chiark / gitweb /
units: for all unit settings that take lists, allow the empty string for resetting...
[elogind.git] / man / systemd.service.xml
index c547948c6e9227af9a39ad11655cade813af2ada..f7cbbb489cc91c0c4cb6e7d8f35a9867cc271ecc 100644 (file)
                 script. This is useful for compatibility with
                 SysV. Note that this compatibility is quite
                 comprehensive but not 100%. For details about the
-                incomptibilities see the <ulink
+                incompatibilities see the <ulink
                 url="http://www.freedesktop.org/wiki/Software/systemd/Incompatibilities">Incompatibilities
                 with SysV</ulink> document.
                 </para>
                                 complete and all communication
                                 channels set up. The child continues
                                 to run as the main daemon
-                                process. This is the behaviour of
+                                process. This is the behavior of
                                 traditional UNIX daemons. If this
                                 setting is used, it is recommended to
                                 also use the
                                 soon as the parent process
                                 exits.</para>
 
-                                <para>Behaviour of
+                                <para>Behavior of
                                 <option>oneshot</option> is similar
                                 to <option>simple</option>, however
                                 it is expected that the process has to
                                 is particularly useful for this type
                                 of service.</para>
 
-                                <para>Behaviour of
+                                <para>Behavior of
                                 <option>dbus</option> is similar to
                                 <option>simple</option>, however it is
                                 expected that the daemon acquires a
                                 <varname>BusName=</varname> is
                                 specified.</para>
 
-                                <para>Behaviour of
+                                <para>Behavior of
                                 <option>notify</option> is similar to
                                 <option>simple</option>, however it is
                                 expected that the daemon sends a
                                 not set, it will be implicitly set to
                                 <option>main</option>.</para>
 
-                                <para>Behaviour of
+                                <para>Behavior of
                                 <option>idle</option> is very similar
                                 to <option>simple</option>, however
-                                actual execution of the service
+                                actual execution of the service
                                 binary is delayed until all jobs are
                                 dispatched. This may be used to avoid
                                 interleaving of output of shell
                                 <listitem><para>Takes a boolean value
                                 that specifies whether systemd should
                                 try to guess the main PID of a service
-                                should if it cannot be determined
+                                if it cannot be determined
                                 reliably. This option is ignored
                                 unless <option>Type=forking</option>
                                 is set and <option>PIDFile=</option>
                                 <term><varname>BusName=</varname></term>
 
                                 <listitem><para>Takes a D-Bus bus
-                                name, where this service is reachable
+                                name, that this service is reachable
                                 as. This option is mandatory for
                                 services where
                                 <varname>Type=</varname> is set to
 
                         <varlistentry>
                                 <term><varname>ExecStart=</varname></term>
-                                <listitem><para>Takes a command line
-                                that is executed when this service
-                                shall be started up. The first token
-                                of the command line must be an
-                                absolute file name, then followed by
-                                arguments for the process. It is
-                                mandatory to set this option for all
-                                services. This option may not be
-                                specified more than once, except when
-                                <varname>Type=oneshot</varname> is
-                                used in which case more than one
-                                <varname>ExecStart=</varname> line is
-                                accepted which are then invoked one by
-                                one, sequentially in the order they
-                                appear in the unit file.</para>
+                                <listitem><para>Commands with their
+                                arguments that are executed when this
+                                service is started.
+                                </para>
 
-                                <para>Optionally, if the absolute file
-                                name is prefixed with
-                                <literal>@</literal>, the second token
-                                will be passed as
-                                <literal>argv[0]</literal> to the
-                                executed process, followed by the
-                                further arguments specified. If the
-                                first token is prefixed with
-                                <literal>-</literal> an exit code of
-                                the command normally considered a
-                                failure (i.e. non-zero exit status or
-                                abnormal exit due to signal) is ignored
-                                and considered success. If both
-                                <literal>-</literal> and
-                                <literal>@</literal> are used for the
-                                same command the former must precede
-                                the latter. Unless
+                                <para>When
+                                <varname>Type=oneshot</varname> is
+                                used, more than one command may be
+                                specified. Multiple command lines may
+                                be concatenated in a single directive,
+                                by separating them with semicolons
+                                (these semicolons must be passed as
+                                separate words). Alternatively, this
+                                directive may be specified more than
+                                once with the same effect. However,
+                                the latter syntax is not recommended
+                                for compatibility with parsers
+                                suitable for XDG
+                                <filename>.desktop</filename> files.
+                                The commands are invoked one by one
+                                sequentially in the order they appear
+                                in the unit file.  When
+                                <varname>Type</varname> is not
+                                <option>oneshot</option>, only one
+                                command may be given. Lone semicolons
+                                may be escaped as
+                                '<literal>\;</literal>'. If the empty
+                                string is assigned to this option the
+                                list of commands to start is reset,
+                                prior assignments of this option will
+                                have no effect.</para>
+
+                                <para>Unless
                                 <varname>Type=forking</varname> is
                                 set, the process started via this
                                 command line will be considered the
-                                main process of the daemon. The
-                                command line accepts % specifiers as
+                                main process of the daemon.</para>
+
+                                <para>The command line accepts
+                                '<literal>%</literal>' specifiers as
                                 described in
-                                <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+                                <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>On top of that basic environment
                                 variable substitution is
                                 supported. Use
                                 <literal>${FOO}</literal> as part of a
-                                word, or as word of its own on the
+                                word, or as word of its own on the
                                 command line, in which case it will be
                                 replaced by the value of the
                                 environment variable including all
                                 literal and absolute path
                                 name.</para>
 
+                                <para>Optionally, if the absolute file
+                                name is prefixed with
+                                '<literal>@</literal>', the second token
+                                will be passed as
+                                <literal>argv[0]</literal> to the
+                                executed process, followed by the
+                                further arguments specified. If the
+                                absolute file name is prefixed with
+                                '<literal>-</literal>' an exit code of
+                                the command normally considered a
+                                failure (i.e. non-zero exit status or
+                                abnormal exit due to signal) is ignored
+                                and considered success. If both
+                                '<literal>-</literal>' and
+                                '<literal>@</literal>' are used they
+                                can appear in either order.</para>
+
                                 <para>Note that this setting does not
                                 directly support shell command
                                 lines. If shell command lines are to
                                 explicitly to a shell implementation
                                 of some kind. Example:
                                 <literal>ExecStart=/bin/sh -c 'dmesg | tac'</literal></para>
+
+                                <para>For services run by a user
+                                instance of systemd the special
+                                environment variable
+                                <literal>MANAGERPID</literal> is set
+                                to the PID of the systemd
+                                instance.</para>
                                 </listitem>
                         </varlistentry>
 
                                 <term><varname>ExecStartPre=</varname></term>
                                 <term><varname>ExecStartPost=</varname></term>
                                 <listitem><para>Additional commands
-                                that are executed before (resp. after)
+                                that are executed before or after
                                 the command in
-                                <varname>ExecStart=</varname>. Multiple
-                                command lines may be concatenated in a
-                                single directive, by separating them
-                                by semicolons (these semicolons must
-                                be passed as separate words). In that
-                                case, the commands are executed one
-                                after the other,
-                                serially. Alternatively, these
-                                directives may be specified more than
-                                once with the same effect. However,
-                                the latter syntax is not recommended
-                                for compatibility with parsers
-                                suitable for XDG
-                                <filename>.desktop</filename> files.
-                                Use of these settings is
-                                optional. Specifier and environment
-                                variable substitution is
-                                supported.</para></listitem>
+                                <varname>ExecStart=</varname>, respectively.
+                                Syntax is the same as for
+                                <varname>ExecStart=</varname>, except
+                                that multiple command lines are allowed
+                                and the commands are executed one
+                                after the other, serially.</para>
+                                </listitem>
                         </varlistentry>
 
                         <varlistentry>
                                 trigger a configuration reload in the
                                 service. This argument takes multiple
                                 command lines, following the same
-                                scheme as pointed out for
-                                <varname>ExecStartPre=</varname>
+                                scheme as described for
+                                <varname>ExecStart=</varname>
                                 above. Use of this setting is
                                 optional. Specifier and environment
                                 variable substitution is supported
                                 here following the same scheme as for
                                 <varname>ExecStart=</varname>. One
-                                special environment variable is set:
-                                if known <literal>$MAINPID</literal> is
-                                set to the main process of the
-                                daemon, and may be used for command
-                                lines like the following:
-                                <command>/bin/kill -HUP
+                                additional special environment
+                                variables is set: if known
+                                <literal>$MAINPID</literal> is set to
+                                the main process of the daemon, and
+                                may be used for command lines like the
+                                following: <command>/bin/kill -HUP
                                 $MAINPID</command>.</para></listitem>
                         </varlistentry>
 
                                 stop the service started via
                                 <varname>ExecStart=</varname>. This
                                 argument takes multiple command lines,
-                                following the same scheme as pointed
-                                out for
-                                <varname>ExecStartPre=</varname>
+                                following the same scheme as described
+                                for <varname>ExecStart=</varname>
                                 above. Use of this setting is
                                 optional. All processes remaining for
                                 a service after the commands
                                 configured in
                                 <varname>ExecStop=</varname>. This
                                 argument takes multiple command lines,
-                                following the same scheme as pointed
-                                out for
-                                <varname>ExecStartPre</varname>. Use
+                                following the same scheme as described
+                                for <varname>ExecStart</varname>. Use
                                 of these settings is
                                 optional. Specifier and environment
                                 variable substitution is
                                 0. If set to
                                 <option>on-failure</option> it will be
                                 restarted only when it exited with an
-                                exit code not equalling 0, when
+                                exit code not equaling 0, when
                                 terminated by a signal (including on
                                 core dump), when an operation (such as
                                 service reload) times out or when the
                                 SIGTERM and SIGPIPE. Exit status
                                 definitions can either be numeric exit
                                 codes or termination signal names, and
-                                are are separated by spaces. Example:
+                                are separated by spaces. Example:
                                 "<literal>SuccessExitStatus=1 2 8
                                 SIGKILL</literal>", ensures that exit
                                 codes 1, 2, 8 and the termination
                                 signal SIGKILL are considered clean
-                                service
-                                terminations.</para></listitem>
+                                service terminations. This option may
+                                appear more than once in which case
+                                the list of successful exit statuses
+                                is merged. If the empty string is
+                                assigned to this option the list is
+                                reset, all prior assignments of this
+                                option will have no
+                                effect.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
                                 logic. Example:
                                 "<literal>RestartPreventExitStatus=1 6
                                 SIGABRT</literal>", ensures that exit
-                                codes 1 and 6 and the termination signal
-                                SIGABRT will not result in automatic
-                                service restarting.</para></listitem>
+                                codes 1 and 6 and the termination
+                                signal SIGABRT will not result in
+                                automatic service restarting. This
+                                option may appear more than once in
+                                which case the list of restart preventing
+                                statuses is merged. If the empty
+                                string is assigned to this option the
+                                list is reset, all prior assignments
+                                of this option will have no
+                                effect.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
                                 same time. Also note that a different
                                 service may be activated on incoming
                                 traffic than inherits the sockets. Or
-                                in other words: The
+                                in other words: the
                                 <varname>Service=</varname> setting of
                                 <filename>.socket</filename> units
-                                doesn't have to match the inverse of the
-                                <varname>Sockets=</varname> setting of
-                                the <filename>.service</filename> it
-                                refers to.</para></listitem>
+                                doesn't have to match the inverse of
+                                the <varname>Sockets=</varname>
+                                setting of the
+                                <filename>.service</filename> it
+                                refers to.</para>
+
+                                <para>This option may appear more than
+                                once, in which case the list of socket
+                                units is merged. If the empty string
+                                is assigned to this option the list of
+                                sockets is reset, all prior uses of
+                                this setting will have no
+                                effect.</para></listitem>
                         </varlistentry>
 
                         <varlistentry>
                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
-                          <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
+                          <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+                          <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                   </para>
         </refsect1>