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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<refentry id="systemd.preset">

<refentryinfo>

<title>systemd.preset</title>

<productname>systemd</productname>

<authorgroup>

<author>

<contrib>Developer</contrib>

<firstname>Lennart</firstname>

<surname>Poettering</surname>

<email>lennart@poettering.net</email>

</author>

</authorgroup>

</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

services 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>It is not recommended to ship preset files

within the respective software packages implementing

the services, 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>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;program&gt;.conf</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 alphabetical

order, regardless in which of the directories they

reside, to guarantee that a specific preset file takes

precedence over another file with an alphabetically

earlier name, if both files contain lines that apply

to the same unit names. It is recommended to prefix

all file names with two-digit number, to simplify

ordering.</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 file name.</para>

</refsect1>

<refsect1>

<title>Example</title>

<example>

<title>Default off example <filename>/usr/lib/systemd/system-preset/99-default.preset</filename>:</title>

<programlisting>disable *</programlisting>

</example>

<para>This disables all units. Due to the file name

prefix <literal>99-</literal> it will be read last and

hence can easily be overridden by spin or

administrator preset policy or suchlike.</para>

<example>

<title>A GNOME spin example <filename>/usr/lib/systemd/system-preset/50-gnome.preset</filename>:</title>

<programlisting>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 <filename>/etc/systemd/system-preset/00-lennart.preset</filename>:</title>

<programlisting>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 file name prefix

<literal>00-</literal> it will be read early and hence

overrides 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>