man/systemctl.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
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   6   This file is part of systemd.
   7
   8   Copyright 2010 Lennart Poettering
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU General Public License as published by
  12   the Free Software Foundation; either version 2 of the License, or
  13   (at your option) any later version.
  14
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  18   General Public License for more details.
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  20   You should have received a copy of the GNU General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
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  23
  24 <refentry id="systemctl">
  25
  26         <refentryinfo>
  27                 <title>systemctl</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>systemctl</refentrytitle>
  42                 <manvolnum>1</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>systemctl</refname>
  47                 <refpurpose>Control the systemd system and session manager</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <cmdsynopsis>
  52                         <command>systemctl <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg> <arg choice="opt" rep="repeat">NAME</arg></command>
  53                 </cmdsynopsis>
  54         </refsynopsisdiv>
  55
  56         <refsect1>
  57                 <title>Description</title>
  58
  59                 <para><command>systemctl</command> may be used to
  60                 introspect and control the state of the
  61                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
  62                 system and session manager.</para>
  63         </refsect1>
  64
  65         <refsect1>
  66                 <title>Options</title>
  67
  68                 <para>The following options are understood:</para>
  69
  70                 <variablelist>
  71                         <varlistentry>
  72                                 <term><option>--help</option></term>
  73                                 <term><option>-h</option></term>
  74
  75                                 <listitem><para>Prints a short help
  76                                 text and exits.</para></listitem>
  77                         </varlistentry>
  78
  79                         <varlistentry>
  80                                 <term><option>--type=</option></term>
  81                                 <term><option>-t</option></term>
  82
  83                                 <listitem><para>When listing units,
  84                                 limit display to certain unit
  85                                 types. If not specified units of all
  86                                 types will be shown. The argument
  87                                 should be a unit type name such as
  88                                 <option>service</option>,
  89                                 <option>socket</option> and
  90                                 similar.</para></listitem>
  91                         </varlistentry>
  92
  93                         <varlistentry>
  94                                 <term><option>--property=</option></term>
  95                                 <term><option>-p</option></term>
  96
  97                                 <listitem><para>When showing
  98                                 unit/job/manager information, limit
  99                                 display to certain properties as
 100                                 specified as argument. If not
 101                                 specified all set properties are
 102                                 shown. The argument should be a
 103                                 property name, such as
 104                                 <literal>MainPID</literal>. If
 105                                 specified more than once all
 106                                 properties with the specified names
 107                                 are shown.</para></listitem>
 108                         </varlistentry>
 109
 110                         <varlistentry>
 111                                 <term><option>--all</option></term>
 112                                 <term><option>-a</option></term>
 113
 114                                 <listitem><para>When listing units,
 115                                 show all units, regardless of their
 116                                 state, including inactive units. When
 117                                 showing unit/job/manager information,
 118                                 show all properties regardless whether
 119                                 they are set or not.</para></listitem>
 120                         </varlistentry>
 121
 122                         <varlistentry>
 123                                 <term><option>--full</option></term>
 124
 125                                 <listitem><para>Do not ellipsize unit
 126                                 names and truncate unit descriptions
 127                                 in the output of
 128                                 <command>list-units</command> and
 129                                 <command>list-jobs</command>.</para></listitem>
 130                         </varlistentry>
 131
 132                         <varlistentry>
 133                                 <term><option>--fail</option></term>
 134
 135                                 <listitem><para>If the requested
 136                                 operation conflicts with a pending
 137                                 unfinished job, fail the command. If
 138                                 this is not specified the requested
 139                                 operation will replace the pending job,
 140                                 if necessary.</para></listitem>
 141                         </varlistentry>
 142
 143                         <varlistentry>
 144                                 <term><option>--quiet</option></term>
 145                                 <term><option>-q</option></term>
 146
 147                                 <listitem><para>Suppress output to
 148                                 STDOUT in
 149                                 <command>snapshot</command>,
 150                                 <command>check</command>,
 151                                 <command>enable</command> and
 152                                 <command>disable</command>.</para></listitem>
 153                         </varlistentry>
 154
 155                         <varlistentry>
 156                                 <term><option>--no-block</option></term>
 157
 158                                 <listitem><para>Do not synchronously wait for
 159                                 the requested operation to finish. If this is
 160                                 not specified the job will be verified,
 161                                 enqueued and <command>systemctl</command> will
 162                                 wait until it is completed. By passing this
 163                                 argument it is only verified and
 164                                 enqueued.</para></listitem> </varlistentry>
 165
 166                         <varlistentry>
 167                                 <term><option>--system</option></term>
 168
 169                                 <listitem><para>Talk to the systemd
 170                                 system manager. (Default)</para></listitem>
 171                         </varlistentry>
 172
 173                         <varlistentry>
 174                                 <term><option>--session</option></term>
 175
 176                                 <listitem><para>Talk to the systemd
 177                                 session manager of the calling user.</para></listitem>
 178                         </varlistentry>
 179
 180                         <varlistentry>
 181                                 <term><option>--order</option></term>
 182                                 <term><option>--require</option></term>
 183
 184                                 <listitem><para>When used in
 185                                 conjunction with the
 186                                 <command>dot</command> command (see
 187                                 below), selects which dependencies are
 188                                 shown in the dependency graph. If
 189                                 <option>--order</option> is passed
 190                                 only dependencies of type
 191                                 <varname>After=</varname> or
 192                                 <varname>Before=</varname> are
 193                                 shown. If <option>--require</option>
 194                                 is passed only dependencies of type
 195                                 <varname>Requires=</varname>,
 196                                 <varname>RequiresOverridable=</varname>,
 197                                 <varname>Requisite=</varname>,
 198                                 <varname>RequisiteOverridable=</varname>,
 199                                 <varname>Wants=</varname> and
 200                                 <varname>Conflicts=</varname> are
 201                                 shown. If neither is passed, shows
 202                                 dependencies of all these
 203                                 types.</para></listitem>
 204                         </varlistentry>
 205
 206                         <varlistentry>
 207                                 <term><option>--no-wall</option></term>
 208
 209                                 <listitem><para>Don't send wall
 210                                 message before
 211                                 halt, power-off, reboot.</para></listitem>
 212                         </varlistentry>
 213
 214                         <varlistentry>
 215                                 <term><option>--global</option></term>
 216
 217                                 <listitem><para>When used with
 218                                 <command>enable</command> and
 219                                 <command>disable</command>, operate on the
 220                                 global session configuŕation
 221                                 directory, thus enabling or disabling
 222                                 a unit file globally for all future
 223                                 sessions of all users.</para></listitem>
 224                         </varlistentry>
 225
 226                         <varlistentry>
 227                                 <term><option>--no-reload</option></term>
 228
 229                                 <listitem><para>When used with
 230                                 <command>enable</command> and
 231                                 <command>disable</command>, do not
 232                                 implicitly reload daemon configuration
 233                                 after executing the
 234                                 changes.</para></listitem>
 235                         </varlistentry>
 236
 237                         <varlistentry>
 238                                 <term><option>--kill-mode=</option></term>
 239
 240                                 <listitem><para>When used with
 241                                 <command>kill</command>, choose the
 242                                 mode how to kill the selected
 243                                 processes. Must be one of
 244                                 <option>control-group</option>,
 245                                 <option>process-group</option> or
 246                                 <option>process</option> to select
 247                                 whether to kill the entire control
 248                                 group, the process group or only the
 249                                 selected process itself. If ommitted
 250                                 defaults to
 251                                 <option>control-group</option> if
 252                                 <option>--kill-who=all</option> is
 253                                 set, or <option>process</option>
 254                                 otherwise. You probably never need to
 255                                 use this switch.</para></listitem>
 256                         </varlistentry>
 257
 258                         <varlistentry>
 259                                 <term><option>--kill-who=</option></term>
 260
 261                                 <listitem><para>When used with
 262                                 <command>kill</command>, choose which
 263                                 processes to kill. Must be one of
 264                                 <option>main</option>,
 265                                 <option>control</option> or
 266                                 <option>all</option> to select whether
 267                                 to kill only the main process of the
 268                                 unit, the control process or all
 269                                 processes of the unit. If ommitted
 270                                 defaults to
 271                                 <option>all</option>.</para></listitem>
 272                         </varlistentry>
 273
 274                         <varlistentry>
 275                                 <term><option>---signal=</option></term>
 276                                 <term><option>-s</option></term>
 277
 278                                 <listitem><para>When used with
 279                                 <command>kill</command>, choose which
 280                                 signal to send to selected
 281                                 processes. Must be one of the well
 282                                 know signal specifiers such as
 283                                 SIGTERM, SIGINT or SIGSTOP. If
 284                                 ommitted defaults to
 285                                 <option>SIGTERM</option>.</para></listitem>
 286                         </varlistentry>
 287
 288                         <varlistentry>
 289                                 <term><option>--force</option></term>
 290
 291                                 <listitem><para>When used with
 292                                 <command>enable</command>, override any
 293                                 existing conflicting
 294                                 symlinks.</para></listitem>
 295                         </varlistentry>
 296
 297                         <varlistentry>
 298                                 <term><option>--defaults</option></term>
 299
 300                                 <listitem><para>When used with
 301                                 <command>disable</command>, ensures
 302                                 that only the symlinks created by
 303                                 <command>enable</command> are removed,
 304                                 not all symlinks pointing to the unit
 305                                 file that shall be
 306                                 disabled.</para></listitem>
 307                         </varlistentry>
 308                 </variablelist>
 309
 310                 <para>The following commands are understood:</para>
 311
 312                 <variablelist>
 313                         <varlistentry>
 314                                 <term><command>list-units</command></term>
 315
 316                                 <listitem><para>List known units.</para></listitem>
 317                         </varlistentry>
 318                         <varlistentry>
 319                                 <term><command>start [NAME...]</command></term>
 320
 321                                 <listitem><para>Start (activate) one
 322                                 or more units specified on the command
 323                                 line.</para></listitem>
 324                         </varlistentry>
 325                         <varlistentry>
 326                                 <term><command>stop [NAME...]</command></term>
 327
 328                                 <listitem><para>Stop (deactivate) one
 329                                 or more units specified on the command
 330                                 line.</para></listitem>
 331                         </varlistentry>
 332                         <varlistentry>
 333                                 <term><command>reload [NAME...]</command></term>
 334
 335                                 <listitem><para>Asks all units listed
 336                                 on the command line to reload their
 337                                 configuration. Note that this will
 338                                 reload the service-specific
 339                                 configuration, not the unit
 340                                 configuration file of systemd. If you
 341                                 want systemd to reload the
 342                                 configuration file of a unit use the
 343                                 <command>daemon-reload</command>
 344                                 command. In other words: for the
 345                                 example case of Apache, this will
 346                                 reload Apache's
 347                                 <filename>httpd.conf</filename> in the
 348                                 web server, not the
 349                                 <filename>apache.service</filename>
 350                                 systemd unit file. </para>
 351
 352                                 <para>This command should not be
 353                                 confused with the
 354                                 <command>daemon-reload</command> or
 355                                 <command>load</command>
 356                                 commands.</para></listitem>
 357
 358                         </varlistentry>
 359                         <varlistentry>
 360                                 <term><command>restart [NAME...]</command></term>
 361
 362                                 <listitem><para>Restart one or more
 363                                 units specified on the command
 364                                 line. If the units are not running yet
 365                                 they will be
 366                                 started.</para></listitem>
 367                         </varlistentry>
 368                         <varlistentry>
 369                                 <term><command>try-restart [NAME...]</command></term>
 370
 371                                 <listitem><para>Restart one or more
 372                                 units specified on the command
 373                                 line. If the units are not running yet
 374                                 the operation will
 375                                 fail.</para></listitem>
 376                         </varlistentry>
 377                         <varlistentry>
 378                                 <term><command>reload-or-restart [NAME...]</command></term>
 379                                 <term><command>reload-or-try-restart [NAME...]</command></term>
 380
 381                                 <listitem><para>Reload one or more
 382                                 units if they support it. If not,
 383                                 restart them instead. Note that for
 384                                 compatibility with SysV and Red Hat
 385                                 init scripts
 386                                 <command>force-reload</command> and
 387                                 <command>condrestart</command> may be
 388                                 used as equivalent commands to
 389                                 <command>reload-or-try-restart</command>.</para></listitem>
 390                         </varlistentry>
 391                         <varlistentry>
 392                                 <term><command>isolate [NAME]</command></term>
 393
 394                                 <listitem><para>Start the unit
 395                                 specified on the command line and its
 396                                 dependencies and stop all others.</para>
 397
 398                                 <para>This is similar to changing the
 399                                 runlevel in a traditional init system. The
 400                                 <command>isolate</command> command will
 401                                 immediately stop processes that are not
 402                                 enabled in the new unit, possibly including
 403                                 the graphical environment or terminal you
 404                                 are currently using.</para>
 405
 406                                 <para>Note that this works only on units
 407                                 where <option>AllowIsolate=</option> is
 408                                 enabled. See
 409                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 410                                 for details.</para></listitem>
 411                         </varlistentry>
 412                         <varlistentry>
 413                                 <term><command>kill [NAME...]</command></term>
 414
 415                                 <listitem><para>Send a signal to one
 416                                 or more processes of the unit. Use
 417                                 <option>--kill-who=</option> to select
 418                                 which process to kill. Use
 419                                 <option>--kill-mode=</option> to
 420                                 select the kill mode and
 421                                 <option>--signal=</option> to select
 422                                 the signal to send.</para></listitem>
 423                         </varlistentry>
 424                         <varlistentry>
 425                                 <term><command>is-active [NAME...]</command></term>
 426
 427                                 <listitem><para>Check whether any of
 428                                 the specified units is active
 429                                 (i.e. running). Returns an exit code
 430                                 0 if at least one is active, non-zero
 431                                 otherwise. Unless
 432                                 <option>--quiet</option> is specified
 433                                 this will also print the current unit
 434                                 state to STDOUT.</para></listitem>
 435                         </varlistentry>
 436                         <varlistentry>
 437                                 <term><command>status [NAME...|PID...]</command></term>
 438
 439                                 <listitem><para>Show terse runtime
 440                                 status information about one or more
 441                                 units. This function is intended to
 442                                 generate human-readable output. If you
 443                                 are looking for computer-parsable
 444                                 output, use <command>show</command>
 445                                 instead. If a PID is passed
 446                                 information about the unit the process
 447                                 of the PID belongs to is
 448                                 shown.</para></listitem>
 449                         </varlistentry>
 450                         <varlistentry>
 451                                 <term><command>show [NAME...|JOB...]</command></term>
 452
 453                                 <listitem><para>Show properties of one
 454                                 or more units, jobs or the manager
 455                                 itself. If no argument is specified
 456                                 properties of the manager will be
 457                                 shown. If a unit name is specified
 458                                 properties of the unit is shown, and
 459                                 if a job id is specified properties of
 460                                 the job is shown. By default, empty
 461                                 properties are suppressed. Use
 462                                 <option>--all</option> to show those
 463                                 too. To select specific properties to
 464                                 show use
 465                                 <option>--property=</option>. This
 466                                 command is intended to be used
 467                                 whenever computer-parsable output is
 468                                 required. Use
 469                                 <command>status</command> if you are
 470                                 looking for formatted human-readable
 471                                 output.</para></listitem>
 472                         </varlistentry>
 473
 474                         <varlistentry>
 475                                 <term><command>reset-failed [NAME...]</command></term>
 476
 477                                 <listitem><para>Reset the
 478                                 '<literal>failed</literal>' state of the
 479                                 specified units, or if no unit name is
 480                                 passed of all units. When a unit fails
 481                                 in some way (i.e. process exiting with
 482                                 non-zero error code, terminating
 483                                 abnormally or timing out) it will
 484                                 automatically enter the
 485                                 '<literal>failed</literal>' state and
 486                                 its exit code and status is recorded
 487                                 for introspection by the administrator
 488                                 until the service is restarted or
 489                                 reset with this
 490                                 command.</para></listitem>
 491                         </varlistentry>
 492
 493                         <varlistentry>
 494                                 <term><command>enable [NAME...]</command></term>
 495
 496                                 <listitem><para>Enable one or more
 497                                 unit files, as specified on the
 498                                 command line. This will create a
 499                                 number of symlinks as encoded in the
 500                                 <literal>[Install]</literal> sections
 501                                 of the unit files. After the symlinks
 502                                 have been created the systemd
 503                                 configuration is reloaded (in a way
 504                                 that is equivalent to
 505                                 <command>daemon-reload</command>) to
 506                                 ensure the changes are taken into
 507                                 account immediately. Note that this
 508                                 does not have the effect that any of
 509                                 the units enabled are also started at
 510                                 the same time. If this is desired a
 511                                 separate <command>start</command>
 512                                 command must be invoked for the
 513                                 unit.</para>
 514
 515                                 <para>This command will
 516                                 print the actions executed. This
 517                                 output may be suppressed by passing
 518                                 <option>--quiet</option>.</para>
 519
 520                                 <para>Note that this operation creates
 521                                 only the suggested symlinks for the
 522                                 units. While this command is the
 523                                 recommended way to manipulate the unit
 524                                 configuration directory, the
 525                                 administrator is free to make
 526                                 additional changes manually, by
 527                                 placing or removing symlinks in the
 528                                 directory. This is particular useful
 529                                 to create configurations that deviate
 530                                 from the suggested default
 531                                 installation. In this case the
 532                                 administrator must make sure to invoke
 533                                 <command>daemon-reload</command>
 534                                 manually as necessary, to ensure his
 535                                 changes are taken into account.</para>
 536
 537                                 <para>Enabling units should not be
 538                                 confused with starting (activating)
 539                                 units, as done by the
 540                                 <command>start</command>
 541                                 command. Enabling and starting units
 542                                 is orthogonal: units may be enabled
 543                                 without being started and started
 544                                 without being enabled. Enabling simply
 545                                 hooks the unit into various suggested
 546                                 places (for example, so that the unit
 547                                 is automatically started on boot or
 548                                 when a particular kind of hardware is
 549                                 plugged in). Starting actually spawns
 550                                 the daemon process (in case of service
 551                                 units), or binds the socket (in case
 552                                 of socket units), and so
 553                                 on.</para>
 554
 555                                 <para>Depending on whether
 556                                 <option>--system</option>,
 557                                 <option>--session</option> or
 558                                 <option>--global</option> is specified
 559                                 this enables the unit for the system,
 560                                 for sessions of the calling user only
 561                                 or for all future session of all
 562                                 users. Note that in the latter case no
 563                                 systemd daemon configuration is
 564                                 reloaded.</para>
 565                                 </listitem>
 566                         </varlistentry>
 567
 568                         <varlistentry>
 569                                 <term><command>disable [NAME...]</command></term>
 570
 571                                 <listitem><para>Disables one or more
 572                                 units. This removes all symlinks to
 573                                 the specified unit files from the unit
 574                                 configuration directory, and hence
 575                                 undoes the changes made by
 576                                 <command>enable</command>. Note
 577                                 however that this by default removes
 578                                 all symlinks to the unit files
 579                                 (i.e. including manual additions), not
 580                                 just those actually created by
 581                                 <command>enable</command>. If only the
 582                                 symlinks that are suggested by default
 583                                 shall be removed, pass
 584                                 <option>--defaults</option>. This
 585                                 implicitly reloads the systemd daemon
 586                                 configuration after completing the
 587                                 disabling of the units. Note that this
 588                                 command does not implicitly stop the
 589                                 units that is being disabled. If this
 590                                 is desired an additional
 591                                 <command>stop</command>command should
 592                                 be executed afterwards.</para>
 593
 594                                 <para>This command will print the
 595                                 actions executed. This output may be
 596                                 suppressed by passing
 597                                 <option>--quiet</option>.</para>
 598                                 </listitem>
 599
 600                                 <para>This command honours
 601                                 <option>--system</option>,
 602                                 <option>--session</option>,
 603                                 <option>--global</option> in a similar
 604                                 way as
 605                                 <command>enable</command>.</para>
 606                         </varlistentry>
 607
 608                         <varlistentry>
 609                                 <term><command>is-enabled [NAME...]</command></term>
 610
 611                                 <listitem><para>Checks whether any of
 612                                 the specified unit files is enabled
 613                                 (as with
 614                                 <command>enable</command>). Returns an
 615                                 exit code of 0 if at least one is
 616                                 enabled, non-zero
 617                                 otherwise.</para></listitem>
 618                         </varlistentry>
 619
 620                         <varlistentry>
 621                                 <term><command>load [NAME...]</command></term>
 622
 623                                 <listitem><para>Load one or more units
 624                                 specified on the command line. This
 625                                 will simply load their configuration
 626                                 from disk, but not start them. To
 627                                 start them you need to use the
 628                                 <command>start</command> command which
 629                                 will implicitly load a unit that has
 630                                 not been loaded yet. Note that systemd
 631                                 garbage collects loaded units that are
 632                                 not active or referenced by an active
 633                                 unit. This means that units loaded
 634                                 this way will usually not stay loaded
 635                                 for long. Also note that this command
 636                                 cannot be used to reload unit
 637                                 configuration. Use the
 638                                 <command>daemon-reload</command>
 639                                 command for that. All in all, this
 640                                 command is of little use except for
 641                                 debugging.</para>
 642                                 <para>This command should not be
 643                                 confused with the
 644                                 <command>daemon-reload</command> or
 645                                 <command>reload</command>
 646                                 commands.</para></listitem>
 647                         </varlistentry>
 648                         <varlistentry>
 649                                 <term><command>list-jobs</command></term>
 650
 651                                 <listitem><para>List jobs that are in progress.</para></listitem>
 652                         </varlistentry>
 653                         <varlistentry>
 654                                 <term><command>cancel [JOB...]</command></term>
 655
 656                                 <listitem><para>Cancel one or more
 657                                 jobs specified on the command line by
 658                                 their numeric job
 659                                 IDs. If not job id is specified cancels all jobs that are pending.</para></listitem>
 660                         </varlistentry>
 661                         <varlistentry>
 662                                 <term><command>monitor</command></term>
 663
 664                                 <listitem><para>Monitor unit/job
 665                                 changes. This is mostly useful for
 666                                 debugging purposes and prints a line
 667                                 each time systemd loads or unloads a
 668                                 unit configuration file, or a unit
 669                                 property changes.</para></listitem>
 670                         </varlistentry>
 671                         <varlistentry>
 672                                 <term><command>dump</command></term>
 673
 674                                 <listitem><para>Dump server
 675                                 status. This will output a (usually
 676                                 very long) human readable manager
 677                                 status dump. Its format is subject to
 678                                 change without notice and should not
 679                                 be parsed by
 680                                 applications.</para></listitem>
 681                         </varlistentry>
 682                         <varlistentry>
 683                                 <term><command>dot</command></term>
 684
 685                                 <listitem><para>Generate textual
 686                                 dependency graph description in dot
 687                                 format for further processing with the
 688                                 GraphViz
 689                                 <citerefentry><refentrytitle>dot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 690                                 tool. Use a command line like
 691                                 <command>systemctl dot | dot -Tsvg >
 692                                 systemd.svg</command> to generate a
 693                                 graphical dependency tree. Unless
 694                                 <option>--order</option> or
 695                                 <option>--require</option> is passed
 696                                 the generated graph will show both
 697                                 ordering and requirement
 698                                 dependencies.</para></listitem>
 699                         </varlistentry>
 700                         <varlistentry>
 701                                 <term><command>snapshot [NAME]</command></term>
 702
 703                                 <listitem><para>Create a snapshot. If
 704                                 a snapshot name is specified, the new
 705                                 snapshot will be named after it. If
 706                                 none is specified an automatic
 707                                 snapshot name is generated. In either
 708                                 case, the snapshot name used is
 709                                 printed to STDOUT, unless
 710                                 <option>--quiet</option> is
 711                                 specified.</para>
 712
 713                                 <para>A snapshot refers to a saved
 714                                 state of the systemd manager. It is
 715                                 implemented itself as unit that is
 716                                 generated dynamically with this
 717                                 command and has dependencies on all
 718                                 units active at the time. At a later
 719                                 time the user may return to this state
 720                                 by using the
 721                                 <command>isolate</command> command on
 722                                 the snapshot unit.</para></listitem>
 723
 724                                 <para>Snapshots are only useful for
 725                                 saving and restoring which units are
 726                                 running or are stopped, they do not
 727                                 save/restore any other
 728                                 state. Snapshots are dynamic and lost
 729                                 on reboot.</para>
 730                         </varlistentry>
 731                         <varlistentry>
 732                                 <term><command>delete [NAME...]</command></term>
 733
 734                                 <listitem><para>Remove a snapshot
 735                                 previously created with
 736                                 <command>snapshot</command>.</para></listitem>
 737                         </varlistentry>
 738                         <varlistentry>
 739                                 <term><command>daemon-reload</command></term>
 740
 741                                 <listitem><para>Reload systemd manager
 742                                 configuration. This will reload all
 743                                 unit files and recreate the entire
 744                                 dependency tree. While the daemon is
 745                                 reloaded, all sockets systemd listens
 746                                 on on behalf of user configuration will
 747                                 stay accessible.</para> <para>This
 748                                 command should not be confused with
 749                                 the <command>load</command> or
 750                                 <command>reload</command>
 751                                 commands.</para></listitem>
 752                         </varlistentry>
 753                         <varlistentry>
 754                                 <term><command>daemon-reexec</command></term>
 755
 756                                 <listitem><para>Reexecute the systemd
 757                                 manager. This will serialize the
 758                                 manager state, reexecute the process
 759                                 and deserialize the state again. This
 760                                 command is of little use except for
 761                                 debugging and package
 762                                 upgrades. Sometimes it might be
 763                                 helpful as a heavy-weight
 764                                 <command>daemon-reload</command>. While
 765                                 the daemon is reexecuted all sockets
 766                                 systemd listens on on behalf of user
 767                                 configuration will stay
 768                                 accessible.</para></listitem>
 769                         </varlistentry>
 770                         <varlistentry>
 771                                 <term><command>daemon-exit</command></term>
 772
 773                                 <listitem><para>Ask the systemd
 774                                 manager to quit. This is only
 775                                 supported for session managers
 776                                 (i.e. in conjunction with the
 777                                 <option>--session</option> option) and
 778                                 will fail otherwise.</para></listitem>
 779                         </varlistentry>
 780                         <varlistentry>
 781                                 <term><command>show-environment</command></term>
 782
 783                                 <listitem><para>Dump the systemd
 784                                 manager environment block. The
 785                                 environment block will be dumped in
 786                                 straight-forward form suitable for
 787                                 sourcing into a shell script. This
 788                                 environment block will be passed to
 789                                 all processes the manager
 790                                 spawns.</para></listitem>
 791                         </varlistentry>
 792                         <varlistentry>
 793                                 <term><command>set-environment [NAME=VALUE...]</command></term>
 794
 795                                 <listitem><para>Set one or more
 796                                 systemd manager environment variables,
 797                                 as specified on the command
 798                                 line.</para></listitem>
 799                         </varlistentry>
 800                         <varlistentry>
 801                                 <term><command>unset-environment [NAME...]</command></term>
 802
 803                                 <listitem><para>Unset one or more
 804                                 systemd manager environment
 805                                 variables. If only a variable name is
 806                                 specified it will be removed
 807                                 regardless of its value. If a variable
 808                                 and a value are specified the variable
 809                                 is only removed if it has the
 810                                 specified value.</para></listitem>
 811                         </varlistentry>
 812
 813                         <varlistentry>
 814                                 <term><command>halt</command></term>
 815
 816                                 <listitem><para>Shut down and halt the
 817                                 system. This is mostly equivalent to
 818                                 <command>start halt.target</command>
 819                                 but also prints a wall message to all
 820                                 users.</para></listitem>
 821                         </varlistentry>
 822                         <varlistentry>
 823                                 <term><command>poweroff</command></term>
 824
 825                                 <listitem><para>Shut down and
 826                                 power-off the system. This is mostly
 827                                 equivalent to <command>start
 828                                 poweroff.target</command> but also
 829                                 prints a wall message to all
 830                                 users.</para></listitem>
 831                         </varlistentry>
 832                         <varlistentry>
 833                                 <term><command>reboot</command></term>
 834
 835                                 <listitem><para>Shut down and
 836                                 reboot the system. This is mostly
 837                                 equivalent to <command>start
 838                                 reboot.target</command> but also
 839                                 prints a wall message to all
 840                                 users.</para></listitem>
 841                         </varlistentry>
 842                         <varlistentry>
 843                                 <term><command>default</command></term>
 844
 845                                 <listitem><para>Enter default
 846                                 mode. This is mostly equivalent to
 847                                 <command>start
 848                                 default.target</command>.</para></listitem>
 849                         </varlistentry>
 850                         <varlistentry>
 851                                 <term><command>rescue</command></term>
 852
 853                                 <listitem><para>Enter rescue
 854                                 mode. This is mostly equivalent to
 855                                 <command>isolate
 856                                 rescue.target</command> but also
 857                                 prints a wall message to all
 858                                 users.</para></listitem>
 859                         </varlistentry>
 860                         <varlistentry>
 861                                 <term><command>emergency</command></term>
 862
 863                                 <listitem><para>Enter emergency
 864                                 mode. This is mostly equivalent to
 865                                 <command>isolate
 866                                 emergency.target</command> but also
 867                                 prints a wall message to all
 868                                 users.</para></listitem>
 869                         </varlistentry>
 870                 </variablelist>
 871
 872         </refsect1>
 873
 874         <refsect1>
 875                 <title>Exit status</title>
 876
 877                 <para>On success 0 is returned, a non-zero failure
 878                 code otherwise.</para>
 879         </refsect1>
 880
 881         <refsect1>
 882                 <title>See Also</title>
 883                 <para>
 884                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 885                         <citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 886                         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 887                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 888                         <citerefentry><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 889                 </para>
 890         </refsect1>
 891
 892 </refentry>