support setting empty values (sanely) & removing support for
[apt.git] / doc / apt_preferences.5.xml
CommitLineData
24f6490f 1<?xml version="1.0" encoding="utf-8" standalone="no"?>
81cf16a2
DK
2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
5abbf5bb
DK
4<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
5<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
6<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
b2e465d6
AL
7]>
8
9<refentry>
ec2853a7 10
5e80de29
AL
11 <refentryinfo>
12 &apt-author.team;
13 &apt-email;
14 &apt-product;
15 <!-- The last update date -->
dabb215c 16 <date>2012-06-09T00:00:00Z</date>
5e80de29
AL
17 </refentryinfo>
18
b2e465d6 19 <refmeta>
24f6490f
AL
20 <refentrytitle>apt_preferences</refentrytitle>
21 <manvolnum>5</manvolnum>
f0599b9c 22 <refmiscinfo class="manual">APT</refmiscinfo>
b2e465d6 23 </refmeta>
ec2853a7 24
b2e465d6
AL
25 <!-- Man page title -->
26 <refnamediv>
24f6490f
AL
27 <refname>apt_preferences</refname>
28 <refpurpose>Preference control file for APT</refpurpose>
b2e465d6 29 </refnamediv>
b2e465d6 30
24f6490f
AL
31<refsect1>
32<title>Description</title>
33<para>The APT preferences file <filename>/etc/apt/preferences</filename>
daa4aa52
DK
34and the fragment files in the <filename>/etc/apt/preferences.d/</filename>
35folder can be used to control which versions of packages will be selected
24f6490f 36for installation.</para>
ec2853a7 37
24f6490f 38<para>Several versions of a package may be available for installation when
ec2853a7 39the &sources-list; file contains references to more than one distribution
5b9d504e
AL
40(for example, <literal>stable</literal> and <literal>testing</literal>).
41APT assigns a priority to each version that is available.
42Subject to dependency constraints, <command>apt-get</command> selects the
408a8e0a 43version with the highest priority for installation.
44477002 44The APT preferences override the priorities that APT assigns to
5b9d504e 45package versions by default, thus giving the user control over which
24f6490f
AL
46one is selected for installation.</para>
47
48<para>Several instances of the same version of a package may be available when
408a8e0a
AL
49the &sources-list; file contains references to more than one source.
50In this case <command>apt-get</command> downloads the instance listed
5b9d504e 51earliest in the &sources-list; file.
44477002 52The APT preferences do not affect the choice of instance, only
24f6490f 53the choice of version.</para>
ec2853a7 54
d9dedf30
DK
55<para>Preferences are a strong power in the hands of a system administrator
56but they can become also their biggest nightmare if used without care!
44477002 57APT will not question the preferences, so wrong settings can
d9dedf30 58lead to uninstallable packages or wrong decisions while upgrading packages.
44477002 59Even more problems will arise if multiple distribution releases are mixed
d9dedf30 60without a good understanding of the following paragraphs.
44477002
JR
61Packages included in a specific release aren't tested in (and
62therefore don't always work as expected in) older or newer releases, or
37049546 63together with other packages from different releases.
d9dedf30
DK
64You have been warned.</para>
65
e29a6bb1
DK
66<para>Note that the files in the <filename>/etc/apt/preferences.d</filename>
67directory are parsed in alphanumeric ascending order and need to obey the
1fc8c922
MV
68following naming convention: The files have either no or "<literal>pref</literal>"
69as filename extension and only contain alphanumeric, hyphen (-),
7376837d 70underscore (_) and period (.) characters.
44477002
JR
71Otherwise APT will print a notice that it has ignored a file, unless that
72file matches a pattern in the <literal>Dir::Ignore-Files-Silently</literal>
0ca491a7 73configuration list - in which case it will be silently ignored.</para>
e29a6bb1 74
24f6490f 75<refsect2><title>APT's Default Priority Assignments</title>
ec2853a7 76
24f6490f 77<para>If there is no preferences file or if there is no entry in the file
408a8e0a
AL
78that applies to a particular version then the priority assigned to that
79version is the priority of the distribution to which that version
80belongs. It is possible to single out a distribution, "the target release",
81which receives a higher priority than other distributions do by default.
82The target release can be set on the <command>apt-get</command> command
83line or in the APT configuration file <filename>/etc/apt/apt.conf</filename>.
99fc3e08
LB
84Note that this has precedence over any general priority you set in the
85<filename>/etc/apt/preferences</filename> file described later, but not
86over specifically pinned packages.
408a8e0a 87For example,
24f6490f 88
408a8e0a
AL
89<programlisting>
90<command>apt-get install -t testing <replaceable>some-package</replaceable></command>
91</programlisting>
92<programlisting>
93APT::Default-Release "stable";
94</programlisting>
ec2853a7
AL
95</para>
96
24f6490f 97<para>If the target release has been specified then APT uses the following
408a8e0a 98algorithm to set the priorities of the versions of a package. Assign:
24f6490f 99
ec2853a7 100<variablelist>
10df254b
DK
101<varlistentry>
102<term>priority 1</term>
103<listitem><simpara>to the versions coming from archives which in their <filename>Release</filename>
fcaf14fe 104files are marked as "NotAutomatic: yes" but <emphasis>not</emphasis> as "ButAutomaticUpgrades: yes"
44477002 105like the Debian <literal>experimental</literal> archive.</simpara></listitem>
10df254b
DK
106</varlistentry>
107
ec2853a7
AL
108<varlistentry>
109<term>priority 100</term>
fcaf14fe
DK
110<listitem><simpara>to the version that is already installed (if any) and to the versions coming
111from archives which in their <filename>Release</filename> files are marked as "NotAutomatic: yes" and
44477002 112"ButAutomaticUpgrades: yes" like the Debian backports archive since <literal>squeeze-backports</literal>.
fcaf14fe 113</simpara></listitem>
ec2853a7 114</varlistentry>
24f6490f 115
ec2853a7
AL
116<varlistentry>
117<term>priority 500</term>
1bdfd2c9 118<listitem><simpara>to the versions that do not belong to the target release.</simpara></listitem>
ec2853a7 119</varlistentry>
24f6490f 120
ec2853a7
AL
121<varlistentry>
122<term>priority 990</term>
1bdfd2c9 123<listitem><simpara>to the versions that belong to the target release.</simpara></listitem>
ec2853a7
AL
124</varlistentry>
125</variablelist>
c38847eb
JAK
126
127The highest of those priorities whose description matches the version is assigned to the
128version.
ec2853a7
AL
129</para>
130
24f6490f 131<para>If the target release has not been specified then APT simply assigns
5b9d504e 132priority 100 to all installed package versions and priority 500 to all
a0a1ce6d 133uninstalled package versions, except versions coming from archives which
10df254b 134in their <filename>Release</filename> files are marked as "NotAutomatic: yes" -
fcaf14fe
DK
135these versions get the priority 1 or priority 100 if it is additionally marked
136as "ButAutomaticUpgrades: yes".</para>
ec2853a7 137
24f6490f 138<para>APT then applies the following rules, listed in order of precedence,
5b9d504e 139to determine which version of a package to install.
ec2853a7 140<itemizedlist>
5b9d504e
AL
141<listitem><simpara>Never downgrade unless the priority of an available
142version exceeds 1000. ("Downgrading" is installing a less recent version
143of a package in place of a more recent version. Note that none of APT's
144default priorities exceeds 1000; such high priorities can only be set in
145the preferences file. Note also that downgrading a package
146can be risky.)</simpara></listitem>
147<listitem><simpara>Install the highest priority version.</simpara></listitem>
148<listitem><simpara>If two or more versions have the same priority,
149install the most recent one (that is, the one with the higher version
150number).</simpara></listitem>
151<listitem><simpara>If two or more versions have the same priority and
152version number but either the packages differ in some of their metadata or the
24f6490f 153<literal>--reinstall</literal> option is given, install the uninstalled one.</simpara></listitem>
ec2853a7
AL
154</itemizedlist>
155</para>
156
24f6490f 157<para>In a typical situation, the installed version of a package (priority 100)
5b9d504e
AL
158is not as recent as one of the versions available from the sources listed in
159the &sources-list; file (priority 500 or 990). Then the package will be upgraded
160when <command>apt-get install <replaceable>some-package</replaceable></command>
161or <command>apt-get upgrade</command> is executed.
ec2853a7
AL
162</para>
163
24f6490f 164<para>More rarely, the installed version of a package is <emphasis>more</emphasis> recent
5b9d504e
AL
165than any of the other available versions. The package will not be downgraded
166when <command>apt-get install <replaceable>some-package</replaceable></command>
24f6490f 167or <command>apt-get upgrade</command> is executed.</para>
ec2853a7 168
24f6490f 169<para>Sometimes the installed version of a package is more recent than the
ec2853a7 170version belonging to the target release, but not as recent as a version
5b9d504e
AL
171belonging to some other distribution. Such a package will indeed be upgraded
172when <command>apt-get install <replaceable>some-package</replaceable></command>
173or <command>apt-get upgrade</command> is executed,
24f6490f
AL
174because at least <emphasis>one</emphasis> of the available versions has a higher
175priority than the installed version.</para>
176</refsect2>
ec2853a7 177
24f6490f 178<refsect2><title>The Effect of APT Preferences</title>
ec2853a7 179
24f6490f 180<para>The APT preferences file allows the system administrator to control the
5b9d504e
AL
181assignment of priorities. The file consists of one or more multi-line records
182separated by blank lines. Records can have one of two forms, a specific form
183and a general form.
ec2853a7
AL
184<itemizedlist>
185<listitem>
1c62ab24 186<simpara>The specific form assigns a priority (a "Pin-Priority") to one or more
44477002 187specified packages with a specified version or version range. For example,
5b9d504e 188the following record assigns a high priority to all versions of
44477002 189the <filename>perl</filename> package whose version number begins with "<literal>&good-perl;</literal>".
1c62ab24 190Multiple packages can be separated by spaces.</simpara>
ec2853a7
AL
191
192<programlisting>
193Package: perl
44477002 194Pin: version &good-perl;*
ec2853a7
AL
195Pin-Priority: 1001
196</programlisting>
197</listitem>
198
24f6490f 199<listitem><simpara>The general form assigns a priority to all of the package versions in a
ec2853a7 200given distribution (that is, to all the versions of packages that are
24f6490f 201listed in a certain <filename>Release</filename> file) or to all of the package
5b9d504e 202versions coming from a particular Internet site, as identified by the
24f6490f 203site's fully qualified domain name.</simpara>
ec2853a7 204
24f6490f 205<simpara>This general-form entry in the APT preferences file applies only
5b9d504e 206to groups of packages. For example, the following record assigns a high
24f6490f 207priority to all package versions available from the local site.</simpara>
ec2853a7
AL
208
209<programlisting>
210Package: *
211Pin: origin ""
212Pin-Priority: 999
213</programlisting>
214
4fb6fdaf
DK
215<simpara>A note of caution: the keyword used here is "<literal>origin</literal>"
216which can be used to match a hostname. The following record will assign a high priority
217to all versions available from the server identified by the hostname "ftp.de.debian.org"</simpara>
218<programlisting>
219Package: *
220Pin: origin "ftp.de.debian.org"
221Pin-Priority: 999
222</programlisting>
223<simpara>This should <emphasis>not</emphasis> be confused with the Origin of a distribution as
24f6490f
AL
224specified in a <filename>Release</filename> file. What follows the "Origin:" tag
225in a <filename>Release</filename> file is not an Internet address
226but an author or vendor name, such as "Debian" or "Ximian".</simpara>
ec2853a7 227
24f6490f
AL
228<simpara>The following record assigns a low priority to all package versions
229belonging to any distribution whose Archive name is "<literal>unstable</literal>".</simpara>
ec2853a7
AL
230
231<programlisting>
232Package: *
233Pin: release a=unstable
704c39d6 234Pin-Priority: 50
ec2853a7
AL
235</programlisting>
236
efc487fb 237<simpara>The following record assigns a high priority to all package versions
e1dd65c9 238belonging to any distribution whose Codename is "<literal>&testing-codename;</literal>".</simpara>
efc487fb
DK
239
240<programlisting>
241Package: *
e1dd65c9 242Pin: release n=&testing-codename;
efc487fb
DK
243Pin-Priority: 900
244</programlisting>
245
24f6490f
AL
246<simpara>The following record assigns a high priority to all package versions
247belonging to any release whose Archive name is "<literal>stable</literal>"
44477002 248and whose release Version number is "<literal>&stable-version;</literal>".</simpara>
ec2853a7
AL
249
250<programlisting>
251Package: *
44477002 252Pin: release a=stable, v=&stable-version;
0493db1e 253Pin-Priority: 500
ec2853a7
AL
254</programlisting>
255</listitem>
256</itemizedlist>
35ea8b15
JAK
257
258The effect of the comma operator is similar to an "and" in logic: All
259conditions must be satisfied for the pin to match. There is one exception:
260For any type of condition (such as two "a" conditions), only the last such
261condition is checked.
ec2853a7
AL
262</para>
263
24f6490f 264</refsect2>
ec2853a7 265
44477002 266<refsect2><title>Regular expressions and &glob; syntax</title>
1a4c9766 267<para>
44477002
JR
268APT also supports pinning by &glob; expressions, and regular
269expressions surrounded by slashes. For example, the following
1a4c9766 270example assigns the priority 500 to all packages from
44477002 271experimental where the name starts with gnome (as a &glob;-like
1fc8c922 272expression) or contains the word kde (as a POSIX extended regular
1a4c9766
JAK
273expression surrounded by slashes).
274</para>
275
276<programlisting>
277Package: gnome* /kde/
14c50b58 278Pin: release a=experimental
1a4c9766
JAK
279Pin-Priority: 500
280</programlisting>
281
282<para>
283The rule for those expressions is that they can occur anywhere
1fc8c922 284where a string can occur. Thus, the following pin assigns the
44477002 285priority 990 to all packages from a release starting with &ubuntu-codename;.
1a4c9766
JAK
286</para>
287
288<programlisting>
289Package: *
44477002 290Pin: release n=&ubuntu-codename;*
1a4c9766
JAK
291Pin-Priority: 990
292</programlisting>
293
2b9b27c3 294<para>
1a4c9766
JAK
295If a regular expression occurs in a <literal>Package</literal> field,
296the behavior is the same as if this regular expression were replaced
297with a list of all package names it matches. It is undecided whether
44477002 298this will change in the future; thus you should always list wild-card
1a4c9766
JAK
299pins first, so later specific pins override it.
300
301The pattern "<literal>*</literal>" in a Package field is not considered
44477002 302a &glob; expression in itself.
2b9b27c3 303</para>
1a4c9766
JAK
304</refsect2>
305
306
307
308
309
24f6490f
AL
310<refsect2>
311<title>How APT Interprets Priorities</title>
ec2853a7 312
5b9d504e
AL
313<para>
314Priorities (P) assigned in the APT preferences file must be positive
ec2853a7
AL
315or negative integers. They are interpreted as follows (roughly speaking):
316
317<variablelist>
5b9d504e 318<varlistentry>
5e594b30 319<term>P &gt;= 1000</term>
5b9d504e
AL
320<listitem><simpara>causes a version to be installed even if this
321constitutes a downgrade of the package</simpara></listitem>
ec2853a7 322</varlistentry>
5b9d504e 323<varlistentry>
5e594b30 324<term>990 &lt;= P &lt; 1000</term>
5b9d504e 325<listitem><simpara>causes a version to be installed
ec2853a7 326even if it does not come from the target release,
5b9d504e 327unless the installed version is more recent</simpara></listitem>
ec2853a7 328</varlistentry>
5b9d504e 329<varlistentry>
5e594b30 330<term>500 &lt;= P &lt; 990</term>
5b9d504e
AL
331<listitem><simpara>causes a version to be installed
332unless there is a version available belonging to the target release
333or the installed version is more recent</simpara></listitem>
ec2853a7 334</varlistentry>
5b9d504e 335<varlistentry>
5e594b30 336<term>100 &lt;= P &lt; 500</term>
5b9d504e
AL
337<listitem><simpara>causes a version to be installed
338unless there is a version available belonging to some other
339distribution or the installed version is more recent</simpara></listitem>
24f6490f 340</varlistentry>
5b9d504e 341<varlistentry>
5e594b30 342<term>0 &lt; P &lt; 100</term>
5b9d504e
AL
343<listitem><simpara>causes a version to be installed
344only if there is no installed version of the package</simpara></listitem>
ec2853a7 345</varlistentry>
5b9d504e
AL
346<varlistentry>
347<term>P &lt; 0</term>
348<listitem><simpara>prevents the version from being installed</simpara></listitem>
ec2853a7 349</varlistentry>
809aa216
JAK
350<varlistentry>
351<term>P = 0</term>
352<listitem><simpara>has undefined behaviour, do not use it.</simpara></listitem>
353</varlistentry>
ec2853a7
AL
354</variablelist>
355</para>
356
85b9b329
JAK
357<para>
358The first specific-form record matching an available package version determines
359the priority of the package version.
360Failing that, the priority of the package is defined as the maximum of all
361priorities defined by generic-form records matching the version.
362Records defined using patterns in the Pin field other than "*" are treated like
363specific-form records.
364</para>
ec2853a7 365
24f6490f
AL
366<para>For example, suppose the APT preferences file contains the three
367records presented earlier:</para>
ec2853a7
AL
368
369<programlisting>
370Package: perl
44477002 371Pin: version &good-perl;*
b2e465d6 372Pin-Priority: 1001
ec2853a7 373
b2e465d6 374Package: *
ec2853a7
AL
375Pin: origin ""
376Pin-Priority: 999
377
378Package: *
379Pin: release unstable
380Pin-Priority: 50
381</programlisting>
382
24f6490f 383<para>Then:
ec2853a7 384<itemizedlist>
24f6490f 385<listitem><simpara>The most recent available version of the <literal>perl</literal>
ec2853a7 386package will be installed, so long as that version's version number begins
44477002
JR
387with "<literal>&good-perl;</literal>". If <emphasis>any</emphasis> &good-perl;* version of <literal>perl</literal> is
388available and the installed version is &bad-perl;*, then <literal>perl</literal> will be
ec2853a7 389downgraded.</simpara></listitem>
24f6490f 390<listitem><simpara>A version of any package other than <literal>perl</literal>
5b9d504e
AL
391that is available from the local system has priority over other versions,
392even versions belonging to the target release.
ec2853a7 393</simpara></listitem>
5b9d504e
AL
394<listitem><simpara>A version of a package whose origin is not the local
395system but some other site listed in &sources-list; and which belongs to
24f6490f 396an <literal>unstable</literal> distribution is only installed if it is selected
5b9d504e 397for installation and no version of the package is already installed.
ec2853a7
AL
398</simpara></listitem>
399</itemizedlist>
400</para>
24f6490f 401</refsect2>
ec2853a7 402
24f6490f
AL
403<refsect2>
404<title>Determination of Package Version and Distribution Properties</title>
ec2853a7 405
24f6490f 406<para>The locations listed in the &sources-list; file should provide
ec2853a7 407<filename>Packages</filename> and <filename>Release</filename> files
24f6490f 408to describe the packages available at that location. </para>
ec2853a7 409
24f6490f 410<para>The <filename>Packages</filename> file is normally found in the directory
ec2853a7
AL
411<filename>.../dists/<replaceable>dist-name</replaceable>/<replaceable>component</replaceable>/<replaceable>arch</replaceable></filename>:
412for example, <filename>.../dists/stable/main/binary-i386/Packages</filename>.
413It consists of a series of multi-line records, one for each package available
414in that directory. Only two lines in each record are relevant for setting
415APT priorities:
416<variablelist>
417<varlistentry>
24f6490f 418<term>the <literal>Package:</literal> line</term>
ec2853a7
AL
419<listitem><simpara>gives the package name</simpara></listitem>
420</varlistentry>
421<varlistentry>
24f6490f 422<term>the <literal>Version:</literal> line</term>
ec2853a7
AL
423<listitem><simpara>gives the version number for the named package</simpara></listitem>
424</varlistentry>
425</variablelist>
426</para>
427
24f6490f 428<para>The <filename>Release</filename> file is normally found in the directory
ec2853a7
AL
429<filename>.../dists/<replaceable>dist-name</replaceable></filename>:
430for example, <filename>.../dists/stable/Release</filename>,
e1dd65c9 431or <filename>.../dists/&stable-codename;/Release</filename>.
24f6490f 432It consists of a single multi-line record which applies to <emphasis>all</emphasis> of
5b9d504e 433the packages in the directory tree below its parent. Unlike the
24f6490f 434<filename>Packages</filename> file, nearly all of the lines in a <filename>Release</filename>
ec2853a7
AL
435file are relevant for setting APT priorities:
436
437<variablelist>
438<varlistentry>
efc487fb 439<term>the <literal>Archive:</literal> or <literal>Suite:</literal> line</term>
5b9d504e 440<listitem><simpara>names the archive to which all the packages
ec2853a7 441in the directory tree belong. For example, the line
efc487fb
DK
442"Archive: stable" or
443"Suite: stable"
5b9d504e 444specifies that all of the packages in the directory
24f6490f
AL
445tree below the parent of the <filename>Release</filename> file are in a
446<literal>stable</literal> archive. Specifying this value in the APT preferences file
ec2853a7
AL
447would require the line:
448</simpara>
ec2853a7
AL
449<programlisting>
450Pin: release a=stable
451</programlisting>
452</listitem>
453</varlistentry>
454
efc487fb
DK
455<varlistentry>
456<term>the <literal>Codename:</literal> line</term>
457<listitem><simpara>names the codename to which all the packages
458in the directory tree belong. For example, the line
e1dd65c9 459"Codename: &testing-codename;"
efc487fb
DK
460specifies that all of the packages in the directory
461tree below the parent of the <filename>Release</filename> file belong to a version named
e1dd65c9 462<literal>&testing-codename;</literal>. Specifying this value in the APT preferences file
efc487fb
DK
463would require the line:
464</simpara>
465<programlisting>
e1dd65c9 466Pin: release n=&testing-codename;
efc487fb
DK
467</programlisting>
468</listitem>
469</varlistentry>
470
ec2853a7 471<varlistentry>
24f6490f 472<term>the <literal>Version:</literal> line</term>
ec2853a7 473<listitem><simpara>names the release version. For example, the
b176de3a 474packages in the tree might belong to Debian release
44477002 475version &stable-version;. Note that there is normally no version number for the
24f6490f 476<literal>testing</literal> and <literal>unstable</literal> distributions because they
5b9d504e
AL
477have not been released yet. Specifying this in the APT preferences
478file would require one of the following lines.
ec2853a7
AL
479</simpara>
480
481<programlisting>
44477002
JR
482Pin: release v=&stable-version;
483Pin: release a=stable, v=&stable-version;
484Pin: release &stable-version;
ec2853a7
AL
485</programlisting>
486
487</listitem>
488</varlistentry>
489
490<varlistentry>
24f6490f 491<term>the <literal>Component:</literal> line</term>
ec2853a7 492<listitem><simpara>names the licensing component associated with the
24f6490f 493packages in the directory tree of the <filename>Release</filename> file.
5b9d504e 494For example, the line "Component: main" specifies that
24f6490f 495all the packages in the directory tree are from the <literal>main</literal>
5b9d504e
AL
496component, which entails that they are licensed under terms listed
497in the Debian Free Software Guidelines. Specifying this component
498in the APT preferences file would require the line:
ec2853a7 499</simpara>
ec2853a7
AL
500<programlisting>
501Pin: release c=main
502</programlisting>
503</listitem>
504</varlistentry>
505
506<varlistentry>
24f6490f 507<term>the <literal>Origin:</literal> line</term>
5b9d504e 508<listitem><simpara>names the originator of the packages in the
24f6490f
AL
509directory tree of the <filename>Release</filename> file. Most commonly, this is
510<literal>Debian</literal>. Specifying this origin in the APT preferences file
ec2853a7
AL
511would require the line:
512</simpara>
ec2853a7
AL
513<programlisting>
514Pin: release o=Debian
515</programlisting>
516</listitem>
517</varlistentry>
518
519<varlistentry>
24f6490f 520<term>the <literal>Label:</literal> line</term>
5b9d504e 521<listitem><simpara>names the label of the packages in the directory tree
24f6490f
AL
522of the <filename>Release</filename> file. Most commonly, this is
523<literal>Debian</literal>. Specifying this label in the APT preferences file
ec2853a7
AL
524would require the line:
525</simpara>
ec2853a7
AL
526<programlisting>
527Pin: release l=Debian
528</programlisting>
529</listitem>
530</varlistentry>
531</variablelist>
532</para>
533
24f6490f 534<para>All of the <filename>Packages</filename> and <filename>Release</filename>
5b9d504e 535files retrieved from locations listed in the &sources-list; file are stored
ec2853a7 536in the directory <filename>/var/lib/apt/lists</filename>, or in the file named
24f6490f 537by the variable <literal>Dir::State::Lists</literal> in the <filename>apt.conf</filename> file.
ec2853a7
AL
538For example, the file
539<filename>debian.lcs.mit.edu_debian_dists_unstable_contrib_binary-i386_Release</filename>
540contains the <filename>Release</filename> file retrieved from the site
24f6490f
AL
541<literal>debian.lcs.mit.edu</literal> for <literal>binary-i386</literal> architecture
542files from the <literal>contrib</literal> component of the <literal>unstable</literal>
543distribution.</para>
544</refsect2>
ec2853a7 545
24f6490f
AL
546<refsect2>
547<title>Optional Lines in an APT Preferences Record</title>
ec2853a7 548
24f6490f
AL
549<para>Each record in the APT preferences file can optionally begin with
550one or more lines beginning with the word <literal>Explanation:</literal>.
551This provides a place for comments.</para>
24f6490f
AL
552</refsect2>
553</refsect1>
ec2853a7 554
24f6490f
AL
555<refsect1>
556<title>Examples</title>
557<refsect2>
558<title>Tracking Stable</title>
ec2853a7 559
24f6490f 560<para>The following APT preferences file will cause APT to assign a
ec2853a7 561priority higher than the default (500) to all package versions belonging
24f6490f
AL
562to a <literal>stable</literal> distribution and a prohibitively low priority to
563package versions belonging to other <literal>Debian</literal> distributions.
ec2853a7
AL
564
565<programlisting>
5b9d504e
AL
566Explanation: Uninstall or do not install any Debian-originated
567Explanation: package versions other than those in the stable distro
ec2853a7
AL
568Package: *
569Pin: release a=stable
570Pin-Priority: 900
571
ec2853a7
AL
572Package: *
573Pin: release o=Debian
574Pin-Priority: -10
575</programlisting>
576</para>
577
24f6490f 578<para>With a suitable &sources-list; file and the above preferences file,
ec2853a7 579any of the following commands will cause APT to upgrade to the
24f6490f 580latest <literal>stable</literal> version(s).
ec2853a7
AL
581
582<programlisting>
583apt-get install <replaceable>package-name</replaceable>
584apt-get upgrade
585apt-get dist-upgrade
586</programlisting>
587</para>
588
24f6490f
AL
589<para>The following command will cause APT to upgrade the specified
590package to the latest version from the <literal>testing</literal> distribution;
5b9d504e
AL
591the package will not be upgraded again unless this command is given
592again.
ec2853a7
AL
593
594<programlisting>
595apt-get install <replaceable>package</replaceable>/testing
596</programlisting>
24f6490f
AL
597</para>
598</refsect2>
ec2853a7 599
24f6490f
AL
600 <refsect2>
601 <title>Tracking Testing or Unstable</title>
ec2853a7 602
24f6490f
AL
603<para>The following APT preferences file will cause APT to assign
604a high priority to package versions from the <literal>testing</literal>
5b9d504e 605distribution, a lower priority to package versions from the
24f6490f
AL
606<literal>unstable</literal> distribution, and a prohibitively low priority
607to package versions from other <literal>Debian</literal> distributions.
ec2853a7
AL
608
609<programlisting>
610Package: *
611Pin: release a=testing
612Pin-Priority: 900
613
614Package: *
615Pin: release a=unstable
616Pin-Priority: 800
617
618Package: *
619Pin: release o=Debian
620Pin-Priority: -10
621</programlisting>
622</para>
623
24f6490f 624<para>With a suitable &sources-list; file and the above preferences file,
5b9d504e 625any of the following commands will cause APT to upgrade to the latest
24f6490f 626<literal>testing</literal> version(s).
ec2853a7
AL
627
628<programlisting>
629apt-get install <replaceable>package-name</replaceable>
630apt-get upgrade
631apt-get dist-upgrade
632</programlisting>
633</para>
634
635<para>The following command will cause APT to upgrade the specified
24f6490f 636package to the latest version from the <literal>unstable</literal> distribution.
5b9d504e 637Thereafter, <command>apt-get upgrade</command> will upgrade
24f6490f 638the package to the most recent <literal>testing</literal> version if that is
5b9d504e 639more recent than the installed version, otherwise, to the most recent
24f6490f 640<literal>unstable</literal> version if that is more recent than the installed
5b9d504e 641version.
ec2853a7
AL
642
643<programlisting>
644apt-get install <replaceable>package</replaceable>/unstable
645</programlisting>
646</para>
efc487fb
DK
647</refsect2>
648
649
650<refsect2>
651<title>Tracking the evolution of a codename release</title>
652
653<para>The following APT preferences file will cause APT to assign a
654priority higher than the default (500) to all package versions belonging
655to a specified codename of a distribution and a prohibitively low priority to
656package versions belonging to other <literal>Debian</literal> distributions,
657codenames and archives.
658Note that with this APT preference APT will follow the migration of a release
659from the archive <literal>testing</literal> to <literal>stable</literal> and
660later <literal>oldstable</literal>. If you want to follow for example the progress
661in <literal>testing</literal> notwithstanding the codename changes you should use
662the example configurations above.
663
664<programlisting>
665Explanation: Uninstall or do not install any Debian-originated package versions
e1dd65c9 666Explanation: other than those in the distribution codenamed with &testing-codename; or sid
efc487fb 667Package: *
e1dd65c9 668Pin: release n=&testing-codename;
efc487fb
DK
669Pin-Priority: 900
670
671Explanation: Debian unstable is always codenamed with sid
672Package: *
4a2bb9e6 673Pin: release n=sid
efc487fb
DK
674Pin-Priority: 800
675
676Package: *
677Pin: release o=Debian
678Pin-Priority: -10
679</programlisting>
680</para>
681
682<para>With a suitable &sources-list; file and the above preferences file,
683any of the following commands will cause APT to upgrade to the
e1dd65c9 684latest version(s) in the release codenamed with <literal>&testing-codename;</literal>.
efc487fb
DK
685
686<programlisting>
687apt-get install <replaceable>package-name</replaceable>
688apt-get upgrade
689apt-get dist-upgrade
690</programlisting>
691</para>
692
693<para>The following command will cause APT to upgrade the specified
694package to the latest version from the <literal>sid</literal> distribution.
695Thereafter, <command>apt-get upgrade</command> will upgrade
e1dd65c9 696the package to the most recent <literal>&testing-codename;</literal> version if that is
efc487fb
DK
697more recent than the installed version, otherwise, to the most recent
698<literal>sid</literal> version if that is more recent than the installed
699version.
ec2853a7 700
efc487fb
DK
701<programlisting>
702apt-get install <replaceable>package</replaceable>/sid
703</programlisting>
704</para>
24f6490f
AL
705</refsect2>
706</refsect1>
ec2853a7 707
daa4aa52
DK
708<refsect1>
709<title>Files</title>
710 <variablelist>
711 &file-preferences;
712 </variablelist>
713</refsect1>
714
24f6490f
AL
715<refsect1>
716<title>See Also</title>
5e80de29 717<para>&apt-get; &apt-cache; &apt-conf; &sources-list;
5b9d504e 718</para>
24f6490f 719</refsect1>
b2e465d6
AL
720
721 &manbugs;
ec2853a7 722
b2e465d6 723</refentry>