man/systemd-run.xml

   1 <?xml version='1.0'?>
   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 -->
   5
   6 <refentry id="systemd-run"
   7           xmlns:xi="http://www.w3.org/2001/XInclude">
   8
   9   <refentryinfo>
  10     <title>systemd-run</title>
  11     <productname>systemd</productname>
  12   </refentryinfo>
  13
  14   <refmeta>
  15     <refentrytitle>systemd-run</refentrytitle>
  16     <manvolnum>1</manvolnum>
  17   </refmeta>
  18
  19   <refnamediv>
  20     <refname>systemd-run</refname>
  21     <refpurpose>Run programs in transient scope units, service units, or path-, socket-, or timer-triggered service units</refpurpose>
  22   </refnamediv>
  23
  24   <refsynopsisdiv>
  25     <cmdsynopsis>
  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>
  30       </arg>
  31     </cmdsynopsis>
  32     <cmdsynopsis>
  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>
  38     </cmdsynopsis>
  39     <cmdsynopsis>
  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>
  45     </cmdsynopsis>
  46     <cmdsynopsis>
  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>
  52     </cmdsynopsis>
  53   </refsynopsisdiv>
  54
  55   <refsect1>
  56     <title>Description</title>
  57
  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>
  62
  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
  68     below).</para>
  69
  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
  75     (see below).</para>
  76
  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>
  84
  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>
  95
  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>
 100   </refsect1>
 101
 102   <refsect1>
 103     <title>Options</title>
 104
 105     <para>The following options are understood:</para>
 106
 107     <variablelist>
 108       <varlistentry>
 109         <term><option>--no-ask-password</option></term>
 110
 111         <listitem><para>Do not query the user for authentication for
 112         privileged operations.</para></listitem>
 113       </varlistentry>
 114
 115       <varlistentry>
 116         <term><option>--scope</option></term>
 117
 118         <listitem>
 119           <para>Create a transient <filename>.scope</filename> unit instead of the default transient
 120           <filename>.service</filename> unit (see above).
 121           </para>
 122         </listitem>
 123       </varlistentry>
 124
 125       <varlistentry>
 126         <term><option>--unit=</option></term>
 127         <term><option>-u</option></term>
 128
 129         <listitem><para>Use this unit name instead of an automatically
 130         generated one.</para></listitem>
 131       </varlistentry>
 132
 133       <varlistentry>
 134         <term><option>--property=</option></term>
 135         <term><option>-p</option></term>
 136
 137         <listitem><para>Sets a property on the scope or service unit that is created. This option takes an assignment
 138         in the same format as
 139         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 140         <command>set-property</command> command.</para>
 141         </listitem>
 142       </varlistentry>
 143
 144       <varlistentry>
 145         <term><option>--description=</option></term>
 146
 147         <listitem><para>Provide a description for the service, scope, path, socket, or timer unit. If not specified,
 148         the command itself will be used as a description. See <varname>Description=</varname> in
 149         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 150         </para></listitem>
 151       </varlistentry>
 152
 153       <varlistentry>
 154         <term><option>--slice=</option></term>
 155
 156         <listitem><para>Make the new <filename>.service</filename> or <filename>.scope</filename> unit part
 157         of the specified slice, instead of <filename>system.slice</filename> (when running in
 158         <option>--system</option> mode) or the root slice (when running in <option>--user</option>
 159         mode).</para>
 160         </listitem>
 161       </varlistentry>
 162
 163       <varlistentry>
 164         <term><option>--slice-inherit</option></term>
 165
 166         <listitem><para>Make the new <filename>.service</filename> or <filename>.scope</filename> unit part
 167         of the inherited slice. This option can be combined with <option>--slice=</option>.</para>
 168
 169         <para>An inherited slice is located within <command>systemd-run</command> slice. Example: if
 170         <command>systemd-run</command> slice is <filename>foo.slice</filename>, and the
 171         <option>--slice=</option> argument is <filename>bar</filename>, the unit will be placed under the
 172         <filename>foo-bar.slice</filename>.</para>
 173
 174         </listitem>
 175       </varlistentry>
 176
 177       <varlistentry>
 178         <term><option>--expand-environment=<replaceable>BOOL</replaceable></option></term>
 179
 180         <listitem><para>Expand environment variables in command arguments. If enabled (the default),
 181         environment variables specified as <literal>${<replaceable>VARIABLE</replaceable>}</literal> will be
 182         expanded in the same way as in commands specified via <varname>ExecStart=</varname> in units. With
 183         <varname>--scope</varname>, this expansion is performed by <command>systemd-run</command> itself, and
 184         in other cases by the service manager that spawns the command. Note that this is similar to, but not
 185         the same as variable expansion in
 186         <citerefentry project='man-pages'><refentrytitle>bash</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 187         and other shells.</para>
 188
 189         <para>See
 190         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 191         for a description of variable expansion. Disabling variable expansion is useful if the specified
 192         command includes or may include a <literal>$</literal> sign.</para>
 193         </listitem>
 194       </varlistentry>
 195
 196       <varlistentry>
 197         <term><option>-r</option></term>
 198         <term><option>--remain-after-exit</option></term>
 199
 200         <listitem><para>After the service process has terminated, keep the service around until it is explicitly
 201         stopped. This is useful to collect runtime information about the service after it finished running. Also see
 202         <varname>RemainAfterExit=</varname> in
 203         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 204         </para>
 205         </listitem>
 206       </varlistentry>
 207
 208       <varlistentry>
 209         <term><option>--send-sighup</option></term>
 210
 211         <listitem><para>When terminating the scope or service unit, send a SIGHUP immediately after SIGTERM. This is
 212         useful to indicate to shells and shell-like processes that the connection has been severed. Also see
 213         <varname>SendSIGHUP=</varname> in
 214         <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 215         </para>
 216         </listitem>
 217       </varlistentry>
 218
 219       <varlistentry>
 220         <term><option>--service-type=</option></term>
 221
 222         <listitem><para>Sets the service type. Also see
 223         <varname>Type=</varname> in
 224         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>. This
 225         option has no effect in conjunction with
 226         <option>--scope</option>. Defaults to
 227         <constant>simple</constant>.</para>
 228         </listitem>
 229       </varlistentry>
 230
 231       <varlistentry>
 232         <term><option>--uid=</option></term>
 233         <term><option>--gid=</option></term>
 234
 235         <listitem><para>Runs the service process under the specified UNIX user and group. Also see
 236         <varname>User=</varname> and <varname>Group=</varname> in
 237         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 238         </listitem>
 239       </varlistentry>
 240
 241       <varlistentry>
 242         <term><option>--nice=</option></term>
 243
 244         <listitem><para>Runs the service process with the specified
 245         nice level. Also see <varname>Nice=</varname> in
 246         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 247         </listitem>
 248       </varlistentry>
 249
 250       <varlistentry>
 251         <term><option>--working-directory=</option></term>
 252
 253         <listitem><para>Runs the service process with the specified working directory. Also see
 254         <varname>WorkingDirectory=</varname> in
 255         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 256         </listitem>
 257       </varlistentry>
 258
 259       <varlistentry>
 260         <term><option>--same-dir</option></term>
 261         <term><option>-d</option></term>
 262
 263         <listitem><para>Similar to <option>--working-directory=</option>, but uses the current working
 264         directory of the caller for the service to execute.</para></listitem>
 265       </varlistentry>
 266
 267       <varlistentry>
 268         <term><option>-E <replaceable>NAME</replaceable>[=<replaceable>VALUE</replaceable>]</option></term>
 269         <term><option>--setenv=<replaceable>NAME</replaceable>[=<replaceable>VALUE</replaceable>]</option></term>
 270
 271         <listitem><para>Runs the service process with the specified environment variable set. This parameter
 272         may be used more than once to set multiple variables. When <literal>=</literal> and
 273         <replaceable>VALUE</replaceable> are omitted, the value of the variable with the same name in the
 274         program environment will be used.</para>
 275
 276         <para>Also see <varname>Environment=</varname> in
 277         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 278         </listitem>
 279       </varlistentry>
 280
 281       <varlistentry>
 282         <term><option>--pty</option></term>
 283         <term><option>-t</option></term>
 284
 285         <listitem><para>When invoking the command, the transient service connects its standard input, output and error
 286         to the terminal <command>systemd-run</command> is invoked on, via a pseudo TTY device. This allows running
 287         programs that expect interactive user input/output as services, such as interactive command shells.</para>
 288
 289         <para>Note that
 290         <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 291         <command>shell</command> command is usually a better alternative for requesting a new, interactive login
 292         session on the local host or a local container.</para>
 293
 294         <para>See below for details on how this switch combines with <option>--pipe</option>.</para></listitem>
 295       </varlistentry>
 296
 297       <varlistentry>
 298         <term><option>--pipe</option></term>
 299         <term><option>-P</option></term>
 300
 301         <listitem><para>If specified, standard input, output, and error of the transient service are inherited from the
 302         <command>systemd-run</command> command itself. This allows <command>systemd-run</command>
 303         to be used within shell pipelines.
 304         Note that this mode is not suitable for interactive command shells and similar, as the
 305         service process will not become a TTY controller when invoked on a terminal. Use <option>--pty</option> instead
 306         in that case.</para>
 307
 308         <para>When both <option>--pipe</option> and <option>--pty</option> are used in combination the more appropriate
 309         option is automatically determined and used. Specifically, when invoked with standard input, output and error
 310         connected to a TTY <option>--pty</option> is used, and otherwise <option>--pipe</option>.</para>
 311
 312         <para>When this option is used the original file descriptors <command>systemd-run</command> receives are passed
 313         to the service processes as-is. If the service runs with different privileges than
 314         <command>systemd-run</command>, this means the service might not be able to re-open the passed file
 315         descriptors, due to normal file descriptor access restrictions. If the invoked process is a shell script that
 316         uses the <command>echo "hello" >/dev/stderr</command> construct for writing messages to stderr, this might
 317         cause problems, as this only works if stderr can be re-opened. To mitigate this use the construct <command>echo
 318         "hello" >&amp;2</command> instead, which is mostly equivalent and avoids this pitfall.</para></listitem>
 319       </varlistentry>
 320
 321       <varlistentry>
 322         <term><option>--shell</option></term>
 323         <term><option>-S</option></term>
 324
 325         <listitem><para>A shortcut for <literal>--pty --same-dir --wait --collect --service-type=exec $SHELL</literal>,
 326         i.e. requests an interactive shell in the current working directory, running in service context, accessible
 327         with a single switch.</para></listitem>
 328       </varlistentry>
 329
 330       <varlistentry>
 331         <term><option>--quiet</option></term>
 332         <term><option>-q</option></term>
 333
 334         <listitem><para>Suppresses additional informational output
 335         while running. This is particularly useful in combination with
 336         <option>--pty</option> when it will suppress the initial
 337         message explaining how to terminate the TTY connection.</para></listitem>
 338       </varlistentry>
 339
 340       <varlistentry>
 341         <term><option>--on-active=</option></term>
 342         <term><option>--on-boot=</option></term>
 343         <term><option>--on-startup=</option></term>
 344         <term><option>--on-unit-active=</option></term>
 345         <term><option>--on-unit-inactive=</option></term>
 346
 347         <listitem><para>Defines a monotonic timer relative to different starting points for starting the specified
 348         command. See <varname>OnActiveSec=</varname>, <varname>OnBootSec=</varname>, <varname>OnStartupSec=</varname>,
 349         <varname>OnUnitActiveSec=</varname> and <varname>OnUnitInactiveSec=</varname> in
 350         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
 351         details. These options are shortcuts for <command>--timer-property=</command> with the relevant properties.
 352         These options may not be combined with <option>--scope</option> or <option>--pty</option>.</para>
 353         </listitem>
 354       </varlistentry>
 355
 356       <varlistentry>
 357         <term><option>--on-calendar=</option></term>
 358
 359         <listitem><para>Defines a calendar timer for starting the specified command. See <varname>OnCalendar=</varname>
 360         in <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>. This
 361         option is a shortcut for <command>--timer-property=OnCalendar=</command>. This option may not be combined with
 362         <option>--scope</option> or <option>--pty</option>.</para>
 363         </listitem>
 364       </varlistentry>
 365
 366       <varlistentry>
 367         <term><option>--on-clock-change</option></term>
 368         <term><option>--on-timezone-change</option></term>
 369
 370         <listitem><para>Defines a trigger based on system clock jumps or timezone changes for starting the
 371         specified command. See <varname>OnClockChange=</varname> and <varname>OnTimezoneChange=</varname> in
 372         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>. These
 373         options are shortcuts for <command>--timer-property=OnClockChange=yes</command> and
 374         <command>--timer-property=OnTimezoneChange=yes</command>. These options may not be combined with
 375         <option>--scope</option> or <option>--pty</option>.</para></listitem>
 376       </varlistentry>
 377
 378       <varlistentry>
 379         <term><option>--path-property=</option></term>
 380         <term><option>--socket-property=</option></term>
 381         <term><option>--timer-property=</option></term>
 382
 383         <listitem><para>Sets a property on the path, socket, or timer unit that is created. This option is
 384         similar to <option>--property=</option>, but applies to the transient path, socket, or timer unit
 385         rather than the transient service unit created. This option takes an assignment in the same format as
 386         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 387         <command>set-property</command> command. These options may not be combined with
 388         <option>--scope</option> or <option>--pty</option>.</para>
 389         </listitem>
 390       </varlistentry>
 391
 392       <varlistentry>
 393         <term><option>--no-block</option></term>
 394
 395         <listitem>
 396           <para>Do not synchronously wait for the unit start operation to finish. If this option is not specified, the
 397           start request for the transient unit will be verified, enqueued and <command>systemd-run</command> will wait
 398           until the unit's start-up is completed. By passing this argument, it is only verified and enqueued. This
 399           option may not be combined with <option>--wait</option>.</para>
 400         </listitem>
 401       </varlistentry>
 402
 403       <varlistentry>
 404         <term><option>--wait</option></term>
 405
 406         <listitem><para>Synchronously wait for the transient service to terminate. If this option is specified, the
 407         start request for the transient unit is verified, enqueued, and waited for. Subsequently the invoked unit is
 408         monitored, and it is waited until it is deactivated again (most likely because the specified command
 409         completed). On exit, terse information about the unit's runtime is shown, including total runtime (as well as
 410         CPU usage, if <option>--property=CPUAccounting=1</option> was set) and the exit code and status of the main
 411         process. This output may be suppressed with <option>--quiet</option>. This option may not be combined with
 412         <option>--no-block</option>, <option>--scope</option> or the various path, socket, or timer options.</para></listitem>
 413       </varlistentry>
 414
 415       <varlistentry>
 416         <term><option>-G</option></term>
 417         <term><option>--collect</option></term>
 418
 419         <listitem><para>Unload the transient unit after it completed, even if it failed. Normally, without this option,
 420         all units that ran and failed are kept in memory until the user explicitly resets their failure state with
 421         <command>systemctl reset-failed</command> or an equivalent command. On the other hand, units that ran
 422         successfully are unloaded immediately. If this option is turned on the "garbage collection" of units is more
 423         aggressive, and unloads units regardless if they exited successfully or failed. This option is a shortcut for
 424         <command>--property=CollectMode=inactive-or-failed</command>, see the explanation for
 425         <varname>CollectMode=</varname> in
 426         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for further
 427         information.</para></listitem>
 428       </varlistentry>
 429
 430       <xi:include href="user-system-options.xml" xpointer="user" />
 431       <xi:include href="user-system-options.xml" xpointer="system" />
 432       <xi:include href="user-system-options.xml" xpointer="host" />
 433       <xi:include href="user-system-options.xml" xpointer="machine" />
 434
 435       <xi:include href="standard-options.xml" xpointer="help" />
 436       <xi:include href="standard-options.xml" xpointer="version" />
 437     </variablelist>
 438
 439     <para>All command line arguments after the first non-option argument become part of the command line of
 440     the launched process.</para>
 441   </refsect1>
 442
 443   <refsect1>
 444     <title>Exit status</title>
 445
 446     <para>On success, 0 is returned. If <command>systemd-run</command> failed to start the service, a
 447     non-zero return value will be returned. If <command>systemd-run</command> waits for the service to
 448     terminate, the return value will be propagated from the service. 0 will be returned on success, including
 449     all the cases where systemd considers a service to have exited cleanly, see the discussion of
 450     <varname>SuccessExitStatus=</varname> in
 451     <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 452     </para>
 453   </refsect1>
 454
 455   <refsect1>
 456     <title>Examples</title>
 457
 458     <example>
 459       <title>Logging environment variables provided by systemd to services</title>
 460
 461       <programlisting># systemd-run env
 462 Running as unit: run-19945.service
 463 # journalctl -u run-19945.service
 464 Sep 08 07:37:21 bupkis systemd[1]: Starting /usr/bin/env...
 465 Sep 08 07:37:21 bupkis systemd[1]: Started /usr/bin/env.
 466 Sep 08 07:37:21 bupkis env[19948]: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
 467 Sep 08 07:37:21 bupkis env[19948]: LANG=en_US.UTF-8
 468 Sep 08 07:37:21 bupkis env[19948]: BOOT_IMAGE=/vmlinuz-3.11.0-0.rc5.git6.2.fc20.x86_64</programlisting>
 469     </example>
 470
 471     <example>
 472       <title>Limiting resources available to a command</title>
 473
 474       <programlisting># systemd-run -p IOWeight=10 updatedb</programlisting>
 475
 476       <para>This command invokes the <citerefentry
 477       project='man-pages'><refentrytitle>updatedb</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 478       tool, but lowers the block I/O weight for it to 10. See
 479       <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 480       for more information on the <varname>IOWeight=</varname> property.</para>
 481     </example>
 482
 483     <example>
 484       <title>Running commands at a specified time</title>
 485
 486       <para>The following command will touch a file after 30 seconds.</para>
 487
 488       <programlisting># date; systemd-run --on-active=30 --timer-property=AccuracySec=100ms /bin/touch /tmp/foo
 489 Mon Dec  8 20:44:24 KST 2014
 490 Running as unit: run-71.timer
 491 Will run service as unit: run-71.service
 492 # journalctl -b -u run-71.timer
 493 -- Journal begins at Fri 2014-12-05 19:09:21 KST, ends at Mon 2014-12-08 20:44:54 KST. --
 494 Dec 08 20:44:38 container systemd[1]: Starting /bin/touch /tmp/foo.
 495 Dec 08 20:44:38 container systemd[1]: Started /bin/touch /tmp/foo.
 496 # journalctl -b -u run-71.service
 497 -- Journal begins at Fri 2014-12-05 19:09:21 KST, ends at Mon 2014-12-08 20:44:54 KST. --
 498 Dec 08 20:44:48 container systemd[1]: Starting /bin/touch /tmp/foo...
 499 Dec 08 20:44:48 container systemd[1]: Started /bin/touch /tmp/foo.</programlisting>
 500     </example>
 501
 502     <example>
 503       <title>Allowing access to the tty</title>
 504
 505       <para>The following command invokes <citerefentry project='man-pages'><refentrytitle>bash</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 506       as a service passing its standard input, output and error to the calling TTY.</para>
 507
 508       <programlisting># systemd-run -t --send-sighup bash</programlisting>
 509     </example>
 510
 511     <example>
 512       <title>Start <command>screen</command> as a user service</title>
 513
 514       <programlisting>$ systemd-run --scope --user screen
 515 Running scope as unit run-r14b0047ab6df45bfb45e7786cc839e76.scope.
 516
 517 $ screen -ls
 518 There is a screen on:
 519         492..laptop     (Detached)
 520 1 Socket in /var/run/screen/S-fatima.
 521 </programlisting>
 522
 523       <para>This starts the <command>screen</command> process as a child of the
 524       <command>systemd --user</command> process that was started by
 525       <filename>user@.service</filename>, in a scope unit. A
 526       <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 527       unit is used instead of a
 528       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 529       unit, because <command>screen</command> will exit when detaching from the terminal,
 530       and a service unit would be terminated. Running <command>screen</command>
 531       as a user unit has the advantage that it is not part of the session scope.
 532       If <varname>KillUserProcesses=yes</varname> is configured in
 533       <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 534       the default, the session scope will be terminated when the user logs
 535       out of that session.</para>
 536
 537       <para>The <filename>user@.service</filename> is started automatically
 538       when the user first logs in, and stays around as long as at least one
 539       login session is open. After the user logs out of the last session,
 540       <filename>user@.service</filename> and all services underneath it
 541       are terminated. This behavior is the default, when "lingering" is
 542       not enabled for that user. Enabling lingering means that
 543       <filename>user@.service</filename> is started automatically during
 544       boot, even if the user is not logged in, and that the service is
 545       not terminated when the user logs out.</para>
 546
 547       <para>Enabling lingering allows the user to run processes without being logged in,
 548       for example to allow <command>screen</command> to persist after the user logs out,
 549       even if the session scope is terminated. In the default configuration, users can
 550       enable lingering for themselves:</para>
 551
 552       <programlisting>$ loginctl enable-linger</programlisting>
 553     </example>
 554
 555     <example>
 556       <title>Variable expansion by the manager</title>
 557
 558       <programlisting>$ systemd-run -t echo "&lt;${INVOCATION_ID}>" '&lt;${INVOCATION_ID}>'
 559       &lt;> &lt;5d0149bfa2c34b79bccb13074001eb20>
 560       </programlisting>
 561
 562       <para>The first argument is expanded by the shell (double quotes), but the second one is not expanded
 563       by the shell (single quotes). <command>echo</command> is called with [<literal>/usr/bin/echo</literal>,
 564       <literal>[]</literal>, <literal>[${INVOCATION_ID}]</literal>] as the argument array, and then
 565       <command>systemd</command> generates <varname>${INVOCATION_ID}</varname> and substitutes it in the
 566       command-line. This substitution could not be done on the client side, because the target ID that will
 567       be set for the service isn't known before the call is made.</para>
 568     </example>
 569
 570     <example>
 571       <title>Variable expansion and output redirection using a shell</title>
 572
 573       <para>Variable expansion by <command>systemd</command> can be disabled with
 574       <varname>--expand-environment=no</varname>.</para>
 575
 576       <para>Disabling variable expansion can be useful if the command to execute contains dollar characters
 577       and escaping them would be inconvenient. For example, when a shell is used:</para>
 578
 579       <programlisting>$ systemd-run --expand-environment=no -t bash \
 580       -c 'echo $SHELL $$ >/dev/stdout'
 581 /bin/bash 12345
 582       </programlisting>
 583
 584       <para>The last argument is passed verbatim to the <command>bash</command> shell which is started by the
 585       service unit. The shell expands <literal>$SHELL</literal> to the path of the shell, and
 586       <literal>$$</literal> to its process number, and then those strings are passed to the
 587       <command>echo</command> built-in and printed to standard output (which in this case is connected to the
 588       calling terminal).</para>
 589     </example>
 590
 591     <example>
 592       <title>Return value</title>
 593
 594       <programlisting>$ systemd-run --user --wait true
 595 $ systemd-run --user --wait -p SuccessExitStatus=11 bash -c 'exit 11'
 596 $ systemd-run --user --wait -p SuccessExitStatus=SIGUSR1 --expand-environment=no \
 597       bash -c 'kill -SIGUSR1 $$'</programlisting>
 598
 599       <para>Those three invocations will succeed, i.e. terminate with an exit code of 0.</para>
 600     </example>
 601   </refsect1>
 602
 603   <refsect1>
 604     <title>See Also</title>
 605     <para>
 606       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 607       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 608       <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 609       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 610       <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 611       <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 612       <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 613       <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 614       <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 615       <citerefentry><refentrytitle>systemd-mount</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 616       <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 617     </para>
 618   </refsect1>
 619
 620 </refentry>