systemd-run(1)

NAME#

systemd-run - Run programs in transient scope units, service units, or path-, socket-, or timer-triggered service units

SYNOPSIS#

systemd-run [OPTIONS...] COMMAND [ARGS...]

systemd-run [OPTIONS...] [PATH OPTIONS...] {COMMAND} [ARGS...]

systemd-run [OPTIONS...] [SOCKET OPTIONS...] {COMMAND} [ARGS...]

systemd-run [OPTIONS...] [TIMER OPTIONS...] {COMMAND} [ARGS...]

DESCRIPTION#

systemd-run may be used to create and start a transient .service or .scope unit and run the specified COMMAND in it. It may also be used to create and start a transient .path, .socket, or .timer unit, that activates a .service unit when elapsing.

If a command is run as transient service unit, it will be started and managed by the service manager like any other service, and thus shows up in the output of systemctl list-units like any other unit. It will run in a clean and detached execution environment, with the service manager as its parent process. In this mode, systemd-run will start the service asynchronously in the background and return after the command has begun execution (unless --no-block, --wait, --pipe, or --pty are specified, see below).

If a command is run as transient scope unit, it will be executed by systemd-run itself as parent process and will thus inherit the execution environment of the caller. However, the processes of the command are managed by the service manager similarly to normal services, and will show up in the output of systemctl list-units. Execution in this case is synchronous, and will return only when the command finishes. This mode is enabled via the --scope switch (see below).

If a command is run with path, socket, or timer options such as --on-calendar= (see below), a transient path, socket, or timer unit is created alongside the service unit for the specified command. Only the transient path, socket, or timer unit is started immediately, the transient service unit will be triggered by the path, socket, or timer unit. If the --unit= option is specified, the COMMAND may be omitted. In this case, systemd-run creates only a .path, .socket, or .timer unit that triggers the specified unit.

By default, services created with systemd-run default to the simple type, see the description of Type= in systemd.service(5) for details. Note that when this type is used, the service manager (and thus the systemd-run command) considers service start-up successful as soon as the fork() for the main service process succeeded, i.e. before the execve() is invoked, and thus even if the specified command cannot be started. Consider using the exec service type (i.e. --property=Type=exec) to ensure that systemd-run returns successfully only if the specified command line has been successfully started.

After systemd-run passes the command to the service manager, the manager performs variable expansion. This means that dollar characters ("$") which should not be expanded need to be escaped as "$$". Expansion can also be disabled using --expand-environment=no.

OPTIONS#

The following options are understood:

--scope

Added in version 206.

--unit=, -u

Added in version 206.

--property=, -p

Added in version 211.

--description=

Added in version 206.

--slice=

Added in version 206.

--slice-inherit

Example: consider systemd-run being invoked in the slice foo.slice, and the --slice= argument is bar. The unit will then be placed under foo-bar.slice.

Added in version 246.

--expand-environment=BOOL

The default is to enable this option in all cases, except for --scope where it is disabled by default, for backward compatibility reasons. Note that this will be changed in a future release, where it will be switched to enabled by default as well.

See systemd.service(5) for a description of variable expansion. Disabling variable expansion is useful if the specified command includes or may include a "$" sign.

Added in version 254.

-r, --remain-after-exit

Added in version 207.

--send-sighup

Added in version 207.

--service-type=

Added in version 211.

--uid=, --gid=

Added in version 211.

--nice=

Added in version 211.

--working-directory=

Added in version 240.

--same-dir, -d

Added in version 240.

-ENAME[=VALUE], --setenv=NAME[=VALUE]

Also see Environment= in systemd.exec(5).

Added in version 211.

--pty, -t

This option will result in systemd-run synchronously waiting for the transient service to terminate, similar to specifying --wait. If specified along with --wait, systemd-run will not exit when manually disconnecting from the pseudo TTY device.

Note that machinectl(1)'s shell command is usually a better alternative for requesting a new, interactive login session on the local host or a local container.

See below for details on how this switch combines with --pipe.

Added in version 219.

--pipe, -P

Note that this mode is not suitable for interactive command shells and similar, as the service process will not become a TTY controller when invoked on a terminal. Use --pty instead in that case.

When both --pipe and --pty are used in combination the more appropriate option is automatically determined and used. Specifically, when invoked with standard input, output and error connected to a TTY --pty is used, and otherwise --pipe.

This option will result in systemd-run synchronously waiting for the transient service to terminate, similar to specifying --wait.

When this option is used the original file descriptors systemd-run receives are passed to the service processes as-is. If the service runs with different privileges than systemd-run, this means the service might not be able to reopen the passed file descriptors, due to normal file descriptor access restrictions. If the invoked process is a shell script that uses the echo "hello" >/dev/stderr construct for writing messages to stderr, this might cause problems, as this only works if stderr can be reopened. To mitigate this use the construct echo "hello" >&2 instead, which is mostly equivalent and avoids this pitfall.

Added in version 235.

--shell, -S

Added in version 240.

--quiet, -q

Added in version 219.

--on-active=, --on-boot=, --on-startup=, --on-unit-active=, --on-unit-inactive=

Added in version 218.

--on-calendar=

Added in version 218.

--on-clock-change, --on-timezone-change

Added in version 242.

--path-property=, --socket-property=, --timer-property=

Added in version 218.

--no-block

Added in version 220.

--wait

Added in version 232.

-G, --collect

Added in version 236.

--ignore-failure

Added in version 256.

--background=COLOR

Added in version 256.

--user

--system

-H, --host=

-M, --machine=

-C, --capsule=

Added in version 256.

--no-ask-password

-h, --help

--version

--json=MODE

All command line arguments after the first non-option argument become part of the command line of the launched process.

EXIT STATUS#

On success, 0 is returned. If systemd-run failed to start the service, a non-zero return value will be returned. If systemd-run waits for the service to terminate, the return value will be propagated from the service. 0 will be returned on success, including all the cases where systemd considers a service to have exited cleanly, see the discussion of SuccessExitStatus= in systemd.service(5).

EXAMPLES#

Example 1. Logging environment variables provided by systemd to services

# systemd-run env
Running as unit: run-19945.service
# journalctl -u run-19945.service
Sep 08 07:37:21 bupkis systemd[1]: Starting /usr/bin/env...
Sep 08 07:37:21 bupkis systemd[1]: Started /usr/bin/env.
Sep 08 07:37:21 bupkis env[19948]: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
Sep 08 07:37:21 bupkis env[19948]: LANG=en_US.UTF-8
Sep 08 07:37:21 bupkis env[19948]: BOOT_IMAGE=/vmlinuz-3.11.0-0.rc5.git6.2.fc20.x86_64

Example 2. Limiting resources available to a command

# systemd-run -p IOWeight=10 updatedb

This command invokes the updatedb(8) tool, but lowers the block I/O weight for it to 10. See systemd.resource-control(5) for more information on the IOWeight= property.

Example 3. Running commands at a specified time

The following command will touch a file after 30 seconds.

# date; systemd-run --on-active=30 --timer-property=AccuracySec=100ms /bin/touch /tmp/foo
Mon Dec  8 20:44:24 KST 2014
Running as unit: run-71.timer
Will run service as unit: run-71.service
# journalctl -b -u run-71.timer
-- Journal begins at Fri 2014-12-05 19:09:21 KST, ends at Mon 2014-12-08 20:44:54 KST. --
Dec 08 20:44:38 container systemd[1]: Starting /bin/touch /tmp/foo.
Dec 08 20:44:38 container systemd[1]: Started /bin/touch /tmp/foo.
# journalctl -b -u run-71.service
-- Journal begins at Fri 2014-12-05 19:09:21 KST, ends at Mon 2014-12-08 20:44:54 KST. --
Dec 08 20:44:48 container systemd[1]: Starting /bin/touch /tmp/foo...
Dec 08 20:44:48 container systemd[1]: Started /bin/touch /tmp/foo.

Example 4. Allowing access to the tty

The following command invokes bash(1) as a service passing its standard input, output and error to the calling TTY.

# systemd-run -t --send-sighup bash

Example 5. Start screen as a user service

$ systemd-run --scope --user screen
Running scope as unit run-r14b0047ab6df45bfb45e7786cc839e76.scope.
$ screen -ls
There is a screen on:
\n
        492..laptop     (Detached)
1 Socket in /var/run/screen/S-fatima.

This starts the screen process as a child of the systemd --user process that was started by [email protected], in a scope unit. A systemd.scope(5) unit is used instead of a systemd.service(5) unit, because screen will exit when detaching from the terminal, and a service unit would be terminated. Running screen as a user unit has the advantage that it is not part of the session scope. If KillUserProcesses=yes is configured in logind.conf(5), the default, the session scope will be terminated when the user logs out of that session.

The [email protected] is started automatically when the user first logs in, and stays around as long as at least one login session is open. After the user logs out of the last session, [email protected] and all services underneath it are terminated. This behavior is the default, when "lingering" is not enabled for that user. Enabling lingering means that [email protected] is started automatically during boot, even if the user is not logged in, and that the service is not terminated when the user logs out.

Enabling lingering allows the user to run processes without being logged in, for example to allow screen to persist after the user logs out, even if the session scope is terminated. In the default configuration, users can enable lingering for themselves:

$ loginctl enable-linger

Example 6. Variable expansion by the manager

$ systemd-run -t echo "<${INVOCATION_ID}>" '<${INVOCATION_ID}>'
\n
      <> <5d0149bfa2c34b79bccb13074001eb20>

The first argument is expanded by the shell (double quotes), but the second one is not expanded by the shell (single quotes). echo(1) is called with ["/usr/bin/echo", "<>", "<${INVOCATION_ID}>"] as the argument array, and then systemd(1) generates ${INVOCATION_ID} and substitutes it in the command-line. This substitution could not be done on the client side, because the target ID that will be set for the service is not known before the call is made.

Example 7. Variable expansion and output redirection using a shell

Variable expansion by systemd(1) can be disabled with --expand-environment=no.

Disabling variable expansion can be useful if the command to execute contains dollar characters and escaping them would be inconvenient. For example, when a shell is used:

$ systemd-run --expand-environment=no -t bash \
\n
      -c 'echo $SHELL $$ >/dev/stdout'
/bin/bash 12345

The last argument is passed verbatim to the bash(1) shell which is started by the service unit. The shell expands "$SHELL" to the path of the shell, and "$$" to its process number, and then those strings are passed to the echo built-in and printed to standard output (which, in this case, is connected to the calling terminal).

Example 8. Return value

$ systemd-run --user --wait true
$ systemd-run --user --wait -p SuccessExitStatus=11 bash -c 'exit 11'
$ systemd-run --user --wait -p SuccessExitStatus=SIGUSR1 --expand-environment=no \
\n
      bash -c 'kill -SIGUSR1 $$'

Those three invocations will succeed, i.e. terminate with an exit code of 0.

SEE ALSO#

systemd(1), systemctl(1), systemd.unit(5), systemd.service(5), systemd.scope(5), systemd.slice(5), systemd.exec(5), systemd.resource-control(5), systemd.timer(5), systemd-mount(1), machinectl(1), run0(1)

NOTES#

1.

ANSI Escape Code (Wikipedia)