</refnamediv>
<refsynopsisdiv>
- <para><filename>systemd.service</filename></para>
- <para><filename>systemd.socket</filename></para>
- <para><filename>systemd.device</filename></para>
- <para><filename>systemd.mount</filename></para>
- <para><filename>systemd.automount</filename></para>
- <para><filename>systemd.swap</filename></para>
- <para><filename>systemd.target</filename></para>
- <para><filename>systemd.path</filename></para>
- <para><filename>systemd.timer</filename></para>
+ <para><filename>systemd.service</filename>,
+ <filename>systemd.socket</filename>,
+ <filename>systemd.device</filename>,
+ <filename>systemd.mount</filename>,
+ <filename>systemd.automount</filename>,
+ <filename>systemd.swap</filename>,
+ <filename>systemd.target</filename>,
+ <filename>systemd.path</filename>,
+ <filename>systemd.timer</filename>,
+ <filename>systemd.snapshot</filename></para>
</refsynopsisdiv>
<refsect1>
about a service, a socket, a device, a mount point, an
automount point, a swap file or partition, a start-up
target, a file system path or a timer controlled and
- supervised by <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The syntax is inspired by XDG
- <filename>.desktop</filename> files, which are in turn
- inspired by Microsoft Windows <filename>.ini</filename>
- files.</para>
+ supervised by
+ <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The
+ syntax is inspired by <ulink
+ url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
+ Desktop Entry Specification</ulink> <filename>.desktop</filename> files, which are in turn
+ inspired by Microsoft Windows
+ <filename>.ini</filename> files.</para>
<para>This man pages lists the common configuration
- options of the all unit types. These options need to
- be configured either in the [Unit] resp. [Install]
+ options of all the unit types. These options need to
+ be configured in the [Unit] resp. [Install]
section of the unit files.</para>
+
+ <para>In addition to the generic [Unit] and [Install]
+ sections described here, each unit should have a
+ type-specific section, e.g. [Service] for a service
+ unit. See the respective man pages for more
+ information.</para>
+
+ <para>Unit files may contain additional options on top
+ of those listed here. If systemd encounters an unknown
+ option it will write a warning log message but
+ continue loading the unit. If an option is prefixed
+ with <option>X-</option> it is ignored completely by
+ systemd. Applications may use this to include
+ additional information in the unit files.</para>
+
+ <para>Boolean arguments used in unit files can be
+ written in various formats. For positive settings the
+ strings <option>1</option>, <option>yes</option>,
+ <option>true</option> and <option>on</option> are
+ equivalent. For negative settings the strings
+ <option>0</option>, <option>no</option>,
+ <option>false</option> and <option>off</option> are
+ equivalent.</para>
+
+ <para>Time span values encoded in unit files can be
+ written in various formats. A stand-alone number
+ specifies a time in seconds. If suffixed with a time
+ unit, the unit is honored. A concatenation of
+ multiple values with units is supported, in which case
+ the values are added up. Example: "50" refers to 50
+ seconds; "2min 200ms" refers to 2 minutes plus 200
+ milliseconds, i.e. 120200ms. The following time units
+ are understood: s, min, h, d, w, ms, us.</para>
+
+ <para>Empty lines and lines starting with # or ; are
+ ignored. This may be used for commenting. Lines ending
+ in a backslash are concatenated with the following
+ line while reading and the backslash is replaced by a
+ space character. This may be used to wrap long lines.</para>
+
+ <para>If a line starts with <option>.include</option>
+ followed by a file name, the specified file will be
+ read as if its contents were listed in place of the
+ <option>.include</option> directive.</para>
+
+ <para>Along with a unit file
+ <filename>foo.service</filename> a directory
+ <filename>foo.service.wants/</filename> may exist. All
+ units symlinked from such a directory are implicitly
+ added as dependencies of type
+ <varname>Wanted=</varname> to the unit. This is useful
+ to hook units into the start-up of other units,
+ without having to modify their unit configuration
+ files. For details about the semantics of
+ <varname>Wanted=</varname> see below. The preferred
+ way to create symlinks in the
+ <filename>.wants/</filename> directory of a service is
+ with the
+ <citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ tool which reads information from the [Install]
+ section of unit files. (See below.)</para>
+
+ <para>Note that while systemd offers a flexible
+ dependency system between units it is recommended to
+ use this functionality only sparsely and instead rely
+ on techniques such as bus-based or socket-based
+ activation which makes dependencies implicit, which
+ both results in a simpler and more flexible
+ system.</para>
+
+ <para>Some unit names reflect paths existing in the
+ file system name space. Example: a device unit
+ <filename>dev-sda.device</filename> refers to a device
+ with the device node <filename>/dev/sda</filename> in
+ the file system namespace. If this applies a special
+ way to escape the path name is used, so that it is
+ usable as part of a file name. Basically, given a
+ path, "/" is replaced by "-", and all unprintable
+ characters and the "-" are replaced by C-style "\x20"
+ escapes. The root directory "/" is encoded as single
+ dash, while otherwise the initial and ending "/" is
+ removed from all paths during transformation. This
+ escaping is reversible.</para>
+
+ <para>Optionally, units may be instantiated from a
+ template file at runtime. This allows creation of
+ multiple units from a single configuration file. If
+ systemd looks for a unit configuration file it will
+ first search for the literal unit name in the
+ filesystem. If that yields no success and the unit
+ name contains an @ character, systemd will look for a
+ unit template that shares the same name but with the
+ instance string (i.e. the part between the @ character
+ and the suffix) removed. Example: if a service
+ <filename>getty@tty3.service</filename> is requested
+ and no file by that name is found, systemd will look
+ for <filename>getty@.service</filename> and
+ instantiate a service from that configuration file if
+ it is found. To refer to the instance string from
+ within the configuration file you may use the special
+ <literal>%i</literal> specifier in many of the
+ configuration options. Other specifiers that may be
+ used are <literal>%n</literal>, <literal>%N</literal>,
+ <literal>%p</literal>, <literal>%P</literal> and
+ <literal>%I</literal>, for the full unit name, the
+ unescaped unit name, the prefix name, the unescaped
+ prefix name and the unescaped instance name,
+ respectively. The prefix name here refers to the
+ string before the @, i.e. "getty" in the example
+ above, where "tty3" is the instance name.</para>
</refsect1>
<refsect1>
that this option is different from the
<varname>Alias=</varname> option from
the [Install] section mentioned
- below. See below for details</para>
+ below. See below for details.</para>
</listitem>
</varlistentry>
+
+ <varlistentry>
+ <term><varname>Description=</varname></term>
+ <listitem><para>A free-form string
+ describing the unit. This is intended
+ for use in UIs to show descriptive
+ information along with the unit
+ name.</para></listitem>
+ </varlistentry>
+
<varlistentry>
<term><varname>Requires=</varname></term>
- <listitem><para>Requirement
+ <listitem><para>Configures requirement
dependencies on other units. If this
- units get activated the units listed
+ unit gets activated, the units listed
here will be activated as well. If one
of the other units gets deactivated or
its activation fails, this unit will
be deactivated. This option may be
specified more than once, in which
case requirement dependencies for all
- listed names are created.</para>
- </listitem>
+ listed names are created. Note that
+ requirement dependencies do not
+ influence the order in which services
+ are started or stopped. This has to be
+ configured independently with the
+ <varname>After=</varname> or
+ <varname>Before=</varname> options. If
+ a unit
+ <filename>foo.service</filename>
+ requires a unit
+ <filename>bar.service</filename> as
+ configured with
+ <varname>Requires=</varname> and no
+ ordering is configured with
+ <varname>After=</varname> or
+ <varname>Before=</varname>, then both
+ units will be started simultaneously
+ and without any delay between them if
+ <filename>foo.service</filename> is
+ activated. Often it is a better choice
+ to use <varname>Wants=</varname>
+ instead of
+ <varname>Requires=</varname> in order
+ to achieve a system that is more
+ robust when dealing with failing
+ services.</para></listitem>
+ </varlistentry>
+
+
+ <varlistentry>
+ <term><varname>RequiresOverridable=</varname></term>
+
+ <listitem><para>Similar to
+ <varname>Requires=</varname>.
+ Dependencies listed in
+ <varname>RequiresOverridable=</varname>
+ which cannot be fulfilled or fail to
+ start are ignored if the startup was
+ explicitly requested by the user. If
+ the start-up was pulled in indirectly
+ by some dependency or automatic
+ start-up of units that is not
+ requested by the user this dependency
+ must be fulfilled and otherwise the
+ transaction fails. Hence, this option
+ may be used to configure dependencies
+ that are normally honored unless the
+ user explicitly starts up the unit, in
+ which case whether they failed or not
+ is irrelevant.</para></listitem>
+
+ </varlistentry>
+ <varlistentry>
+ <term><varname>Requisite=</varname></term>
+ <term><varname>RequisiteOverridable=</varname></term>
+
+ <listitem><para>Similar to
+ <varname>Requires=</varname>
+ resp. <varname>RequiresOverridable=</varname>. However,
+ if a unit listed here is not started
+ already it will not be started and the
+ transaction fails
+ immediately.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Wants=</varname></term>
+
+ <listitem><para>A weaker version of
+ <varname>Requires=</varname>. A unit
+ listed in this option will be started
+ if the configuring unit is. However,
+ if the listed unit fails to start up
+ or cannot be added to the transaction
+ this has no impact on the validity of
+ the transaction as a whole. This is
+ the recommended way to hook start-up
+ of one unit to the start-up of another
+ unit. Note that dependencies of this
+ type may also be configured outside of
+ the unit configuration file by
+ adding a symlink to a
+ <filename>.wants/</filename> directory
+ accompanying the unit file. For
+ details see above.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Conflicts=</varname></term>
+
+ <listitem><para>Configures negative
+ requirement dependencies. If a unit
+ has a
+ <varname>Conflicts=</varname> setting
+ on another unit, starting the former
+ will stop the latter and vice
+ versa. Note that this setting is
+ independent of and orthogonal to the
+ <varname>After=</varname> and
+ <varname>Before=</varname> ordering
+ dependencies.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>Before=</varname></term>
+ <term><varname>After=</varname></term>
+
+ <listitem><para>Configures ordering
+ dependencies between units. If a unit
+ <filename>foo.service</filename>
+ contains a setting
+ <option>Before=bar.service</option>
+ and both units are being started,
+ <filename>bar.service</filename>'s
+ start-up is delayed until
+ <filename>foo.service</filename> is
+ started up. Note that this setting is
+ independent of and orthogonal to the
+ requirement dependencies as configured
+ by <varname>Requires=</varname>. It is
+ a common pattern to include a unit
+ name in both the
+ <varname>After=</varname> and
+ <varname>Requires=</varname> option in
+ which case the unit listed will be
+ started before the unit that is
+ configured with these options. This
+ option may be specified more than
+ once, in which case ordering
+ dependencies for all listed names are
+ created. <varname>After=</varname> is
+ the inverse of
+ <varname>Before=</varname>, i.e. while
+ <varname>After=</varname> ensures that
+ the configured unit is started after
+ the listed unit finished starting up,
+ <varname>Before=</varname> ensures the
+ opposite, i.e. that the configured
+ unit is fully started up before the
+ listed unit is started. Note that when
+ two units with an ordering dependency
+ between them are shut down, the
+ inverse of the start-up order is
+ applied. i.e. if a unit is configured
+ with <varname>After=</varname> on
+ another unit, the former is stopped
+ before the latter if both are shut
+ down. If one unit with an ordering
+ dependency on another unit is shut
+ down while the latter is started up,
+ the shut down is ordered before the
+ start-up regardless whether the
+ ordering dependency is actually of
+ type <varname>After=</varname> or
+ <varname>Before=</varname>. If two
+ units have no ordering dependencies
+ between them they are shut down
+ resp. started up simultaneously, and
+ no ordering takes
+ place. </para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>RecursiveStop=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument. If <option>true</option> and
+ the unit stops without being requested
+ by the user, all units
+ depending on it will be stopped as
+ well. (e.g. if a service exits or
+ crashes on its own behalf, units using
+ it will be stopped) Note that normally
+ if a unit stops without a user request,
+ units depending on it will not be
+ terminated. Only if the user requested
+ shutdown of a unit, all units depending
+ on that unit will be shut down as well
+ and at the same time. Defaults to
+ <option>false</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>StopWhenUnneeded=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument. If <option>true</option>
+ this unit will be stopped when it is
+ no longer used. Note that in order to
+ minimize the work to be executed,
+ systemd will not stop units by default
+ unless they are conflicting with other
+ units, or the user explicitly
+ requested their shut down. If this
+ option is set, a unit will be
+ automatically cleaned up if no other
+ active unit requires it. Defaults to
+ <option>false</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>OnlyByDependency=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument. If <option>true</option>
+ this unit can only be activated
+ indirectly. In this case explicit
+ start-up requested by the user is
+ denied, however if it is started as a
+ dependency of another unit, start-up
+ will succeed. This is mostly a safety
+ feature to ensure that the user does
+ not accidentally activate units that are
+ not intended to be activated
+ explicitly. This option defaults to
+ <option>false</option>.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><varname>DefaultDependencies=</varname></term>
+
+ <listitem><para>Takes a boolean
+ argument. If <option>true</option>
+ (the default), a few default
+ dependencies will implicitly be
+ created for the unit. The actual
+ dependencies created depend on the
+ unit type. For example, for service
+ units, these dependencies ensure that
+ the service is started only after
+ basic system initialization is
+ completed and is properly terminated on
+ system shutdown. See the respective
+ man pages for details. Generally, only
+ services involved with early boot or
+ late shutdown should set this option
+ to <option>false</option>. It is
+ highly recommended to leave this
+ option enabled for the majority of
+ common units. If set to
+ <option>false</option> this option
+ does not disable all implicit
+ dependencies, just non-essential
+ ones.</para></listitem>
</varlistentry>
+
</variablelist>
<para>Unit file may include a [Install] section, which
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
during runtime. It is used exclusively by the
<citerefentry><refentrytitle>systemd-install</refentrytitle><manvolnum>1</manvolnum></citerefentry>
- during installation of a unit:</para>
+ tool during installation of a unit:</para>
<variablelist>
<varlistentry>
name. This option may be specified
more than once, in which case all
listed names are used. At installation
- time
+ time,
<command>systemd-install</command>
will create symlinks from these names
to the unit file name. Note that this
unconditionally if the unit is
loaded. The names from
<varname>Alias=</varname> apply only
- if the unit is actually installed with
- the <command>systemd-install</command>
+ if the unit has actually been
+ installed with the
+ <command>systemd-install</command>
tool. Also, if systemd searches for a
unit, it will discover symlinked alias
- names, but not names configured only
- with <varname>Names=</varname>. It is
- a common pattern to list a name in both
- options. In this case, a unit will be
- active under all names if installed,
- but also if not installed but
- requested
- explicitly.</para></listitem>
+ names as configured with
+ <varname>Alias=</varname>, but not
+ names configured with
+ <varname>Names=</varname> only. It is
+ a common pattern to list a name in
+ 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
+ main name.</para></listitem>
+ </varlistentry>
+
+ <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
+ too. <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>
<citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
- <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
~ianmdlvl / elogind.git / blobdiff