2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
6 <refentry id=
"systemd-run"
7 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
10 <title>systemd-run
</title>
11 <productname>systemd
</productname>
15 <refentrytitle>systemd-run
</refentrytitle>
16 <manvolnum>1</manvolnum>
20 <refname>systemd-run
</refname>
21 <refpurpose>Run programs in transient scope units, service units, or path-, socket-, or timer-triggered service units
</refpurpose>
26 <command>systemd-run
</command>
27 <arg choice=
"opt" rep=
"repeat">OPTIONS
</arg>
28 <arg choice=
"plain"><replaceable>COMMAND
</replaceable>
29 <arg choice=
"opt" rep=
"repeat">ARGS
</arg>
33 <command>systemd-run
</command>
34 <arg choice=
"opt" rep=
"repeat">OPTIONS
</arg>
35 <arg choice=
"opt" rep=
"repeat">PATH OPTIONS
</arg>
36 <arg choice=
"req"><replaceable>COMMAND
</replaceable></arg>
37 <arg choice=
"opt" rep=
"repeat">ARGS
</arg>
40 <command>systemd-run
</command>
41 <arg choice=
"opt" rep=
"repeat">OPTIONS
</arg>
42 <arg choice=
"opt" rep=
"repeat">SOCKET OPTIONS
</arg>
43 <arg choice=
"req"><replaceable>COMMAND
</replaceable></arg>
44 <arg choice=
"opt" rep=
"repeat">ARGS
</arg>
47 <command>systemd-run
</command>
48 <arg choice=
"opt" rep=
"repeat">OPTIONS
</arg>
49 <arg choice=
"opt" rep=
"repeat">TIMER OPTIONS
</arg>
50 <arg choice=
"req"><replaceable>COMMAND
</replaceable></arg>
51 <arg choice=
"opt" rep=
"repeat">ARGS
</arg>
56 <title>Description
</title>
58 <para><command>systemd-run
</command> may be used to create and start a transient
<filename>.service
</filename> or
59 <filename>.scope
</filename> unit and run the specified
<replaceable>COMMAND
</replaceable> in it. It may also be
60 used to create and start a transient
<filename>.path
</filename>,
<filename>.socket
</filename>, or
61 <filename>.timer
</filename> unit, that activates a
<filename>.service
</filename> unit when elapsing.
</para>
63 <para>If a command is run as transient service unit, it will be started and managed by the service manager like any
64 other service, and thus shows up in the output of
<command>systemctl list-units
</command> like any other unit. It
65 will run in a clean and detached execution environment, with the service manager as its parent process. In this
66 mode,
<command>systemd-run
</command> will start the service asynchronously in the background and return after the
67 command has begun execution (unless
<option>--no-block
</option> or
<option>--wait
</option> are specified, see
70 <para>If a command is run as transient scope unit, it will be executed by
<command>systemd-run
</command>
71 itself as parent process and will thus inherit the execution environment of the caller. However, the
72 processes of the command are managed by the service manager similarly to normal services, and will show
73 up in the output of
<command>systemctl list-units
</command>. Execution in this case is synchronous, and
74 will return only when the command finishes. This mode is enabled via the
<option>--scope
</option> switch
77 <para>If a command is run with path, socket, or timer options such as
<option>--on-calendar=
</option> (see below),
78 a transient path, socket, or timer unit is created alongside the service unit for the specified command. Only the
79 transient path, socket, or timer unit is started immediately, the transient service unit will be triggered by the
80 path, socket, or timer unit. If the
<option>--unit=
</option> option is specified, the
81 <replaceable>COMMAND
</replaceable> may be omitted. In this case,
<command>systemd-run
</command> creates only a
82 <filename>.path
</filename>,
<filename>.socket
</filename>, or
<filename>.timer
</filename> unit that triggers the
83 specified unit.
</para>
85 <para>By default, services created with
<command>systemd-run
</command> default to the
86 <option>simple
</option> type, see the description of
<varname>Type=
</varname> in
87 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
88 details. Note that when this type is used, the service manager (and thus the
89 <command>systemd-run
</command> command) considers service start-up successful as soon as the
90 <function>fork()
</function> for the main service process succeeded, i.e. before the
91 <function>execve()
</function> is invoked, and thus even if the specified command cannot be started.
92 Consider using the
<option>exec
</option> service type (i.e.
<option>--property=Type=exec
</option>) to
93 ensure that
<command>systemd-run
</command> returns successfully only if the specified command line has
94 been successfully started.
</para>
96 <para>After
<command>systemd-run
</command> passes the command to the service manager, the manager
97 performs variable expansion. This means that dollar characters (
<literal>$
</literal>) which should not be
98 expanded need to be escaped as
<literal>$$
</literal>. Expansion can also be disabled using
99 <varname>--expand-environment=no
</varname>.
</para>
103 <title>Options
</title>
105 <para>The following options are understood:
</para>
109 <term><option>--no-ask-password
</option></term>
111 <listitem><para>Do not query the user for authentication for
112 privileged operations.
</para>
114 <xi:include href=
"version-info.xml" xpointer=
"v226"/></listitem>
118 <term><option>--scope
</option></term>
121 <para>Create a transient
<filename>.scope
</filename> unit instead of the default transient
122 <filename>.service
</filename> unit (see above).
125 <xi:include href=
"version-info.xml" xpointer=
"v206"/>
130 <term><option>--unit=
</option></term>
131 <term><option>-u
</option></term>
133 <listitem><para>Use this unit name instead of an automatically
134 generated one.
</para></listitem>
138 <term><option>--property=
</option></term>
139 <term><option>-p
</option></term>
141 <listitem><para>Sets a property on the scope or service unit that is created. This option takes an assignment
142 in the same format as
143 <citerefentry><refentrytitle>systemctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
144 <command>set-property
</command> command.
</para>
146 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
151 <term><option>--description=
</option></term>
153 <listitem><para>Provide a description for the service, scope, path, socket, or timer unit. If not specified,
154 the command itself will be used as a description. See
<varname>Description=
</varname> in
155 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
158 <xi:include href=
"version-info.xml" xpointer=
"v206"/></listitem>
162 <term><option>--slice=
</option></term>
164 <listitem><para>Make the new
<filename>.service
</filename> or
<filename>.scope
</filename> unit part
165 of the specified slice, instead of
<filename>system.slice
</filename> (when running in
166 <option>--system
</option> mode) or the root slice (when running in
<option>--user
</option>
169 <xi:include href=
"version-info.xml" xpointer=
"v206"/>
174 <term><option>--slice-inherit
</option></term>
176 <listitem><para>Make the new
<filename>.service
</filename> or
<filename>.scope
</filename> unit part
177 of the inherited slice. This option can be combined with
<option>--slice=
</option>.
</para>
179 <para>An inherited slice is located within
<command>systemd-run
</command> slice. Example: if
180 <command>systemd-run
</command> slice is
<filename>foo.slice
</filename>, and the
181 <option>--slice=
</option> argument is
<filename>bar
</filename>, the unit will be placed under the
182 <filename>foo-bar.slice
</filename>.
</para>
184 <xi:include href=
"version-info.xml" xpointer=
"v246"/>
190 <term><option>--expand-environment=
<replaceable>BOOL
</replaceable></option></term>
192 <listitem><para>Expand environment variables in command arguments. If enabled, environment variables
193 specified as
<literal>${
<replaceable>VARIABLE
</replaceable>}
</literal> will be expanded in the same
194 way as in commands specified via
<varname>ExecStart=
</varname> in units. With
195 <varname>--scope
</varname>, this expansion is performed by
<command>systemd-run
</command> itself, and
196 in other cases by the service manager that spawns the command. Note that this is similar to, but not
197 the same as variable expansion in
198 <citerefentry project='man-pages'
><refentrytitle>bash
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
199 and other shells.
</para>
201 <para>The default is to enable this option in all cases, except for
<varname>--scope
</varname> where
202 it is disabled by default, for backward compatibility reasons. Note that this will be changed in a
203 future release, where it will be switched to enabled by default as well.
</para>
206 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
207 for a description of variable expansion. Disabling variable expansion is useful if the specified
208 command includes or may include a
<literal>$
</literal> sign.
</para>
210 <xi:include href=
"version-info.xml" xpointer=
"v254"/>
215 <term><option>-r
</option></term>
216 <term><option>--remain-after-exit
</option></term>
218 <listitem><para>After the service process has terminated, keep the service around until it is explicitly
219 stopped. This is useful to collect runtime information about the service after it finished running. Also see
220 <varname>RemainAfterExit=
</varname> in
221 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
227 <term><option>--send-sighup
</option></term>
229 <listitem><para>When terminating the scope or service unit, send a SIGHUP immediately after SIGTERM. This is
230 useful to indicate to shells and shell-like processes that the connection has been severed. Also see
231 <varname>SendSIGHUP=
</varname> in
232 <citerefentry><refentrytitle>systemd.kill
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
235 <xi:include href=
"version-info.xml" xpointer=
"v207"/>
240 <term><option>--service-type=
</option></term>
242 <listitem><para>Sets the service type. Also see
243 <varname>Type=
</varname> in
244 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>. This
245 option has no effect in conjunction with
246 <option>--scope
</option>. Defaults to
247 <constant>simple
</constant>.
</para>
249 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
254 <term><option>--uid=
</option></term>
255 <term><option>--gid=
</option></term>
257 <listitem><para>Runs the service process under the specified UNIX user and group. Also see
258 <varname>User=
</varname> and
<varname>Group=
</varname> in
259 <citerefentry><refentrytitle>systemd.exec
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
261 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
266 <term><option>--nice=
</option></term>
268 <listitem><para>Runs the service process with the specified
269 nice level. Also see
<varname>Nice=
</varname> in
270 <citerefentry><refentrytitle>systemd.exec
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
272 <xi:include href=
"version-info.xml" xpointer=
"v211"/>
277 <term><option>--working-directory=
</option></term>
279 <listitem><para>Runs the service process with the specified working directory. Also see
280 <varname>WorkingDirectory=
</varname> in
281 <citerefentry><refentrytitle>systemd.exec
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
283 <xi:include href=
"version-info.xml" xpointer=
"v240"/>
288 <term><option>--same-dir
</option></term>
289 <term><option>-d
</option></term>
291 <listitem><para>Similar to
<option>--working-directory=
</option>, but uses the current working
292 directory of the caller for the service to execute.
</para>
294 <xi:include href=
"version-info.xml" xpointer=
"v240"/></listitem>
298 <term><option>-E
<replaceable>NAME
</replaceable>[=
<replaceable>VALUE
</replaceable>]
</option></term>
299 <term><option>--setenv=
<replaceable>NAME
</replaceable>[=
<replaceable>VALUE
</replaceable>]
</option></term>
301 <listitem><para>Runs the service process with the specified environment variable set. This parameter
302 may be used more than once to set multiple variables. When
<literal>=
</literal> and
303 <replaceable>VALUE
</replaceable> are omitted, the value of the variable with the same name in the
304 program environment will be used.
</para>
306 <para>Also see
<varname>Environment=
</varname> in
307 <citerefentry><refentrytitle>systemd.exec
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
309 <xi:include href=
"version-info.xml" xpointer=
"v250"/>
314 <term><option>--pty
</option></term>
315 <term><option>-t
</option></term>
317 <listitem><para>When invoking the command, the transient service connects its standard input, output and error
318 to the terminal
<command>systemd-run
</command> is invoked on, via a pseudo TTY device. This allows running
319 programs that expect interactive user input/output as services, such as interactive command shells.
</para>
322 <citerefentry><refentrytitle>machinectl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
323 <command>shell
</command> command is usually a better alternative for requesting a new, interactive login
324 session on the local host or a local container.
</para>
326 <para>See below for details on how this switch combines with
<option>--pipe
</option>.
</para>
328 <xi:include href=
"version-info.xml" xpointer=
"v219"/></listitem>
332 <term><option>--pipe
</option></term>
333 <term><option>-P
</option></term>
335 <listitem><para>If specified, standard input, output, and error of the transient service are inherited from the
336 <command>systemd-run
</command> command itself. This allows
<command>systemd-run
</command>
337 to be used within shell pipelines.
338 Note that this mode is not suitable for interactive command shells and similar, as the
339 service process will not become a TTY controller when invoked on a terminal. Use
<option>--pty
</option> instead
342 <para>When both
<option>--pipe
</option> and
<option>--pty
</option> are used in combination the more appropriate
343 option is automatically determined and used. Specifically, when invoked with standard input, output and error
344 connected to a TTY
<option>--pty
</option> is used, and otherwise
<option>--pipe
</option>.
</para>
346 <para>When this option is used the original file descriptors
<command>systemd-run
</command> receives are passed
347 to the service processes as-is. If the service runs with different privileges than
348 <command>systemd-run
</command>, this means the service might not be able to re-open the passed file
349 descriptors, due to normal file descriptor access restrictions. If the invoked process is a shell script that
350 uses the
<command>echo
"hello" >/dev/stderr
</command> construct for writing messages to stderr, this might
351 cause problems, as this only works if stderr can be re-opened. To mitigate this use the construct
<command>echo
352 "hello" >&2</command> instead, which is mostly equivalent and avoids this pitfall.
</para>
354 <xi:include href=
"version-info.xml" xpointer=
"v235"/></listitem>
358 <term><option>--shell
</option></term>
359 <term><option>-S
</option></term>
361 <listitem><para>A shortcut for
<literal>--pty --same-dir --wait --collect --service-type=exec $SHELL
</literal>,
362 i.e. requests an interactive shell in the current working directory, running in service context, accessible
363 with a single switch.
</para>
365 <xi:include href=
"version-info.xml" xpointer=
"v240"/></listitem>
369 <term><option>--quiet
</option></term>
370 <term><option>-q
</option></term>
372 <listitem><para>Suppresses additional informational output
373 while running. This is particularly useful in combination with
374 <option>--pty
</option> when it will suppress the initial
375 message explaining how to terminate the TTY connection.
</para>
377 <xi:include href=
"version-info.xml" xpointer=
"v219"/></listitem>
381 <term><option>--on-active=
</option></term>
382 <term><option>--on-boot=
</option></term>
383 <term><option>--on-startup=
</option></term>
384 <term><option>--on-unit-active=
</option></term>
385 <term><option>--on-unit-inactive=
</option></term>
387 <listitem><para>Defines a monotonic timer relative to different starting points for starting the specified
388 command. See
<varname>OnActiveSec=
</varname>,
<varname>OnBootSec=
</varname>,
<varname>OnStartupSec=
</varname>,
389 <varname>OnUnitActiveSec=
</varname> and
<varname>OnUnitInactiveSec=
</varname> in
390 <citerefentry><refentrytitle>systemd.timer
</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
391 details. These options are shortcuts for
<command>--timer-property=
</command> with the relevant properties.
392 These options may not be combined with
<option>--scope
</option> or
<option>--pty
</option>.
</para>
394 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
399 <term><option>--on-calendar=
</option></term>
401 <listitem><para>Defines a calendar timer for starting the specified command. See
<varname>OnCalendar=
</varname>
402 in
<citerefentry><refentrytitle>systemd.timer
</refentrytitle><manvolnum>5</manvolnum></citerefentry>. This
403 option is a shortcut for
<command>--timer-property=OnCalendar=
</command>. This option may not be combined with
404 <option>--scope
</option> or
<option>--pty
</option>.
</para>
406 <xi:include href=
"version-info.xml" xpointer=
"v218"/>
411 <term><option>--on-clock-change
</option></term>
412 <term><option>--on-timezone-change
</option></term>
414 <listitem><para>Defines a trigger based on system clock jumps or timezone changes for starting the
415 specified command. See
<varname>OnClockChange=
</varname> and
<varname>OnTimezoneChange=
</varname> in
416 <citerefentry><refentrytitle>systemd.timer
</refentrytitle><manvolnum>5</manvolnum></citerefentry>. These
417 options are shortcuts for
<command>--timer-property=OnClockChange=yes
</command> and
418 <command>--timer-property=OnTimezoneChange=yes
</command>. These options may not be combined with
419 <option>--scope
</option> or
<option>--pty
</option>.
</para>
421 <xi:include href=
"version-info.xml" xpointer=
"v242"/></listitem>
425 <term><option>--path-property=
</option></term>
426 <term><option>--socket-property=
</option></term>
427 <term><option>--timer-property=
</option></term>
429 <listitem><para>Sets a property on the path, socket, or timer unit that is created. This option is
430 similar to
<option>--property=
</option>, but applies to the transient path, socket, or timer unit
431 rather than the transient service unit created. This option takes an assignment in the same format as
432 <citerefentry><refentrytitle>systemctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
433 <command>set-property
</command> command. These options may not be combined with
434 <option>--scope
</option> or
<option>--pty
</option>.
</para>
439 <term><option>--no-block
</option></term>
442 <para>Do not synchronously wait for the unit start operation to finish. If this option is not specified, the
443 start request for the transient unit will be verified, enqueued and
<command>systemd-run
</command> will wait
444 until the unit's start-up is completed. By passing this argument, it is only verified and enqueued. This
445 option may not be combined with
<option>--wait
</option>.
</para>
447 <xi:include href=
"version-info.xml" xpointer=
"v220"/>
452 <term><option>--wait
</option></term>
454 <listitem><para>Synchronously wait for the transient service to terminate. If this option is specified, the
455 start request for the transient unit is verified, enqueued, and waited for. Subsequently the invoked unit is
456 monitored, and it is waited until it is deactivated again (most likely because the specified command
457 completed). On exit, terse information about the unit's runtime is shown, including total runtime (as well as
458 CPU usage, if
<option>--property=CPUAccounting=
1</option> was set) and the exit code and status of the main
459 process. This output may be suppressed with
<option>--quiet
</option>. This option may not be combined with
460 <option>--no-block
</option>,
<option>--scope
</option> or the various path, socket, or timer options.
</para>
462 <xi:include href=
"version-info.xml" xpointer=
"v232"/></listitem>
466 <term><option>-G
</option></term>
467 <term><option>--collect
</option></term>
469 <listitem><para>Unload the transient unit after it completed, even if it failed. Normally, without this option,
470 all units that ran and failed are kept in memory until the user explicitly resets their failure state with
471 <command>systemctl reset-failed
</command> or an equivalent command. On the other hand, units that ran
472 successfully are unloaded immediately. If this option is turned on the
"garbage collection" of units is more
473 aggressive, and unloads units regardless if they exited successfully or failed. This option is a shortcut for
474 <command>--property=CollectMode=inactive-or-failed
</command>, see the explanation for
475 <varname>CollectMode=
</varname> in
476 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry> for further
479 <xi:include href=
"version-info.xml" xpointer=
"v236"/></listitem>
482 <xi:include href=
"user-system-options.xml" xpointer=
"user" />
483 <xi:include href=
"user-system-options.xml" xpointer=
"system" />
484 <xi:include href=
"user-system-options.xml" xpointer=
"host" />
485 <xi:include href=
"user-system-options.xml" xpointer=
"machine" />
487 <xi:include href=
"standard-options.xml" xpointer=
"help" />
488 <xi:include href=
"standard-options.xml" xpointer=
"version" />
491 <para>All command line arguments after the first non-option argument become part of the command line of
492 the launched process.
</para>
496 <title>Exit status
</title>
498 <para>On success,
0 is returned. If
<command>systemd-run
</command> failed to start the service, a
499 non-zero return value will be returned. If
<command>systemd-run
</command> waits for the service to
500 terminate, the return value will be propagated from the service.
0 will be returned on success, including
501 all the cases where systemd considers a service to have exited cleanly, see the discussion of
502 <varname>SuccessExitStatus=
</varname> in
503 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
508 <title>Examples
</title>
511 <title>Logging environment variables provided by systemd to services
</title>
513 <programlisting># systemd-run env
514 Running as unit: run-
19945.service
515 # journalctl -u run-
19945.service
516 Sep
08 07:
37:
21 bupkis systemd[
1]: Starting /usr/bin/env...
517 Sep
08 07:
37:
21 bupkis systemd[
1]: Started /usr/bin/env.
518 Sep
08 07:
37:
21 bupkis env[
19948]: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
519 Sep
08 07:
37:
21 bupkis env[
19948]: LANG=en_US.UTF-
8
520 Sep
08 07:
37:
21 bupkis env[
19948]: BOOT_IMAGE=/vmlinuz-
3.11.0-
0.rc5.git6.2.fc20.x86_64
</programlisting>
524 <title>Limiting resources available to a command
</title>
526 <programlisting># systemd-run -p IOWeight=
10 updatedb
</programlisting>
528 <para>This command invokes the
<citerefentry
529 project='man-pages'
><refentrytitle>updatedb
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
530 tool, but lowers the block I/O weight for it to
10. See
531 <citerefentry><refentrytitle>systemd.resource-control
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
532 for more information on the
<varname>IOWeight=
</varname> property.
</para>
536 <title>Running commands at a specified time
</title>
538 <para>The following command will touch a file after
30 seconds.
</para>
540 <programlisting># date; systemd-run --on-active=
30 --timer-property=AccuracySec=
100ms /bin/touch /tmp/foo
541 Mon Dec
8 20:
44:
24 KST
2014
542 Running as unit: run-
71.timer
543 Will run service as unit: run-
71.service
544 # journalctl -b -u run-
71.timer
545 -- Journal begins at Fri
2014-
12-
05 19:
09:
21 KST, ends at Mon
2014-
12-
08 20:
44:
54 KST. --
546 Dec
08 20:
44:
38 container systemd[
1]: Starting /bin/touch /tmp/foo.
547 Dec
08 20:
44:
38 container systemd[
1]: Started /bin/touch /tmp/foo.
548 # journalctl -b -u run-
71.service
549 -- Journal begins at Fri
2014-
12-
05 19:
09:
21 KST, ends at Mon
2014-
12-
08 20:
44:
54 KST. --
550 Dec
08 20:
44:
48 container systemd[
1]: Starting /bin/touch /tmp/foo...
551 Dec
08 20:
44:
48 container systemd[
1]: Started /bin/touch /tmp/foo.
</programlisting>
555 <title>Allowing access to the tty
</title>
557 <para>The following command invokes
<citerefentry project='man-pages'
><refentrytitle>bash
</refentrytitle><manvolnum>1</manvolnum></citerefentry>
558 as a service passing its standard input, output and error to the calling TTY.
</para>
560 <programlisting># systemd-run -t --send-sighup bash
</programlisting>
564 <title>Start
<command>screen
</command> as a user service
</title>
566 <programlisting>$ systemd-run --scope --user screen
567 Running scope as unit run-r14b0047ab6df45bfb45e7786cc839e76.scope.
570 There is a screen on:
571 492..laptop (Detached)
572 1 Socket in /var/run/screen/S-fatima.
575 <para>This starts the
<command>screen
</command> process as a child of the
576 <command>systemd --user
</command> process that was started by
577 <filename>user@.service
</filename>, in a scope unit. A
578 <citerefentry><refentrytitle>systemd.scope
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
579 unit is used instead of a
580 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
581 unit, because
<command>screen
</command> will exit when detaching from the terminal,
582 and a service unit would be terminated. Running
<command>screen
</command>
583 as a user unit has the advantage that it is not part of the session scope.
584 If
<varname>KillUserProcesses=yes
</varname> is configured in
585 <citerefentry><refentrytitle>logind.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
586 the default, the session scope will be terminated when the user logs
587 out of that session.
</para>
589 <para>The
<filename>user@.service
</filename> is started automatically
590 when the user first logs in, and stays around as long as at least one
591 login session is open. After the user logs out of the last session,
592 <filename>user@.service
</filename> and all services underneath it
593 are terminated. This behavior is the default, when
"lingering" is
594 not enabled for that user. Enabling lingering means that
595 <filename>user@.service
</filename> is started automatically during
596 boot, even if the user is not logged in, and that the service is
597 not terminated when the user logs out.
</para>
599 <para>Enabling lingering allows the user to run processes without being logged in,
600 for example to allow
<command>screen
</command> to persist after the user logs out,
601 even if the session scope is terminated. In the default configuration, users can
602 enable lingering for themselves:
</para>
604 <programlisting>$ loginctl enable-linger
</programlisting>
608 <title>Variable expansion by the manager
</title>
610 <programlisting>$ systemd-run -t echo
"<${INVOCATION_ID}>" '
<${INVOCATION_ID}
>'
611 <> <5d0149bfa2c34b79bccb13074001eb20
>
614 <para>The first argument is expanded by the shell (double quotes), but the second one is not expanded
615 by the shell (single quotes).
<command>echo
</command> is called with [
<literal>/usr/bin/echo
</literal>,
616 <literal>[]
</literal>,
<literal>[${INVOCATION_ID}]
</literal>] as the argument array, and then
617 <command>systemd
</command> generates
<varname>${INVOCATION_ID}
</varname> and substitutes it in the
618 command-line. This substitution could not be done on the client side, because the target ID that will
619 be set for the service isn't known before the call is made.
</para>
623 <title>Variable expansion and output redirection using a shell
</title>
625 <para>Variable expansion by
<command>systemd
</command> can be disabled with
626 <varname>--expand-environment=no
</varname>.
</para>
628 <para>Disabling variable expansion can be useful if the command to execute contains dollar characters
629 and escaping them would be inconvenient. For example, when a shell is used:
</para>
631 <programlisting>$ systemd-run --expand-environment=no -t bash \
632 -c 'echo $SHELL $$
>/dev/stdout'
636 <para>The last argument is passed verbatim to the
<command>bash
</command> shell which is started by the
637 service unit. The shell expands
<literal>$SHELL
</literal> to the path of the shell, and
638 <literal>$$
</literal> to its process number, and then those strings are passed to the
639 <command>echo
</command> built-in and printed to standard output (which in this case is connected to the
640 calling terminal).
</para>
644 <title>Return value
</title>
646 <programlisting>$ systemd-run --user --wait true
647 $ systemd-run --user --wait -p SuccessExitStatus=
11 bash -c 'exit
11'
648 $ systemd-run --user --wait -p SuccessExitStatus=SIGUSR1 --expand-environment=no \
649 bash -c 'kill -SIGUSR1 $$'
</programlisting>
651 <para>Those three invocations will succeed, i.e. terminate with an exit code of
0.
</para>
656 <title>See Also
</title>
658 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
659 <citerefentry><refentrytitle>systemctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
660 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
661 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
662 <citerefentry><refentrytitle>systemd.scope
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
663 <citerefentry><refentrytitle>systemd.slice
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
664 <citerefentry><refentrytitle>systemd.exec
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
665 <citerefentry><refentrytitle>systemd.resource-control
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
666 <citerefentry><refentrytitle>systemd.timer
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
667 <citerefentry><refentrytitle>systemd-mount
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
668 <citerefentry><refentrytitle>machinectl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>