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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="systemd.target">
<refentryinfo>
<title>systemd.target</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>systemd.target</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd.target</refname>
<refpurpose>Target unit configuration</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename><replaceable>target</replaceable>.target</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>A unit configuration file whose name ends in <literal>.target</literal> encodes information about a
target unit of systemd. Target units are used to group units and to set synchronization points for
ordering dependencies with other unit files.</para>
<para>This unit type has no specific options. See
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for the
common options of all unit configuration files. The common configuration items are configured in the
generic [Unit] and [Install] sections. A separate [Target] section does not exist, since no
target-specific options may be configured.</para>
<para>Target units do not offer any additional functionality on top of the generic functionality provided
by units. They merely group units, allowing a single target name to be used in <varname>Wants=</varname>
and <varname>Requires=</varname> settings to establish a dependency on a set of units defined by the
target, and in <varname>Before=</varname> and <varname>After=</varname> settings to establish ordering.
Targets establish standardized names for synchronization points during boot and shutdown. Importantly,
see <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for examples and descriptions of standard systemd targets.</para>
<para>Target units provide a more flexible replacement for SysV runlevels in the classic SysV init
system. For compatibility reasons special target units such as <filename>runlevel3.target</filename>
exist which are used by the SysV runlevel compatibility code in systemd, see
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
details.</para>
<para>Note that a target unit file must not be empty, lest it be considered a masked unit. It is
recommended to provide a [Unit] section which includes informative <varname>Description=</varname> and
<varname>Documentation=</varname> options.</para>
</refsect1>
<refsect1>
<title>Automatic Dependencies</title>
<refsect2>
<title>Implicit Dependencies</title>
<para>There are no implicit dependencies for target units.</para>
</refsect2>
<refsect2>
<title>Default Dependencies</title>
<para>The following dependencies are added unless
<varname>DefaultDependencies=no</varname> is set:</para>
<itemizedlist>
<listitem><para>Target units will automatically complement all configured dependencies of type
<varname>Wants=</varname> or <varname>Requires=</varname> with dependencies of type
<varname>After=</varname> unless <varname>DefaultDependencies=no</varname> is set in the specified
units.</para>
<para>Note that the reverse is not true. For example, defining <option>Wants=that.target</option> in
<filename index='false'>some.service</filename> will not automatically add the
<option>After=that.target</option> ordering dependency for <filename>some.service</filename>.
Instead, <filename>some.service</filename> should use the primary synchronization function of target
type units, by setting a specific <option>After=that.target</option> or
<option>Before=that.target</option> ordering dependency in its .service unit file.
</para></listitem>
<listitem><para>Target units automatically gain <varname>Conflicts=</varname>
and <varname>Before=</varname> dependencies against
<filename>shutdown.target</filename>.</para></listitem>
</itemizedlist>
</refsect2>
</refsect1>
<refsect1>
<title>Options</title>
<para>Target unit files may include [Unit] and [Install] sections, which are described in
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
No options specific to this file type are supported.</para>
</refsect1>
<refsect1>
<title>Example</title>
<example>
<title>Simple standalone target</title>
<programlisting># emergency-net.target
[Unit]
Description=Emergency Mode with Networking
Requires=emergency.target systemd-networkd.service
After=emergency.target systemd-networkd.service
AllowIsolate=yes</programlisting>
<para>When adding dependencies to other units, it's important to check if they set
<varname>DefaultDependencies=</varname>. Service units, unless they set
<varname>DefaultDependencies=no</varname>, automatically get a dependency on
<filename>sysinit.target</filename>. In this case, both
<filename>emergency.target</filename> and <filename>systemd-networkd.service</filename>
have <varname>DefaultDependencies=no</varname>, so they are suitable for use
in this target, and do not pull in <filename>sysinit.target</filename>.</para>
<para>You can now switch into this emergency mode by running <varname>systemctl
isolate emergency-net.target</varname> or by passing the option
<varname>systemd.unit=emergency-net.target</varname> on the kernel command
line.</para>
<para>Other units can have <varname>WantedBy=emergency-net.target</varname> in the
<varname>[Install]</varname> section. After they are enabled using
<command>systemctl enable</command>, they will be started before
<varname>emergency-net.target</varname> is started. It is also possible to add
arbitrary units as dependencies of <filename>emergency.target</filename> without
modifying them by using <command>systemctl add-wants</command>.
</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.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
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