Merge remote-tracking branch 'mvo/feature/srv-records' into debian/experimental

[apt.git] / doc / apt_preferences.5.xml

diff --git a/doc/apt_preferences.5.xml b/doc/apt_preferences.5.xml
index abcf567445f603ff84ea4350594049df16014320..79132e007088de0f7c1a5f37a2d951c16005c49a 100644 (file)
--- a/doc/apt_preferences.5.xml
+++ b/doc/apt_preferences.5.xml
@@ -1,10 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <?xml version="1.0" encoding="utf-8" standalone="no"?>

-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
-  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
-
-<!ENTITY % aptent SYSTEM "apt.ent">
-%aptent;
-
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
+  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
+<!ENTITY % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;

 ]>
 
 <refentry>
 ]>
 
 <refentry>


@@ -14,7 +13,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
    &apt-email;
    &apt-product;
    <!-- The last update date -->

-   <date>16 February 2010</date>
+   <date>2012-06-09T00:00:00Z</date>

  </refentryinfo>
 
  <refmeta>
  </refentryinfo>
 
  <refmeta>


@@ -42,7 +41,7 @@ the &sources-list; file contains references to more than one distribution
 APT assigns a priority to each version that is available.
 Subject to dependency constraints, <command>apt-get</command> selects the
 version with the highest priority for installation.
 APT assigns a priority to each version that is available.
 Subject to dependency constraints, <command>apt-get</command> selects the
 version with the highest priority for installation.

-The APT preferences file overrides the priorities that APT assigns to
+The APT preferences override the priorities that APT assigns to

 package versions by default, thus giving the user control over which
 one is selected for installation.</para>
 
 package versions by default, thus giving the user control over which
 one is selected for installation.</para>
 


@@ -50,26 +49,28 @@ one is selected for installation.</para>
 the &sources-list; file contains references to more than one source.
 In this case <command>apt-get</command> downloads the instance listed
 earliest in the &sources-list; file.
 the &sources-list; file contains references to more than one source.
 In this case <command>apt-get</command> downloads the instance listed
 earliest in the &sources-list; file.

-The APT preferences file does not affect the choice of instance, only
+The APT preferences do not affect the choice of instance, only

 the choice of version.</para>
 
 <para>Preferences are a strong power in the hands of a system administrator
 but they can become also their biggest nightmare if used without care!
 the choice of version.</para>
 
 <para>Preferences are a strong power in the hands of a system administrator
 but they can become also their biggest nightmare if used without care!

-APT will not questioning the preferences so wrong settings will therefore
+APT will not question the preferences, so wrong settings can

 lead to uninstallable packages or wrong decisions while upgrading packages.
 lead to uninstallable packages or wrong decisions while upgrading packages.

-Even more problems will arise if multiply distribution releases are mixed
+Even more problems will arise if multiple distribution releases are mixed

 without a good understanding of the following paragraphs.
 without a good understanding of the following paragraphs.

-Packages included in a specific release aren't tested in and
-therefore doesn't always work as expected in older or newer releases or
+Packages included in a specific release aren't tested in (and
+therefore don't always work as expected in) older or newer releases, or

 together with other packages from different releases.
 You have been warned.</para>
 
 <para>Note that the files in the <filename>/etc/apt/preferences.d</filename>
 directory are parsed in alphanumeric ascending order and need to obey the
 together with other packages from different releases.
 You have been warned.</para>
 
 <para>Note that the files in the <filename>/etc/apt/preferences.d</filename>
 directory are parsed in alphanumeric ascending order and need to obey the

-following naming convention: The files have no or "<literal>pref</literal>"
-as filename extension and which only contain alphanumeric,  hyphen (-),
-underscore (_) and period (.) characters - otherwise they will be silently
-ignored.</para>
+following naming convention: The files have either no or "<literal>pref</literal>"
+as filename extension and only contain alphanumeric, hyphen (-),
+underscore (_) and period (.) characters.
+Otherwise APT will print a notice that it has ignored a file, unless that
+file matches a pattern in the <literal>Dir::Ignore-Files-Silently</literal>
+configuration list - in which case it will be silently ignored.</para>

 
 <refsect2><title>APT's Default Priority Assignments</title>
 
 
 <refsect2><title>APT's Default Priority Assignments</title>
 


@@ -100,31 +101,39 @@ algorithm to set the priorities of the versions of a package.  Assign:
 <varlistentry>
 <term>priority 1</term>
 <listitem><simpara>to the versions coming from archives which in their <filename>Release</filename>
 <varlistentry>
 <term>priority 1</term>
 <listitem><simpara>to the versions coming from archives which in their <filename>Release</filename>

-files are marked as "NotAutomatic: yes" like the debian experimental archive.</simpara></listitem>
+files are marked as "NotAutomatic: yes" but <emphasis>not</emphasis> as "ButAutomaticUpgrades: yes"
+like the Debian <literal>experimental</literal> archive.</simpara></listitem>

 </varlistentry>
 
 <varlistentry>
 <term>priority 100</term>
 </varlistentry>
 
 <varlistentry>
 <term>priority 100</term>

-<listitem><simpara>to the version that is already installed (if any).</simpara></listitem>
+<listitem><simpara>to the version that is already installed (if any) and to the versions coming
+from archives which in their <filename>Release</filename> files are marked as "NotAutomatic: yes" and
+"ButAutomaticUpgrades: yes" like the Debian backports archive since <literal>squeeze-backports</literal>.
+</simpara></listitem>

 </varlistentry>
 
 <varlistentry>
 <term>priority 500</term>
 </varlistentry>
 
 <varlistentry>
 <term>priority 500</term>

-<listitem><simpara>to the versions that are not installed and do not belong to the target release.</simpara></listitem>
+<listitem><simpara>to the versions that do not belong to the target release.</simpara></listitem>

 </varlistentry>
 
 <varlistentry>
 <term>priority 990</term>
 </varlistentry>
 
 <varlistentry>
 <term>priority 990</term>

-<listitem><simpara>to the versions that are not installed and belong to the target release.</simpara></listitem>
+<listitem><simpara>to the versions that belong to the target release.</simpara></listitem>

 </varlistentry>
 </variablelist>
 </varlistentry>
 </variablelist>

+
+The highest of those priorities whose description matches the version is assigned to the
+version.

 </para>
 
 <para>If the target release has not been specified then APT simply assigns
 priority 100 to all installed package versions and priority 500 to all
 </para>
 
 <para>If the target release has not been specified then APT simply assigns
 priority 100 to all installed package versions and priority 500 to all

-uninstalled package versions, expect versions coming from archives which
+uninstalled package versions, except versions coming from archives which

 in their <filename>Release</filename> files are marked as "NotAutomatic: yes" -
 in their <filename>Release</filename> files are marked as "NotAutomatic: yes" -

-these versions get the priority 1.</para>
+these versions get the priority 1 or priority 100 if it is additionally marked
+as "ButAutomaticUpgrades: yes".</para>

 
 <para>APT then applies the following rules, listed in order of precedence,
 to determine which version of a package to install.
 
 <para>APT then applies the following rules, listed in order of precedence,
 to determine which version of a package to install.


@@ -175,14 +184,14 @@ and a general form.
 <itemizedlist>
 <listitem>
 <simpara>The specific form assigns a priority (a "Pin-Priority") to one or more
 <itemizedlist>
 <listitem>
 <simpara>The specific form assigns a priority (a "Pin-Priority") to one or more

-specified packages and specified version or version range.  For example,
+specified packages with a specified version or version range.  For example,

 the following record assigns a high priority to all versions of
 the following record assigns a high priority to all versions of

-the <filename>perl</filename> package whose version number begins with "<literal>5.8</literal>".
+the <filename>perl</filename> package whose version number begins with "<literal>&good-perl;</literal>".

 Multiple packages can be separated by spaces.</simpara>
 
 <programlisting>
 Package: perl
 Multiple packages can be separated by spaces.</simpara>
 
 <programlisting>
 Package: perl

-Pin: version 5.8*
+Pin: version &good-perl;*

 Pin-Priority: 1001
 </programlisting>
 </listitem>
 Pin-Priority: 1001
 </programlisting>
 </listitem>


@@ -236,19 +245,68 @@ Pin-Priority: 900
 
 <simpara>The following record assigns a high priority to all package versions
 belonging to any release whose Archive name is "<literal>stable</literal>"
 
 <simpara>The following record assigns a high priority to all package versions
 belonging to any release whose Archive name is "<literal>stable</literal>"

-and whose release Version number is "<literal>3.0</literal>".</simpara>
+and whose release Version number is "<literal>&stable-version;</literal>".</simpara>

 
 <programlisting>
 Package: *
 
 <programlisting>
 Package: *

-Pin: release a=stable, v=3.0
+Pin: release a=stable, v=&stable-version;

 Pin-Priority: 500
 </programlisting>
 </listitem>
 </itemizedlist>
 Pin-Priority: 500
 </programlisting>
 </listitem>
 </itemizedlist>

+
+The effect of the comma operator is similar to an "and" in logic: All
+conditions must be satisfied for the pin to match. There is one exception:
+For any type of condition (such as two "a" conditions), only the last such
+condition is checked.
+</para>
+
+</refsect2>
+
+<refsect2><title>Regular expressions and &glob; syntax</title>
+<para>
+APT also supports pinning by &glob; expressions, and regular
+expressions surrounded by slashes. For example, the following
+example assigns the priority 500 to all packages from
+experimental where the name starts with gnome (as a &glob;-like
+expression) or contains the word kde (as a POSIX extended regular
+expression surrounded by slashes).
+</para>
+
+<programlisting>
+Package: gnome* /kde/
+Pin: release a=experimental
+Pin-Priority: 500
+</programlisting>
+
+<para>
+The rule for those expressions is that they can occur anywhere
+where a string can occur. Thus, the following pin assigns the
+priority 990 to all packages from a release starting with &ubuntu-codename;.

 </para>
 
 </para>
 

+<programlisting>
+Package: *
+Pin: release n=&ubuntu-codename;*
+Pin-Priority: 990
+</programlisting>
+
+<para>
+If a regular expression occurs in a <literal>Package</literal> field,
+the behavior is the same as if this regular expression were replaced
+with a list of all package names it matches. It is undecided whether
+this will change in the future; thus you should always list wild-card
+pins first, so later specific pins override it.
+
+The pattern "<literal>*</literal>" in a Package field is not considered
+a &glob; expression in itself.
+</para>

 </refsect2>
 
 </refsect2>
 

+
+
+
+

 <refsect2>
 <title>How APT Interprets Priorities</title>
 
 <refsect2>
 <title>How APT Interprets Priorities</title>
 


@@ -258,30 +316,30 @@ or negative integers.  They are interpreted as follows (roughly speaking):
 
 <variablelist>
 <varlistentry>
 
 <variablelist>
 <varlistentry>

-<term>P &gt; 1000</term>
+<term>P &gt;= 1000</term>

 <listitem><simpara>causes a version to be installed even if this
 constitutes a downgrade of the package</simpara></listitem>
 </varlistentry>
 <varlistentry>
 <listitem><simpara>causes a version to be installed even if this
 constitutes a downgrade of the package</simpara></listitem>
 </varlistentry>
 <varlistentry>

-<term>990 &lt; P &lt;=1000</term>
+<term>990 &lt;= P &lt; 1000</term>

 <listitem><simpara>causes a version to be installed
 even if it does not come from the target release,
 unless the installed version is more recent</simpara></listitem>
 </varlistentry>
 <varlistentry>
 <listitem><simpara>causes a version to be installed
 even if it does not come from the target release,
 unless the installed version is more recent</simpara></listitem>
 </varlistentry>
 <varlistentry>

-<term>500 &lt; P &lt;=990</term>
+<term>500 &lt;= P &lt; 990</term>

 <listitem><simpara>causes a version to be installed
 unless there is a version available belonging to the target release
 or the installed version is more recent</simpara></listitem>
 </varlistentry>
 <varlistentry>
 <listitem><simpara>causes a version to be installed
 unless there is a version available belonging to the target release
 or the installed version is more recent</simpara></listitem>
 </varlistentry>
 <varlistentry>

-<term>100 &lt; P &lt;=500</term>
+<term>100 &lt;= P &lt; 500</term>

 <listitem><simpara>causes a version to be installed
 unless there is a version available belonging to some other
 distribution or the installed version is more recent</simpara></listitem>
 </varlistentry>
 <varlistentry>
 <listitem><simpara>causes a version to be installed
 unless there is a version available belonging to some other
 distribution or the installed version is more recent</simpara></listitem>
 </varlistentry>
 <varlistentry>

-<term>0 &lt; P &lt;=100</term>
+<term>0 &lt; P &lt; 100</term>

 <listitem><simpara>causes a version to be installed
 only if there is no installed version of the package</simpara></listitem>
 </varlistentry>
 <listitem><simpara>causes a version to be installed
 only if there is no installed version of the package</simpara></listitem>
 </varlistentry>


@@ -289,21 +347,28 @@ only if there is no installed version of the package</simpara></listitem>
 <term>P &lt; 0</term>
 <listitem><simpara>prevents the version from being installed</simpara></listitem>
 </varlistentry>
 <term>P &lt; 0</term>
 <listitem><simpara>prevents the version from being installed</simpara></listitem>
 </varlistentry>

+<varlistentry>
+<term>P = 0</term>
+<listitem><simpara>has undefined behaviour, do not use it.</simpara></listitem>
+</varlistentry>

 </variablelist>
 </para>
 
 </variablelist>
 </para>
 

-<para>If any specific-form records match an available package version then the
-first such record determines the priority of the package version.  
-Failing that,
-if any general-form records match an available package version then the
-first such record determines the priority of the package version.</para>
+<para>
+The first specific-form record matching an available package version determines
+the priority of the package version.
+Failing that, the priority of the package is defined as the maximum of all
+priorities defined by generic-form records matching the version.
+Records defined using patterns in the Pin field other than "*" are treated like
+specific-form records.
+</para>

 
 <para>For example, suppose the APT preferences file contains the three
 records presented earlier:</para>
 
 <programlisting>
 Package: perl
 
 <para>For example, suppose the APT preferences file contains the three
 records presented earlier:</para>
 
 <programlisting>
 Package: perl

-Pin: version 5.8*
+Pin: version &good-perl;*

 Pin-Priority: 1001
 
 Package: *
 Pin-Priority: 1001
 
 Package: *


@@ -319,8 +384,8 @@ Pin-Priority: 50
 <itemizedlist>
 <listitem><simpara>The most recent available version of the <literal>perl</literal>
 package will be installed, so long as that version's version number begins
 <itemizedlist>
 <listitem><simpara>The most recent available version of the <literal>perl</literal>
 package will be installed, so long as that version's version number begins

-with "<literal>5.8</literal>".  If <emphasis>any</emphasis> 5.8* version of <literal>perl</literal> is
-available and the installed version is 5.9*, then <literal>perl</literal> will be
+with "<literal>&good-perl;</literal>".  If <emphasis>any</emphasis> &good-perl;* version of <literal>perl</literal> is
+available and the installed version is &bad-perl;*, then <literal>perl</literal> will be

 downgraded.</simpara></listitem>
 <listitem><simpara>A version of any package other than <literal>perl</literal>
 that is available from the local system has priority over other versions,
 downgraded.</simpara></listitem>
 <listitem><simpara>A version of any package other than <literal>perl</literal>
 that is available from the local system has priority over other versions,


@@ -406,17 +471,17 @@ Pin: release n=&testing-codename;
 <varlistentry>
 <term>the <literal>Version:</literal> line</term>
 <listitem><simpara>names the release version.  For example, the
 <varlistentry>
 <term>the <literal>Version:</literal> line</term>
 <listitem><simpara>names the release version.  For example, the

-packages in the tree might belong to Debian GNU/Linux release
-version 3.0.  Note that there is normally no version number for the
+packages in the tree might belong to Debian release
+version &stable-version;.  Note that there is normally no version number for the

 <literal>testing</literal> and <literal>unstable</literal> distributions because they
 have not been released yet.  Specifying this in the APT preferences
 file would require one of the following lines.
 </simpara>
 
 <programlisting>
 <literal>testing</literal> and <literal>unstable</literal> distributions because they
 have not been released yet.  Specifying this in the APT preferences
 file would require one of the following lines.
 </simpara>
 
 <programlisting>

-Pin: release v=3.0
-Pin: release a=stable, v=3.0
-Pin: release 3.0
+Pin: release v=&stable-version;
+Pin: release a=stable, v=&stable-version;
+Pin: release &stable-version;

 </programlisting>
 
 </listitem>
 </programlisting>
 
 </listitem>