apt-helper: Check that we can open stdout

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

diff --git a/doc/apt_preferences.5.xml b/doc/apt_preferences.5.xml
index d8ebf4d60f72046213c3ca2388877794efcf9dfa..513a0c135f7c693ab2200cdeefb70b165e260ea5 100644 (file)
--- a/doc/apt_preferences.5.xml
+++ b/doc/apt_preferences.5.xml
@@ -1,13 +1,9 @@
 <?xml version="1.0" encoding="utf-8" standalone="no"?>
 <!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 % aptent SYSTEM "apt.ent"> %aptent;
+<!ENTITY % aptverbatiment SYSTEM "apt-verbatim.ent"> %aptverbatiment;
+<!ENTITY % aptvendor SYSTEM "apt-vendor.ent"> %aptvendor;
 ]>
 
 <refentry>
@@ -17,7 +13,7 @@
    &apt-email;
    &apt-product;
    <!-- The last update date -->
-   <date>2010-02-16T00:00:00Z</date>
+   <date>2015-08-15T00:00:00Z</date>
  </refentryinfo>
 
  <refmeta>
@@ -119,14 +115,17 @@ from archives which in their <filename>Release</filename> files are marked as "N
 
 <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>
-<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>
+
+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
@@ -255,6 +254,11 @@ 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>
@@ -271,7 +275,7 @@ expression surrounded by slashes).
 
 <programlisting>
 Package: gnome* /kde/
-Pin: release n=experimental
+Pin: release a=experimental
 Pin-Priority: 500
 </programlisting>
 
@@ -312,30 +316,30 @@ or negative integers.  They are interpreted as follows (roughly speaking):
 
 <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>
-<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>
-<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>
-<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>
-<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>
@@ -343,14 +347,21 @@ 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>
+<varlistentry>
+<term>P = 0</term>
+<listitem><simpara>has undefined behaviour, do not use it.</simpara></listitem>
+</varlistentry>
 </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>