless the filename ends in a slash, in which
84       case the whole directory is included.  #clear is used to erase a part
85       of the configuration tree. The specified element and all its
86       descendants are erased. (Note that these lines also need to end with a
87       semicolon.)
88
89       The #clear command is the only way to delete a list or a complete
90       scope. Reopening a scope (or using the syntax described below with an
91       appended ::) will not override previously written entries. Options can
92       only be overridden by addressing a new value to them - lists and scopes
93       can't be overridden, only cleared.
94
95       All of the APT tools take an -o option which allows an arbitrary
96       configuration directive to be specified on the command line. The syntax
97       is a full option name (APT::Get::Assume-Yes for instance) followed by
98       an equals sign then the new value of the option. To append a new
99       element to a list, add a trailing :: to the name of the list. (As you
100       might suspect, the scope syntax can't be used on the command line.)
101
102       Note that appending items to a list using :: only works for one item
103       per line, and that you should not use it in combination with the scope
104       syntax (which adds :: implicitly). Using both syntaxes together will
105       trigger a bug which some users unfortunately depend on: an option with
106       the unusual name "::" which acts like every other option with a name.
107       This introduces many problems; for one thing, users who write multiple
108       lines in this wrong syntax in the hope of appending to a list will
109       achieve the opposite, as only the last assignment for this option "::"
110       will be used. Future versions of APT will raise errors and stop working
111       if they encounter this misuse, so please correct such statements now
112       while APT doesn't explicitly complain about them.
113

THE APT GROUP

115       This group of options controls general APT behavior as well as holding
116       the options for all of the tools.
117
118       Architecture
119           System Architecture; sets the architecture to use when fetching
120           files and parsing package lists. The internal default is the
121           architecture apt was compiled for.
122
123       Architectures
124           All Architectures the system supports. For instance, CPUs
125           implementing the amd64 (also called x86-64) instruction set are
126           also able to execute binaries compiled for the i386 (x86)
127           instruction set. This list is used when fetching files and parsing
128           package lists. The initial default is always the system's native
129           architecture (APT::Architecture), and foreign architectures are
130           added to the default list when they are registered via dpkg
131           --add-architecture.
132
133       Compressor
134           This scope defines which compression formats are supported, how
135           compression and decompression can be performed if support for this
136           format isn't built into apt directly and a cost-value indicating
137           how costly it is to compress something in this format. As an
138           example the following configuration stanza would allow apt to
139           download and uncompress as well as create and store files with the
140           low-cost .reversed file extension which it will pass to the command
141           rev without additional commandline parameters for compression and
142           uncompression:
143
144               APT::Compressor::rev {
145                    Name "rev";
146                    Extension ".reversed";
147                    Binary "rev";
148                    CompressArg {};
149                    UncompressArg {};
150                    Cost "10";
151               };
152
153       Build-Profiles
154           List of all build profiles enabled for build-dependency resolution,
155           without the "profile." namespace prefix. By default this list is
156           empty. The DEB_BUILD_PROFILES as used by dpkg-buildpackage(1)
157           overrides the list notation.
158
159       Default-Release
160           Default release to install packages from if more than one version
161           is available. Contains release name, codename or release version.
162           Examples: 'stable', 'testing', 'unstable', 'bullseye', 'bookworm',
163           '4.0', '5.0*'. See also apt_preferences(5).
164
165       Ignore-Hold
166           Ignore held packages; this global option causes the problem
167           resolver to ignore held packages in its decision making.
168
169       Clean-Installed
170           Defaults to on. When turned on the autoclean feature will remove
171           any packages which can no longer be downloaded from the cache. If
172           turned off then packages that are locally installed are also
173           excluded from cleaning - but note that APT provides no direct means
174           to reinstall them.
175
176       Immediate-Configure
177           Defaults to on, which will cause APT to install essential and
178           important packages as soon as possible in an install/upgrade
179           operation, in order to limit the effect of a failing dpkg(1) call.
180           If this option is disabled, APT treats an important package in the
181           same way as an extra package: between the unpacking of the package
182           A and its configuration there can be many other unpack or
183           configuration calls for other unrelated packages B, C etc. If these
184           cause the dpkg(1) call to fail (e.g. because package B's maintainer
185           scripts generate an error), this results in a system state in which
186           package A is unpacked but unconfigured - so any package depending
187           on A is now no longer guaranteed to work, as its dependency on A is
188           no longer satisfied.
189
190           The immediate configuration marker is also applied in the
191           potentially problematic case of circular dependencies, since a
192           dependency with the immediate flag is equivalent to a
193           Pre-Dependency. In theory this allows APT to recognise a situation
194           in which it is unable to perform immediate configuration, abort,
195           and suggest to the user that the option should be temporarily
196           deactivated in order to allow the operation to proceed. Note the
197           use of the word "theory" here; in the real world this problem has
198           rarely been encountered, in non-stable distribution versions, and
199           was caused by wrong dependencies of the package in question or by a
200           system in an already broken state; so you should not blindly
201           disable this option, as the scenario mentioned above is not the
202           only problem it can help to prevent in the first place.
203
204           Before a big operation like dist-upgrade is run with this option
205           disabled you should try to explicitly install the package APT is
206           unable to configure immediately; but please make sure you also
207           report your problem to your distribution and to the APT team with
208           the bug link below, so they can work on improving or correcting the
209           upgrade process.
210
211       Force-LoopBreak
212           Never enable this option unless you really know what you are doing.
213           It permits APT to temporarily remove an essential package to break
214           a Conflicts/Conflicts or Conflicts/Pre-Depends loop between two
215           essential packages.  Such a loop should never exist and is a grave
216           bug. This option will work if the essential packages are not tar,
217           gzip, libc, dpkg, dash or anything that those packages depend on.
218
219       Cache-Start, Cache-Grow, Cache-Limit
220           APT uses since version 0.7.26 a resizable memory mapped cache file
221           to store the available information.  Cache-Start acts as a hint of
222           the size the cache will grow to, and is therefore the amount of
223           memory APT will request at startup. The default value is 20971520
224           bytes (~20 MB). Note that this amount of space needs to be
225           available for APT; otherwise it will likely fail ungracefully, so
226           for memory restricted devices this value should be lowered while on
227           systems with a lot of configured sources it should be increased.
228           Cache-Grow defines in bytes with the default of 1048576 (~1 MB) how
229           much the cache size will be increased in the event the space
230           defined by Cache-Start is not enough. This value will be applied
231           again and again until either the cache is big enough to store all
232           information or the size of the cache reaches the Cache-Limit. The
233           default of Cache-Limit is 0 which stands for no limit. If
234           Cache-Grow is set to 0 the automatic growth of the cache is
235           disabled.
236
237       Build-Essential
238           Defines which packages are considered essential build dependencies.
239
240       Get
241           The Get subsection controls the apt-get(8) tool; please see its
242           documentation for more information about the options here.
243
244       Cache
245           The Cache subsection controls the apt-cache(8) tool; please see its
246           documentation for more information about the options here.
247
248       CDROM
249           The CDROM subsection controls the apt-cdrom(8) tool; please see its
250           documentation for more information about the options here.
251

THE ACQUIRE GROUP

253       The Acquire group of options controls the download of packages as well
254       as the various "acquire methods" responsible for the download itself
255       (see also sources.list(5)).
256
257       Check-Date
258           Security related option defaulting to true, enabling time-related
259           checks. Disabling it means that the machine's time cannot be
260           trusted, and APT will hence disable all time-related checks, such
261           as Check-Valid-Until and verifying that the Date field of a release
262           file is not in the future.
263
264       Max-FutureTime
265           Maximum time (in seconds) before its creation (as indicated by the
266           Date header) that the Release file should be considered valid. The
267           default value is 10. Archive specific settings can be made by
268           appending the label of the archive to the option name. Preferably,
269           the same can be achieved for specific sources.list(5) entries by
270           using the Date-Max-Future option there.
271
272       Check-Valid-Until
273           Security related option defaulting to true, as giving a Release
274           file's validation an expiration date prevents replay attacks over a
275           long timescale, and can also for example help users to identify
276           mirrors that are no longer updated - but the feature depends on the
277           correctness of the clock on the user system. Archive maintainers
278           are encouraged to create Release files with the Valid-Until header,
279           but if they don't or a stricter value is desired the Max-ValidTime
280           option below can be used. The Check-Valid-Until option of
281           sources.list(5) entries should be preferred to disable the check
282           selectively instead of using this global override.
283
284       Max-ValidTime
285           Maximum time (in seconds) after its creation (as indicated by the
286           Date header) that the Release file should be considered valid. If
287           the Release file itself includes a Valid-Until header the earlier
288           date of the two is used as the expiration date. The default value
289           is 0 which stands for "valid forever". Archive specific settings
290           can be made by appending the label of the archive to the option
291           name. Preferably, the same can be achieved for specific
292           sources.list(5) entries by using the Valid-Until-Max option there.
293
294       Min-ValidTime
295           Minimum time (in seconds) after its creation (as indicated by the
296           Date header) that the Release file should be considered valid. Use
297           this if you need to use a seldom updated (local) mirror of a more
298           frequently updated archive with a Valid-Until header instead of
299           completely disabling the expiration date checking. Archive specific
300           settings can and should be used by appending the label of the
301           archive to the option name. Preferably, the same can be achieved
302           for specific sources.list(5) entries by using the Valid-Until-Min
303           option there.
304
305       AllowTLS
306           Allow use of the internal TLS support in the http method. If set to
307           false, this completely disables support for TLS in apt's own
308           methods (excluding the curl-based https method). No TLS-related
309           functions will be called anymore.
310
311       PDiffs
312           Try to download deltas called PDiffs for indexes (like Packages
313           files) instead of downloading whole ones. True by default.
314           Preferably, this can be set for specific sources.list(5) entries or
315           index files by using the PDiffs option there.
316
317           Two sub-options to limit the use of PDiffs are also available:
318           FileLimit can be used to specify a maximum number of PDiff files
319           should be downloaded to update a file.  SizeLimit on the other hand
320           is the maximum percentage of the size of all patches compared to
321           the size of the targeted file. If one of these limits is exceeded
322           the complete file is downloaded instead of the patches.
323
324       By-Hash
325           Try to download indexes via an URI constructed from a hashsum of
326           the expected file rather than downloaded via a well-known stable
327           filename. True by default, but automatically disabled if the source
328           indicates no support for it. Usage can be forced with the special
329           value "force". Preferably, this can be set for specific
330           sources.list(5) entries or index files by using the By-Hash option
331           there.
332
333       Queue-Mode
334           Queuing mode; Queue-Mode can be one of host or access which
335           determines how APT parallelizes outgoing connections.  host means
336           that one connection per target host will be opened, access means
337           that one connection per URI type will be opened.
338
339       Retries
340           Number of retries to perform. If this is non-zero APT will retry
341           failed files the given number of times.
342
343       Source-Symlinks
344           Use symlinks for source archives. If set to true then source
345           archives will be symlinked when possible instead of copying. True
346           is the default.
347
348       http https
349           The options in these scopes configure APT's acquire transports for
350           the protocols HTTP and HTTPS and are documented in the apt-
351           transport-http(1) and apt-transport-https(1) manpages respectively.
352
353       ftp
354           ftp::Proxy sets the default proxy to use for FTP URIs. It is in the
355           standard form of ftp://[[user][:pass]@]host[:port]/. Per host
356           proxies can also be specified by using the form ftp::Proxy::<host>
357           with the special keyword DIRECT meaning to use no proxies. If no
358           one of the above settings is specified, ftp_proxy environment
359           variable will be used. To use an FTP proxy you will have to set the
360           ftp::ProxyLogin script in the configuration file. This entry
361           specifies the commands to send to tell the proxy server what to
362           connect to. Please see
363           /usr/share/doc/apt/examples/configure-index.gz for an example of
364           how to do this. The substitution variables representing the
365           corresponding URI component are $(PROXY_USER), $(PROXY_PASS),
366           $(SITE_USER), $(SITE_PASS), $(SITE) and $(SITE_PORT).
367
368           The option timeout sets the timeout timer used by the method; this
369           value applies to the connection as well as the data timeout.
370
371           Several settings are provided to control passive mode. Generally it
372           is safe to leave passive mode on; it works in nearly every
373           environment. However, some situations require that passive mode be
374           disabled and port mode FTP used instead. This can be done globally
375           or for connections that go through a proxy or for a specific host
376           (see the sample config file for examples).
377
378           It is possible to proxy FTP over HTTP by setting the ftp_proxy
379           environment variable to an HTTP URL - see the discussion of the
380           http method above for syntax. You cannot set this in the
381           configuration file and it is not recommended to use FTP over HTTP
382           due to its low efficiency.
383
384           The setting ForceExtended controls the use of RFC2428 EPSV and EPRT
385           commands. The default is false, which means these commands are only
386           used if the control connection is IPv6. Setting this to true forces
387           their use even on IPv4 connections. Note that most FTP servers do
388           not support RFC2428.
389
390       cdrom
391           For URIs using the cdrom method, the only configurable option is
392           the mount point, cdrom::Mount, which must be the mount point for
393           the CD-ROM (or DVD, or whatever) drive as specified in /etc/fstab.
394           It is possible to provide alternate mount and unmount commands if
395           your mount point cannot be listed in the fstab. The syntax is to
396           put
397
398               /cdrom/::Mount "foo";
399
400           within the cdrom block. It is important to have the trailing slash.
401           Unmount commands can be specified using UMount.
402
403       gpgv
404           For GPGV URIs the only configurable option is gpgv::Options, which
405           passes additional parameters to gpgv.
406
407       CompressionTypes
408           List of compression types which are understood by the acquire
409           methods. Files like Packages can be available in various
410           compression formats. By default the acquire methods can decompress
411           and recompress many common formats like xz and gzip; with this
412           scope the supported formats can be queried, modified as well as
413           support for more formats added (see also APT::Compressor). The
414           syntax for this is:
415
416               Acquire::CompressionTypes::FileExtension "Methodname";
417
418           Also, the Order subgroup can be used to define in which order the
419           acquire system will try to download the compressed files. The
420           acquire system will try the first and proceed with the next
421           compression type in this list on error, so to prefer one over the
422           other type simply add the preferred type first - types not already
423           added will be implicitly appended to the end of the list, so e.g.
424
425               Acquire::CompressionTypes::Order:: "gz";
426
427           can be used to prefer gzip compressed files over all other
428           compression formats. If xz should be preferred over gzip and bzip2
429           the configure setting should look like this:
430
431               Acquire::CompressionTypes::Order { "xz"; "gz"; };
432
433           It is not needed to add bz2 to the list explicitly as it will be
434           added automatically.
435
436           Note that the Dir::Bin::Methodname will be checked at run time. If
437           this option has been set and support for this format isn't directly
438           built into apt, the method will only be used if this file exists;
439           e.g. for the bzip2 method (the inbuilt) setting is:
440
441               Dir::Bin::bzip2 "/bin/bzip2";
442
443           Note also that list entries specified on the command line will be
444           added at the end of the list specified in the configuration files,
445           but before the default entries. To prefer a type in this case over
446           the ones specified in the configuration files you can set the
447           option direct - not in list style. This will not override the
448           defined list; it will only prefix the list with this type.
449
450           The special type uncompressed can be used to give uncompressed
451           files a preference, but note that most archives don't provide
452           uncompressed files so this is mostly only usable for local mirrors.
453
454       GzipIndexes
455           When downloading gzip compressed indexes (Packages, Sources, or
456           Translations), keep them gzip compressed locally instead of
457           unpacking them. This saves quite a lot of disk space at the expense
458           of more CPU requirements when building the local package caches.
459           False by default.
460
461       Languages
462           The Languages subsection controls which Translation files are
463           downloaded and in which order APT tries to display the
464           description-translations. APT will try to display the first
465           available description in the language which is listed first.
466           Languages can be defined with their short or long language codes.
467           Note that not all archives provide Translation files for every
468           language - the long language codes are especially rare.
469
470           The default list includes "environment" and "en". "environment" has
471           a special meaning here: it will be replaced at runtime with the
472           language codes extracted from the LC_MESSAGES environment variable.
473           It will also ensure that these codes are not included twice in the
474           list. If LC_MESSAGES is set to "C" only the Translation-en file (if
475           available) will be used. To force APT to use no Translation file
476           use the setting Acquire::Languages=none. "none" is another special
477           meaning code which will stop the search for a suitable Translation
478           file. This tells APT to download these translations too, without
479           actually using them unless the environment specifies the languages.
480           So the following example configuration will result in the order
481           "en, de" in an English locale or "de, en" in a German one. Note
482           that "fr" is downloaded, but not used unless APT is used in a
483           French locale (where the order would be "fr, de, en").
484
485               Acquire::Languages { "environment"; "de"; "en"; "none"; "fr"; };
486
487           Note: To prevent problems resulting from APT being executed in
488           different environments (e.g. by different users or by other
489           programs) all Translation files which are found in
490           /var/lib/apt/lists/ will be added to the end of the list (after an
491           implicit "none").
492
493       ForceIPv4
494           When downloading, force to use only the IPv4 protocol.
495
496       ForceIPv6
497           When downloading, force to use only the IPv6 protocol.
498
499       MaxReleaseFileSize
500           The maximum file size of Release/Release.gpg/InRelease files. The
501           default is 10MB.
502
503       EnableSrvRecords
504           This option controls if apt will use the DNS SRV server record as
505           specified in RFC 2782 to select an alternative server to connect
506           to. The default is "true".
507
508       AllowInsecureRepositories
509           Allow update operations to load data files from repositories
510           without sufficient security information. The default value is
511           "false". Concept, implications as well as alternatives are detailed
512           in apt-secure(8).
513
514       AllowWeakRepositories
515           Allow update operations to load data files from repositories which
516           provide security information, but these are deemed no longer
517           cryptographically strong enough. The default value is "false".
518           Concept, implications as well as alternatives are detailed in apt-
519           secure(8).
520
521       AllowDowngradeToInsecureRepositories
522           Allow that a repository that was previously gpg signed to become
523           unsigned during an update operation. When there is no valid
524           signature for a previously trusted repository apt will refuse the
525           update. This option can be used to override this protection. You
526           almost certainly never want to enable this. The default is false.
527           Concept, implications as well as alternatives are detailed in apt-
528           secure(8).
529
530       Changelogs::URI scope
531           Acquiring changelogs can only be done if an URI is known from where
532           to get them. Preferable the Release file indicates this in a
533           'Changelogs' field. If this isn't available the Label/Origin field
534           of the Release file is used to check if a
535           Acquire::Changelogs::URI::Label::LABEL or
536           Acquire::Changelogs::URI::Origin::ORIGIN option exists and if so
537           this value is taken. The value in the Release file can be
538           overridden with Acquire::Changelogs::URI::Override::Label::LABEL or
539           Acquire::Changelogs::URI::Override::Origin::ORIGIN. The value
540           should be a normal URI to a text file, except that package specific
541           data is replaced with the placeholder @CHANGEPATH@. The value for
542           it is: 1. if the package is from a component (e.g.  main) this is
543           the first part otherwise it is omitted, 2. the first letter of
544           source package name, except if the source package name starts with
545           'lib' in which case it will be the first four letters. 3. The
546           complete source package name. 4. the complete name again and 5. the
547           source version. The first (if present), second, third and fourth
548           part are separated by a slash ('/') and between the fourth and
549           fifth part is an underscore ('_'). The special value 'no' is
550           available for this option indicating that this source can't be used
551           to acquire changelog files from. Another source will be tried if
552           available in this case.
553

BINARY SPECIFIC CONFIGURATION

555       Especially with the introduction of the apt binary it can be useful to
556       set certain options only for a specific binary as even options which
557       look like they would effect only a certain binary like
558       APT::Get::Show-Versions effect apt-get as well as apt.
559
560       Setting an option for a specific binary only can be achieved by setting
561       the option inside the Binary::specific-binary scope. Setting the option
562       APT::Get::Show-Versions for the apt only can e.g. by done by setting
563       Binary::apt::APT::Get::Show-Versions instead.
564
565       Note that as seen in the DESCRIPTION section further above you can't
566       set binary-specific options on the commandline itself nor in
567       configuration files loaded via the commandline.
568

DIRECTORIES

570       The Dir::State section has directories that pertain to local state
571       information.  lists is the directory to place downloaded package lists
572       in and status is the name of the dpkg(1) status file.  preferences is
573       the name of the APT preferences file.  Dir::State contains the default
574       directory to prefix on all sub-items if they do not start with / or ./.
575
576       Dir::Cache contains locations pertaining to local cache information,
577       such as the two package caches srcpkgcache and pkgcache as well as the
578       location to place downloaded archives, Dir::Cache::archives. Generation
579       of caches can be turned off by setting pkgcache or srcpkgcache to "".
580       This will slow down startup but save disk space. It is probably
581       preferable to turn off the pkgcache rather than the srcpkgcache. Like
582       Dir::State the default directory is contained in Dir::Cache
583
584       Dir::Etc contains the location of configuration files, sourcelist gives
585       the location of the sourcelist and main is the default configuration
586       file (setting has no effect, unless it is done from the config file
587       specified by APT_CONFIG).
588
589       The Dir::Parts setting reads in all the config fragments in lexical
590       order from the directory specified. After this is done then the main
591       config file is loaded.
592
593       Binary programs are pointed to by Dir::Bin.  Dir::Bin::Methods
594       specifies the location of the method handlers and gzip, bzip2, lzma,
595       dpkg, apt-get dpkg-source dpkg-buildpackage and apt-cache specify the
596       location of the respective programs.
597
598       The configuration item RootDir has a special meaning. If set, all paths
599       will be relative to RootDir, even paths that are specified absolutely.
600       So, for instance, if RootDir is set to /tmp/staging and
601       Dir::State::status is set to /var/lib/dpkg/status, then the status file
602       will be looked up in /tmp/staging/var/lib/dpkg/status. If you want to
603       prefix only relative paths, set Dir instead.
604
605       The Ignore-Files-Silently list can be used to specify which files APT
606       should silently ignore while parsing the files in the fragment
607       directories. Per default a file which ends with .disabled, ~, .bak or
608       .dpkg-[a-z]+ is silently ignored. As seen in the last default value
609       these patterns can use regular expression syntax.
610

APT IN DSELECT

612       When APT is used as a dselect(1) method several configuration
613       directives control the default behavior. These are in the DSelect
614       section.
615
616       Clean
617           Cache Clean mode; this value may be one of always, prompt, auto,
618           pre-auto and never.  always and prompt will remove all packages
619           from the cache after upgrading, prompt (the default) does so
620           conditionally.  auto removes only those packages which are no
621           longer downloadable (replaced with a new version for instance).
622           pre-auto performs this action before downloading new packages.
623
624       options
625           The contents of this variable are passed to apt-get(8) as command
626           line options when it is run for the install phase.
627
628       Updateoptions
629           The contents of this variable are passed to apt-get(8) as command
630           line options when it is run for the update phase.
631
632       PromptAfterUpdate
633           If true the [U]pdate operation in dselect(1) will always prompt to
634           continue. The default is to prompt only on error.
635

HOW APT CALLS DPKG(1)

637       Several configuration directives control how APT invokes dpkg(1). These
638       are in the DPkg section.
639
640       options
641           This is a list of options to pass to dpkg(1). The options must be
642           specified using the list notation and each list item is passed as a
643           single argument to dpkg(1).
644
645       Path
646           This is a string that defines the PATH environment variable used
647           when running dpkg. It may be set to any valid value of that
648           environment variable; or the empty string, in which case the
649           variable is not changed.
650
651       Pre-Invoke, Post-Invoke
652           This is a list of shell commands to run before/after invoking
653           dpkg(1). Like options this must be specified in list notation. The
654           commands are invoked in order using /bin/sh; should any fail APT
655           will abort.
656
657       Pre-Install-Pkgs
658           This is a list of shell commands to run before invoking dpkg(1).
659           Like options this must be specified in list notation. The commands
660           are invoked in order using /bin/sh; should any fail APT will abort.
661           APT will pass the filenames of all .deb files it is going to
662           install to the commands, one per line on the requested file
663           descriptor, defaulting to standard input.
664
665           Version 2 of this protocol sends more information through the
666           requested file descriptor: a line with the text VERSION 2, the APT
667           configuration space, and a list of package actions with filename
668           and version information.
669
670           Each configuration directive line has the form key=value. Special
671           characters (equal signs, newlines, nonprintable characters,
672           quotation marks, and percent signs in key and newlines,
673           nonprintable characters, and percent signs in value) are %-encoded.
674           Lists are represented by multiple key::=value lines with the same
675           key. The configuration section ends with a blank line.
676
677           Package action lines consist of five fields in Version 2: package
678           name (without architecture qualification even if foreign), old
679           version, direction of version change (< for upgrades, > for
680           downgrades, = for no change), new version, action. The version
681           fields are "-" for no version at all (for example when installing a
682           package for the first time; no version is treated as earlier than
683           any real version, so that is an upgrade, indicated as - < 1.23.4).
684           The action field is "**CONFIGURE**" if the package is being
685           configured, "**REMOVE**" if it is being removed, or the filename of
686           a .deb file if it is being unpacked.
687
688           In Version 3 after each version field follows the architecture of
689           this version, which is "-" if there is no version, and a field
690           showing the MultiArch type "same", "foreign", "allowed" or "none".
691           Note that "none" is an incorrect typename which is just kept to
692           remain compatible, it should be read as "no" and users are
693           encouraged to support both.
694
695           The version of the protocol to be used for the command cmd can be
696           chosen by setting DPkg::Tools::options::cmd::Version accordingly,
697           the default being version 1. If APT isn't supporting the requested
698           version it will send the information in the highest version it has
699           support for instead.
700
701           The file descriptor to be used to send the information can be
702           requested with DPkg::Tools::options::cmd::InfoFD which defaults to
703           0 for standard input and is available since version 0.9.11. Support
704           for the option can be detected by looking for the environment
705           variable APT_HOOK_INFO_FD which contains the number of the used
706           file descriptor as a confirmation.
707
708       Run-Directory
709           APT chdirs to this directory before invoking dpkg(1), the default
710           is /.
711
712       Build-options
713           These options are passed to dpkg-buildpackage(1) when compiling
714           packages; the default is to disable signing and produce all
715           binaries.
716
717       DPkg::ConfigurePending
718           If this option is set APT will call dpkg --configure --pending to
719           let dpkg(1) handle all required configurations and triggers. This
720           option is activated by default, but deactivating it could be useful
721           if you want to run APT multiple times in a row - e.g. in an
722           installer. In this scenario you could deactivate this option in all
723           but the last run.
724

PERIODIC AND ARCHIVES OPTIONS

726       APT::Periodic and APT::Archives groups of options configure behavior of
727       apt periodic updates, which is done by the
728       /usr/lib/apt/apt.systemd.daily script. See the top of this script for
729       the brief documentation of these options.
730

DEBUG OPTIONS

732       Enabling options in the Debug:: section will cause debugging
733       information to be sent to the standard error stream of the program
734       utilizing the apt libraries, or enable special program modes that are
735       primarily useful for debugging the behavior of apt. Most of these
736       options are not interesting to a normal user, but a few may be:
737
738       •   Debug::pkgProblemResolver enables output about the decisions made
739           by dist-upgrade, upgrade, install, remove, purge.
740
741       •   Debug::NoLocking disables all file locking. This can be used to run
742           some operations (for instance, apt-get -s install) as a non-root
743           user.
744
745       •   Debug::pkgDPkgPM prints out the actual command line each time that
746           apt invokes dpkg(1).
747
748       •   Debug::IdentCdrom disables the inclusion of statfs data in CD-ROM
749           IDs.
750
751       A full list of debugging options to apt follows.
752
753       Debug::Acquire::cdrom
754           Print information related to accessing cdrom:// sources.
755
756       Debug::Acquire::ftp
757           Print information related to downloading packages using FTP.
758
759       Debug::Acquire::http
760           Print information related to downloading packages using HTTP.
761
762       Debug::Acquire::https
763           Print information related to downloading packages using HTTPS.
764
765       Debug::Acquire::gpgv
766           Print information related to verifying cryptographic signatures
767           using gpg.
768
769       Debug::aptcdrom
770           Output information about the process of accessing collections of
771           packages stored on CD-ROMs.
772
773       Debug::BuildDeps
774           Describes the process of resolving build-dependencies in apt-
775           get(8).
776
777       Debug::Hashes
778           Output each cryptographic hash that is generated by the apt
779           libraries.
780
781       Debug::IdentCDROM
782           Do not include information from statfs, namely the number of used
783           and free blocks on the CD-ROM filesystem, when generating an ID for
784           a CD-ROM.
785
786       Debug::NoLocking
787           Disable all file locking. For instance, this will allow two
788           instances of “apt-get update” to run at the same time.
789
790       Debug::pkgAcquire
791           Log when items are added to or removed from the global download
792           queue.
793
794       Debug::pkgAcquire::Auth
795           Output status messages and errors related to verifying checksums
796           and cryptographic signatures of downloaded files.
797
798       Debug::pkgAcquire::Diffs
799           Output information about downloading and applying package index
800           list diffs, and errors relating to package index list diffs.
801
802       Debug::pkgAcquire::RRed
803           Output information related to patching apt package lists when
804           downloading index diffs instead of full indices.
805
806       Debug::pkgAcquire::Worker
807           Log all interactions with the sub-processes that actually perform
808           downloads.
809
810       Debug::pkgAutoRemove
811           Log events related to the automatically-installed status of
812           packages and to the removal of unused packages.
813
814       Debug::pkgDepCache::AutoInstall
815           Generate debug messages describing which packages are being
816           automatically installed to resolve dependencies. This corresponds
817           to the initial auto-install pass performed in, e.g., apt-get
818           install, and not to the full apt dependency resolver; see
819           Debug::pkgProblemResolver for that.
820
821       Debug::pkgDepCache::Marker
822           Generate debug messages describing which packages are marked as
823           keep/install/remove while the ProblemResolver does his work. Each
824           addition or deletion may trigger additional actions; they are shown
825           indented two additional spaces under the original entry. The format
826           for each line is MarkKeep, MarkDelete or MarkInstall followed by
827           package-name <a.b.c -> d.e.f | x.y.z> (section) where a.b.c is the
828           current version of the package, d.e.f is the version considered for
829           installation and x.y.z is a newer version, but not considered for
830           installation (because of a low pin score). The later two can be
831           omitted if there is none or if it is the same as the installed
832           version.  section is the name of the section the package appears
833           in.
834
835       Debug::pkgDPkgPM
836           When invoking dpkg(1), output the precise command line with which
837           it is being invoked, with arguments separated by a single space
838           character.
839
840       Debug::pkgDPkgProgressReporting
841           Output all the data received from dpkg(1) on the status file
842           descriptor and any errors encountered while parsing it.
843
844       Debug::pkgOrderList
845           Generate a trace of the algorithm that decides the order in which
846           apt should pass packages to dpkg(1).
847
848       Debug::pkgPackageManager
849           Output status messages tracing the steps performed when invoking
850           dpkg(1).
851
852       Debug::pkgPolicy
853           Output the priority of each package list on startup.
854
855       Debug::pkgProblemResolver
856           Trace the execution of the dependency resolver (this applies only
857           to what happens when a complex dependency problem is encountered).
858
859       Debug::pkgProblemResolver::ShowScores
860           Display a list of all installed packages with their calculated
861           score used by the pkgProblemResolver. The description of the
862           package is the same as described in Debug::pkgDepCache::Marker
863
864       Debug::sourceList
865           Print information about the vendors read from
866           /etc/apt/vendors.list.
867
868       Debug::RunScripts
869           Display the external commands that are called by apt hooks. This
870           includes e.g. the config options DPkg::{Pre,Post}-Invoke or
871           APT::Update::{Pre,Post}-Invoke.
872

EXAMPLES

874       /usr/share/doc/apt/examples/configure-index.gz is a configuration file
875       showing example values for all possible options.
876

FILES

878       /etc/apt/apt.conf
879           APT configuration file. Configuration Item: Dir::Etc::Main.
880
881       /etc/apt/apt.conf.d/
882           APT configuration file fragments. Configuration Item:
883           Dir::Etc::Parts.
884

SEE ALSO

886       apt-cache(8), apt-config(8), apt_preferences(5).
887

BUGS

889       APT bug page[1]. If you wish to report a bug in APT, please see
890       /usr/share/doc/debian/bug-reporting.txt or the reportbug(1) command.
891

AUTHORS

893       Jason Gunthorpe
894
895       APT team
896
897       Daniel Burrows <dburrows@debian.org>
898           Initial documentation of Debug::*.
899

NOTES

901        1. APT bug page
902           http://bugs.debian.org/src:apt
903
904
905
906APT 2.3.5                        04 April 2019                     APT.CONF(5)
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