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<refentry id="systemd.service">
<refentryinfo>
<title>systemd.service</title>
<productname>systemd</productname>
-
- <authorgroup>
- <author>
- <contrib>Developer</contrib>
- <firstname>Lennart</firstname>
- <surname>Poettering</surname>
- <email>lennart@poettering.net</email>
- </author>
- </authorgroup>
</refentryinfo>
<refmeta>
<title>Description</title>
<para>A unit configuration file whose name ends in
- <filename>.service</filename> encodes information about a process
+ <literal>.service</literal> encodes information about a process
controlled and supervised by systemd.</para>
<para>This man page lists the configuration options specific to
</refsect1>
<refsect1>
- <title>Implicit Dependencies</title>
-
- <para>The following dependencies are implicitly added:</para>
-
- <itemizedlist>
- <listitem><para>Services with <varname>Type=dbus</varname> set automatically
- acquire dependencies of type <varname>Requires=</varname> and
- <varname>After=</varname> on
- <filename>dbus.socket</filename>.</para></listitem>
-
- <listitem><para>Socket activated services are automatically ordered after
- their activating <filename>.socket</filename> units via an
- automatic <varname>After=</varname> dependency.
- Services also pull in all <filename>.socket</filename> units
- listed in <varname>Sockets=</varname> via automatic
- <varname>Wants=</varname> and <varname>After=</varname> dependencies.</para></listitem>
- </itemizedlist>
-
- <para>Additional implicit dependencies may be added as result of
- execution and resource control parameters as documented in
- <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- and
- <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+ <title>Service Templates</title>
+
+ <para>It is possible for <command>systemd</command> services to take a single argument via the
+ <literal><replaceable>service</replaceable>@<replaceable>argument</replaceable>.service</literal>
+ syntax. Such services are called "instantiated" services, while the unit definition without the
+ <replaceable>argument</replaceable> parameter is called a "template". An example could be a
+ <filename>dhcpcd@.service</filename> service template which takes a network interface as a
+ parameter to form an instantiated service. Within the service file, this parameter or "instance
+ name" can be accessed with %-specifiers. See
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ for details.</para>
</refsect1>
<refsect1>
- <title>Default Dependencies</title>
-
- <para>The following dependencies are added unless <varname>DefaultDependencies=no</varname> is set:</para>
-
- <itemizedlist>
- <listitem><para>Service units will have dependencies of type <varname>Requires=</varname> and
- <varname>After=</varname> on <filename>sysinit.target</filename>, a dependency of type <varname>After=</varname> on
- <filename>basic.target</filename> as well as dependencies of type <varname>Conflicts=</varname> and
- <varname>Before=</varname> on <filename>shutdown.target</filename>. These ensure that normal service units pull in
- basic system initialization, and are terminated cleanly prior to system shutdown. Only services involved with early
- boot or late system shutdown should disable this option.</para></listitem>
-
- <listitem><para>Instanced service units (i.e. service units with an <literal>@</literal> in their name) are assigned by
- default a per-template slice unit (see
- <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>), named after the
- template unit, containing all instances of the specific template. This slice is normally stopped at shutdown,
- together with all template instances. If that is not desired, set <varname>DefaultDependencies=no</varname> in the
- template unit, and either define your own per-template slice unit file that also sets
- <varname>DefaultDependencies=no</varname>, or set <varname>Slice=system.slice</varname> (or another suitable slice)
- in the template unit. Also see
- <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
- </para></listitem>
- </itemizedlist>
+ <title>Automatic Dependencies</title>
+
+ <refsect2>
+ <title>Implicit Dependencies</title>
+
+ <para>The following dependencies are implicitly added:</para>
+
+ <itemizedlist>
+ <listitem><para>Services with <varname>Type=dbus</varname> set automatically
+ acquire dependencies of type <varname>Requires=</varname> and
+ <varname>After=</varname> on
+ <filename>dbus.socket</filename>.</para></listitem>
+
+ <listitem><para>Socket activated services are automatically ordered after
+ their activating <filename>.socket</filename> units via an
+ automatic <varname>After=</varname> dependency.
+ Services also pull in all <filename>.socket</filename> units
+ listed in <varname>Sockets=</varname> via automatic
+ <varname>Wants=</varname> and <varname>After=</varname> dependencies.</para></listitem>
+ </itemizedlist>
+
+ <para>Additional implicit dependencies may be added as result of
+ execution and resource control parameters as documented in
+ <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+ and
+ <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+ </refsect2>
+
+ <refsect2>
+ <title>Default Dependencies</title>
+
+ <para>The following dependencies are added unless <varname>DefaultDependencies=no</varname> is set:</para>
+
+ <itemizedlist>
+ <listitem><para>Service units will have dependencies of type <varname>Requires=</varname> and
+ <varname>After=</varname> on <filename>sysinit.target</filename>, a dependency of type <varname>After=</varname> on
+ <filename>basic.target</filename> as well as dependencies of type <varname>Conflicts=</varname> and
+ <varname>Before=</varname> on <filename>shutdown.target</filename>. These ensure that normal service units pull in
+ basic system initialization, and are terminated cleanly prior to system shutdown. Only services involved with early
+ boot or late system shutdown should disable this option.</para></listitem>
+
+ <listitem><para>Instanced service units (i.e. service units with an <literal>@</literal> in their name) are assigned by
+ default a per-template slice unit (see
+ <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>), named after the
+ template unit, containing all instances of the specific template. This slice is normally stopped at shutdown,
+ together with all template instances. If that is not desired, set <varname>DefaultDependencies=no</varname> in the
+ template unit, and either define your own per-template slice unit file that also sets
+ <varname>DefaultDependencies=no</varname>, or set <varname>Slice=system.slice</varname> (or another suitable slice)
+ in the template unit. Also see
+ <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
+ </para></listitem>
+ </itemizedlist>
+ </refsect2>
</refsect1>
<refsect1>
<varname>PrivateNetwork=</varname><option>yes</option>.</para>
<para>Behavior of <option>idle</option> is very similar to <option>simple</option>; however, actual execution
- of the service binary is delayed until all active jobs are dispatched. This may be used to avoid interleaving
+ of the service program is delayed until all active jobs are dispatched. This may be used to avoid interleaving
of output of shell services with the status output on the console. Note that this type is useful only to
improve console output, it is not useful as a general unit ordering tool, and the effect of this service type
- is subject to a 5s time-out, after which the service binary is invoked anyway.</para>
+ is subject to a 5s time-out, after which the service program is invoked anyway.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>PIDFile=</varname></term>
- <listitem><para>Takes an absolute filename pointing to the
- PID file of this daemon. Use of this option is recommended for
- services where <varname>Type=</varname> is set to
- <option>forking</option>. systemd will read the PID of the
- main process of the daemon after start-up of the service.
- systemd will not write to the file configured here, although
- it will remove the file after the service has shut down if it
- still exists.
- </para>
- </listitem>
+ <listitem><para>Takes an absolute path referring to the PID file of the service. Usage of this option is
+ recommended for services where <varname>Type=</varname> is set to <option>forking</option>. The service manager
+ will read the PID of the main process of the service from this file after start-up of the service. The service
+ manager will not write to the file configured here, although it will remove the file after the service has shut
+ down if it still exists. The PID file does not need to be owned by a privileged user, but if it is owned by an
+ unprivileged user additional safety restrictions are enforced: the file may not be a symlink to a file owned by
+ a different user (neither directly nor indirectly), and the PID file must refer to a process already belonging
+ to the service.</para></listitem>
</varlistentry>
<varlistentry>
<varname>ExecStop=</varname> line set. (Services lacking both <varname>ExecStart=</varname> and
<varname>ExecStop=</varname> are not valid.)</para>
- <para>For each of the specified commands, the first argument must be an absolute path to an
- executable. Optionally, this filename may be prefixed with a number of special characters:</para>
+ <para>For each of the specified commands, the first argument must be either an absolute path to an executable
+ or a simple file name without any slashes. Optionally, this filename may be prefixed with a number of special
+ characters:</para>
<table>
<title>Special executable prefixes</title>
<row>
<entry><literal>!</literal></entry>
- <entry>Similar to the <literal>+</literal> character discussed above this permits invoking command lines with elevated privileges. However, unlike <literal>+</literal> the <literal>!</literal> character exclusively alters the effect of <varname>User=</varname>, <varname>Group=</varname> and <varname>SupplementaryGroups=</varname>, i.e. only the stanzas the affect user and group credentials. Note that this setting may be combined with <varname>DynamicUser=</varname>, in which case a dynamic user/group pair is allocated before the command is invoked, but credential changing is left to the executed process itself.</entry>
+ <entry>Similar to the <literal>+</literal> character discussed above this permits invoking command lines with elevated privileges. However, unlike <literal>+</literal> the <literal>!</literal> character exclusively alters the effect of <varname>User=</varname>, <varname>Group=</varname> and <varname>SupplementaryGroups=</varname>, i.e. only the stanzas that affect user and group credentials. Note that this setting may be combined with <varname>DynamicUser=</varname>, in which case a dynamic user/group pair is allocated before the command is invoked, but credential changing is left to the executed process itself.</entry>
</row>
<row>
<varname>Type=oneshot</varname> is used, in which case the
timeout is disabled by default (see
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
+ </para>
+
+ <para>If a service of <varname>Type=notify</varname> sends <literal>EXTEND_TIMEOUT_USEC=…</literal>, this may cause
+ the start time to be extended beyond <varname>TimeoutStartSec=</varname>. The first receipt of this message
+ must occur before <varname>TimeoutStartSec=</varname> is exceeded, and once the start time has exended beyond
+ <varname>TimeoutStartSec=</varname>, the service manager will allow the service to continue to start, provided
+ the service repeats <literal>EXTEND_TIMEOUT_USEC=…</literal> within the interval specified until the service
+ startup status is finished by <literal>READY=1</literal>. (see
+ <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>).
</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>TimeoutStopSec=</varname></term>
- <listitem><para>Configures the time to wait for stop. If a
- service is asked to stop, but does not terminate in the
- specified time, it will be terminated forcibly via
- <constant>SIGTERM</constant>, and after another timeout of
- equal duration with <constant>SIGKILL</constant> (see
- <varname>KillMode=</varname> in
+ <listitem><para>This option serves two purposes. First, it configures the time to wait for each
+ <constant>ExecStop=</constant> command. If any of them times out, subsequent <constant>ExecStop=</constant> commands
+ are skipped and the service will be terminated by <constant>SIGTERM</constant>. If no <constant>ExecStop=</constant>
+ commands are specified, the service gets the <constant>SIGTERM</constant> immediately. Second, it configures the time
+ to wait for the service itself to stop. If it doesn't terminate in the specified time, it will be forcibly terminated
+ by <constant>SIGKILL</constant> (see <varname>KillMode=</varname> in
<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
Takes a unit-less value in seconds, or a time span value such
as "5min 20s". Pass <literal>infinity</literal> to disable the
<varname>DefaultTimeoutStopSec=</varname> from the manager
configuration file (see
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
+ </para>
+
+ <para>If a service of <varname>Type=notify</varname> sends <literal>EXTEND_TIMEOUT_USEC=…</literal>, this may cause
+ the stop time to be extended beyond <varname>TimeoutStopSec=</varname>. The first receipt of this message
+ must occur before <varname>TimeoutStopSec=</varname> is exceeded, and once the stop time has exended beyond
+ <varname>TimeoutStopSec=</varname>, the service manager will allow the service to continue to stop, provided
+ the service repeats <literal>EXTEND_TIMEOUT_USEC=…</literal> within the interval specified, or terminates itself
+ (see <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>).
</para></listitem>
</varlistentry>
active for longer than the specified time it is terminated and put into a failure state. Note that this setting
does not have any effect on <varname>Type=oneshot</varname> services, as they terminate immediately after
activation completed. Pass <literal>infinity</literal> (the default) to configure no runtime
- limit.</para></listitem>
+ limit.</para>
+
+ <para>If a service of <varname>Type=notify</varname> sends <literal>EXTEND_TIMEOUT_USEC=…</literal>, this may cause
+ the runtime to be extended beyond <varname>RuntimeMaxSec=</varname>. The first receipt of this message
+ must occur before <varname>RuntimeMaxSec=</varname> is exceeded, and once the runtime has exended beyond
+ <varname>RuntimeMaxSec=</varname>, the service manager will allow the service to continue to run, provided
+ the service repeats <literal>EXTEND_TIMEOUT_USEC=…</literal> within the interval specified until the service
+ shutdown is achieved by <literal>STOPPING=1</literal> (or termination). (see
+ <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>).
+ </para></listitem>
</varlistentry>
<varlistentry>
limiting configured with <varname>StartLimitIntervalSec=</varname>
and <varname>StartLimitBurst=</varname>, see
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
- for details.</para>
+ for details. A restarted service enters the failed state only
+ after the start limits are reached.</para>
<para>Setting this to <option>on-failure</option> is the
recommended choice for long-running services, in order to
passed to the service manager from a specific service are passed back to the service's main process on the next
service restart. Any file descriptors passed to the service manager are automatically closed when
<constant>POLLHUP</constant> or <constant>POLLERR</constant> is seen on them, or when the service is fully
- stopped and no job is queued or being executed for it.</para></listitem>
+ stopped and no job is queued or being executed for it. If this option is used, <varname>NotifyAccess=</varname>
+ (see above) should be set to open access to the notification socket provided by systemd. If
+ <varname>NotifyAccess=</varname> is not set, it will be implicitly set to
+ <option>main</option>.</para></listitem>
</varlistentry>
<varlistentry>
<literal>&</literal>, and <emphasis>other elements of shell
syntax are not supported</emphasis>.</para>
- <para>The command to execute must be an absolute path name. It may
- contain spaces, but control characters are not allowed.</para>
+ <para>The command to execute may contain spaces, but control characters are not allowed.</para>
- <para>The command line accepts <literal>%</literal> specifiers as
- described in
- <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
- Note that the first argument of the command line (i.e. the program
- to execute) may not include specifiers.</para>
+ <para>The command line accepts <literal>%</literal> specifiers as described in
+ <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
<para>Basic environment variable substitution is supported. Use
<literal>${FOO}</literal> as part of a word, or as a word of its
For this type of expansion, quotes are respected when splitting
into words, and afterwards removed.</para>
+ <para>If the command is not a full (absolute) path, it will be resolved to a full path using a
+ fixed search path determinted at compilation time. Searched directories include
+ <filename>/usr/local/bin/</filename>, <filename>/usr/bin/</filename>, <filename>/bin/</filename>
+ on systems using split <filename>/usr/bin/</filename> and <filename>/bin/</filename>
+ directories, and their <filename>sbin/</filename> counterparts on systems using split
+ <filename>bin/</filename> and <filename>sbin/</filename>. It is thus safe to use just the
+ executable name in case of executables located in any of the "standard" directories, and an
+ absolute path must be used in other cases. Using an absolute path is recommended to avoid
+ ambiguity. Hint: this search path may be queried using
+ <command>systemd-path search-binaries-default</command>.</para>
+
<para>Example:</para>
<programlisting>Environment="ONE=one" 'TWO=two two'
-ExecStart=/bin/echo $ONE $TWO ${TWO}</programlisting>
+ExecStart=echo $ONE $TWO ${TWO}</programlisting>
<para>This will execute <command>/bin/echo</command> with four
arguments: <literal>one</literal>, <literal>two</literal>,
<programlisting>Environment=ONE='one' "TWO='two two' too" THREE=
ExecStart=/bin/echo ${ONE} ${TWO} ${THREE}
ExecStart=/bin/echo $ONE $TWO $THREE</programlisting>
- <para>This results in <filename>echo</filename> being
+ <para>This results in <filename>/bin/echo</filename> being
called twice, the first time with arguments
<literal>'one'</literal>,
<literal>'two two' too</literal>, <literal></literal>,
<para>Note that shell command lines are not directly supported. If
shell command lines are to be used, they need to be passed
explicitly to a shell implementation of some kind. Example:</para>
- <programlisting>ExecStart=/bin/sh -c 'dmesg | tac'</programlisting>
+ <programlisting>ExecStart=sh -c 'dmesg | tac'</programlisting>
<para>Example:</para>
- <programlisting>ExecStart=/bin/echo one ; /bin/echo "two two"</programlisting>
+ <programlisting>ExecStart=echo one ; echo "two two"</programlisting>
- <para>This will execute <command>/bin/echo</command> two times,
+ <para>This will execute <command>echo</command> two times,
each time with one argument: <literal>one</literal> and
<literal>two two</literal>, respectively. Because two commands are
specified, <varname>Type=oneshot</varname> must be used.</para>
<para>Example:</para>
- <programlisting>ExecStart=/bin/echo / >/dev/null & \; \
-/bin/ls</programlisting>
+ <programlisting>ExecStart=echo / >/dev/null & \; \
+ls</programlisting>
- <para>This will execute <command>/bin/echo</command>
+ <para>This will execute <command>echo</command>
with five arguments: <literal>/</literal>,
<literal>>/dev/null</literal>,
<literal>&</literal>, <literal>;</literal>, and
- <literal>/bin/ls</literal>.</para>
+ <literal>ls</literal>.</para>
<table>
<title>C escapes supported in command lines and environment variables</title>
projects / thirdparty / systemd.git / blobdiff