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>
 113
 114         <xi:include href="version-info.xml" xpointer="v226"/></listitem>
 115       </varlistentry>
 116
 117       <varlistentry>
 118         <term><option>--scope</option></term>
 119
 120         <listitem>
 121           <para>Create a transient <filename>.scope</filename> unit instead of the default transient
 122           <filename>.service</filename> unit (see above).
 123           </para>
 124
 125         <xi:include href="version-info.xml" xpointer="v206"/>
 126         </listitem>
 127       </varlistentry>
 128
 129       <varlistentry>
 130         <term><option>--unit=</option></term>
 131         <term><option>-u</option></term>
 132
 133         <listitem><para>Use this unit name instead of an automatically
 134         generated one.</para>
 135
 136         <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 137       </varlistentry>
 138
 139       <varlistentry>
 140         <term><option>--property=</option></term>
 141         <term><option>-p</option></term>
 142
 143         <listitem><para>Sets a property on the scope or service unit that is created. This option takes an assignment
 144         in the same format as
 145         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 146         <command>set-property</command> command.</para>
 147
 148         <xi:include href="version-info.xml" xpointer="v211"/>
 149         </listitem>
 150       </varlistentry>
 151
 152       <varlistentry>
 153         <term><option>--description=</option></term>
 154
 155         <listitem><para>Provide a description for the service, scope, path, socket, or timer unit. If not specified,
 156         the command itself will be used as a description. See <varname>Description=</varname> in
 157         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 158         </para>
 159
 160         <xi:include href="version-info.xml" xpointer="v206"/></listitem>
 161       </varlistentry>
 162
 163       <varlistentry>
 164         <term><option>--slice=</option></term>
 165
 166         <listitem><para>Make the new <filename>.service</filename> or <filename>.scope</filename> unit part
 167         of the specified slice, instead of <filename>system.slice</filename> (when running in
 168         <option>--system</option> mode) or the root slice (when running in <option>--user</option>
 169         mode).</para>
 170
 171         <xi:include href="version-info.xml" xpointer="v206"/>
 172         </listitem>
 173       </varlistentry>
 174
 175       <varlistentry>
 176         <term><option>--slice-inherit</option></term>
 177
 178         <listitem><para>Make the new <filename>.service</filename> or <filename>.scope</filename> unit part
 179         of the inherited slice. This option can be combined with <option>--slice=</option>.</para>
 180
 181         <para>An inherited slice is located within <command>systemd-run</command> slice. Example: if
 182         <command>systemd-run</command> slice is <filename>foo.slice</filename>, and the
 183         <option>--slice=</option> argument is <filename>bar</filename>, the unit will be placed under the
 184         <filename>foo-bar.slice</filename>.</para>
 185
 186         <xi:include href="version-info.xml" xpointer="v246"/>
 187
 188         </listitem>
 189       </varlistentry>
 190
 191       <varlistentry>
 192         <term><option>--expand-environment=<replaceable>BOOL</replaceable></option></term>
 193
 194         <listitem><para>Expand environment variables in command arguments. If enabled, environment variables
 195         specified as <literal>${<replaceable>VARIABLE</replaceable>}</literal> will be expanded in the same
 196         way as in commands specified via <varname>ExecStart=</varname> in units. With
 197         <varname>--scope</varname>, this expansion is performed by <command>systemd-run</command> itself, and
 198         in other cases by the service manager that spawns the command. Note that this is similar to, but not
 199         the same as variable expansion in
 200         <citerefentry project='man-pages'><refentrytitle>bash</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 201         and other shells.</para>
 202
 203         <para>The default is to enable this option in all cases, except for <varname>--scope</varname> where
 204         it is disabled by default, for backward compatibility reasons. Note that this will be changed in a
 205         future release, where it will be switched to enabled by default as well.</para>
 206
 207         <para>See
 208         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 209         for a description of variable expansion. Disabling variable expansion is useful if the specified
 210         command includes or may include a <literal>$</literal> sign.</para>
 211
 212         <xi:include href="version-info.xml" xpointer="v254"/>
 213         </listitem>
 214       </varlistentry>
 215
 216       <varlistentry>
 217         <term><option>-r</option></term>
 218         <term><option>--remain-after-exit</option></term>
 219
 220         <listitem><para>After the service process has terminated, keep the service around until it is explicitly
 221         stopped. This is useful to collect runtime information about the service after it finished running. Also see
 222         <varname>RemainAfterExit=</varname> in
 223         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 224         </para>
 225
 226         <xi:include href="version-info.xml" xpointer="v207"/>
 227         </listitem>
 228       </varlistentry>
 229
 230       <varlistentry>
 231         <term><option>--send-sighup</option></term>
 232
 233         <listitem><para>When terminating the scope or service unit, send a SIGHUP immediately after SIGTERM. This is
 234         useful to indicate to shells and shell-like processes that the connection has been severed. Also see
 235         <varname>SendSIGHUP=</varname> in
 236         <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 237         </para>
 238
 239         <xi:include href="version-info.xml" xpointer="v207"/>
 240         </listitem>
 241       </varlistentry>
 242
 243       <varlistentry>
 244         <term><option>--service-type=</option></term>
 245
 246         <listitem><para>Sets the service type. Also see
 247         <varname>Type=</varname> in
 248         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>. This
 249         option has no effect in conjunction with
 250         <option>--scope</option>. Defaults to
 251         <constant>simple</constant>.</para>
 252
 253         <xi:include href="version-info.xml" xpointer="v211"/>
 254         </listitem>
 255       </varlistentry>
 256
 257       <varlistentry>
 258         <term><option>--uid=</option></term>
 259         <term><option>--gid=</option></term>
 260
 261         <listitem><para>Runs the service process under the specified UNIX user and group. Also see
 262         <varname>User=</varname> and <varname>Group=</varname> in
 263         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 264
 265         <xi:include href="version-info.xml" xpointer="v211"/>
 266         </listitem>
 267       </varlistentry>
 268
 269       <varlistentry>
 270         <term><option>--nice=</option></term>
 271
 272         <listitem><para>Runs the service process with the specified
 273         nice level. Also see <varname>Nice=</varname> in
 274         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 275
 276         <xi:include href="version-info.xml" xpointer="v211"/>
 277         </listitem>
 278       </varlistentry>
 279
 280       <varlistentry>
 281         <term><option>--working-directory=</option></term>
 282
 283         <listitem><para>Runs the service process with the specified working directory. Also see
 284         <varname>WorkingDirectory=</varname> in
 285         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 286
 287         <xi:include href="version-info.xml" xpointer="v240"/>
 288         </listitem>
 289       </varlistentry>
 290
 291       <varlistentry>
 292         <term><option>--same-dir</option></term>
 293         <term><option>-d</option></term>
 294
 295         <listitem><para>Similar to <option>--working-directory=</option>, but uses the current working
 296         directory of the caller for the service to execute.</para>
 297
 298         <xi:include href="version-info.xml" xpointer="v240"/></listitem>
 299       </varlistentry>
 300
 301       <varlistentry>
 302         <term><option>-E <replaceable>NAME</replaceable>[=<replaceable>VALUE</replaceable>]</option></term>
 303         <term><option>--setenv=<replaceable>NAME</replaceable>[=<replaceable>VALUE</replaceable>]</option></term>
 304
 305         <listitem><para>Runs the service process with the specified environment variable set. This parameter
 306         may be used more than once to set multiple variables. When <literal>=</literal> and
 307         <replaceable>VALUE</replaceable> are omitted, the value of the variable with the same name in the
 308         program environment will be used.</para>
 309
 310         <para>Also see <varname>Environment=</varname> in
 311         <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 312
 313         <xi:include href="version-info.xml" xpointer="v211"/>
 314         </listitem>
 315       </varlistentry>
 316
 317       <varlistentry>
 318         <term><option>--pty</option></term>
 319         <term><option>-t</option></term>
 320
 321         <listitem><para>When invoking the command, the transient service connects its standard input, output and error
 322         to the terminal <command>systemd-run</command> is invoked on, via a pseudo TTY device. This allows running
 323         programs that expect interactive user input/output as services, such as interactive command shells.</para>
 324
 325         <para>Note that
 326         <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 327         <command>shell</command> command is usually a better alternative for requesting a new, interactive login
 328         session on the local host or a local container.</para>
 329
 330         <para>See below for details on how this switch combines with <option>--pipe</option>.</para>
 331
 332         <xi:include href="version-info.xml" xpointer="v219"/></listitem>
 333       </varlistentry>
 334
 335       <varlistentry>
 336         <term><option>--pipe</option></term>
 337         <term><option>-P</option></term>
 338
 339         <listitem><para>If specified, standard input, output, and error of the transient service are inherited from the
 340         <command>systemd-run</command> command itself. This allows <command>systemd-run</command>
 341         to be used within shell pipelines.
 342         Note that this mode is not suitable for interactive command shells and similar, as the
 343         service process will not become a TTY controller when invoked on a terminal. Use <option>--pty</option> instead
 344         in that case.</para>
 345
 346         <para>When both <option>--pipe</option> and <option>--pty</option> are used in combination the more appropriate
 347         option is automatically determined and used. Specifically, when invoked with standard input, output and error
 348         connected to a TTY <option>--pty</option> is used, and otherwise <option>--pipe</option>.</para>
 349
 350         <para>When this option is used the original file descriptors <command>systemd-run</command> receives are passed
 351         to the service processes as-is. If the service runs with different privileges than
 352         <command>systemd-run</command>, this means the service might not be able to re-open the passed file
 353         descriptors, due to normal file descriptor access restrictions. If the invoked process is a shell script that
 354         uses the <command>echo "hello" >/dev/stderr</command> construct for writing messages to stderr, this might
 355         cause problems, as this only works if stderr can be re-opened. To mitigate this use the construct <command>echo
 356         "hello" >&amp;2</command> instead, which is mostly equivalent and avoids this pitfall.</para>
 357
 358         <xi:include href="version-info.xml" xpointer="v235"/></listitem>
 359       </varlistentry>
 360
 361       <varlistentry>
 362         <term><option>--shell</option></term>
 363         <term><option>-S</option></term>
 364
 365         <listitem><para>A shortcut for <literal>--pty --same-dir --wait --collect --service-type=exec $SHELL</literal>,
 366         i.e. requests an interactive shell in the current working directory, running in service context, accessible
 367         with a single switch.</para>
 368
 369         <xi:include href="version-info.xml" xpointer="v240"/></listitem>
 370       </varlistentry>
 371
 372       <varlistentry>
 373         <term><option>--quiet</option></term>
 374         <term><option>-q</option></term>
 375
 376         <listitem><para>Suppresses additional informational output
 377         while running. This is particularly useful in combination with
 378         <option>--pty</option> when it will suppress the initial
 379         message explaining how to terminate the TTY connection.</para>
 380
 381         <xi:include href="version-info.xml" xpointer="v219"/></listitem>
 382       </varlistentry>
 383
 384       <varlistentry>
 385         <term><option>--on-active=</option></term>
 386         <term><option>--on-boot=</option></term>
 387         <term><option>--on-startup=</option></term>
 388         <term><option>--on-unit-active=</option></term>
 389         <term><option>--on-unit-inactive=</option></term>
 390
 391         <listitem><para>Defines a monotonic timer relative to different starting points for starting the specified
 392         command. See <varname>OnActiveSec=</varname>, <varname>OnBootSec=</varname>, <varname>OnStartupSec=</varname>,
 393         <varname>OnUnitActiveSec=</varname> and <varname>OnUnitInactiveSec=</varname> in
 394         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
 395         details. These options are shortcuts for <command>--timer-property=</command> with the relevant properties.
 396         These options may not be combined with <option>--scope</option> or <option>--pty</option>.</para>
 397
 398         <xi:include href="version-info.xml" xpointer="v218"/>
 399         </listitem>
 400       </varlistentry>
 401
 402       <varlistentry>
 403         <term><option>--on-calendar=</option></term>
 404
 405         <listitem><para>Defines a calendar timer for starting the specified command. See <varname>OnCalendar=</varname>
 406         in <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>. This
 407         option is a shortcut for <command>--timer-property=OnCalendar=</command>. This option may not be combined with
 408         <option>--scope</option> or <option>--pty</option>.</para>
 409
 410         <xi:include href="version-info.xml" xpointer="v218"/>
 411         </listitem>
 412       </varlistentry>
 413
 414       <varlistentry>
 415         <term><option>--on-clock-change</option></term>
 416         <term><option>--on-timezone-change</option></term>
 417
 418         <listitem><para>Defines a trigger based on system clock jumps or timezone changes for starting the
 419         specified command. See <varname>OnClockChange=</varname> and <varname>OnTimezoneChange=</varname> in
 420         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>. These
 421         options are shortcuts for <command>--timer-property=OnClockChange=yes</command> and
 422         <command>--timer-property=OnTimezoneChange=yes</command>. These options may not be combined with
 423         <option>--scope</option> or <option>--pty</option>.</para>
 424
 425         <xi:include href="version-info.xml" xpointer="v242"/></listitem>
 426       </varlistentry>
 427
 428       <varlistentry>
 429         <term><option>--path-property=</option></term>
 430         <term><option>--socket-property=</option></term>
 431         <term><option>--timer-property=</option></term>
 432
 433         <listitem><para>Sets a property on the path, socket, or timer unit that is created. This option is
 434         similar to <option>--property=</option>, but applies to the transient path, socket, or timer unit
 435         rather than the transient service unit created. This option takes an assignment in the same format as
 436         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 437         <command>set-property</command> command. These options may not be combined with
 438         <option>--scope</option> or <option>--pty</option>.</para>
 439
 440         <xi:include href="version-info.xml" xpointer="v218"/>
 441         </listitem>
 442       </varlistentry>
 443
 444       <varlistentry>
 445         <term><option>--no-block</option></term>
 446
 447         <listitem>
 448           <para>Do not synchronously wait for the unit start operation to finish. If this option is not specified, the
 449           start request for the transient unit will be verified, enqueued and <command>systemd-run</command> will wait
 450           until the unit's start-up is completed. By passing this argument, it is only verified and enqueued. This
 451           option may not be combined with <option>--wait</option>.</para>
 452
 453           <xi:include href="version-info.xml" xpointer="v220"/>
 454         </listitem>
 455       </varlistentry>
 456
 457       <varlistentry>
 458         <term><option>--wait</option></term>
 459
 460         <listitem><para>Synchronously wait for the transient service to terminate. If this option is specified, the
 461         start request for the transient unit is verified, enqueued, and waited for. Subsequently the invoked unit is
 462         monitored, and it is waited until it is deactivated again (most likely because the specified command
 463         completed). On exit, terse information about the unit's runtime is shown, including total runtime (as well as
 464         CPU usage, if <option>--property=CPUAccounting=1</option> was set) and the exit code and status of the main
 465         process. This output may be suppressed with <option>--quiet</option>. This option may not be combined with
 466         <option>--no-block</option>, <option>--scope</option> or the various path, socket, or timer options.</para>
 467
 468         <xi:include href="version-info.xml" xpointer="v232"/></listitem>
 469       </varlistentry>
 470
 471       <varlistentry>
 472         <term><option>-G</option></term>
 473         <term><option>--collect</option></term>
 474
 475         <listitem><para>Unload the transient unit after it completed, even if it failed. Normally, without this option,
 476         all units that ran and failed are kept in memory until the user explicitly resets their failure state with
 477         <command>systemctl reset-failed</command> or an equivalent command. On the other hand, units that ran
 478         successfully are unloaded immediately. If this option is turned on the "garbage collection" of units is more
 479         aggressive, and unloads units regardless if they exited successfully or failed. This option is a shortcut for
 480         <command>--property=CollectMode=inactive-or-failed</command>, see the explanation for
 481         <varname>CollectMode=</varname> in
 482         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for further
 483         information.</para>
 484
 485         <xi:include href="version-info.xml" xpointer="v236"/></listitem>
 486       </varlistentry>
 487
 488       <xi:include href="user-system-options.xml" xpointer="user" />
 489       <xi:include href="user-system-options.xml" xpointer="system" />
 490       <xi:include href="user-system-options.xml" xpointer="host" />
 491       <xi:include href="user-system-options.xml" xpointer="machine" />
 492
 493       <xi:include href="standard-options.xml" xpointer="help" />
 494       <xi:include href="standard-options.xml" xpointer="version" />
 495     </variablelist>
 496
 497     <para>All command line arguments after the first non-option argument become part of the command line of
 498     the launched process.</para>
 499   </refsect1>
 500
 501   <refsect1>
 502     <title>Exit status</title>
 503
 504     <para>On success, 0 is returned. If <command>systemd-run</command> failed to start the service, a
 505     non-zero return value will be returned. If <command>systemd-run</command> waits for the service to
 506     terminate, the return value will be propagated from the service. 0 will be returned on success, including
 507     all the cases where systemd considers a service to have exited cleanly, see the discussion of
 508     <varname>SuccessExitStatus=</varname> in
 509     <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 510     </para>
 511   </refsect1>
 512
 513   <refsect1>
 514     <title>Examples</title>
 515
 516     <example>
 517       <title>Logging environment variables provided by systemd to services</title>
 518
 519       <programlisting># systemd-run env
 520 Running as unit: run-19945.service
 521 # journalctl -u run-19945.service
 522 Sep 08 07:37:21 bupkis systemd[1]: Starting /usr/bin/env...
 523 Sep 08 07:37:21 bupkis systemd[1]: Started /usr/bin/env.
 524 Sep 08 07:37:21 bupkis env[19948]: PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin
 525 Sep 08 07:37:21 bupkis env[19948]: LANG=en_US.UTF-8
 526 Sep 08 07:37:21 bupkis env[19948]: BOOT_IMAGE=/vmlinuz-3.11.0-0.rc5.git6.2.fc20.x86_64</programlisting>
 527     </example>
 528
 529     <example>
 530       <title>Limiting resources available to a command</title>
 531
 532       <programlisting># systemd-run -p IOWeight=10 updatedb</programlisting>
 533
 534       <para>This command invokes the <citerefentry
 535       project='man-pages'><refentrytitle>updatedb</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 536       tool, but lowers the block I/O weight for it to 10. See
 537       <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 538       for more information on the <varname>IOWeight=</varname> property.</para>
 539     </example>
 540
 541     <example>
 542       <title>Running commands at a specified time</title>
 543
 544       <para>The following command will touch a file after 30 seconds.</para>
 545
 546       <programlisting># date; systemd-run --on-active=30 --timer-property=AccuracySec=100ms /bin/touch /tmp/foo
 547 Mon Dec  8 20:44:24 KST 2014
 548 Running as unit: run-71.timer
 549 Will run service as unit: run-71.service
 550 # journalctl -b -u run-71.timer
 551 -- Journal begins at Fri 2014-12-05 19:09:21 KST, ends at Mon 2014-12-08 20:44:54 KST. --
 552 Dec 08 20:44:38 container systemd[1]: Starting /bin/touch /tmp/foo.
 553 Dec 08 20:44:38 container systemd[1]: Started /bin/touch /tmp/foo.
 554 # journalctl -b -u run-71.service
 555 -- Journal begins at Fri 2014-12-05 19:09:21 KST, ends at Mon 2014-12-08 20:44:54 KST. --
 556 Dec 08 20:44:48 container systemd[1]: Starting /bin/touch /tmp/foo...
 557 Dec 08 20:44:48 container systemd[1]: Started /bin/touch /tmp/foo.</programlisting>
 558     </example>
 559
 560     <example>
 561       <title>Allowing access to the tty</title>
 562
 563       <para>The following command invokes <citerefentry project='man-pages'><refentrytitle>bash</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 564       as a service passing its standard input, output and error to the calling TTY.</para>
 565
 566       <programlisting># systemd-run -t --send-sighup bash</programlisting>
 567     </example>
 568
 569     <example>
 570       <title>Start <command>screen</command> as a user service</title>
 571
 572       <programlisting>$ systemd-run --scope --user screen
 573 Running scope as unit run-r14b0047ab6df45bfb45e7786cc839e76.scope.
 574
 575 $ screen -ls
 576 There is a screen on:
 577         492..laptop     (Detached)
 578 1 Socket in /var/run/screen/S-fatima.
 579 </programlisting>
 580
 581       <para>This starts the <command>screen</command> process as a child of the
 582       <command>systemd --user</command> process that was started by
 583       <filename>user@.service</filename>, in a scope unit. A
 584       <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 585       unit is used instead of a
 586       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 587       unit, because <command>screen</command> will exit when detaching from the terminal,
 588       and a service unit would be terminated. Running <command>screen</command>
 589       as a user unit has the advantage that it is not part of the session scope.
 590       If <varname>KillUserProcesses=yes</varname> is configured in
 591       <citerefentry><refentrytitle>logind.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 592       the default, the session scope will be terminated when the user logs
 593       out of that session.</para>
 594
 595       <para>The <filename>user@.service</filename> is started automatically
 596       when the user first logs in, and stays around as long as at least one
 597       login session is open. After the user logs out of the last session,
 598       <filename>user@.service</filename> and all services underneath it
 599       are terminated. This behavior is the default, when "lingering" is
 600       not enabled for that user. Enabling lingering means that
 601       <filename>user@.service</filename> is started automatically during
 602       boot, even if the user is not logged in, and that the service is
 603       not terminated when the user logs out.</para>
 604
 605       <para>Enabling lingering allows the user to run processes without being logged in,
 606       for example to allow <command>screen</command> to persist after the user logs out,
 607       even if the session scope is terminated. In the default configuration, users can
 608       enable lingering for themselves:</para>
 609
 610       <programlisting>$ loginctl enable-linger</programlisting>
 611     </example>
 612
 613     <example>
 614       <title>Variable expansion by the manager</title>
 615
 616       <programlisting>$ systemd-run -t echo "&lt;${INVOCATION_ID}>" '&lt;${INVOCATION_ID}>'
 617       &lt;> &lt;5d0149bfa2c34b79bccb13074001eb20>
 618       </programlisting>
 619
 620       <para>The first argument is expanded by the shell (double quotes), but the second one is not expanded
 621       by the shell (single quotes). <command>echo</command> is called with [<literal>/usr/bin/echo</literal>,
 622       <literal>[]</literal>, <literal>[${INVOCATION_ID}]</literal>] as the argument array, and then
 623       <command>systemd</command> generates <varname>${INVOCATION_ID}</varname> and substitutes it in the
 624       command-line. This substitution could not be done on the client side, because the target ID that will
 625       be set for the service isn't known before the call is made.</para>
 626     </example>
 627
 628     <example>
 629       <title>Variable expansion and output redirection using a shell</title>
 630
 631       <para>Variable expansion by <command>systemd</command> can be disabled with
 632       <varname>--expand-environment=no</varname>.</para>
 633
 634       <para>Disabling variable expansion can be useful if the command to execute contains dollar characters
 635       and escaping them would be inconvenient. For example, when a shell is used:</para>
 636
 637       <programlisting>$ systemd-run --expand-environment=no -t bash \
 638       -c 'echo $SHELL $$ >/dev/stdout'
 639 /bin/bash 12345
 640       </programlisting>
 641
 642       <para>The last argument is passed verbatim to the <command>bash</command> shell which is started by the
 643       service unit. The shell expands <literal>$SHELL</literal> to the path of the shell, and
 644       <literal>$$</literal> to its process number, and then those strings are passed to the
 645       <command>echo</command> built-in and printed to standard output (which in this case is connected to the
 646       calling terminal).</para>
 647     </example>
 648
 649     <example>
 650       <title>Return value</title>
 651
 652       <programlisting>$ systemd-run --user --wait true
 653 $ systemd-run --user --wait -p SuccessExitStatus=11 bash -c 'exit 11'
 654 $ systemd-run --user --wait -p SuccessExitStatus=SIGUSR1 --expand-environment=no \
 655       bash -c 'kill -SIGUSR1 $$'</programlisting>
 656
 657       <para>Those three invocations will succeed, i.e. terminate with an exit code of 0.</para>
 658     </example>
 659   </refsect1>
 660
 661   <refsect1>
 662     <title>See Also</title>
 663     <para>
 664       <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 665       <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 666       <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 667       <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 668       <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 669       <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 670       <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 671       <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 672       <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 673       <citerefentry><refentrytitle>systemd-mount</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 674       <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 675     </para>
 676   </refsect1>
 677
 678 </refentry>