1434 lines
67 KiB
XML
1434 lines
67 KiB
XML
<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
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<!ENTITY % entities SYSTEM "custom-entities.ent" >
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%entities;
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]>
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
|
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd.unit">
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<refentryinfo>
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<title>systemd.unit</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd.unit</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd.unit</refname>
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<refpurpose>Unit configuration</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename><replaceable>service</replaceable>.service</filename>,
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<filename><replaceable>socket</replaceable>.socket</filename>,
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<filename><replaceable>device</replaceable>.device</filename>,
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<filename><replaceable>mount</replaceable>.mount</filename>,
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<filename><replaceable>automount</replaceable>.automount</filename>,
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<filename><replaceable>swap</replaceable>.swap</filename>,
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<filename><replaceable>target</replaceable>.target</filename>,
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<filename><replaceable>path</replaceable>.path</filename>,
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<filename><replaceable>timer</replaceable>.timer</filename>,
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<filename><replaceable>slice</replaceable>.slice</filename>,
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<filename><replaceable>scope</replaceable>.scope</filename></para>
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<para><literallayout><filename>/etc/systemd/system/*</filename>
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<filename>/run/systemd/system/*</filename>
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<filename>/usr/lib/systemd/system/*</filename>
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<filename>...</filename>
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</literallayout></para>
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<para><literallayout><filename>$XDG_CONFIG_HOME/systemd/user/*</filename>
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<filename>$HOME/.config/systemd/user/*</filename>
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<filename>/etc/systemd/user/*</filename>
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<filename>$XDG_RUNTIME_DIR/systemd/user/*</filename>
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<filename>/run/systemd/user/*</filename>
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<filename>$XDG_DATA_HOME/systemd/user/*</filename>
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<filename>$HOME/.local/share/systemd/user/*</filename>
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<filename>/usr/lib/systemd/user/*</filename>
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<filename>...</filename>
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</literallayout></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>A unit configuration file encodes information about a
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service, a socket, a device, a mount point, an automount point, a
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swap file or partition, a start-up target, a watched file system
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path, a timer controlled and supervised by
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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a resource management slice or
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a group of externally created processes. The syntax is inspired by
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<ulink
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url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
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Desktop Entry Specification</ulink> <filename>.desktop</filename>
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files, which are in turn inspired by Microsoft Windows
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<filename>.ini</filename> files.</para>
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<para>This man page lists the common configuration options of all
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the unit types. These options need to be configured in the [Unit]
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or [Install] sections of the unit files.</para>
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<para>In addition to the generic [Unit] and [Install] sections
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described here, each unit may have a type-specific section, e.g.
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[Service] for a service unit. See the respective man pages for
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more information:
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<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
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</para>
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<para>Various settings are allowed to be specified more than once,
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in which case the interpretation depends on the setting. Often,
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multiple settings form a list, and setting to an empty value
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"resets", which means that previous assignments are ignored. When
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this is allowed, it is mentioned in the description of the
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setting. Note that using multiple assignments to the same value
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makes the unit file incompatible with parsers for the XDG
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<filename>.desktop</filename> file format.</para>
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<para>Unit files are loaded from a set of paths determined during
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compilation, described in the next section.</para>
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<para>Unit files may contain additional options on top of those
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listed here. If systemd encounters an unknown option, it will
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write a warning log message but continue loading the unit. If an
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option or section name is prefixed with <option>X-</option>, it is
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ignored completely by systemd. Options within an ignored section
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do not need the prefix. Applications may use this to include
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additional information in the unit files.</para>
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<para>Boolean arguments used in unit files can be written in
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various formats. For positive settings the strings
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<option>1</option>, <option>yes</option>, <option>true</option>
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and <option>on</option> are equivalent. For negative settings, the
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strings <option>0</option>, <option>no</option>,
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<option>false</option> and <option>off</option> are
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equivalent.</para>
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<para>Time span values encoded in unit files can be written in
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various formats. A stand-alone number specifies a time in seconds.
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If suffixed with a time unit, the unit is honored. A concatenation
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of multiple values with units is supported, in which case the
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values are added up. Example: "50" refers to 50 seconds; "2min
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200ms" refers to 2 minutes plus 200 milliseconds, i.e. 120200ms.
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The following time units are understood: s, min, h, d, w, ms, us.
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For details see
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<citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
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<para>Empty lines and lines starting with # or ; are
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ignored. This may be used for commenting. Lines ending
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in a backslash are concatenated with the following
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line while reading and the backslash is replaced by a
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space character. This may be used to wrap long lines.</para>
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<para>Along with a unit file <filename>foo.service</filename>, the
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directory <filename>foo.service.wants/</filename> may exist. All
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unit files symlinked from such a directory are implicitly added as
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dependencies of type <varname>Wants=</varname> to the unit. This
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is useful to hook units into the start-up of other units, without
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having to modify their unit files. For details about the semantics
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of <varname>Wants=</varname>, see below. The preferred way to
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create symlinks in the <filename>.wants/</filename> directory of a
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unit file is with the <command>enable</command> command of the
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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tool which reads information from the [Install] section of unit
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files (see below). A similar functionality exists for
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<varname>Requires=</varname> type dependencies as well, the
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directory suffix is <filename>.requires/</filename> in this
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case.</para>
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<para>Along with a unit file <filename>foo.service</filename>, a
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directory <filename>foo.service.d/</filename> may exist. All files
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with the suffix <literal>.conf</literal> from this directory will
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be parsed after the file itself is parsed. This is useful to alter
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or add configuration settings to a unit, without having to modify
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their unit files. Make sure that the file that is included has the
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appropriate section headers before any directive. Note that, for
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instanced units, this logic will first look for the instance
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<literal>.d/</literal> subdirectory and read its
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<literal>.conf</literal> files, followed by the template
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<literal>.d/</literal> subdirectory and reads its
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<literal>.conf</literal> files.</para>
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<!-- Note that we do not document .include here, as we
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consider it mostly obsolete, and want people to
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use .d/ drop-ins instead. -->
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<para>Some unit names reflect paths existing in the file system
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namespace. Example: a device unit
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<filename>dev-sda.device</filename> refers to a device with the
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device node <filename noindex='true'>/dev/sda</filename> in the
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file system namespace. If this applies, a special way to escape
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the path name is used, so that the result is usable as part of a
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filename. Basically, given a path, "/" is replaced by "-", and all
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other characters which are not ASCII alphanumerics are replaced by
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C-style "\x2d" escapes (except that "_" is never replaced and "."
|
|
is only replaced when it would be the first character in the
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escaped path). The root directory "/" is encoded as single dash,
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while otherwise the initial and ending "/" are removed from all
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paths during transformation. This escaping is reversible. Properly
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escaped paths can be generated using the
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<citerefentry><refentrytitle>systemd-escape</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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command.</para>
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<para>Optionally, units may be instantiated from a
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template file at runtime. This allows creation of
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multiple units from a single configuration file. If
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systemd looks for a unit configuration file, it will
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first search for the literal unit name in the
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file system. If that yields no success and the unit
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name contains an <literal>@</literal> character, systemd will look for a
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unit template that shares the same name but with the
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instance string (i.e. the part between the <literal>@</literal> character
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and the suffix) removed. Example: if a service
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<filename>getty@tty3.service</filename> is requested
|
|
and no file by that name is found, systemd will look
|
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for <filename>getty@.service</filename> and
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instantiate a service from that configuration file if
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it is found.</para>
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<para>To refer to the instance string from within the
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configuration file you may use the special <literal>%i</literal>
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specifier in many of the configuration options. See below for
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details.</para>
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<para>If a unit file is empty (i.e. has the file size 0) or is
|
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symlinked to <filename>/dev/null</filename>, its configuration
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will not be loaded and it appears with a load state of
|
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<literal>masked</literal>, and cannot be activated. Use this as an
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effective way to fully disable a unit, making it impossible to
|
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start it even manually.</para>
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<para>The unit file format is covered by the
|
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<ulink
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url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
|
|
Stability Promise</ulink>.</para>
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</refsect1>
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|
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<refsect1>
|
|
<title>Automatic Dependencies</title>
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|
|
<para>Note that while systemd offers a flexible dependency system
|
|
between units it is recommended to use this functionality only
|
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sparingly and instead rely on techniques such as bus-based or
|
|
socket-based activation which make dependencies implicit,
|
|
resulting in a both simpler and more flexible system.</para>
|
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|
<para>A number of unit dependencies are automatically established,
|
|
depending on unit configuration. On top of that, for units with
|
|
<varname>DefaultDependencies=yes</varname> (the default) a couple
|
|
of additional dependencies are added. The precise effect of
|
|
<varname>DefaultDependencies=yes</varname> depends on the unit
|
|
type (see below).</para>
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|
|
<para>If <varname>DefaultDependencies=yes</varname> is set, units
|
|
that are referenced by other units of type
|
|
<filename>.target</filename> via a <varname>Wants=</varname> or
|
|
<varname>Requires=</varname> dependency might automatically gain
|
|
an <varname>Before=</varname> dependency too. See
|
|
<citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
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for details.</para>
|
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</refsect1>
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<refsect1>
|
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<title>Unit File Load Path</title>
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<para>Unit files are loaded from a set of paths determined during
|
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compilation, described in the two tables below. Unit files found
|
|
in directories listed earlier override files with the same name in
|
|
directories lower in the list.</para>
|
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|
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<para>When the variable <varname>$SYSTEMD_UNIT_PATH</varname> is set,
|
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the contents of this variable overrides the unit load path. If
|
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<varname>$SYSTEMD_UNIT_PATH</varname> ends with an empty component
|
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(<literal>:</literal>), the usual unit load path will be appended
|
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to the contents of the variable.</para>
|
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|
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<table>
|
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<title>
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Load path when running in system mode (<option>--system</option>).
|
|
</title>
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<tgroup cols='2'>
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<colspec colname='path' />
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|
<colspec colname='expl' />
|
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<thead>
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<row>
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<entry>Path</entry>
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<entry>Description</entry>
|
|
</row>
|
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</thead>
|
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<tbody>
|
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<row>
|
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<entry><filename>/etc/systemd/system</filename></entry>
|
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<entry>Local configuration</entry>
|
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</row>
|
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<row>
|
|
<entry><filename>/run/systemd/system</filename></entry>
|
|
<entry>Runtime units</entry>
|
|
</row>
|
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<row>
|
|
<entry><filename>/usr/lib/systemd/system</filename></entry>
|
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<entry>Units of installed packages</entry>
|
|
</row>
|
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</tbody>
|
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</tgroup>
|
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</table>
|
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|
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<table>
|
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<title>
|
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Load path when running in user mode (<option>--user</option>).
|
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</title>
|
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|
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<tgroup cols='2'>
|
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<colspec colname='path' />
|
|
<colspec colname='expl' />
|
|
<thead>
|
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<row>
|
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<entry>Path</entry>
|
|
<entry>Description</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><filename>$XDG_CONFIG_HOME/systemd/user</filename></entry>
|
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<entry>User configuration (only used when $XDG_CONFIG_HOME is set)</entry>
|
|
</row>
|
|
<row>
|
|
<entry><filename>$HOME/.config/systemd/user</filename></entry>
|
|
<entry>User configuration (only used when $XDG_CONFIG_HOME is not set)</entry>
|
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</row>
|
|
<row>
|
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<entry><filename>/etc/systemd/user</filename></entry>
|
|
<entry>Local configuration</entry>
|
|
</row>
|
|
<row>
|
|
<entry><filename>$XDG_RUNTIME_DIR/systemd/user</filename></entry>
|
|
<entry>Runtime units (only used when $XDG_RUNTIME_DIR is set)</entry>
|
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</row>
|
|
<row>
|
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<entry><filename>/run/systemd/user</filename></entry>
|
|
<entry>Runtime units</entry>
|
|
</row>
|
|
<row>
|
|
<entry><filename>$XDG_DATA_HOME/systemd/user</filename></entry>
|
|
<entry>Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is set)</entry>
|
|
</row>
|
|
<row>
|
|
<entry><filename>$HOME/.local/share/systemd/user</filename></entry>
|
|
<entry>Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is not set)</entry>
|
|
</row>
|
|
<row>
|
|
<entry><filename>/usr/lib/systemd/user</filename></entry>
|
|
<entry>Units of packages that have been installed system-wide</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>Additional units might be loaded into systemd ("linked")
|
|
from directories not on the unit load path. See the
|
|
<command>link</command> command for
|
|
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
|
|
Also, some units are dynamically created via a
|
|
<citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>[Unit] Section Options</title>
|
|
|
|
<para>The unit file may include a [Unit] section, which carries
|
|
generic information about the unit that is not dependent on the
|
|
type of unit:</para>
|
|
|
|
<variablelist class='unit-directives'>
|
|
|
|
<varlistentry>
|
|
<term><varname>Description=</varname></term>
|
|
<listitem><para>A free-form string describing the unit. This
|
|
is intended for use in UIs to show descriptive information
|
|
along with the unit name. The description should contain a
|
|
name that means something to the end user. <literal>Apache2
|
|
Web Server</literal> is a good example. Bad examples are
|
|
<literal>high-performance light-weight HTTP server</literal>
|
|
(too generic) or <literal>Apache2</literal> (too specific and
|
|
meaningless for people who do not know
|
|
Apache).</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>Documentation=</varname></term>
|
|
<listitem><para>A space-separated list of URIs referencing
|
|
documentation for this unit or its configuration. Accepted are
|
|
only URIs of the types <literal>http://</literal>,
|
|
<literal>https://</literal>, <literal>file:</literal>,
|
|
<literal>info:</literal>, <literal>man:</literal>. For more
|
|
information about the syntax of these URIs, see <citerefentry
|
|
project='man-pages'><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
|
|
The URIs should be listed in order of relevance, starting with
|
|
the most relevant. It is a good idea to first reference
|
|
documentation that explains what the unit's purpose is,
|
|
followed by how it is configured, followed by any other
|
|
related documentation. This option may be specified more than
|
|
once, in which case the specified list of URIs is merged. If
|
|
the empty string is assigned to this option, the list is reset
|
|
and all prior assignments will have no
|
|
effect.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>Requires=</varname></term>
|
|
|
|
<listitem><para>Configures requirement dependencies on other
|
|
units. If this unit gets activated, the units listed here will
|
|
be activated as well. If one of the other units gets
|
|
deactivated or its activation fails, this unit will be
|
|
deactivated. This option may be specified more than once or
|
|
multiple space-separated units may be specified in one option
|
|
in which case requirement dependencies for all listed names
|
|
will be created. Note that requirement dependencies do not
|
|
influence the order in which services are started or stopped.
|
|
This has to be configured independently with the
|
|
<varname>After=</varname> or <varname>Before=</varname>
|
|
options. If a unit <filename>foo.service</filename> requires a
|
|
unit <filename>bar.service</filename> as configured with
|
|
<varname>Requires=</varname> and no ordering is configured
|
|
with <varname>After=</varname> or <varname>Before=</varname>,
|
|
then both units will be started simultaneously and without any
|
|
delay between them if <filename>foo.service</filename> is
|
|
activated. Often, it is a better choice to use
|
|
<varname>Wants=</varname> instead of
|
|
<varname>Requires=</varname> in order to achieve a system that
|
|
is more robust when dealing with failing services.</para>
|
|
|
|
<para>Note that dependencies of this type may also be
|
|
configured outside of the unit configuration file by adding a
|
|
symlink to a <filename>.requires/</filename> directory
|
|
accompanying the unit file. For details, see
|
|
above.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>Requisite=</varname></term>
|
|
|
|
<listitem><para>Similar to <varname>Requires=</varname>.
|
|
However, if the units listed here are not started already,
|
|
they will not be started and the transaction will fail
|
|
immediately. </para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>Wants=</varname></term>
|
|
|
|
<listitem><para>A weaker version of
|
|
<varname>Requires=</varname>. Units listed in this option will
|
|
be started if the configuring unit is. However, if the listed
|
|
units fail to start or cannot be added to the transaction,
|
|
this has no impact on the validity of the transaction as a
|
|
whole. This is the recommended way to hook start-up of one
|
|
unit to the start-up of another unit.</para>
|
|
|
|
<para>Note that dependencies of this type may also be
|
|
configured outside of the unit configuration file by adding
|
|
symlinks to a <filename>.wants/</filename> directory
|
|
accompanying the unit file. For details, see
|
|
above.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>BindsTo=</varname></term>
|
|
|
|
<listitem><para>Configures requirement dependencies, very
|
|
similar in style to <varname>Requires=</varname>, however in
|
|
addition to this behavior, it also declares that this unit is
|
|
stopped when any of the units listed suddenly disappears.
|
|
Units can suddenly, unexpectedly disappear if a service
|
|
terminates on its own choice, a device is unplugged or a mount
|
|
point unmounted without involvement of
|
|
systemd.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>PartOf=</varname></term>
|
|
|
|
<listitem><para>Configures dependencies similar to
|
|
<varname>Requires=</varname>, but limited to stopping and
|
|
restarting of units. When systemd stops or restarts the units
|
|
listed here, the action is propagated to this unit. Note that
|
|
this is a one-way dependency — changes to this unit do not
|
|
affect the listed units. </para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>Conflicts=</varname></term>
|
|
|
|
<listitem><para>A space-separated list of unit names.
|
|
Configures negative requirement dependencies. If a unit has a
|
|
<varname>Conflicts=</varname> setting on another unit,
|
|
starting the former will stop the latter and vice versa. Note
|
|
that this setting is independent of and orthogonal to the
|
|
<varname>After=</varname> and <varname>Before=</varname>
|
|
ordering dependencies.</para>
|
|
|
|
<para>If a unit A that conflicts with a unit B is scheduled to
|
|
be started at the same time as B, the transaction will either
|
|
fail (in case both are required part of the transaction) or be
|
|
modified to be fixed (in case one or both jobs are not a
|
|
required part of the transaction). In the latter case, the job
|
|
that is not the required will be removed, or in case both are
|
|
not required, the unit that conflicts will be started and the
|
|
unit that is conflicted is stopped.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>Before=</varname></term>
|
|
<term><varname>After=</varname></term>
|
|
|
|
<listitem><para>A space-separated list of unit names.
|
|
Configures ordering dependencies between units. If a unit
|
|
<filename>foo.service</filename> contains a setting
|
|
<option>Before=bar.service</option> and both units are being
|
|
started, <filename>bar.service</filename>'s start-up is
|
|
delayed until <filename>foo.service</filename> is started up.
|
|
Note that this setting is independent of and orthogonal to the
|
|
requirement dependencies as configured by
|
|
<varname>Requires=</varname>. It is a common pattern to
|
|
include a unit name in both the <varname>After=</varname> and
|
|
<varname>Requires=</varname> option, in which case the unit
|
|
listed will be started before the unit that is configured with
|
|
these options. This option may be specified more than once, in
|
|
which case ordering dependencies for all listed names are
|
|
created. <varname>After=</varname> is the inverse of
|
|
<varname>Before=</varname>, i.e. while
|
|
<varname>After=</varname> ensures that the configured unit is
|
|
started after the listed unit finished starting up,
|
|
<varname>Before=</varname> ensures the opposite, i.e. that the
|
|
configured unit is fully started up before the listed unit is
|
|
started. Note that when two units with an ordering dependency
|
|
between them are shut down, the inverse of the start-up order
|
|
is applied. i.e. if a unit is configured with
|
|
<varname>After=</varname> on another unit, the former is
|
|
stopped before the latter if both are shut down. If one unit
|
|
with an ordering dependency on another unit is shut down while
|
|
the latter is started up, the shut down is ordered before the
|
|
start-up regardless of whether the ordering dependency is
|
|
actually of type <varname>After=</varname> or
|
|
<varname>Before=</varname>. If two units have no ordering
|
|
dependencies between them, they are shut down or started up
|
|
simultaneously, and no ordering takes place.
|
|
</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>OnFailure=</varname></term>
|
|
|
|
<listitem><para>A space-separated list of one or more units
|
|
that are activated when this unit enters the
|
|
<literal>failed</literal> state.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>PropagatesReloadTo=</varname></term>
|
|
<term><varname>ReloadPropagatedFrom=</varname></term>
|
|
|
|
<listitem><para>A space-separated list of one or more units
|
|
where reload requests on this unit will be propagated to, or
|
|
reload requests on the other unit will be propagated to this
|
|
unit, respectively. Issuing a reload request on a unit will
|
|
automatically also enqueue a reload request on all units that
|
|
the reload request shall be propagated to via these two
|
|
settings.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>JoinsNamespaceOf=</varname></term>
|
|
|
|
<listitem><para>For units that start processes (such as
|
|
service units), lists one or more other units whose network
|
|
and/or temporary file namespace to join. This only applies to
|
|
unit types which support the
|
|
<varname>PrivateNetwork=</varname> and
|
|
<varname>PrivateTmp=</varname> directives (see
|
|
<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
|
for details). If a unit that has this setting set is started,
|
|
its processes will see the same <filename>/tmp</filename>,
|
|
<filename>/tmp/var</filename> and network namespace as one
|
|
listed unit that is started. If multiple listed units are
|
|
already started, it is not defined which namespace is joined.
|
|
Note that this setting only has an effect if
|
|
<varname>PrivateNetwork=</varname> and/or
|
|
<varname>PrivateTmp=</varname> is enabled for both the unit
|
|
that joins the namespace and the unit whose namespace is
|
|
joined.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>RequiresMountsFor=</varname></term>
|
|
|
|
<listitem><para>Takes a space-separated list of absolute
|
|
paths. Automatically adds dependencies of type
|
|
<varname>Requires=</varname> and <varname>After=</varname> for
|
|
all mount units required to access the specified path.</para>
|
|
|
|
<para>Mount points marked with <option>noauto</option> are not
|
|
mounted automatically and will be ignored for the purposes of
|
|
this option. If such a mount should be a requirement for this
|
|
unit, direct dependencies on the mount units may be added
|
|
(<varname>Requires=</varname> and <varname>After=</varname> or
|
|
some other combination). </para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>OnFailureJobMode=</varname></term>
|
|
|
|
<listitem><para>Takes a value of
|
|
<literal>fail</literal>,
|
|
<literal>replace</literal>,
|
|
<literal>replace-irreversibly</literal>,
|
|
<literal>isolate</literal>,
|
|
<literal>flush</literal>,
|
|
<literal>ignore-dependencies</literal> or
|
|
<literal>ignore-requirements</literal>. Defaults to
|
|
<literal>replace</literal>. Specifies how the units listed in
|
|
<varname>OnFailure=</varname> will be enqueued. See
|
|
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
|
|
<option>--job-mode=</option> option for details on the
|
|
possible values. If this is set to <literal>isolate</literal>,
|
|
only a single unit may be listed in
|
|
<varname>OnFailure=</varname>..</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>IgnoreOnIsolate=</varname></term>
|
|
|
|
<listitem><para>Takes a boolean argument. If
|
|
<option>true</option>, this unit will not be stopped when
|
|
isolating another unit. Defaults to
|
|
<option>false</option>.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>StopWhenUnneeded=</varname></term>
|
|
|
|
<listitem><para>Takes a boolean argument. If
|
|
<option>true</option>, this unit will be stopped when it is no
|
|
longer used. Note that, in order to minimize the work to be
|
|
executed, systemd will not stop units by default unless they
|
|
are conflicting with other units, or the user explicitly
|
|
requested their shut down. If this option is set, a unit will
|
|
be automatically cleaned up if no other active unit requires
|
|
it. Defaults to <option>false</option>.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>RefuseManualStart=</varname></term>
|
|
<term><varname>RefuseManualStop=</varname></term>
|
|
|
|
<listitem><para>Takes a boolean argument. If
|
|
<option>true</option>, this unit can only be activated or
|
|
deactivated indirectly. In this case, explicit start-up or
|
|
termination requested by the user is denied, however if it is
|
|
started or stopped as a dependency of another unit, start-up
|
|
or termination will succeed. This is mostly a safety feature
|
|
to ensure that the user does not accidentally activate units
|
|
that are not intended to be activated explicitly, and not
|
|
accidentally deactivate units that are not intended to be
|
|
deactivated. These options default to
|
|
<option>false</option>.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>AllowIsolate=</varname></term>
|
|
|
|
<listitem><para>Takes a boolean argument. If
|
|
<option>true</option>, this unit may be used with the
|
|
<command>systemctl isolate</command> command. Otherwise, this
|
|
will be refused. It probably is a good idea to leave this
|
|
disabled except for target units that shall be used similar to
|
|
runlevels in SysV init systems, just as a precaution to avoid
|
|
unusable system states. This option defaults to
|
|
<option>false</option>.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>DefaultDependencies=</varname></term>
|
|
|
|
<listitem><para>Takes a boolean argument. If
|
|
<option>true</option>, (the default), a few default
|
|
dependencies will implicitly be created for the unit. The
|
|
actual dependencies created depend on the unit type. For
|
|
example, for service units, these dependencies ensure that the
|
|
service is started only after basic system initialization is
|
|
completed and is properly terminated on system shutdown. See
|
|
the respective man pages for details. Generally, only services
|
|
involved with early boot or late shutdown should set this
|
|
option to <option>false</option>. It is highly recommended to
|
|
leave this option enabled for the majority of common units. If
|
|
set to <option>false</option>, this option does not disable
|
|
all implicit dependencies, just non-essential
|
|
ones.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>JobTimeoutSec=</varname></term>
|
|
<term><varname>JobTimeoutAction=</varname></term>
|
|
<term><varname>JobTimeoutRebootArgument=</varname></term>
|
|
|
|
<listitem><para>When a job for this unit is queued, a time-out
|
|
may be configured. If this time limit is reached, the job will
|
|
be cancelled, the unit however will not change state or even
|
|
enter the <literal>failed</literal> mode. This value defaults
|
|
to 0 (job timeouts disabled), except for device units. NB:
|
|
this timeout is independent from any unit-specific timeout
|
|
(for example, the timeout set with
|
|
<varname>TimeoutStartSec=</varname> in service units) as the
|
|
job timeout has no effect on the unit itself, only on the job
|
|
that might be pending for it. Or in other words: unit-specific
|
|
timeouts are useful to abort unit state changes, and revert
|
|
them. The job timeout set with this option however is useful
|
|
to abort only the job waiting for the unit state to
|
|
change.</para>
|
|
|
|
<para><varname>JobTimeoutAction=</varname>
|
|
optionally configures an additional
|
|
action to take when the time-out is
|
|
hit. It takes the same values as the
|
|
per-service
|
|
<varname>StartLimitAction=</varname>
|
|
setting, see
|
|
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
|
for details. Defaults to
|
|
<option>none</option>. <varname>JobTimeoutRebootArgument=</varname>
|
|
configures an optional reboot string
|
|
to pass to the
|
|
<citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
|
system call.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>ConditionArchitecture=</varname></term>
|
|
<term><varname>ConditionVirtualization=</varname></term>
|
|
<term><varname>ConditionHost=</varname></term>
|
|
<term><varname>ConditionKernelCommandLine=</varname></term>
|
|
<term><varname>ConditionSecurity=</varname></term>
|
|
<term><varname>ConditionCapability=</varname></term>
|
|
<term><varname>ConditionACPower=</varname></term>
|
|
<term><varname>ConditionNeedsUpdate=</varname></term>
|
|
<term><varname>ConditionFirstBoot=</varname></term>
|
|
<term><varname>ConditionPathExists=</varname></term>
|
|
<term><varname>ConditionPathExistsGlob=</varname></term>
|
|
<term><varname>ConditionPathIsDirectory=</varname></term>
|
|
<term><varname>ConditionPathIsSymbolicLink=</varname></term>
|
|
<term><varname>ConditionPathIsMountPoint=</varname></term>
|
|
<term><varname>ConditionPathIsReadWrite=</varname></term>
|
|
<term><varname>ConditionDirectoryNotEmpty=</varname></term>
|
|
<term><varname>ConditionFileNotEmpty=</varname></term>
|
|
<term><varname>ConditionFileIsExecutable=</varname></term>
|
|
|
|
<!-- We do not document ConditionNull=
|
|
here, as it is not particularly
|
|
useful and probably just
|
|
confusing. -->
|
|
|
|
<listitem><para>Before starting a unit verify that the
|
|
specified condition is true. If it is not true, the starting
|
|
of the unit will be skipped, however all ordering dependencies
|
|
of it are still respected. A failing condition will not result
|
|
in the unit being moved into a failure state. The condition is
|
|
checked at the time the queued start job is to be
|
|
executed.</para>
|
|
|
|
<para><varname>ConditionArchitecture=</varname> may be used to
|
|
check whether the system is running on a specific
|
|
architecture. Takes one of
|
|
<varname>x86</varname>,
|
|
<varname>x86-64</varname>,
|
|
<varname>ppc</varname>,
|
|
<varname>ppc-le</varname>,
|
|
<varname>ppc64</varname>,
|
|
<varname>ppc64-le</varname>,
|
|
<varname>ia64</varname>,
|
|
<varname>parisc</varname>,
|
|
<varname>parisc64</varname>,
|
|
<varname>s390</varname>,
|
|
<varname>s390x</varname>,
|
|
<varname>sparc</varname>,
|
|
<varname>sparc64</varname>,
|
|
<varname>mips</varname>,
|
|
<varname>mips-le</varname>,
|
|
<varname>mips64</varname>,
|
|
<varname>mips64-le</varname>,
|
|
<varname>alpha</varname>,
|
|
<varname>arm</varname>,
|
|
<varname>arm-be</varname>,
|
|
<varname>arm64</varname>,
|
|
<varname>arm64-be</varname>,
|
|
<varname>sh</varname>,
|
|
<varname>sh64</varname>,
|
|
<varname>m86k</varname>,
|
|
<varname>tilegx</varname>,
|
|
<varname>cris</varname> to test
|
|
against a specific architecture. The architecture is
|
|
determined from the information returned by
|
|
<citerefentry project='man-pages'><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
|
|
and is thus subject to
|
|
<citerefentry><refentrytitle>personality</refentrytitle><manvolnum>2</manvolnum></citerefentry>.
|
|
Note that a <varname>Personality=</varname> setting in the
|
|
same unit file has no effect on this condition. A special
|
|
architecture name <varname>native</varname> is mapped to the
|
|
architecture the system manager itself is compiled for. The
|
|
test may be negated by prepending an exclamation mark.</para>
|
|
|
|
<para><varname>ConditionVirtualization=</varname> may be used
|
|
to check whether the system is executed in a virtualized
|
|
environment and optionally test whether it is a specific
|
|
implementation. Takes either boolean value to check if being
|
|
executed in any virtualized environment, or one of
|
|
<varname>vm</varname> and
|
|
<varname>container</varname> to test against a generic type of
|
|
virtualization solution, or one of
|
|
<varname>qemu</varname>,
|
|
<varname>kvm</varname>,
|
|
<varname>zvm</varname>,
|
|
<varname>vmware</varname>,
|
|
<varname>microsoft</varname>,
|
|
<varname>oracle</varname>,
|
|
<varname>xen</varname>,
|
|
<varname>bochs</varname>,
|
|
<varname>uml</varname>,
|
|
<varname>openvz</varname>,
|
|
<varname>lxc</varname>,
|
|
<varname>lxc-libvirt</varname>,
|
|
<varname>systemd-nspawn</varname>,
|
|
<varname>docker</varname>,
|
|
<varname>rkt</varname> to test
|
|
against a specific implementation. See
|
|
<citerefentry><refentrytitle>systemd-detect-virt</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
|
for a full list of known virtualization technologies and their
|
|
identifiers. If multiple virtualization technologies are
|
|
nested, only the innermost is considered. The test may be
|
|
negated by prepending an exclamation mark.</para>
|
|
|
|
<para><varname>ConditionHost=</varname> may be used to match
|
|
against the hostname or machine ID of the host. This either
|
|
takes a hostname string (optionally with shell style globs)
|
|
which is tested against the locally set hostname as returned
|
|
by
|
|
<citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
|
|
or a machine ID formatted as string (see
|
|
<citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
|
|
The test may be negated by prepending an exclamation
|
|
mark.</para>
|
|
|
|
<para><varname>ConditionKernelCommandLine=</varname> may be
|
|
used to check whether a specific kernel command line option is
|
|
set (or if prefixed with the exclamation mark unset). The
|
|
argument must either be a single word, or an assignment (i.e.
|
|
two words, separated <literal>=</literal>). In the former case
|
|
the kernel command line is searched for the word appearing as
|
|
is, or as left hand side of an assignment. In the latter case,
|
|
the exact assignment is looked for with right and left hand
|
|
side matching.</para>
|
|
|
|
<para><varname>ConditionSecurity=</varname> may be used to
|
|
check whether the given security module is enabled on the
|
|
system. Currently, the recognized values values are
|
|
<varname>selinux</varname>,
|
|
<varname>apparmor</varname>,
|
|
<varname>ima</varname>,
|
|
<varname>smack</varname> and
|
|
<varname>audit</varname>. The test may be negated by
|
|
prepending an exclamation mark.</para>
|
|
|
|
<para><varname>ConditionCapability=</varname> may be used to
|
|
check whether the given capability exists in the capability
|
|
bounding set of the service manager (i.e. this does not check
|
|
whether capability is actually available in the permitted or
|
|
effective sets, see
|
|
<citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
|
|
for details). Pass a capability name such as
|
|
<literal>CAP_MKNOD</literal>, possibly prefixed with an
|
|
exclamation mark to negate the check.</para>
|
|
|
|
<para><varname>ConditionACPower=</varname> may be used to
|
|
check whether the system has AC power, or is exclusively
|
|
battery powered at the time of activation of the unit. This
|
|
takes a boolean argument. If set to <varname>true</varname>,
|
|
the condition will hold only if at least one AC connector of
|
|
the system is connected to a power source, or if no AC
|
|
connectors are known. Conversely, if set to
|
|
<varname>false</varname>, the condition will hold only if
|
|
there is at least one AC connector known and all AC connectors
|
|
are disconnected from a power source.</para>
|
|
|
|
<para><varname>ConditionNeedsUpdate=</varname> takes one of
|
|
<filename>/var</filename> or <filename>/etc</filename> as
|
|
argument, possibly prefixed with a <literal>!</literal> (for
|
|
inverting the condition). This condition may be used to
|
|
conditionalize units on whether the specified directory
|
|
requires an update because <filename>/usr</filename>'s
|
|
modification time is newer than the stamp file
|
|
<filename>.updated</filename> in the specified directory. This
|
|
is useful to implement offline updates of the vendor operating
|
|
system resources in <filename>/usr</filename> that require
|
|
updating of <filename>/etc</filename> or
|
|
<filename>/var</filename> on the next following boot. Units
|
|
making use of this condition should order themselves before
|
|
<citerefentry><refentrytitle>systemd-update-done.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
|
|
to make sure they run before the stamp file's modification
|
|
time gets reset indicating a completed update.</para>
|
|
|
|
<para><varname>ConditionFirstBoot=</varname> takes a boolean
|
|
argument. This condition may be used to conditionalize units
|
|
on whether the system is booting up with an unpopulated
|
|
<filename>/etc</filename> directory. This may be used to
|
|
populate <filename>/etc</filename> on the first boot after
|
|
factory reset, or when a new system instances boots up for the
|
|
first time.</para>
|
|
|
|
<para>With <varname>ConditionPathExists=</varname> a file
|
|
existence condition is checked before a unit is started. If
|
|
the specified absolute path name does not exist, the condition
|
|
will fail. If the absolute path name passed to
|
|
<varname>ConditionPathExists=</varname> is prefixed with an
|
|
exclamation mark (<literal>!</literal>), the test is negated,
|
|
and the unit is only started if the path does not
|
|
exist.</para>
|
|
|
|
<para><varname>ConditionPathExistsGlob=</varname> is similar
|
|
to <varname>ConditionPathExists=</varname>, but checks for the
|
|
existence of at least one file or directory matching the
|
|
specified globbing pattern.</para>
|
|
|
|
<para><varname>ConditionPathIsDirectory=</varname> is similar
|
|
to <varname>ConditionPathExists=</varname> but verifies
|
|
whether a certain path exists and is a directory.</para>
|
|
|
|
<para><varname>ConditionPathIsSymbolicLink=</varname> is
|
|
similar to <varname>ConditionPathExists=</varname> but
|
|
verifies whether a certain path exists and is a symbolic
|
|
link.</para>
|
|
|
|
<para><varname>ConditionPathIsMountPoint=</varname> is similar
|
|
to <varname>ConditionPathExists=</varname> but verifies
|
|
whether a certain path exists and is a mount point.</para>
|
|
|
|
<para><varname>ConditionPathIsReadWrite=</varname> is similar
|
|
to <varname>ConditionPathExists=</varname> but verifies
|
|
whether the underlying file system is readable and writable
|
|
(i.e. not mounted read-only).</para>
|
|
|
|
<para><varname>ConditionDirectoryNotEmpty=</varname> is
|
|
similar to <varname>ConditionPathExists=</varname> but
|
|
verifies whether a certain path exists and is a non-empty
|
|
directory.</para>
|
|
|
|
<para><varname>ConditionFileNotEmpty=</varname> is similar to
|
|
<varname>ConditionPathExists=</varname> but verifies whether a
|
|
certain path exists and refers to a regular file with a
|
|
non-zero size.</para>
|
|
|
|
<para><varname>ConditionFileIsExecutable=</varname> is similar
|
|
to <varname>ConditionPathExists=</varname> but verifies
|
|
whether a certain path exists, is a regular file and marked
|
|
executable.</para>
|
|
|
|
<para>If multiple conditions are specified, the unit will be
|
|
executed if all of them apply (i.e. a logical AND is applied).
|
|
Condition checks can be prefixed with a pipe symbol (|) in
|
|
which case a condition becomes a triggering condition. If at
|
|
least one triggering condition is defined for a unit, then the
|
|
unit will be executed if at least one of the triggering
|
|
conditions apply and all of the non-triggering conditions. If
|
|
you prefix an argument with the pipe symbol and an exclamation
|
|
mark, the pipe symbol must be passed first, the exclamation
|
|
second. Except for
|
|
<varname>ConditionPathIsSymbolicLink=</varname>, all path
|
|
checks follow symlinks. If any of these options is assigned
|
|
the empty string, the list of conditions is reset completely,
|
|
all previous condition settings (of any kind) will have no
|
|
effect.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>AssertArchitecture=</varname></term>
|
|
<term><varname>AssertVirtualization=</varname></term>
|
|
<term><varname>AssertHost=</varname></term>
|
|
<term><varname>AssertKernelCommandLine=</varname></term>
|
|
<term><varname>AssertSecurity=</varname></term>
|
|
<term><varname>AssertCapability=</varname></term>
|
|
<term><varname>AssertACPower=</varname></term>
|
|
<term><varname>AssertNeedsUpdate=</varname></term>
|
|
<term><varname>AssertFirstBoot=</varname></term>
|
|
<term><varname>AssertPathExists=</varname></term>
|
|
<term><varname>AssertPathExistsGlob=</varname></term>
|
|
<term><varname>AssertPathIsDirectory=</varname></term>
|
|
<term><varname>AssertPathIsSymbolicLink=</varname></term>
|
|
<term><varname>AssertPathIsMountPoint=</varname></term>
|
|
<term><varname>AssertPathIsReadWrite=</varname></term>
|
|
<term><varname>AssertDirectoryNotEmpty=</varname></term>
|
|
<term><varname>AssertFileNotEmpty=</varname></term>
|
|
<term><varname>AssertFileIsExecutable=</varname></term>
|
|
|
|
<listitem><para>Similar to the
|
|
<varname>ConditionArchitecture=</varname>,
|
|
<varname>ConditionVirtualization=</varname>, etc., condition
|
|
settings described above, these settings add assertion checks
|
|
to the start-up of the unit. However, unlike the conditions
|
|
settings, any assertion setting that is not met results in
|
|
failure of the start job it was triggered
|
|
by.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>SourcePath=</varname></term>
|
|
<listitem><para>A path to a configuration file this unit has
|
|
been generated from. This is primarily useful for
|
|
implementation of generator tools that convert configuration
|
|
from an external configuration file format into native unit
|
|
files. This functionality should not be used in normal
|
|
units.</para></listitem>
|
|
</varlistentry>
|
|
|
|
</variablelist>
|
|
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>[Install] Section Options</title>
|
|
|
|
<para>Unit file may include an <literal>[Install]</literal>
|
|
section, which carries installation information for the unit. This
|
|
section is not interpreted by
|
|
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
|
during runtime. It is used exclusively by the
|
|
<command>enable</command> and <command>disable</command> commands
|
|
of the
|
|
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
|
tool during installation of a unit:</para>
|
|
|
|
<variablelist class='unit-directives'>
|
|
<varlistentry>
|
|
<term><varname>Alias=</varname></term>
|
|
|
|
<listitem><para>A space-separated list of additional names
|
|
this unit shall be installed under. The names listed here must
|
|
have the same suffix (i.e. type) as the unit file name. This
|
|
option may be specified more than once, in which case all
|
|
listed names are used. At installation time,
|
|
<command>systemctl enable</command> will create symlinks from
|
|
these names to the unit filename.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>WantedBy=</varname></term>
|
|
<term><varname>RequiredBy=</varname></term>
|
|
|
|
<listitem><para>This option may be used more than once, or a
|
|
space-separated list of unit names may be given. A symbolic
|
|
link is created in the <filename>.wants/</filename> or
|
|
<filename>.requires/</filename> directory of each of the
|
|
listed units when this unit is installed by <command>systemctl
|
|
enable</command>. This has the effect that a dependency of
|
|
type <varname>Wants=</varname> or <varname>Requires=</varname>
|
|
is added from the listed unit to the current unit. The primary
|
|
result is that the current unit will be started when the
|
|
listed unit is started. See the description of
|
|
<varname>Wants=</varname> and <varname>Requires=</varname> in
|
|
the [Unit] section for details.</para>
|
|
|
|
<para><command>WantedBy=foo.service</command> in a service
|
|
<filename>bar.service</filename> is mostly equivalent to
|
|
<command>Alias=foo.service.wants/bar.service</command> in the
|
|
same file. In case of template units, <command>systemctl
|
|
enable</command> must be called with an instance name, and
|
|
this instance will be added to the
|
|
<filename>.wants/</filename> or
|
|
<filename>.requires/</filename> list of the listed unit. E.g.
|
|
<command>WantedBy=getty.target</command> in a service
|
|
<filename>getty@.service</filename> will result in
|
|
<command>systemctl enable getty@tty2.service</command>
|
|
creating a
|
|
<filename>getty.target.wants/getty@tty2.service</filename>
|
|
link to <filename>getty@.service</filename>.
|
|
</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>Also=</varname></term>
|
|
|
|
<listitem><para>Additional units to install/deinstall when
|
|
this unit is installed/deinstalled. If the user requests
|
|
installation/deinstallation of a unit with this option
|
|
configured, <command>systemctl enable</command> and
|
|
<command>systemctl disable</command> will automatically
|
|
install/uninstall units listed in this option as well.</para>
|
|
|
|
<para>This option may be used more than once, or a
|
|
space-separated list of unit names may be
|
|
given.</para></listitem>
|
|
</varlistentry>
|
|
|
|
<varlistentry>
|
|
<term><varname>DefaultInstance=</varname></term>
|
|
|
|
<listitem><para>In template unit files, this specifies for
|
|
which instance the unit shall be enabled if the template is
|
|
enabled without any explicitly set instance. This option has
|
|
no effect in non-template unit files. The specified string
|
|
must be usable as instance identifier.</para></listitem>
|
|
</varlistentry>
|
|
</variablelist>
|
|
|
|
<para>The following specifiers are interpreted in the Install
|
|
section: %n, %N, %p, %i, %U, %u, %m, %H, %b, %v. For their meaning
|
|
see the next section.
|
|
</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Specifiers</title>
|
|
|
|
<para>Many settings resolve specifiers which may be used to write
|
|
generic unit files referring to runtime or unit parameters that
|
|
are replaced when the unit files are loaded. The following
|
|
specifiers are understood:</para>
|
|
|
|
<table>
|
|
<title>Specifiers available in unit files</title>
|
|
<tgroup cols='3' align='left' colsep='1' rowsep='1'>
|
|
<colspec colname="spec" />
|
|
<colspec colname="mean" />
|
|
<colspec colname="detail" />
|
|
<thead>
|
|
<row>
|
|
<entry>Specifier</entry>
|
|
<entry>Meaning</entry>
|
|
<entry>Details</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry><literal>%n</literal></entry>
|
|
<entry>Full unit name</entry>
|
|
<entry></entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%N</literal></entry>
|
|
<entry>Unescaped full unit name</entry>
|
|
<entry>Same as <literal>%n</literal>, but with escaping undone</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%p</literal></entry>
|
|
<entry>Prefix name</entry>
|
|
<entry>For instantiated units, this refers to the string before the <literal>@</literal> character of the unit name. For non-instantiated units, this refers to the name of the unit with the type suffix removed.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%P</literal></entry>
|
|
<entry>Unescaped prefix name</entry>
|
|
<entry>Same as <literal>%p</literal>, but with escaping undone</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%i</literal></entry>
|
|
<entry>Instance name</entry>
|
|
<entry>For instantiated units: this is the string between the <literal>@</literal> character and the suffix of the unit name.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%I</literal></entry>
|
|
<entry>Unescaped instance name</entry>
|
|
<entry>Same as <literal>%i</literal>, but with escaping undone</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%f</literal></entry>
|
|
<entry>Unescaped filename</entry>
|
|
<entry>This is either the unescaped instance name (if applicable) with <filename>/</filename> prepended (if applicable), or the prefix name prepended with <filename>/</filename>.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%c</literal></entry>
|
|
<entry>Control group path of the unit</entry>
|
|
<entry>This path does not include the <filename>/sys/fs/cgroup/systemd/</filename> prefix.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%r</literal></entry>
|
|
<entry>Control group path of the slice the unit is placed in</entry>
|
|
<entry>This usually maps to the parent cgroup path of <literal>%c</literal>.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%R</literal></entry>
|
|
<entry>Root control group path below which slices and units are placed</entry>
|
|
<entry>For system instances, this resolves to <filename>/</filename>, except in containers, where this maps to the container's root control group path.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%t</literal></entry>
|
|
<entry>Runtime directory</entry>
|
|
<entry>This is either <filename>/run</filename> (for the system manager) or the path <literal>$XDG_RUNTIME_DIR</literal> resolves to (for user managers).</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%u</literal></entry>
|
|
<entry>User name</entry>
|
|
<entry>This is the name of the user running the service manager instance. In case of the system manager this resolves to <literal>root</literal>.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%U</literal></entry>
|
|
<entry>User UID</entry>
|
|
<entry>This is the numeric UID of the user running the service manager instance. In case of the system manager this resolves to <literal>0</literal>.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%h</literal></entry>
|
|
<entry>User home directory</entry>
|
|
<entry>This is the home directory of the user running the service manager instance. In case of the system manager this resolves to <literal>/root</literal>.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%s</literal></entry>
|
|
<entry>User shell</entry>
|
|
<entry>This is the shell of the user running the service manager instance. In case of the system manager this resolves to <literal>/bin/sh</literal>.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%m</literal></entry>
|
|
<entry>Machine ID</entry>
|
|
<entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%b</literal></entry>
|
|
<entry>Boot ID</entry>
|
|
<entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%H</literal></entry>
|
|
<entry>Host name</entry>
|
|
<entry>The hostname of the running system at the point in time the unit configuration is loaded.</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%v</literal></entry>
|
|
<entry>Kernel release</entry>
|
|
<entry>Identical to <command>uname -r</command> output</entry>
|
|
</row>
|
|
<row>
|
|
<entry><literal>%%</literal></entry>
|
|
<entry>Single percent sign</entry>
|
|
<entry>Use <literal>%%</literal> in place of <literal>%</literal> to specify a single percent sign.</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
|
|
<para>Please note that specifiers <literal>%U</literal>,
|
|
<literal>%h</literal>, <literal>%s</literal> are mostly useless
|
|
when systemd is running in system mode. PID 1 cannot query the
|
|
user account database for information, so the specifiers only work
|
|
as shortcuts for things which are already specified in a different
|
|
way in the unit file. They are fully functional when systemd is
|
|
running in <option>--user</option> mode.</para>
|
|
</refsect1>
|
|
|
|
<refsect1>
|
|
<title>Examples</title>
|
|
|
|
<example>
|
|
<title>Allowing units to be enabled</title>
|
|
|
|
<para>The following snippet (highlighted) allows a unit (e.g.
|
|
<filename>foo.service</filename>) to be enabled via
|
|
<command>systemctl enable</command>:</para>
|
|
|
|
<programlisting>[Unit]
|
|
Description=Foo
|
|
|
|
[Service]
|
|
ExecStart=/usr/sbin/foo-daemon
|
|
|
|
<emphasis>[Install]</emphasis>
|
|
<emphasis>WantedBy=multi-user.target</emphasis></programlisting>
|
|
|
|
<para>After running <command>systemctl enable</command>, a
|
|
symlink
|
|
<filename>/etc/systemd/system/multi-user.target.wants/foo.service</filename>
|
|
linking to the actual unit will be created. It tells systemd to
|
|
pull in the unit when starting
|
|
<filename>multi-user.target</filename>. The inverse
|
|
<command>systemctl disable</command> will remove that symlink
|
|
again.</para>
|
|
</example>
|
|
|
|
<example>
|
|
<title>Overriding vendor settings</title>
|
|
|
|
<para>There are two methods of overriding vendor settings in
|
|
unit files: copying the unit file from
|
|
<filename>/usr/lib/systemd/system</filename> to
|
|
<filename>/etc/systemd/system</filename> and modifying the
|
|
chosen settings. Alternatively, one can create a directory named
|
|
<filename><replaceable>unit</replaceable>.d/</filename> within
|
|
<filename>/etc/systemd/system</filename> and place a drop-in
|
|
file <filename><replaceable>name</replaceable>.conf</filename>
|
|
there that only changes the specific settings one is interested
|
|
in. Note that multiple such drop-in files are read if
|
|
present.</para>
|
|
|
|
<para>The advantage of the first method is that one easily
|
|
overrides the complete unit, the vendor unit is not parsed at
|
|
all anymore. It has the disadvantage that improvements to the
|
|
unit file by the vendor are not automatically incorporated on
|
|
updates.</para>
|
|
|
|
<para>The advantage of the second method is that one only
|
|
overrides the settings one specifically wants, where updates to
|
|
the unit by the vendor automatically apply. This has the
|
|
disadvantage that some future updates by the vendor might be
|
|
incompatible with the local changes.</para>
|
|
|
|
<para>Note that for drop-in files, if one wants to remove
|
|
entries from a setting that is parsed as a list (and is not a
|
|
dependency), such as <varname>ConditionPathExists=</varname> (or
|
|
e.g. <varname>ExecStart=</varname> in service units), one needs
|
|
to first clear the list before re-adding all entries except the
|
|
one that is to be removed. See below for an example.</para>
|
|
|
|
<para>This also applies for user instances of systemd, but with
|
|
different locations for the unit files. See the section on unit
|
|
load paths for further details.</para>
|
|
|
|
<para>Suppose there is a vendor-supplied unit
|
|
<filename>/usr/lib/systemd/system/httpd.service</filename> with
|
|
the following contents:</para>
|
|
|
|
<programlisting>[Unit]
|
|
Description=Some HTTP server
|
|
After=remote-fs.target sqldb.service
|
|
Requires=sqldb.service
|
|
AssertPathExists=/srv/webserver
|
|
|
|
[Service]
|
|
Type=notify
|
|
ExecStart=/usr/sbin/some-fancy-httpd-server
|
|
Nice=5
|
|
|
|
[Install]
|
|
WantedBy=multi-user.target</programlisting>
|
|
|
|
<para>Now one wants to change some settings as an administrator:
|
|
firstly, in the local setup, <filename>/srv/webserver</filename>
|
|
might not exist, because the HTTP server is configured to use
|
|
<filename>/srv/www</filename> instead. Secondly, the local
|
|
configuration makes the HTTP server also depend on a memory
|
|
cache service, <filename>memcached.service</filename>, that
|
|
should be pulled in (<varname>Requires=</varname>) and also be
|
|
ordered appropriately (<varname>After=</varname>). Thirdly, in
|
|
order to harden the service a bit more, the administrator would
|
|
like to set the <varname>PrivateTmp=</varname> setting (see
|
|
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
|
|
for details). And lastly, the administrator would like to reset
|
|
the niceness of the service to its default value of 0.</para>
|
|
|
|
<para>The first possibility is to copy the unit file to
|
|
<filename>/etc/systemd/system/httpd.service</filename> and
|
|
change the chosen settings:</para>
|
|
|
|
<programlisting>[Unit]
|
|
Description=Some HTTP server
|
|
After=remote-fs.target sqldb.service <emphasis>memcached.service</emphasis>
|
|
Requires=sqldb.service <emphasis>memcached.service</emphasis>
|
|
AssertPathExists=<emphasis>/srv/www</emphasis>
|
|
|
|
[Service]
|
|
Type=notify
|
|
ExecStart=/usr/sbin/some-fancy-httpd-server
|
|
<emphasis>Nice=0</emphasis>
|
|
<emphasis>PrivateTmp=yes</emphasis>
|
|
|
|
[Install]
|
|
WantedBy=multi-user.target</programlisting>
|
|
|
|
<para>Alternatively, the administrator could create a drop-in
|
|
file
|
|
<filename>/etc/systemd/system/httpd.service.d/local.conf</filename>
|
|
with the following contents:</para>
|
|
|
|
<programlisting>[Unit]
|
|
After=memcached.service
|
|
Requires=memcached.service
|
|
# Reset all assertions and then re-add the condition we want
|
|
AssertPathExists=
|
|
AssertPathExists=/srv/www
|
|
|
|
[Service]
|
|
Nice=0
|
|
PrivateTmp=yes</programlisting>
|
|
|
|
<para>Note that dependencies (<varname>After=</varname>, etc.)
|
|
cannot be reset to an empty list, so dependencies can only be
|
|
added in drop-ins. If you want to remove dependencies, you have
|
|
to override the entire unit.</para>
|
|
</example>
|
|
</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.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
|
|
<citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
|
|
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
|
|
<citerefentry project='man-pages'><refentrytitle>uname</refentrytitle><manvolnum>1</manvolnum></citerefentry>
|
|
</para>
|
|
</refsect1>
|
|
|
|
</refentry>
|