1APT_PREFERENCES(5) APT APT_PREFERENCES(5)
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6 apt_preferences - Preference control file for APT
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9 The APT preferences file /etc/apt/preferences and the fragment files in
10 the /etc/apt/preferences.d/ folder can be used to control which
11 versions of packages will be selected for installation.
12 Several versions of a package may be available for installation when
14 the sources.list(5) file contains references to more than one
15 distribution (for example, stable and testing). APT assigns a priority
16 to each version that is available. Subject to dependency constraints,
17 apt-get selects the version with the highest priority for installation.
18 The APT preferences override the priorities that APT assigns to package
19 versions by default, thus giving the user control over which one is
20 selected for installation.
21 Several instances of the same version of a package may be available
23 when the sources.list(5) file contains references to more than one
24 source. In this case apt-get downloads the instance listed earliest in
25 the sources.list(5) file. The APT preferences do not affect the choice
26 of instance, only the choice of version.
27 Preferences are a strong power in the hands of a system administrator
29 but they can become also their biggest nightmare if used without care!
30 APT will not question the preferences, so wrong settings can lead to
31 uninstallable packages or wrong decisions while upgrading packages.
32 Even more problems will arise if multiple distribution releases are
33 mixed without a good understanding of the following paragraphs.
34 Packages included in a specific release aren't tested in (and therefore
35 don't always work as expected in) older or newer releases, or together
36 with other packages from different releases. You have been warned.
37 Note that the files in the /etc/apt/preferences.d directory are parsed
39 in alphanumeric ascending order and need to obey the following naming
40 convention: The files have either no or "pref" as filename extension
41 and only contain alphanumeric, hyphen (-), underscore (_) and period
42 (.) characters. Otherwise APT will print a notice that it has ignored a
43 file, unless that file matches a pattern in the
44 Dir::Ignore-Files-Silently configuration list - in which case it will
45 be silently ignored.
46 APT's Default Priority Assignments
48 If there is no preferences file or if there is no entry in the file
49 that applies to a particular version then the priority assigned to that
50 version is the priority of the distribution to which that version
51 belongs. It is possible to single out a distribution, "the target
52 release", which receives a higher priority than other distributions do
53 by default. The target release can be set on the apt-get command line
54 or in the APT configuration file /etc/apt/apt.conf. Note that this has
55 precedence over any general priority you set in the
56 /etc/apt/preferences file described later, but not over specifically
57 pinned packages. For example,
58 apt-get install -t testing some-package
60 APT::Default-Release "stable";
64 If the target release has been specified then APT uses the following
66 algorithm to set the priorities of the versions of a package. Assign:
67 priority 1
69 to the versions coming from archives which in their Release files
70 are marked as "NotAutomatic: yes" but not as "ButAutomaticUpgrades:
71 yes" like the Debian experimental archive.
72 priority 100
74 to the version that is already installed (if any) and to the
75 versions coming from archives which in their Release files are
76 marked as "NotAutomatic: yes" and "ButAutomaticUpgrades: yes" like
77 the Debian backports archive since squeeze-backports.
78 priority 500
80 to the versions that do not belong to the target release.
81 priority 990
83 to the versions that belong to the target release.
84 The highest of those priorities whose description matches the version
85 is assigned to the version.
86 If the target release has not been specified then APT simply assigns
88 priority 100 to all installed package versions and priority 500 to all
89 uninstalled package versions, except versions coming from archives
90 which in their Release files are marked as "NotAutomatic: yes" - these
91 versions get the priority 1 or priority 100 if it is additionally
92 marked as "ButAutomaticUpgrades: yes".
93 APT then applies the following rules, listed in order of precedence, to
95 determine which version of a package to install.
96 · Never downgrade unless the priority of an available version exceeds
98 1000. ("Downgrading" is installing a less recent version of a
99 package in place of a more recent version. Note that none of APT's
100 default priorities exceeds 1000; such high priorities can only be
101 set in the preferences file. Note also that downgrading a package
102 can be risky.)
103 · Install the highest priority version.
105 · If two or more versions have the same priority, install the most
107 recent one (that is, the one with the higher version number).
108 · If two or more versions have the same priority and version number
110 but either the packages differ in some of their metadata or the
111 --reinstall option is given, install the uninstalled one.
112 In a typical situation, the installed version of a package (priority
114 100) is not as recent as one of the versions available from the sources
115 listed in the sources.list(5) file (priority 500 or 990). Then the
116 package will be upgraded when apt-get install some-package or apt-get
117 upgrade is executed.
118 More rarely, the installed version of a package is more recent than any
120 of the other available versions. The package will not be downgraded
121 when apt-get install some-package or apt-get upgrade is executed.
122 Sometimes the installed version of a package is more recent than the
124 version belonging to the target release, but not as recent as a version
125 belonging to some other distribution. Such a package will indeed be
126 upgraded when apt-get install some-package or apt-get upgrade is
127 executed, because at least one of the available versions has a higher
128 priority than the installed version.
129 The Effect of APT Preferences
131 The APT preferences file allows the system administrator to control the
132 assignment of priorities. The file consists of one or more multi-line
133 records separated by blank lines. Records can have one of two forms, a
134 specific form and a general form.
135 · The specific form assigns a priority (a "Pin-Priority") to one or
137 more specified packages with a specified version or version range.
138 For example, the following record assigns a high priority to all
139 versions of the perl package whose version number begins with
140 "5.20". Multiple packages can be separated by spaces.
141 Package: perl
143 Pin: version 5.20*
144 Pin-Priority: 1001
145 · The general form assigns a priority to all of the package versions
147 in a given distribution (that is, to all the versions of packages
148 that are listed in a certain Release file) or to all of the package
149 versions coming from a particular Internet site, as identified by
150 the site's fully qualified domain name.
151 This general-form entry in the APT preferences file applies only to
153 groups of packages. For example, the following record assigns a
154 high priority to all package versions available from the local
155 site.
156 Package: *
158 Pin: origin ""
159 Pin-Priority: 999
160 A note of caution: the keyword used here is "origin" which can be
162 used to match a hostname. The following record will assign a high
163 priority to all versions available from the server identified by
164 the hostname "ftp.de.debian.org"
165 Package: *
167 Pin: origin "ftp.de.debian.org"
168 Pin-Priority: 999
169 This should not be confused with the Origin of a distribution as
171 specified in a Release file. What follows the "Origin:" tag in a
172 Release file is not an Internet address but an author or vendor
173 name, such as "Debian" or "Ximian".
174 The following record assigns a low priority to all package versions
176 belonging to any distribution whose Archive name is "unstable".
177 Package: *
179 Pin: release a=unstable
180 Pin-Priority: 50
181 The following record assigns a high priority to all package
183 versions belonging to any distribution whose Codename is
184 "bullseye".
185 Package: *
187 Pin: release n=bullseye
188 Pin-Priority: 900
189 The following record assigns a high priority to all package
191 versions belonging to any release whose Archive name is "stable"
192 and whose release Version number is "10".
193 Package: *
195 Pin: release a=stable, v=10
196 Pin-Priority: 500
197 The effect of the comma operator is similar to an "and" in logic: All
199 conditions must be satisfied for the pin to match. There is one
200 exception: For any type of condition (such as two "a" conditions), only
201 the last such condition is checked.
202 Regular expressions and glob(7) syntax
204 APT also supports pinning by glob(7) expressions, and regular
205 expressions surrounded by slashes. For example, the following example
206 assigns the priority 500 to all packages from experimental where the
207 name starts with gnome (as a glob(7)-like expression) or contains the
208 word kde (as a POSIX extended regular expression surrounded by
209 slashes).
210 Package: gnome* /kde/
212 Pin: release a=experimental
213 Pin-Priority: 500
214 The rule for those expressions is that they can occur anywhere where a
216 string can occur. Thus, the following pin assigns the priority 990 to
217 all packages from a release starting with focal.
218 Package: *
220 Pin: release n=focal*
221 Pin-Priority: 990
222 If a regular expression occurs in a Package field, the behavior is the
224 same as if this regular expression were replaced with a list of all
225 package names it matches. It is undecided whether this will change in
226 the future; thus you should always list wild-card pins first, so later
227 specific pins override it. The pattern "*" in a Package field is not
228 considered a glob(7) expression in itself.
229 Pinning by source package
231 APT supports pinning by source packages. To pin by a source package,
232 prepend "src:" to the package name.
233 For example, to pin all binaries produced by the apt source package of
235 this APT's version to 990, you can do:
236 Package: src:apt
238 Pin: version 2.0.2
239 Pin-Priority: 990
240 Source package pinning can be combined with regular expressions and
242 glob patterns, and can also take a binary architecture.
243 For example, let's pin all binaries for all architectures produced by
245 any source package containing apt in its name to 990:
246 Package: src:*apt*:any
248 Pin: version *
249 Pin-Priority: 990
250 How APT Interprets Priorities
252 Priorities (P) assigned in the APT preferences file must be positive or
253 negative integers. They are interpreted as follows (roughly speaking):
254 P >= 1000
256 causes a version to be installed even if this constitutes a
257 downgrade of the package
258 990 <= P < 1000
260 causes a version to be installed even if it does not come from the
261 target release, unless the installed version is more recent
262 500 <= P < 990
264 causes a version to be installed unless there is a version
265 available belonging to the target release or the installed version
266 is more recent
267 100 <= P < 500
269 causes a version to be installed unless there is a version
270 available belonging to some other distribution or the installed
271 version is more recent
272 0 < P < 100
274 causes a version to be installed only if there is no installed
275 version of the package
276 P < 0
278 prevents the version from being installed
279 P = 0
281 has undefined behaviour, do not use it.
282 The first specific-form record matching an available package version
284 determines the priority of the package version. Failing that, the
285 priority of the package is defined as the maximum of all priorities
286 defined by generic-form records matching the version. Records defined
287 using patterns in the Pin field other than "*" are treated like
288 specific-form records.
289 For example, suppose the APT preferences file contains the three
291 records presented earlier:
292 Package: perl
294 Pin: version 5.20*
295 Pin-Priority: 1001
296 Package: *
298 Pin: origin ""
299 Pin-Priority: 999
300 Package: *
302 Pin: release unstable
303 Pin-Priority: 50
304 Then:
306 · The most recent available version of the perl package will be
308 installed, so long as that version's version number begins with
309 "5.20". If any 5.20* version of perl is available and the installed
310 version is 5.24*, then perl will be downgraded.
311 · A version of any package other than perl that is available from the
313 local system has priority over other versions, even versions
314 belonging to the target release.
315 · A version of a package whose origin is not the local system but
317 some other site listed in sources.list(5) and which belongs to an
318 unstable distribution is only installed if it is selected for
319 installation and no version of the package is already installed.
320 Determination of Package Version and Distribution Properties
323 The locations listed in the sources.list(5) file should provide
324 Packages and Release files to describe the packages available at that
325 location.
326 The Packages file is normally found in the directory
328 .../dists/dist-name/component/arch: for example,
329 .../dists/stable/main/binary-i386/Packages. It consists of a series of
330 multi-line records, one for each package available in that directory.
331 Only two lines in each record are relevant for setting APT priorities:
332 the Package: line
334 gives the package name
335 the Version: line
337 gives the version number for the named package
338 The Release file is normally found in the directory
340 .../dists/dist-name: for example, .../dists/stable/Release, or
341 .../dists/buster/Release. It consists of a single multi-line record
342 which applies to all of the packages in the directory tree below its
343 parent. Unlike the Packages file, nearly all of the lines in a Release
344 file are relevant for setting APT priorities:
345 the Archive: or Suite: line
347 names the archive to which all the packages in the directory tree
348 belong. For example, the line "Archive: stable" or "Suite: stable"
349 specifies that all of the packages in the directory tree below the
350 parent of the Release file are in a stable archive. Specifying this
351 value in the APT preferences file would require the line:
352 Pin: release a=stable
354 the Codename: line
356 names the codename to which all the packages in the directory tree
357 belong. For example, the line "Codename: bullseye" specifies that
358 all of the packages in the directory tree below the parent of the
359 Release file belong to a version named bullseye. Specifying this
360 value in the APT preferences file would require the line:
361 Pin: release n=bullseye
363 the Version: line
365 names the release version. For example, the packages in the tree
366 might belong to Debian release version 10. Note that there is
367 normally no version number for the testing and unstable
368 distributions because they have not been released yet. Specifying
369 this in the APT preferences file would require one of the following
370 lines.
371 Pin: release v=10
373 Pin: release a=stable, v=10
374 Pin: release 10
375 the Component: line
377 names the licensing component associated with the packages in the
378 directory tree of the Release file. For example, the line
379 "Component: main" specifies that all the packages in the directory
380 tree are from the main component, which entails that they are
381 licensed under terms listed in the Debian Free Software Guidelines.
382 Specifying this component in the APT preferences file would require
383 the line:
384 Pin: release c=main
386 the Origin: line
388 names the originator of the packages in the directory tree of the
389 Release file. Most commonly, this is Debian. Specifying this origin
390 in the APT preferences file would require the line:
391 Pin: release o=Debian
393 the Label: line
395 names the label of the packages in the directory tree of the
396 Release file. Most commonly, this is Debian. Specifying this label
397 in the APT preferences file would require the line:
398 Pin: release l=Debian
400 All of the Packages and Release files retrieved from locations listed
402 in the sources.list(5) file are stored in the directory
403 /var/lib/apt/lists, or in the file named by the variable
404 Dir::State::Lists in the apt.conf file. For example, the file
405 debian.lcs.mit.edu_debian_dists_unstable_contrib_binary-i386_Release
406 contains the Release file retrieved from the site debian.lcs.mit.edu
407 for binary-i386 architecture files from the contrib component of the
408 unstable distribution.
409 Optional Lines in an APT Preferences Record
411 Each record in the APT preferences file can optionally begin with one
412 or more lines beginning with the word Explanation:. This provides a
413 place for comments.
414
416 Tracking Stable
417 The following APT preferences file will cause APT to assign a priority
418 higher than the default (500) to all package versions belonging to a
419 stable distribution and a prohibitively low priority to package
420 versions belonging to other Debian distributions.
421 Explanation: Uninstall or do not install any Debian-originated
423 Explanation: package versions other than those in the stable distro
424 Package: *
425 Pin: release a=stable
426 Pin-Priority: 900
427 Package: *
429 Pin: release o=Debian
430 Pin-Priority: -10
431 With a suitable sources.list(5) file and the above preferences file,
433 any of the following commands will cause APT to upgrade to the latest
434 stable version(s).
435 apt-get install package-name
437 apt-get upgrade
438 apt-get dist-upgrade
439 The following command will cause APT to upgrade the specified package
441 to the latest version from the testing distribution; the package will
442 not be upgraded again unless this command is given again.
443 apt-get install package/testing
445 Tracking Testing or Unstable
448 The following APT preferences file will cause APT to assign a high
449 priority to package versions from the testing distribution, a lower
450 priority to package versions from the unstable distribution, and a
451 prohibitively low priority to package versions from other Debian
452 distributions.
453 Package: *
455 Pin: release a=testing
456 Pin-Priority: 900
457 Package: *
459 Pin: release a=unstable
460 Pin-Priority: 800
461 Package: *
463 Pin: release o=Debian
464 Pin-Priority: -10
465 With a suitable sources.list(5) file and the above preferences file,
467 any of the following commands will cause APT to upgrade to the latest
468 testing version(s).
469 apt-get install package-name
471 apt-get upgrade
472 apt-get dist-upgrade
473 The following command will cause APT to upgrade the specified package
475 to the latest version from the unstable distribution. Thereafter,
476 apt-get upgrade will upgrade the package to the most recent testing
477 version if that is more recent than the installed version, otherwise,
478 to the most recent unstable version if that is more recent than the
479 installed version.
480 apt-get install package/unstable
482 Tracking the evolution of a codename release
485 The following APT preferences file will cause APT to assign a priority
486 higher than the default (500) to all package versions belonging to a
487 specified codename of a distribution and a prohibitively low priority
488 to package versions belonging to other Debian distributions, codenames
489 and archives. Note that with this APT preference APT will follow the
490 migration of a release from the archive testing to stable and later
491 oldstable. If you want to follow for example the progress in testing
492 notwithstanding the codename changes you should use the example
493 configurations above.
494 Explanation: Uninstall or do not install any Debian-originated package versions
496 Explanation: other than those in the distribution codenamed with bullseye or sid
497 Package: *
498 Pin: release n=bullseye
499 Pin-Priority: 900
500 Explanation: Debian unstable is always codenamed with sid
502 Package: *
503 Pin: release n=sid
504 Pin-Priority: 800
505 Package: *
507 Pin: release o=Debian
508 Pin-Priority: -10
509 With a suitable sources.list(5) file and the above preferences file,
511 any of the following commands will cause APT to upgrade to the latest
512 version(s) in the release codenamed with bullseye.
513 apt-get install package-name
515 apt-get upgrade
516 apt-get dist-upgrade
517 The following command will cause APT to upgrade the specified package
519 to the latest version from the sid distribution. Thereafter, apt-get
520 upgrade will upgrade the package to the most recent bullseye version if
521 that is more recent than the installed version, otherwise, to the most
522 recent sid version if that is more recent than the installed version.
523 apt-get install package/sid
525
528 /etc/apt/preferences
529 Version preferences file. This is where you would specify
530 "pinning", i.e. a preference to get certain packages from a
531 separate source or from a different version of a distribution.
532 Configuration Item: Dir::Etc::Preferences.
533 /etc/apt/preferences.d/
535 File fragments for the version preferences. Configuration Item:
536 Dir::Etc::PreferencesParts.
537
539 apt-get(8) apt-cache(8) apt.conf(5) sources.list(5)
540
542 APT bug page[1]. If you wish to report a bug in APT, please see
543 /usr/share/doc/debian/bug-reporting.txt or the reportbug(1) command.
544
546 APT team
547
549 1. APT bug page
550 http://bugs.debian.org/src:apt
551APT 2.0.2 17 January 2020 APT_PREFERENCES(5)