diff options
| -rw-r--r-- | doc/apt_preferences.5.sgml | 58 |
1 files changed, 22 insertions, 36 deletions
diff --git a/doc/apt_preferences.5.sgml b/doc/apt_preferences.5.sgml index 1a6ddf9f7..817586548 100644 --- a/doc/apt_preferences.5.sgml +++ b/doc/apt_preferences.5.sgml @@ -34,46 +34,42 @@ the &sources-list; file contains references to more than one distribution (for example, <literal>stable</literal> and <literal>testing</literal>). 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. If multiple -versions are available with equal priorities, the higher version will -be selected. +version with the highest priority for installation. The APT preferences file overrides the priorities that APT assigns to package versions by default, thus giving the user control over which one is selected for installation. </para> - <para> -If the selected version of a package is available from more than one -source, for example if more than one mirror of the same packages is -listed in <filename>sources.list</>, apt will select the source listed +Several instances of the same version of a package may be available when +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 which download source is -used, only which versions of packages are selected for installation. +The APT preferences file does not affect the choice of instance, only +the choice of version. </para> <RefSect2><Title>APT's Default Priority Assignments</> <para> -If there is no preferences file, or if there is no entry in the file -that applies to a particular version, then certain defaults are -supplied. +If there is no preferences file or if there is no entry in the file +that applies to a particular version then the priority assigned to that +version is the priority of the distribution to which that version +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>. +For example, +<programlisting> +<command>apt-get install -t testing <replaceable>some-package</replaceable></command> +</programlisting> +<programlisting> +APT::Default-Release "stable"; +</programlisting> </para> -<variablelist> -<varlistentry> -<term>Installed packages</term> -<listitem><simpara>The currently installed version of a package, if any, is -assigned priority 100.</simpara></listitem> -</varlistentry> - -<varlistentry> -<term></term> -<listitem><simpara>The currently installed version of a package, if any, is -assigned priority 100.</simpara></listitem> -</varlistentry> - <para> +If the target release has been specified then APT uses the following +algorithm to set the priorities of the versions of a package. Assign: <variablelist> <varlistentry> <term>priority 100</term> @@ -90,16 +86,6 @@ assigned priority 100.</simpara></listitem> </variablelist> </para> -For example, -<programlisting> -<command>apt-get install -t testing <replaceable>some-package</replaceable></command> -</programlisting> -<programlisting> -APT::Default-Release "stable"; -</programlisting> -</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 |