X-Git-Url: https://git.saurik.com/apt.git/blobdiff_plain/fb2894d268d4821e0dd4f2b803ff2043b1ec3162..4fb6fdaf95de3db51ef386de7b494ed4c889bedc:/doc/apt_preferences.5.xml

diff --git a/doc/apt_preferences.5.xml b/doc/apt_preferences.5.xml
index ab0107d36..c927f327a 100644
--- a/doc/apt_preferences.5.xml
+++ b/doc/apt_preferences.5.xml
@@ -14,12 +14,13 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>29 February 2004</date>
+   <date>16 February 2010</date>
  </refentryinfo>
 
  <refmeta>
    <refentrytitle>apt_preferences</refentrytitle>
    <manvolnum>5</manvolnum>
+   <refmiscinfo class="manual">APT</refmiscinfo>
  </refmeta>
 
  <!-- Man page title -->
@@ -31,7 +32,8 @@
 <refsect1>
 <title>Description</title>
 <para>The APT preferences file <filename>/etc/apt/preferences</filename>
-can be used to control which versions of packages will be selected
+and the fragment files in the <filename>/etc/apt/preferences.d/</filename>
+folder can be used to control which versions of packages will be selected
 for installation.</para>
 
 <para>Several versions of a package may be available for installation when
@@ -51,6 +53,24 @@ earliest in the &sources-list; file.
 The APT preferences file does 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!
+APT will not questioning the preferences so wrong settings will therefore
+lead to uninstallable packages or wrong decisions while upgrading packages.
+Even more problems will arise if multiply distribution releases are mixed
+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
+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>
+
 <refsect2><title>APT's Default Priority Assignments</title>
 
 <para>If there is no preferences file or if there is no entry in the file
@@ -60,6 +80,9 @@ belongs.  It is possible to single out a distribution, "the target release",
 which receives a higher priority than other distributions do by default.
 The target release can be set on the <command>apt-get</command> command
 line or in the APT configuration file <filename>/etc/apt/apt.conf</filename>.
+Note that this has precedence over any general priority you set in the
+<filename>/etc/apt/preferences</filename> file described later, but not
+over specifically pinned packages.
 For example,
 
 <programlisting>
@@ -172,8 +195,15 @@ Pin: origin ""
 Pin-Priority: 999
 </programlisting>
 
-<simpara>A note of caution: the keyword used here is "<literal>origin</literal>".
-This should not be confused with the Origin of a distribution as
+<simpara>A note of caution: the keyword used here is "<literal>origin</literal>"
+which can be used to match a hostname. The following record will assign a high priority
+to all versions available from the server identified by the hostname "ftp.de.debian.org"</simpara>
+<programlisting>
+Package: *
+Pin: origin "ftp.de.debian.org"
+Pin-Priority: 999
+</programlisting>
+<simpara>This should <emphasis>not</emphasis> be confused with the Origin of a distribution as
 specified in a <filename>Release</filename> file.  What follows the "Origin:" tag
 in a <filename>Release</filename> file is not an Internet address
 but an author or vendor name, such as "Debian" or "Ximian".</simpara>
@@ -184,7 +214,16 @@ belonging to any distribution whose Archive name is "<literal>unstable</literal>
 <programlisting>
 Package: *
 Pin: release a=unstable
-Pin-Priority: 500
+Pin-Priority: 50
+</programlisting>
+
+<simpara>The following record assigns a high priority to all package versions
+belonging to any distribution whose Codename is "<literal>squeeze</literal>".</simpara>
+
+<programlisting>
+Package: *
+Pin: release n=squeeze
+Pin-Priority: 900
 </programlisting>
 
 <simpara>The following record assigns a high priority to all package versions
@@ -324,10 +363,11 @@ file are relevant for setting APT priorities:
 
 <variablelist>
 <varlistentry>
-<term>the <literal>Archive:</literal> line</term>
+<term>the <literal>Archive:</literal> or <literal>Suite:</literal> line</term>
 <listitem><simpara>names the archive to which all the packages
 in the directory tree belong.  For example, the line
-"Archive: stable"
+"Archive: stable" or
+"Suite: stable"
 specifies that all of the packages in the directory
 tree below the parent of the <filename>Release</filename> file are in a
 <literal>stable</literal> archive.  Specifying this value in the APT preferences file
@@ -339,6 +379,22 @@ Pin: release a=stable
 </listitem>
 </varlistentry>
 
+<varlistentry>
+<term>the <literal>Codename:</literal> line</term>
+<listitem><simpara>names the codename to which all the packages
+in the directory tree belong.  For example, the line
+"Codename: squeeze"
+specifies that all of the packages in the directory
+tree below the parent of the <filename>Release</filename> file belong to a version named
+<literal>squeeze</literal>.  Specifying this value in the APT preferences file
+would require the line:
+</simpara>
+<programlisting>
+Pin: release n=squeeze
+</programlisting>
+</listitem>
+</varlistentry>
+
 <varlistentry>
 <term>the <literal>Version:</literal> line</term>
 <listitem><simpara>names the release version.  For example, the
@@ -422,7 +478,7 @@ one or more lines beginning with the word <literal>Explanation:</literal>.
 This provides a place for comments.</para>
 
 <para>The <literal>Pin-Priority:</literal> line in each APT preferences record is
-optional.  If omitted, APT assigs a priority of 1 less than the last value
+optional.  If omitted, APT assigns a priority of 1 less than the last value
 specified on a line beginning with <literal>Pin-Priority: release ...</literal>.</para>
 </refsect2>
 </refsect1>
@@ -519,10 +575,74 @@ version.
 apt-get install <replaceable>package</replaceable>/unstable
 </programlisting>
 </para>
+</refsect2>
+
+
+<refsect2>
+<title>Tracking the evolution of a codename release</title>
+
+<para>The following APT preferences file will cause APT to assign a
+priority higher than the default (500) to all package versions belonging
+to a specified codename of a distribution and a prohibitively low priority to
+package versions belonging to other <literal>Debian</literal> distributions,
+codenames and archives.
+Note that with this APT preference APT will follow the migration of a release
+from the archive <literal>testing</literal> to <literal>stable</literal> and
+later <literal>oldstable</literal>. If you want to follow for example the progress
+in <literal>testing</literal> notwithstanding the codename changes you should use
+the example configurations above.
+
+<programlisting>
+Explanation: Uninstall or do not install any Debian-originated package versions
+Explanation: other than those in the distribution codenamed with squeeze or sid
+Package: *
+Pin: release n=squeeze
+Pin-Priority: 900
+
+Explanation: Debian unstable is always codenamed with sid
+Package: *
+Pin: release n=sid
+Pin-Priority: 800
+
+Package: *
+Pin: release o=Debian
+Pin-Priority: -10
+</programlisting>
+</para>
+
+<para>With a suitable &sources-list; file and the above preferences file,
+any of the following commands will cause APT to upgrade to the
+latest version(s) in the release codenamed with <literal>squeeze</literal>.
 
+<programlisting>
+apt-get install <replaceable>package-name</replaceable>
+apt-get upgrade
+apt-get dist-upgrade
+</programlisting>
+</para>
+
+<para>The following command will cause APT to upgrade the specified
+package to the latest version from the <literal>sid</literal> distribution.
+Thereafter, <command>apt-get upgrade</command> will upgrade
+the package to the most recent <literal>squeeze</literal> version if that is
+more recent than the installed version, otherwise, to the most recent
+<literal>sid</literal> version if that is more recent than the installed
+version.
+
+<programlisting>
+apt-get install <replaceable>package</replaceable>/sid
+</programlisting>
+</para>
 </refsect2>
 </refsect1>
 
+<refsect1>
+<title>Files</title>
+  <variablelist>
+    &file-preferences;
+  </variablelist>
+</refsect1>
+
 <refsect1>
 <title>See Also</title>
 <para>&apt-get; &apt-cache; &apt-conf; &sources-list;
@@ -532,4 +652,3 @@ apt-get install <replaceable>package</replaceable>/unstable
  &manbugs;
 
 </refentry>
-