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+<?xml version="1.0"?>
+<!--*-nxml-*-->
+<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+<!--
+ SPDX-License-Identifier: LGPL-2.1+
+-->
+<refentry id="systemd.preset">
+
+ <refentryinfo>
+ <title>systemd.preset</title>
+ <productname>systemd</productname>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>systemd.preset</refentrytitle>
+ <manvolnum>5</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>systemd.preset</refname>
+ <refpurpose>Service enablement presets</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <para><filename>/etc/systemd/system-preset/*.preset</filename></para>
+ <para><filename>/run/systemd/system-preset/*.preset</filename></para>
+ <para><filename>/usr/lib/systemd/system-preset/*.preset</filename></para>
+ <para><filename>/etc/systemd/user-preset/*.preset</filename></para>
+ <para><filename>/run/systemd/user-preset/*.preset</filename></para>
+ <para><filename>/usr/lib/systemd/user-preset/*.preset</filename></para>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>Preset files may be used to encode policy which units shall
+ be enabled by default and which ones shall be disabled. They are
+ read by <command>systemctl preset</command> (for more information
+ see
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>)
+ which uses this information to enable or disable a unit according
+ to preset policy. <command>systemctl preset</command> is used by
+ the post install scriptlets of RPM packages (or other OS package
+ formats), to enable/disable specific units by default on package
+ installation, enforcing distribution, spin or administrator preset
+ policy. This allows choosing a certain set of units to be
+ enabled/disabled even before installing the actual package.</para>
+
+ <para>For more information on the preset logic please have a look
+ at the <ulink
+ url="https://www.freedesktop.org/wiki/Software/systemd/Preset">Presets</ulink>
+ document.</para>
+
+ <para>It is not recommended to ship preset files within the
+ respective software packages implementing the units, but rather
+ centralize them in a distribution or spin default policy, which
+ can be amended by administrator policy.</para>
+
+ <para>If no preset files exist, <command>systemctl
+ preset</command> will enable all units that are installed by
+ default. If this is not desired and all units shall rather be
+ disabled, it is necessary to ship a preset file with a single,
+ catchall "<filename>disable *</filename>" line. (See example 1,
+ below.)</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Preset File Format</title>
+
+ <para>The preset files contain a list of directives consisting of
+ either the word <literal>enable</literal> or
+ <literal>disable</literal> followed by a space and a unit name
+ (possibly with shell style wildcards), separated by newlines.
+ Empty lines and lines whose first non-whitespace character is # or
+ ; are ignored.</para>
+
+ <para>Presets must refer to the "real" unit file, and not to any aliases. See
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for a description of unit aliasing.</para>
+
+ <para>Two different directives are understood:
+ <literal>enable</literal> may be used to enable units by default,
+ <literal>disable</literal> to disable units by default.</para>
+
+ <para>If multiple lines apply to a unit name, the first matching
+ one takes precedence over all others.</para>
+
+ <para>Each preset file shall be named in the style of
+ <filename>&lt;priority&gt;-&lt;policy-name&gt;.preset</filename>. Files
+ in <filename>/etc/</filename> override files with the same name in
+ <filename>/usr/lib/</filename> and <filename>/run/</filename>.
+ Files in <filename>/run/</filename> override files with the same
+ name in <filename>/usr/lib/</filename>. Packages should install
+ their preset files in <filename>/usr/lib/</filename>. Files in
+ <filename>/etc/</filename> are reserved for the local
+ administrator, who may use this logic to override the preset files
+ installed by vendor packages. All preset files are sorted by their
+ filename in lexicographic order, regardless of which of the
+ directories they reside in. If multiple files specify the same
+ unit name, the entry in the file with the lexicographically
+ earliest name will be applied. It is recommended to prefix all
+ filenames with a two-digit number and a dash, to simplify the
+ ordering of the files.</para>
+
+ <para>If the administrator wants to disable a preset file supplied
+ by the vendor, the recommended way is to place a symlink to
+ <filename>/dev/null</filename> in
+ <filename>/etc/systemd/system-preset/</filename> bearing the same
+ filename.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Examples</title>
+
+ <example>
+ <title>Default to off</title>
+
+ <programlisting># /usr/lib/systemd/system-preset/99-default.preset
+
+disable *</programlisting>
+ </example>
+
+ <para>This disables all units. Due to the filename prefix
+ <literal>99-</literal>, it will be read last and hence can easily
+ be overridden by spin or administrator preset policy.</para>
+
+ <example>
+ <title>A GNOME spin</title>
+
+ <programlisting># /usr/lib/systemd/system-preset/50-gnome.preset
+
+enable gdm.service
+enable colord.service
+enable accounts-daemon.service
+enable avahi-daemon.*</programlisting>
+
+ </example>
+
+ <para>This enables the three mentioned units, plus all
+ <filename>avahi-daemon</filename> regardless of which unit type. A
+ file like this could be useful for inclusion in a GNOME spin of a
+ distribution. It will ensure that the units necessary for GNOME
+ are properly enabled as they are installed. It leaves all other
+ units untouched, and subject to other (later) preset files, for
+ example like the one from the first example above.</para>
+
+ <example>
+ <title>Administrator policy</title>
+
+ <programlisting># /etc/systemd/system-preset/00-lennart.preset
+
+enable httpd.service
+enable sshd.service
+enable postfix.service
+disable *</programlisting>
+ </example>
+
+ <para>This enables three specific services and disables all
+ others. This is useful for administrators to specifically select
+ the units to enable, and disable all others. Due to the filename
+ prefix <literal>00-</literal> it will be read early and
+ override all other preset policy files.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+ <para>
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd-delta</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>