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, environment variables
 181         specified as <literal>${<replaceable>VARIABLE</replaceable>}</literal> will be expanded in the same
 182         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>The default is to enable this option in all cases, except for <varname>--scope</varname> where
 190         it is disabled by default, for backward compatibility reasons. Note that this will be changed in a
 191         future release, where it will be switched to enabled by default as well.</para>
 192
 193         <para>See
 194         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 195         for a description of variable expansion. Disabling variable expansion is useful if the specified
 196         command includes or may include a <literal>$</literal> sign.</para>
 197         </listitem>
 198       </varlistentry>
 199
 200       <varlistentry>
 201         <term><option>-r</option></term>
 202         <term><option>--remain-after-exit</option></term>
 203
 204         <listitem><para>After the service process has terminated, keep the service around until it is explicitly
 205         stopped. This is useful to collect runtime information about the service after it finished running. Also see
 206         <varname>RemainAfterExit=</varname> in
 207         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 208         </para>
 209         </listitem>
 210       </varlistentry>
 211
 212       <varlistentry>
 213         <term><option>--send-sighup</option></term>
 214
 215         <listitem><para>When terminating the scope or service unit, send a SIGHUP immediately after SIGTERM. This is
 216         useful to indicate to shells and shell-like processes that the connection has been severed. Also see
 217         <varname>SendSIGHUP=</varname> in
 218         <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 219         </para>
 220         </listitem>
 221       </varlistentry>
 222
 223       <varlistentry>
 224         <term><option>--service-type=</option></term>
 225
 226         <listitem><para>Sets the service type. Also see
 227         <varname>Type=</varname> in
 228         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>. This
 229         option has no effect in conjunction with
 230         <option>--scope</option>. Defaults to
 231         <constant>simple</constant>.</para>
 232         </listitem>
 233       </varlistentry>
 234
 235       <varlistentry>
 236         <term><option>--uid=</option></term>
 237         <term><option>--gid=</option></term>
 238
 239         <listitem><para>Runs the service process under the specified UNIX user and group. Also see
 240         <varname>User=</varname> and <varname>Group=</varname> in
 241         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 242         </listitem>
 243       </varlistentry>
 244
 245       <varlistentry>
 246         <term><option>--nice=</option></term>
 247
 248         <listitem><para>Runs the service process with the specified
 249         nice level. Also see <varname>Nice=</varname> in
 250         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 251         </listitem>
 252       </varlistentry>
 253
 254       <varlistentry>
 255         <term><option>--working-directory=</option></term>
 256
 257         <listitem><para>Runs the service process with the specified working directory. Also see
 258         <varname>WorkingDirectory=</varname> in
 259         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 260         </listitem>
 261       </varlistentry>
 262
 263       <varlistentry>
 264         <term><option>--same-dir</option></term>
 265         <term><option>-d</option></term>
 266
 267         <listitem><para>Similar to <option>--working-directory=</option>, but uses the current working
 268         directory of the caller for the service to execute.</para></listitem>
 269       </varlistentry>
 270
 271       <varlistentry>
 272         <term><option>-E <replaceable>NAME</replaceable>[=<replaceable>VALUE</replaceable>]</option></term>
 273         <term><option>--setenv=<replaceable>NAME</replaceable>[=<replaceable>VALUE</replaceable>]</option></term>
 274
 275         <listitem><para>Runs the service process with the specified environment variable set. This parameter
 276         may be used more than once to set multiple variables. When <literal>=</literal> and
 277         <replaceable>VALUE</replaceable> are omitted, the value of the variable with the same name in the
 278         program environment will be used.</para>
 279
 280         <para>Also see <varname>Environment=</varname> in
 281         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 282         </listitem>
 283       </varlistentry>
 284
 285       <varlistentry>
 286         <term><option>--pty</option></term>
 287         <term><option>-t</option></term>
 288
 289         <listitem><para>When invoking the command, the transient service connects its standard input, output and error
 290         to the terminal <command>systemd-run</command> is invoked on, via a pseudo TTY device. This allows running
 291         programs that expect interactive user input/output as services, such as interactive command shells.</para>
 292
 293         <para>Note that
 294         <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 295         <command>shell</command> command is usually a better alternative for requesting a new, interactive login
 296         session on the local host or a local container.</para>
 297
 298         <para>See below for details on how this switch combines with <option>--pipe</option>.</para></listitem>
 299       </varlistentry>
 300
 301       <varlistentry>
 302         <term><option>--pipe</option></term>
 303         <term><option>-P</option></term>
 304
 305         <listitem><para>If specified, standard input, output, and error of the transient service are inherited from the
 306         <command>systemd-run</command> command itself. This allows <command>systemd-run</command>
 307         to be used within shell pipelines.
 308         Note that this mode is not suitable for interactive command shells and similar, as the
 309         service process will not become a TTY controller when invoked on a terminal. Use <option>--pty</option> instead
 310         in that case.</para>
 311
 312         <para>When both <option>--pipe</option> and <option>--pty</option> are used in combination the more appropriate
 313         option is automatically determined and used. Specifically, when invoked with standard input, output and error
 314         connected to a TTY <option>--pty</option> is used, and otherwise <option>--pipe</option>.</para>
 315
 316         <para>When this option is used the original file descriptors <command>systemd-run</command> receives are passed
 317         to the service processes as-is. If the service runs with different privileges than
 318         <command>systemd-run</command>, this means the service might not be able to re-open the passed file
 319         descriptors, due to normal file descriptor access restrictions. If the invoked process is a shell script that
 320         uses the <command>echo "hello" >/dev/stderr</command> construct for writing messages to stderr, this might
 321         cause problems, as this only works if stderr can be re-opened. To mitigate this use the construct <command>echo
 322         "hello" >&amp;2</command> instead, which is mostly equivalent and avoids this pitfall.</para></listitem>
 323       </varlistentry>
 324
 325       <varlistentry>
 326         <term><option>--shell</option></term>
 327         <term><option>-S</option></term>
 328
 329         <listitem><para>A shortcut for <literal>--pty --same-dir --wait --collect --service-type=exec $SHELL</literal>,
 330         i.e. requests an interactive shell in the current working directory, running in service context, accessible
 331         with a single switch.</para></listitem>
 332       </varlistentry>
 333
 334       <varlistentry>
 335         <term><option>--quiet</option></term>
 336         <term><option>-q</option></term>
 337
 338         <listitem><para>Suppresses additional informational output
 339         while running. This is particularly useful in combination with
 340         <option>--pty</option> when it will suppress the initial
 341         message explaining how to terminate the TTY connection.</para></listitem>
 342       </varlistentry>
 343
 344       <varlistentry>
 345         <term><option>--on-active=</option></term>
 346         <term><option>--on-boot=</option></term>
 347         <term><option>--on-startup=</option></term>
 348         <term><option>--on-unit-active=</option></term>
 349         <term><option>--on-unit-inactive=</option></term>
 350
 351         <listitem><para>Defines a monotonic timer relative to different starting points for starting the specified
 352         command. See <varname>OnActiveSec=</varname>, <varname>OnBootSec=</varname>, <varname>OnStartupSec=</varname>,
 353         <varname>OnUnitActiveSec=</varname> and <varname>OnUnitInactiveSec=</varname> in
 354         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
 355         details. These options are shortcuts for <command>--timer-property=</command> with the relevant properties.
 356         These options may not be combined with <option>--scope</option> or <option>--pty</option>.</para>
 357         </listitem>
 358       </varlistentry>
 359
 360       <varlistentry>
 361         <term><option>--on-calendar=</option></term>
 362
 363         <listitem><para>Defines a calendar timer for starting the specified command. See <varname>OnCalendar=</varname>
 364         in <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>. This
 365         option is a shortcut for <command>--timer-property=OnCalendar=</command>. This option may not be combined with
 366         <option>--scope</option> or <option>--pty</option>.</para>
 367         </listitem>
 368       </varlistentry>
 369
 370       <varlistentry>
 371         <term><option>--on-clock-change</option></term>
 372         <term><option>--on-timezone-change</option></term>
 373
 374         <listitem><para>Defines a trigger based on system clock jumps or timezone changes for starting the
 375         specified command. See <varname>OnClockChange=</varname> and <varname>OnTimezoneChange=</varname> in
 376         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>. These
 377         options are shortcuts for <command>--timer-property=OnClockChange=yes</command> and
 378         <command>--timer-property=OnTimezoneChange=yes</command>. These options may not be combined with
 379         <option>--scope</option> or <option>--pty</option>.</para></listitem>
 380       </varlistentry>
 381
 382       <varlistentry>
 383         <term><option>--path-property=</option></term>
 384         <term><option>--socket-property=</option></term>
 385         <term><option>--timer-property=</option></term>
 386
 387         <listitem><para>Sets a property on the path, socket, or timer unit that is created. This option is
 388         similar to <option>--property=</option>, but applies to the transient path, socket, or timer unit
 389         rather than the transient service unit created. This option takes an assignment in the same format as
 390         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 391         <command>set-property</command> command. These options may not be combined with
 392         <option>--scope</option> or <option>--pty</option>.</para>
 393         </listitem>
 394       </varlistentry>
 395
 396       <varlistentry>
 397         <term><option>--no-block</option></term>
 398
 399         <listitem>
 400           <para>Do not synchronously wait for the unit start operation to finish. If this option is not specified, the
 401           start request for the transient unit will be verified, enqueued and <command>systemd-run</command> will wait
 402           until the unit's start-up is completed. By passing this argument, it is only verified and enqueued. This
 403           option may not be combined with <option>--wait</option>.</para>
 404         </listitem>
 405       </varlistentry>
 406
 407       <varlistentry>
 408         <term><option>--wait</option></term>
 409
 410         <listitem><para>Synchronously wait for the transient service to terminate. If this option is specified, the
 411         start request for the transient unit is verified, enqueued, and waited for. Subsequently the invoked unit is
 412         monitored, and it is waited until it is deactivated again (most likely because the specified command
 413         completed). On exit, terse information about the unit's runtime is shown, including total runtime (as well as
 414         CPU usage, if <option>--property=CPUAccounting=1</option> was set) and the exit code and status of the main
 415         process. This output may be suppressed with <option>--quiet</option>. This option may not be combined with
 416         <option>--no-block</option>, <option>--scope</option> or the various path, socket, or timer options.</para></listitem>
 417       </varlistentry>
 418
 419       <varlistentry>
 420         <term><option>-G</option></term>
 421         <term><option>--collect</option></term>
 422
 423         <listitem><para>Unload the transient unit after it completed, even if it failed. Normally, without this option,
 424         all units that ran and failed are kept in memory until the user explicitly resets their failure state with
 425         <command>systemctl reset-failed</command> or an equivalent command. On the other hand, units that ran
 426         successfully are unloaded immediately. If this option is turned on the "garbage collection" of units is more
 427         aggressive, and unloads units regardless if they exited successfully or failed. This option is a shortcut for
 428         <command>--property=CollectMode=inactive-or-failed</command>, see the explanation for
 429         <varname>CollectMode=</varname> in
 430         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for further
 431         information.</para></listitem>
 432       </varlistentry>
 433
 434       <xi:include href="user-system-options.xml" xpointer="user" />
 435       <xi:include href="user-system-options.xml" xpointer="system" />
 436       <xi:include href="user-system-options.xml" xpointer="host" />
 437       <xi:include href="user-system-options.xml" xpointer="machine" />
 438
 439       <xi:include href="standard-options.xml" xpointer="help" />
 440       <xi:include href="standard-options.xml" xpointer="version" />
 441     </variablelist>
 442
 443     <para>All command line arguments after the first non-option argument become part of the command line of
 444     the launched process.</para>
 445   </refsect1>
 446
 447   <refsect1>
 448     <title>Exit status</title>
 449
 450     <para>On success, 0 is returned. If <command>systemd-run</command> failed to start the service, a
 451     non-zero return value will be returned. If <command>systemd-run</command> waits for the service to
 452     terminate, the return value will be propagated from the service. 0 will be returned on success, including
 453     all the cases where systemd considers a service to have exited cleanly, see the discussion of
 454     <varname>SuccessExitStatus=</varname> in
 455     <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 456     </para>
 457   </refsect1>
 458
 459   <refsect1>
 460     <title>Examples</title>
 461
 462     <example>
 463       <title>Logging environment variables provided by systemd to services</title>
 464
 465       <programlisting># systemd-run env
 466 Running as unit: run-19945.service
 467 # journalctl -u run-19945.service
 468 Sep 08 07:37:21 bupkis systemd[1]: Starting /usr/bin/env...
 469 Sep 08 07:37:21 bupkis systemd[1]: Started /usr/bin/env.
 470 Sep 08 07:37:21 bupkis env[19948]: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
 471 Sep 08 07:37:21 bupkis env[19948]: LANG=en_US.UTF-8
 472 Sep 08 07:37:21 bupkis env[19948]: BOOT_IMAGE=/vmlinuz-3.11.0-0.rc5.git6.2.fc20.x86_64</programlisting>
 473     </example>
 474
 475     <example>
 476       <title>Limiting resources available to a command</title>
 477
 478       <programlisting># systemd-run -p IOWeight=10 updatedb</programlisting>
 479
 480       <para>This command invokes the <citerefentry
 481       project='man-pages'><refentrytitle>updatedb</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 482       tool, but lowers the block I/O weight for it to 10. See
 483       <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 484       for more information on the <varname>IOWeight=</varname> property.</para>
 485     </example>
 486
 487     <example>
 488       <title>Running commands at a specified time</title>
 489
 490       <para>The following command will touch a file after 30 seconds.</para>
 491
 492       <programlisting># date; systemd-run --on-active=30 --timer-property=AccuracySec=100ms /bin/touch /tmp/foo
 493 Mon Dec  8 20:44:24 KST 2014
 494 Running as unit: run-71.timer
 495 Will run service as unit: run-71.service
 496 # journalctl -b -u run-71.timer
 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 20:44:38 container systemd[1]: Starting /bin/touch /tmp/foo.
 499 Dec 08 20:44:38 container systemd[1]: Started /bin/touch /tmp/foo.
 500 # journalctl -b -u run-71.service
 501 -- Journal begins at Fri 2014-12-05 19:09:21 KST, ends at Mon 2014-12-08 20:44:54 KST. --
 502 Dec 08 20:44:48 container systemd[1]: Starting /bin/touch /tmp/foo...
 503 Dec 08 20:44:48 container systemd[1]: Started /bin/touch /tmp/foo.</programlisting>
 504     </example>
 505
 506     <example>
 507       <title>Allowing access to the tty</title>
 508
 509       <para>The following command invokes <citerefentry project='man-pages'><refentrytitle>bash</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 510       as a service passing its standard input, output and error to the calling TTY.</para>
 511
 512       <programlisting># systemd-run -t --send-sighup bash</programlisting>
 513     </example>
 514
 515     <example>
 516       <title>Start <command>screen</command> as a user service</title>
 517
 518       <programlisting>$ systemd-run --scope --user screen
 519 Running scope as unit run-r14b0047ab6df45bfb45e7786cc839e76.scope.
 520
 521 $ screen -ls
 522 There is a screen on:
 523         492..laptop     (Detached)
 524 1 Socket in /var/run/screen/S-fatima.
 525 </programlisting>
 526
 527       <para>This starts the <command>screen</command> process as a child of the
 528       <command>systemd --user</command> process that was started by
 529       <filename>user@.service</filename>, in a scope unit. A
 530       <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 531       unit is used instead of a
 532       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 533       unit, because <command>screen</command> will exit when detaching from the terminal,
 534       and a service unit would be terminated. Running <command>screen</command>
 535       as a user unit has the advantage that it is not part of the session scope.
 536       If <varname>KillUserProcesses=yes</varname> is configured in
 537       <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 538       the default, the session scope will be terminated when the user logs
 539       out of that session.</para>
 540
 541       <para>The <filename>user@.service</filename> is started automatically
 542       when the user first logs in, and stays around as long as at least one
 543       login session is open. After the user logs out of the last session,
 544       <filename>user@.service</filename> and all services underneath it
 545       are terminated. This behavior is the default, when "lingering" is
 546       not enabled for that user. Enabling lingering means that
 547       <filename>user@.service</filename> is started automatically during
 548       boot, even if the user is not logged in, and that the service is
 549       not terminated when the user logs out.</para>
 550
 551       <para>Enabling lingering allows the user to run processes without being logged in,
 552       for example to allow <command>screen</command> to persist after the user logs out,
 553       even if the session scope is terminated. In the default configuration, users can
 554       enable lingering for themselves:</para>
 555
 556       <programlisting>$ loginctl enable-linger</programlisting>
 557     </example>
 558
 559     <example>
 560       <title>Variable expansion by the manager</title>
 561
 562       <programlisting>$ systemd-run -t echo "&lt;${INVOCATION_ID}>" '&lt;${INVOCATION_ID}>'
 563       &lt;> &lt;5d0149bfa2c34b79bccb13074001eb20>
 564       </programlisting>
 565
 566       <para>The first argument is expanded by the shell (double quotes), but the second one is not expanded
 567       by the shell (single quotes). <command>echo</command> is called with [<literal>/usr/bin/echo</literal>,
 568       <literal>[]</literal>, <literal>[${INVOCATION_ID}]</literal>] as the argument array, and then
 569       <command>systemd</command> generates <varname>${INVOCATION_ID}</varname> and substitutes it in the
 570       command-line. This substitution could not be done on the client side, because the target ID that will
 571       be set for the service isn't known before the call is made.</para>
 572     </example>
 573
 574     <example>
 575       <title>Variable expansion and output redirection using a shell</title>
 576
 577       <para>Variable expansion by <command>systemd</command> can be disabled with
 578       <varname>--expand-environment=no</varname>.</para>
 579
 580       <para>Disabling variable expansion can be useful if the command to execute contains dollar characters
 581       and escaping them would be inconvenient. For example, when a shell is used:</para>
 582
 583       <programlisting>$ systemd-run --expand-environment=no -t bash \
 584       -c 'echo $SHELL $$ >/dev/stdout'
 585 /bin/bash 12345
 586       </programlisting>
 587
 588       <para>The last argument is passed verbatim to the <command>bash</command> shell which is started by the
 589       service unit. The shell expands <literal>$SHELL</literal> to the path of the shell, and
 590       <literal>$$</literal> to its process number, and then those strings are passed to the
 591       <command>echo</command> built-in and printed to standard output (which in this case is connected to the
 592       calling terminal).</para>
 593     </example>
 594
 595     <example>
 596       <title>Return value</title>
 597
 598       <programlisting>$ systemd-run --user --wait true
 599 $ systemd-run --user --wait -p SuccessExitStatus=11 bash -c 'exit 11'
 600 $ systemd-run --user --wait -p SuccessExitStatus=SIGUSR1 --expand-environment=no \
 601       bash -c 'kill -SIGUSR1 $$'</programlisting>
 602
 603       <para>Those three invocations will succeed, i.e. terminate with an exit code of 0.</para>
 604     </example>
 605   </refsect1>
 606
 607   <refsect1>
 608     <title>See Also</title>
 609     <para>
 610       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 611       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 612       <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 613       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 614       <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 615       <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 616       <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 617       <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 618       <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 619       <citerefentry><refentrytitle>systemd-mount</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 620       <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 621     </para>
 622   </refsect1>
 623
 624 </refentry>