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man: finish systemd.unit.5
This commit is contained in:
Lennart Poettering
parent
436c44a5d6
commit
11e299550e
@ -48,15 +48,15 @@
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</refnamediv>
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<refsynopsisdiv>
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<para><filename>systemd.service</filename></para>
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<para><filename>systemd.socket</filename></para>
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<para><filename>systemd.device</filename></para>
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<para><filename>systemd.mount</filename></para>
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<para><filename>systemd.automount</filename></para>
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<para><filename>systemd.swap</filename></para>
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<para><filename>systemd.target</filename></para>
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<para><filename>systemd.path</filename></para>
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<para><filename>systemd.timer</filename></para>
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<para><filename>systemd.service</filename>,
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<filename>systemd.socket</filename>,
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<filename>systemd.device</filename>,
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<filename>systemd.mount</filename>,
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<filename>systemd.automount</filename>,
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<filename>systemd.swap</filename>,
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<filename>systemd.target</filename>,
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<filename>systemd.path</filename>,
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<filename>systemd.timer</filename></para>
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</refsynopsisdiv>
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<refsect1>
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@ -66,15 +66,74 @@
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about a service, a socket, a device, a mount point, an
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automount point, a swap file or partition, a start-up
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target, a file system path or a timer controlled and
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supervised by <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The syntax is inspired by XDG
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<filename>.desktop</filename> files, which are in turn
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inspired by Microsoft Windows <filename>.ini</filename>
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files.</para>
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supervised by
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The
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syntax is inspired by <ulink
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url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
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Desktop Entry Specificiation</ulink> <filename>.desktop</filename> files, which are in turn
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inspired by Microsoft Windows
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<filename>.ini</filename> files.</para>
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<para>This man pages lists the common configuration
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options of the all unit types. These options need to
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be configured either in the [Unit] resp. [Install]
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be configured in the [Unit] resp. [Install]
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section of the unit files.</para>
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<para>In addition to the generic [Unit] and [Install]
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sections described here each unit should have a
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type-specific section, e.g. [Service] for a service
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unit. See the respective man pages for more
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information.</para>
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<para>Unit files may contain additional options on top
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of those listed here. If systemd encounters an unknown
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option it will write a warning log message but
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continue loading the unit. If an option is prefixed
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with <option>X-</option> it is ignored completely by
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systemd. 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
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written in various forms. For positive settings the
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strings <option>1</option>, <option>yes</option>,
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<option>true</option> and <option>on</option> are
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equivalent. For negative settings the strings
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<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>Empty lines and lines starting with # or ; are
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ignored. This may be used for commenting.</para>
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<para>If a line starts with <option>.include</option>
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followed by a file name the specified file will be
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read as if its contents where listed in place of the
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<option>.include</option> directive.</para>
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<para>Along with a unit file
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<filename>foo.service</filename> a directory
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<filename>foo.service.wants/</filename> may exist. All
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units symlinked from such a directory are implicitly
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added as dependencies of type
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<varname>Wanted=</varname> to the unit. This is useful
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to hook units into the start-up of other units,
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without having to modify their unit configuration
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files. For details about the semantics of
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<varname>Wanted=</varname> see below. The preferred
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way to create symlinks in the
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<filename>.wants/</filename> directory of a service is
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with the
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<citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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tool which reads information from the [Install]
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section of unit files. (See below.)</para>
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<para>Note that while systemd offers a flexible
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dependency system between units it is recommended to
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use this functionality only sparsely and instead rely
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on techniques such as bus-based or socket-based
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activation which makes dependencies implicit, which
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both results in a simpler and more flexible
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system.</para>
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</refsect1>
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<refsect1>
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@ -97,13 +156,23 @@
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that this option is different from the
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<varname>Alias=</varname> option from
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the [Install] section mentioned
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below. See below for details</para>
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below. See below for details.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Description=</varname></term>
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<listitem><para>A free-form string
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describing the unit. This is intended for use
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in UIs wanting to show
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descriptive information along with the
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unit name.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Requires=</varname></term>
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<listitem><para>Requirement
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<listitem><para>Configures requirement
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dependencies on other units. If this
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units get activated the units listed
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here will be activated as well. If one
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@ -112,9 +181,224 @@
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be deactivated. This option may be
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specified more than once, in which
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case requirement dependencies for all
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listed names are created.</para>
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</listitem>
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listed names are created. Note that
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requirement dependencies do not
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influence the order in which services
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are started or stopped. This has to be
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configured independently with the
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<varname>After=</varname> or
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<varname>Before=</varname> options. If
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a unit
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<filename>foo.service</filename>
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requires a unit
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<filename>bar.service</filename> as
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configured with
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<varname>Requires=</varname> and no
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ordering is configured with
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<varname>After=</varname> or
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<varname>Before=</varname>, then both
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units will be started simultaneously
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and without any delay between them if
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<filename>foo.service</filename> is
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activated. Often it is a better choice
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to use <varname>Wants=</varname>
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instead of
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<varname>Requires=</varname> in order
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to achieve a system that is more
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robust when dealing with failing
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services.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>RequiresOverridable=</varname></term>
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<listitem><para>Similar to
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<varname>Requires=</varname>.
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Dependencies listed in
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<varname>RequiresOverridable=</varname>
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which cannot be fulfilled or fail to
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start are ignored iff the startup was
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explicitly requested by the user. If
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the start-up was pulled in indirectly
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by some dependency or automatic
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start-up of units that is not
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requested by the user this dependency
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must be fulfilled and otherwise the
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transaction fails. Hence, this option
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may be used to configure dependencies
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that are normally honoured unless the
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user explicitly starts up the unit, in
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which case whether they failed or not
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is irrelevant.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Requisite=</varname></term>
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<term><varname>RequisiteOverridable=</varname></term>
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<listitem><para>Similar to
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<varname>Requires=</varname>
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resp. <varname>RequiresOverridable=</varname>. However,
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if a unit listed here is not started
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already it will not be started and the
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transaction fails
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immediately.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Wants=</varname></term>
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<listitem><para>A weaker version of
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<varname>Requires=</varname>. A unit
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listed in this option will be started
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if the configuring unit is. However,
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it the listed unit fails to start up
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or cannot be added to the transaction
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this has no impact on the validity of
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the transaction as a whole. This is
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the recommended way to hook start-up
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of one unit to the start-up of another
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unit. Note that dependencies of this
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type may also be configured outside of
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the unit configuration file by
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adding a symlink to a
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<filename>.wants/</filename> directory
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accompanying the unit file. For
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details see above.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Conflicts=</varname></term>
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<listitem><para>Configures negative
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requirement dependencies. If a unit
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that has a
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<varname>Conflicts=</varname> setting
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on another unit starting the former
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will stop the latter and vice
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versa. Note that this setting is
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independent of and orthogonal to the
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<varname>After=</varname> and
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<varname>Before=</varname> ordering
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dependencies.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Before=</varname></term>
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<term><varname>After=</varname></term>
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<listitem><para>Configures ordering
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dependencies between units. If a unit
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<filename>foo.service</filename>
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contains a setting
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<option>Before=bar.service</option>
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and both units are being started
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<filename>bar.service</filename>'s
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start-up is delayed until
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<filename>foo.service</filename> is
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started up. Note that this setting is
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independent of and orthogonal to the
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requirement dependencies as configured
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by <varname>Requires=</varname>. It is
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a common pattern to include a unit
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name in both the
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<varname>After=</varname> and
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<varname>Requires=</varname> option in
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which case the unit listed will be
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started before the unit that is
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configured with these options. This
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option may be specified more than
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once, in which case ordering
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dependencies for all listed names are
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created. <varname>After=</varname> is
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the inverse of
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<varname>Before=</varname>, i.e. while
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<varname>After=</varname> ensures that
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the configured unit is started after
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the listed unit finished starting up,
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<varname>Before=</varname> ensures the
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opposite, i.e. that the configured
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unit is fully started up before the
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listed unit is started. Note that when
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two units with an ordering dependency
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between them are shut down, the
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inverse of of the start-up order is
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applied. i.e. if a unit is configured
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with <varname>After=</varname> on
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another unit, the former is stopped
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before the latter if both are shut
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down. If one unit with an ordering
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dependency on another unit is shut
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down while the latter is started up,
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the shut down is ordered before the
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start-up regardless whether the
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ordering dependency is actually of
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type <varname>After=</varname> or
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<varname>Before=</varname>. If two
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units have no ordering dependencies
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between them they are shut down
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resp. started up simultaneously, and
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no ordering takes
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place. </para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>RecursiveStop=</varname></term>
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<listitem><para>Takes a boolean
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argument. If <option>true</option> and
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the unit stops without this being
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requested by the user all units
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depending on it will be stopped as
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well. (e.g. if a service exits or
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crashes on its own behalf, units using
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it will be stopped) Note that normally
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if a unit stops without user request
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units depending on it will not be
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terminated. Only if the user requested
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shutdown of a unit all units depending
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on the unit will be shut down as well
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and at the same time. Defaults to
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<option>false</option>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>StopWhenUnneeded=</varname></term>
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<listitem><para>Takes a boolean
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argument. If <option>true</option>
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this unit will be stopped when it is
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no longer used. Note that in order to
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minimize the work to be executed
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systemd will by default not stop units
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unless they are conflicting with other
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units, or the user explicitly
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requested their shut down. If this
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option is set a unit will be
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automatically cleaned up if no other
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active unit requires it. Defaults to
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<option>false</option>.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>OnlyByDependency=</varname></term>
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<listitem><para>Takes a boolean
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argument. If <option>true</option>
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this unit may only be activated
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indirectly. In this case explicit
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start-up requested by the user is
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denied, however if it is started as
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dependency of another unit start-up
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will succeed. This is mostly a safety
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feature to ensure that the user does
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not accidently activate units that are
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not intended to be activated
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explicitly. This option defaults to
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<option>false</option>.</para></listitem>
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</varlistentry>
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</variablelist>
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<para>Unit file may include a [Install] section, which
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@ -123,7 +407,7 @@
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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during runtime. It is used exclusively by the
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<citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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during installation of a unit:</para>
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tool during installation of a unit:</para>
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<variablelist>
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<varlistentry>
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@ -148,18 +432,52 @@
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unconditionally if the unit is
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loaded. The names from
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<varname>Alias=</varname> apply only
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if the unit is actually installed with
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the <command>systemd-install</command>
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if the unit has actually been
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installed with the
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<command>systemd-install</command>
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tool. Also, if systemd searches for a
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unit, it will discover symlinked alias
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names, but not names configured only
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with <varname>Names=</varname>. It is
|
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a common pattern to list a name in both
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options. In this case, a unit will be
|
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active under all names if installed,
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but also if not installed but
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requested
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explicitly.</para></listitem>
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names as configured with
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<varname>Alias=</varname>, but not
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names configured with
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<varname>Names=</varname> only. It is
|
||||
a common pattern to list a name in
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||||
both options. In this case, a unit
|
||||
will be active under all names if
|
||||
installed, but also if not installed
|
||||
but requested explicitly under its
|
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main name.</para></listitem>
|
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</varlistentry>
|
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|
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<varlistentry>
|
||||
<term><varname>WantedBy=</varname></term>
|
||||
|
||||
<listitem><para>Installs a symlink in
|
||||
the <filename>.wants/</filename>
|
||||
subdirectory for a unit. This has the
|
||||
effect that when the listed unit name
|
||||
is activated the unit listing it is
|
||||
activated
|
||||
to. <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.</para></listitem>
|
||||
</varlistentry>
|
||||
|
||||
<varlistentry>
|
||||
<term><varname>Also=</varname></term>
|
||||
|
||||
<listitem><para>Additional units to
|
||||
install when this unit is
|
||||
installed. If the user requests
|
||||
installation of a unit with this
|
||||
option configured
|
||||
<command>systemd-install</command>
|
||||
will automatically install units
|
||||
listed in this option as
|
||||
well.</para></listitem>
|
||||
</varlistentry>
|
||||
</variablelist>
|
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|
||||
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||||
Loading…
Reference in New Issue
Block a user