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<refentry id="systemd.target">
<refsect1>
<title>Description</title>
- <para>A unit configuration file whose name ends in
- <literal>.target</literal> encodes information about a target unit
- of systemd, which is used for grouping units and as well-known
- synchronization points during start-up.</para>
+ <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 exist
- merely to group units via dependencies (useful as boot targets),
- and to establish standardized names for synchronization points
- used in dependencies between units. Among other things, target
- units are a more flexible replacement for SysV runlevels in the
- classic SysV init system. (And 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>
+ <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>
<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. Note that <varname>Wants=</varname> or
- <varname>Requires=</varname> must be defined in the target unit itself — if
- you for example define <varname>Wants=</varname>some.target in
- some.service, the automatic ordering will not be added.</para></listitem>
+ <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
</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>
<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>
+ <para><simplelist type="inline">
+ <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
+ <member><citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
+ <member><citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
+ <member><citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
+ <member><citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
+ </simplelist></para>
</refsect1>
</refentry>
projects / thirdparty / systemd.git / blobdiff