diff options
Diffstat (limited to 'man/systemd.target.xml')
| -rw-r--r-- | man/systemd.target.xml | 138 |
1 files changed, 138 insertions, 0 deletions
diff --git a/man/systemd.target.xml b/man/systemd.target.xml new file mode 100644 index 0000000..10aa91a --- /dev/null +++ b/man/systemd.target.xml @@ -0,0 +1,138 @@ +<?xml version='1.0'?> <!--*-nxml-*--> +<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> + +<!-- + SPDX-License-Identifier: LGPL-2.1+ +--> + +<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, which is used for grouping units and as well-known + synchronization points during start-up.</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> + </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. 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 automatically gain <varname>Conflicts=</varname> + and <varname>Before=</varname> dependencies against + <filename>shutdown.target</filename>.</para></listitem> + </itemizedlist> + </refsect2> + </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> |