</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>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>
<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
+ <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
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 / commitdiff
