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diff --git a/man/systemd.target.xml b/man/systemd.target.xml new file mode 100644 index 0000000..f650825 --- /dev/null +++ b/man/systemd.target.xml @@ -0,0 +1,150 @@ +<?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> |