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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  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18   General Public License for more details.
  19
  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>--version</option></term>
  81
  82                                 <listitem><para>Prints a short version
  83                                 string and exits.</para></listitem>
  84                         </varlistentry>
  85
  86                         <varlistentry>
  87                                 <term><option>--type=</option></term>
  88                                 <term><option>-t</option></term>
  89
  90                                 <listitem><para>When listing units,
  91                                 limit display to certain unit
  92                                 types. If not specified units of all
  93                                 types will be shown. The argument
  94                                 should be a unit type name such as
  95                                 <option>service</option>,
  96                                 <option>socket</option> and
  97                                 similar.</para></listitem>
  98                         </varlistentry>
  99
 100                         <varlistentry>
 101                                 <term><option>--property=</option></term>
 102                                 <term><option>-p</option></term>
 103
 104                                 <listitem><para>When showing
 105                                 unit/job/manager information, limit
 106                                 display to certain properties as
 107                                 specified as argument. If not
 108                                 specified all set properties are
 109                                 shown. The argument should be a
 110                                 property name, such as
 111                                 <literal>MainPID</literal>. If
 112                                 specified more than once all
 113                                 properties with the specified names
 114                                 are shown.</para></listitem>
 115                         </varlistentry>
 116
 117                         <varlistentry>
 118                                 <term><option>--all</option></term>
 119                                 <term><option>-a</option></term>
 120
 121                                 <listitem><para>When listing units,
 122                                 show all units, regardless of their
 123                                 state, including inactive units. When
 124                                 showing unit/job/manager information,
 125                                 show all properties regardless whether
 126                                 they are set or not.</para></listitem>
 127                         </varlistentry>
 128
 129                         <varlistentry>
 130                                 <term><option>--full</option></term>
 131
 132                                 <listitem><para>Do not ellipsize unit
 133                                 names and truncate unit descriptions
 134                                 in the output of
 135                                 <command>list-units</command> and
 136                                 <command>list-jobs</command>.</para></listitem>
 137                         </varlistentry>
 138
 139                         <varlistentry>
 140                                 <term><option>--fail</option></term>
 141
 142                                 <listitem><para>If the requested
 143                                 operation conflicts with a pending
 144                                 unfinished job, fail the command. If
 145                                 this is not specified the requested
 146                                 operation will replace the pending job,
 147                                 if necessary.</para></listitem>
 148                         </varlistentry>
 149
 150                         <varlistentry>
 151                                 <term><option>--quiet</option></term>
 152                                 <term><option>-q</option></term>
 153
 154                                 <listitem><para>Suppress output to
 155                                 STDOUT in
 156                                 <command>snapshot</command>,
 157                                 <command>check</command>,
 158                                 <command>enable</command> and
 159                                 <command>disable</command>.</para></listitem>
 160                         </varlistentry>
 161
 162                         <varlistentry>
 163                                 <term><option>--no-block</option></term>
 164
 165                                 <listitem><para>Do not synchronously wait for
 166                                 the requested operation to finish. If this is
 167                                 not specified the job will be verified,
 168                                 enqueued and <command>systemctl</command> will
 169                                 wait until it is completed. By passing this
 170                                 argument it is only verified and
 171                                 enqueued.</para></listitem> </varlistentry>
 172
 173                         <varlistentry>
 174                                 <term><option>--system</option></term>
 175
 176                                 <listitem><para>Talk to the systemd
 177                                 system manager. (Default)</para></listitem>
 178                         </varlistentry>
 179
 180                         <varlistentry>
 181                                 <term><option>--session</option></term>
 182
 183                                 <listitem><para>Talk to the systemd
 184                                 session manager of the calling user.</para></listitem>
 185                         </varlistentry>
 186
 187                         <varlistentry>
 188                                 <term><option>--order</option></term>
 189                                 <term><option>--require</option></term>
 190
 191                                 <listitem><para>When used in
 192                                 conjunction with the
 193                                 <command>dot</command> command (see
 194                                 below), selects which dependencies are
 195                                 shown in the dependency graph. If
 196                                 <option>--order</option> is passed
 197                                 only dependencies of type
 198                                 <varname>After=</varname> or
 199                                 <varname>Before=</varname> are
 200                                 shown. If <option>--require</option>
 201                                 is passed only dependencies of type
 202                                 <varname>Requires=</varname>,
 203                                 <varname>RequiresOverridable=</varname>,
 204                                 <varname>Requisite=</varname>,
 205                                 <varname>RequisiteOverridable=</varname>,
 206                                 <varname>Wants=</varname> and
 207                                 <varname>Conflicts=</varname> are
 208                                 shown. If neither is passed, shows
 209                                 dependencies of all these
 210                                 types.</para></listitem>
 211                         </varlistentry>
 212
 213                         <varlistentry>
 214                                 <term><option>--no-wall</option></term>
 215
 216                                 <listitem><para>Don't send wall
 217                                 message before
 218                                 halt, power-off, reboot.</para></listitem>
 219                         </varlistentry>
 220
 221                         <varlistentry>
 222                                 <term><option>--global</option></term>
 223
 224                                 <listitem><para>When used with
 225                                 <command>enable</command> and
 226                                 <command>disable</command>, operate on the
 227                                 global session configuŕation
 228                                 directory, thus enabling or disabling
 229                                 a unit file globally for all future
 230                                 sessions of all users.</para></listitem>
 231                         </varlistentry>
 232
 233                         <varlistentry>
 234                                 <term><option>--no-reload</option></term>
 235
 236                                 <listitem><para>When used with
 237                                 <command>enable</command> and
 238                                 <command>disable</command>, do not
 239                                 implicitly reload daemon configuration
 240                                 after executing the
 241                                 changes.</para></listitem>
 242                         </varlistentry>
 243
 244                         <varlistentry>
 245                                 <term><option>--kill-mode=</option></term>
 246
 247                                 <listitem><para>When used with
 248                                 <command>kill</command>, choose the
 249                                 mode how to kill the selected
 250                                 processes. Must be one of
 251                                 <option>control-group</option>,
 252                                 <option>process-group</option> or
 253                                 <option>process</option> to select
 254                                 whether to kill the entire control
 255                                 group, the process group or only the
 256                                 selected process itself. If ommitted
 257                                 defaults to
 258                                 <option>control-group</option> if
 259                                 <option>--kill-who=all</option> is
 260                                 set, or <option>process</option>
 261                                 otherwise. You probably never need to
 262                                 use this switch.</para></listitem>
 263                         </varlistentry>
 264
 265                         <varlistentry>
 266                                 <term><option>--kill-who=</option></term>
 267
 268                                 <listitem><para>When used with
 269                                 <command>kill</command>, choose which
 270                                 processes to kill. Must be one of
 271                                 <option>main</option>,
 272                                 <option>control</option> or
 273                                 <option>all</option> to select whether
 274                                 to kill only the main process of the
 275                                 unit, the control process or all
 276                                 processes of the unit. If ommitted
 277                                 defaults to
 278                                 <option>all</option>.</para></listitem>
 279                         </varlistentry>
 280
 281                         <varlistentry>
 282                                 <term><option>---signal=</option></term>
 283                                 <term><option>-s</option></term>
 284
 285                                 <listitem><para>When used with
 286                                 <command>kill</command>, choose which
 287                                 signal to send to selected
 288                                 processes. Must be one of the well
 289                                 know signal specifiers such as
 290                                 SIGTERM, SIGINT or SIGSTOP. If
 291                                 ommitted defaults to
 292                                 <option>SIGTERM</option>.</para></listitem>
 293                         </varlistentry>
 294
 295                         <varlistentry>
 296                                 <term><option>--force</option></term>
 297                                 <term><option>-f</option></term>
 298
 299                                 <listitem><para>When used with
 300                                 <command>enable</command>, override any
 301                                 existing conflicting
 302                                 symlinks.</para></listitem>
 303
 304                                 <listitem><para>When used with
 305                                 <command>halt</command>,
 306                                 <command>poweroff</command>,
 307                                 <command>reboot</command> or
 308                                 <command>kexec</command> execute
 309                                 selected operation without shutting
 310                                 down all units. However, all processes
 311                                 will be killed forcibly and all file
 312                                 systems are unmounted or remounted
 313                                 read-only. This is hence a drastic but
 314                                 relatively safe option to request an
 315                                 immediate reboot.</para></listitem>
 316                         </varlistentry>
 317
 318                         <varlistentry>
 319                                 <term><option>--defaults</option></term>
 320
 321                                 <listitem><para>When used with
 322                                 <command>disable</command>, ensures
 323                                 that only the symlinks created by
 324                                 <command>enable</command> are removed,
 325                                 not all symlinks pointing to the unit
 326                                 file that shall be
 327                                 disabled.</para></listitem>
 328                         </varlistentry>
 329                 </variablelist>
 330
 331                 <para>The following commands are understood:</para>
 332
 333                 <variablelist>
 334                         <varlistentry>
 335                                 <term><command>list-units</command></term>
 336
 337                                 <listitem><para>List known units.</para></listitem>
 338                         </varlistentry>
 339                         <varlistentry>
 340                                 <term><command>start [NAME...]</command></term>
 341
 342                                 <listitem><para>Start (activate) one
 343                                 or more units specified on the command
 344                                 line.</para></listitem>
 345                         </varlistentry>
 346                         <varlistentry>
 347                                 <term><command>stop [NAME...]</command></term>
 348
 349                                 <listitem><para>Stop (deactivate) one
 350                                 or more units specified on the command
 351                                 line.</para></listitem>
 352                         </varlistentry>
 353                         <varlistentry>
 354                                 <term><command>reload [NAME...]</command></term>
 355
 356                                 <listitem><para>Asks all units listed
 357                                 on the command line to reload their
 358                                 configuration. Note that this will
 359                                 reload the service-specific
 360                                 configuration, not the unit
 361                                 configuration file of systemd. If you
 362                                 want systemd to reload the
 363                                 configuration file of a unit use the
 364                                 <command>daemon-reload</command>
 365                                 command. In other words: for the
 366                                 example case of Apache, this will
 367                                 reload Apache's
 368                                 <filename>httpd.conf</filename> in the
 369                                 web server, not the
 370                                 <filename>apache.service</filename>
 371                                 systemd unit file. </para>
 372
 373                                 <para>This command should not be
 374                                 confused with the
 375                                 <command>daemon-reload</command> or
 376                                 <command>load</command>
 377                                 commands.</para></listitem>
 378
 379                         </varlistentry>
 380                         <varlistentry>
 381                                 <term><command>restart [NAME...]</command></term>
 382
 383                                 <listitem><para>Restart one or more
 384                                 units specified on the command
 385                                 line. If the units are not running yet
 386                                 they will be
 387                                 started.</para></listitem>
 388                         </varlistentry>
 389                         <varlistentry>
 390                                 <term><command>try-restart [NAME...]</command></term>
 391
 392                                 <listitem><para>Restart one or more
 393                                 units specified on the command
 394                                 line. If the units are not running yet
 395                                 the operation will
 396                                 fail.</para></listitem>
 397                         </varlistentry>
 398                         <varlistentry>
 399                                 <term><command>reload-or-restart [NAME...]</command></term>
 400                                 <term><command>reload-or-try-restart [NAME...]</command></term>
 401
 402                                 <listitem><para>Reload one or more
 403                                 units if they support it. If not,
 404                                 restart them instead. Note that for
 405                                 compatibility with SysV and Red Hat
 406                                 init scripts
 407                                 <command>force-reload</command> and
 408                                 <command>condrestart</command> may be
 409                                 used as equivalent commands to
 410                                 <command>reload-or-try-restart</command>.</para></listitem>
 411                         </varlistentry>
 412                         <varlistentry>
 413                                 <term><command>isolate [NAME]</command></term>
 414
 415                                 <listitem><para>Start the unit
 416                                 specified on the command line and its
 417                                 dependencies and stop all others.</para>
 418
 419                                 <para>This is similar to changing the
 420                                 runlevel in a traditional init system. The
 421                                 <command>isolate</command> command will
 422                                 immediately stop processes that are not
 423                                 enabled in the new unit, possibly including
 424                                 the graphical environment or terminal you
 425                                 are currently using.</para>
 426
 427                                 <para>Note that this works only on units
 428                                 where <option>AllowIsolate=</option> is
 429                                 enabled. See
 430                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 431                                 for details.</para></listitem>
 432                         </varlistentry>
 433                         <varlistentry>
 434                                 <term><command>kill [NAME...]</command></term>
 435
 436                                 <listitem><para>Send a signal to one
 437                                 or more processes of the unit. Use
 438                                 <option>--kill-who=</option> to select
 439                                 which process to kill. Use
 440                                 <option>--kill-mode=</option> to
 441                                 select the kill mode and
 442                                 <option>--signal=</option> to select
 443                                 the signal to send.</para></listitem>
 444                         </varlistentry>
 445                         <varlistentry>
 446                                 <term><command>is-active [NAME...]</command></term>
 447
 448                                 <listitem><para>Check whether any of
 449                                 the specified units is active
 450                                 (i.e. running). Returns an exit code
 451                                 0 if at least one is active, non-zero
 452                                 otherwise. Unless
 453                                 <option>--quiet</option> is specified
 454                                 this will also print the current unit
 455                                 state to STDOUT.</para></listitem>
 456                         </varlistentry>
 457                         <varlistentry>
 458                                 <term><command>status [NAME...|PID...]</command></term>
 459
 460                                 <listitem><para>Show terse runtime
 461                                 status information about one or more
 462                                 units. This function is intended to
 463                                 generate human-readable output. If you
 464                                 are looking for computer-parsable
 465                                 output, use <command>show</command>
 466                                 instead. If a PID is passed
 467                                 information about the unit the process
 468                                 of the PID belongs to is
 469                                 shown.</para></listitem>
 470                         </varlistentry>
 471                         <varlistentry>
 472                                 <term><command>show [NAME...|JOB...]</command></term>
 473
 474                                 <listitem><para>Show properties of one
 475                                 or more units, jobs or the manager
 476                                 itself. If no argument is specified
 477                                 properties of the manager will be
 478                                 shown. If a unit name is specified
 479                                 properties of the unit is shown, and
 480                                 if a job id is specified properties of
 481                                 the job is shown. By default, empty
 482                                 properties are suppressed. Use
 483                                 <option>--all</option> to show those
 484                                 too. To select specific properties to
 485                                 show use
 486                                 <option>--property=</option>. This
 487                                 command is intended to be used
 488                                 whenever computer-parsable output is
 489                                 required. Use
 490                                 <command>status</command> if you are
 491                                 looking for formatted human-readable
 492                                 output.</para></listitem>
 493                         </varlistentry>
 494
 495                         <varlistentry>
 496                                 <term><command>reset-failed [NAME...]</command></term>
 497
 498                                 <listitem><para>Reset the
 499                                 '<literal>failed</literal>' state of the
 500                                 specified units, or if no unit name is
 501                                 passed of all units. When a unit fails
 502                                 in some way (i.e. process exiting with
 503                                 non-zero error code, terminating
 504                                 abnormally or timing out) it will
 505                                 automatically enter the
 506                                 '<literal>failed</literal>' state and
 507                                 its exit code and status is recorded
 508                                 for introspection by the administrator
 509                                 until the service is restarted or
 510                                 reset with this
 511                                 command.</para></listitem>
 512                         </varlistentry>
 513
 514                         <varlistentry>
 515                                 <term><command>enable [NAME...]</command></term>
 516
 517                                 <listitem><para>Enable one or more
 518                                 unit files, as specified on the
 519                                 command line. This will create a
 520                                 number of symlinks as encoded in the
 521                                 <literal>[Install]</literal> sections
 522                                 of the unit files. After the symlinks
 523                                 have been created the systemd
 524                                 configuration is reloaded (in a way
 525                                 that is equivalent to
 526                                 <command>daemon-reload</command>) to
 527                                 ensure the changes are taken into
 528                                 account immediately. Note that this
 529                                 does not have the effect that any of
 530                                 the units enabled are also started at
 531                                 the same time. If this is desired a
 532                                 separate <command>start</command>
 533                                 command must be invoked for the
 534                                 unit.</para>
 535
 536                                 <para>This command will
 537                                 print the actions executed. This
 538                                 output may be suppressed by passing
 539                                 <option>--quiet</option>.</para>
 540
 541                                 <para>Note that this operation creates
 542                                 only the suggested symlinks for the
 543                                 units. While this command is the
 544                                 recommended way to manipulate the unit
 545                                 configuration directory, the
 546                                 administrator is free to make
 547                                 additional changes manually, by
 548                                 placing or removing symlinks in the
 549                                 directory. This is particular useful
 550                                 to create configurations that deviate
 551                                 from the suggested default
 552                                 installation. In this case the
 553                                 administrator must make sure to invoke
 554                                 <command>daemon-reload</command>
 555                                 manually as necessary, to ensure his
 556                                 changes are taken into account.</para>
 557
 558                                 <para>Enabling units should not be
 559                                 confused with starting (activating)
 560                                 units, as done by the
 561                                 <command>start</command>
 562                                 command. Enabling and starting units
 563                                 is orthogonal: units may be enabled
 564                                 without being started and started
 565                                 without being enabled. Enabling simply
 566                                 hooks the unit into various suggested
 567                                 places (for example, so that the unit
 568                                 is automatically started on boot or
 569                                 when a particular kind of hardware is
 570                                 plugged in). Starting actually spawns
 571                                 the daemon process (in case of service
 572                                 units), or binds the socket (in case
 573                                 of socket units), and so
 574                                 on.</para>
 575
 576                                 <para>Depending on whether
 577                                 <option>--system</option>,
 578                                 <option>--session</option> or
 579                                 <option>--global</option> is specified
 580                                 this enables the unit for the system,
 581                                 for sessions of the calling user only
 582                                 or for all future session of all
 583                                 users. Note that in the latter case no
 584                                 systemd daemon configuration is
 585                                 reloaded.</para>
 586                                 </listitem>
 587                         </varlistentry>
 588
 589                         <varlistentry>
 590                                 <term><command>disable [NAME...]</command></term>
 591
 592                                 <listitem><para>Disables one or more
 593                                 units. This removes all symlinks to
 594                                 the specified unit files from the unit
 595                                 configuration directory, and hence
 596                                 undoes the changes made by
 597                                 <command>enable</command>. Note
 598                                 however that this by default removes
 599                                 all symlinks to the unit files
 600                                 (i.e. including manual additions), not
 601                                 just those actually created by
 602                                 <command>enable</command>. If only the
 603                                 symlinks that are suggested by default
 604                                 shall be removed, pass
 605                                 <option>--defaults</option>. This
 606                                 implicitly reloads the systemd daemon
 607                                 configuration after completing the
 608                                 disabling of the units. Note that this
 609                                 command does not implicitly stop the
 610                                 units that is being disabled. If this
 611                                 is desired an additional
 612                                 <command>stop</command>command should
 613                                 be executed afterwards.</para>
 614
 615                                 <para>This command will print the
 616                                 actions executed. This output may be
 617                                 suppressed by passing
 618                                 <option>--quiet</option>.</para>
 619                                 </listitem>
 620
 621                                 <para>This command honours
 622                                 <option>--system</option>,
 623                                 <option>--session</option>,
 624                                 <option>--global</option> in a similar
 625                                 way as
 626                                 <command>enable</command>.</para>
 627                         </varlistentry>
 628
 629                         <varlistentry>
 630                                 <term><command>is-enabled [NAME...]</command></term>
 631
 632                                 <listitem><para>Checks whether any of
 633                                 the specified unit files is enabled
 634                                 (as with
 635                                 <command>enable</command>). Returns an
 636                                 exit code of 0 if at least one is
 637                                 enabled, non-zero
 638                                 otherwise.</para></listitem>
 639                         </varlistentry>
 640
 641                         <varlistentry>
 642                                 <term><command>load [NAME...]</command></term>
 643
 644                                 <listitem><para>Load one or more units
 645                                 specified on the command line. This
 646                                 will simply load their configuration
 647                                 from disk, but not start them. To
 648                                 start them you need to use the
 649                                 <command>start</command> command which
 650                                 will implicitly load a unit that has
 651                                 not been loaded yet. Note that systemd
 652                                 garbage collects loaded units that are
 653                                 not active or referenced by an active
 654                                 unit. This means that units loaded
 655                                 this way will usually not stay loaded
 656                                 for long. Also note that this command
 657                                 cannot be used to reload unit
 658                                 configuration. Use the
 659                                 <command>daemon-reload</command>
 660                                 command for that. All in all, this
 661                                 command is of little use except for
 662                                 debugging.</para>
 663                                 <para>This command should not be
 664                                 confused with the
 665                                 <command>daemon-reload</command> or
 666                                 <command>reload</command>
 667                                 commands.</para></listitem>
 668                         </varlistentry>
 669                         <varlistentry>
 670                                 <term><command>list-jobs</command></term>
 671
 672                                 <listitem><para>List jobs that are in progress.</para></listitem>
 673                         </varlistentry>
 674                         <varlistentry>
 675                                 <term><command>cancel [JOB...]</command></term>
 676
 677                                 <listitem><para>Cancel one or more
 678                                 jobs specified on the command line by
 679                                 their numeric job
 680                                 IDs. If not job id is specified cancels all jobs that are pending.</para></listitem>
 681                         </varlistentry>
 682                         <varlistentry>
 683                                 <term><command>monitor</command></term>
 684
 685                                 <listitem><para>Monitor unit/job
 686                                 changes. This is mostly useful for
 687                                 debugging purposes and prints a line
 688                                 each time systemd loads or unloads a
 689                                 unit configuration file, or a unit
 690                                 property changes.</para></listitem>
 691                         </varlistentry>
 692                         <varlistentry>
 693                                 <term><command>dump</command></term>
 694
 695                                 <listitem><para>Dump server
 696                                 status. This will output a (usually
 697                                 very long) human readable manager
 698                                 status dump. Its format is subject to
 699                                 change without notice and should not
 700                                 be parsed by
 701                                 applications.</para></listitem>
 702                         </varlistentry>
 703                         <varlistentry>
 704                                 <term><command>dot</command></term>
 705
 706                                 <listitem><para>Generate textual
 707                                 dependency graph description in dot
 708                                 format for further processing with the
 709                                 GraphViz
 710                                 <citerefentry><refentrytitle>dot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 711                                 tool. Use a command line like
 712                                 <command>systemctl dot | dot -Tsvg >
 713                                 systemd.svg</command> to generate a
 714                                 graphical dependency tree. Unless
 715                                 <option>--order</option> or
 716                                 <option>--require</option> is passed
 717                                 the generated graph will show both
 718                                 ordering and requirement
 719                                 dependencies.</para></listitem>
 720                         </varlistentry>
 721                         <varlistentry>
 722                                 <term><command>snapshot [NAME]</command></term>
 723
 724                                 <listitem><para>Create a snapshot. If
 725                                 a snapshot name is specified, the new
 726                                 snapshot will be named after it. If
 727                                 none is specified an automatic
 728                                 snapshot name is generated. In either
 729                                 case, the snapshot name used is
 730                                 printed to STDOUT, unless
 731                                 <option>--quiet</option> is
 732                                 specified.</para>
 733
 734                                 <para>A snapshot refers to a saved
 735                                 state of the systemd manager. It is
 736                                 implemented itself as unit that is
 737                                 generated dynamically with this
 738                                 command and has dependencies on all
 739                                 units active at the time. At a later
 740                                 time the user may return to this state
 741                                 by using the
 742                                 <command>isolate</command> command on
 743                                 the snapshot unit.</para></listitem>
 744
 745                                 <para>Snapshots are only useful for
 746                                 saving and restoring which units are
 747                                 running or are stopped, they do not
 748                                 save/restore any other
 749                                 state. Snapshots are dynamic and lost
 750                                 on reboot.</para>
 751                         </varlistentry>
 752                         <varlistentry>
 753                                 <term><command>delete [NAME...]</command></term>
 754
 755                                 <listitem><para>Remove a snapshot
 756                                 previously created with
 757                                 <command>snapshot</command>.</para></listitem>
 758                         </varlistentry>
 759                         <varlistentry>
 760                                 <term><command>daemon-reload</command></term>
 761
 762                                 <listitem><para>Reload systemd manager
 763                                 configuration. This will reload all
 764                                 unit files and recreate the entire
 765                                 dependency tree. While the daemon is
 766                                 reloaded, all sockets systemd listens
 767                                 on on behalf of user configuration will
 768                                 stay accessible.</para> <para>This
 769                                 command should not be confused with
 770                                 the <command>load</command> or
 771                                 <command>reload</command>
 772                                 commands.</para></listitem>
 773                         </varlistentry>
 774                         <varlistentry>
 775                                 <term><command>daemon-reexec</command></term>
 776
 777                                 <listitem><para>Reexecute the systemd
 778                                 manager. This will serialize the
 779                                 manager state, reexecute the process
 780                                 and deserialize the state again. This
 781                                 command is of little use except for
 782                                 debugging and package
 783                                 upgrades. Sometimes it might be
 784                                 helpful as a heavy-weight
 785                                 <command>daemon-reload</command>. While
 786                                 the daemon is reexecuted all sockets
 787                                 systemd listens on on behalf of user
 788                                 configuration will stay
 789                                 accessible.</para></listitem>
 790                         </varlistentry>
 791                         <varlistentry>
 792                                 <term><command>show-environment</command></term>
 793
 794                                 <listitem><para>Dump the systemd
 795                                 manager environment block. The
 796                                 environment block will be dumped in
 797                                 straight-forward form suitable for
 798                                 sourcing into a shell script. This
 799                                 environment block will be passed to
 800                                 all processes the manager
 801                                 spawns.</para></listitem>
 802                         </varlistentry>
 803                         <varlistentry>
 804                                 <term><command>set-environment [NAME=VALUE...]</command></term>
 805
 806                                 <listitem><para>Set one or more
 807                                 systemd manager environment variables,
 808                                 as specified on the command
 809                                 line.</para></listitem>
 810                         </varlistentry>
 811                         <varlistentry>
 812                                 <term><command>unset-environment [NAME...]</command></term>
 813
 814                                 <listitem><para>Unset one or more
 815                                 systemd manager environment
 816                                 variables. If only a variable name is
 817                                 specified it will be removed
 818                                 regardless of its value. If a variable
 819                                 and a value are specified the variable
 820                                 is only removed if it has the
 821                                 specified value.</para></listitem>
 822                         </varlistentry>
 823                         <varlistentry>
 824                                 <term><command>default</command></term>
 825
 826                                 <listitem><para>Enter default
 827                                 mode. This is mostly equivalent to
 828                                 <command>start
 829                                 default.target</command>.</para></listitem>
 830                         </varlistentry>
 831                         <varlistentry>
 832                                 <term><command>rescue</command></term>
 833
 834                                 <listitem><para>Enter rescue
 835                                 mode. This is mostly equivalent to
 836                                 <command>isolate
 837                                 rescue.target</command> but also
 838                                 prints a wall message to all
 839                                 users.</para></listitem>
 840                         </varlistentry>
 841                         <varlistentry>
 842                                 <term><command>emergency</command></term>
 843
 844                                 <listitem><para>Enter emergency
 845                                 mode. This is mostly equivalent to
 846                                 <command>isolate
 847                                 emergency.target</command> but also
 848                                 prints a wall message to all
 849                                 users.</para></listitem>
 850                         </varlistentry>
 851                         <varlistentry>
 852                                 <term><command>halt</command></term>
 853
 854                                 <listitem><para>Shut down and halt the
 855                                 system. This is mostly equivalent to
 856                                 <command>start halt.target</command>
 857                                 but also prints a wall message to all
 858                                 users.  If
 859                                 combined with <option>--force</option>
 860                                 shutdown of all running services is
 861                                 skipped, however all processes killed
 862                                 and all file systems unmounted or
 863                                 mounted read-only, immediately
 864                                 followed by the
 865                                 system halt.</para></listitem>
 866                         </varlistentry>
 867                         <varlistentry>
 868                                 <term><command>poweroff</command></term>
 869
 870                                 <listitem><para>Shut down and
 871                                 power-off the system. This is mostly
 872                                 equivalent to <command>start
 873                                 poweroff.target</command> but also
 874                                 prints a wall message to all
 875                                 users. If
 876                                 combined with <option>--force</option>
 877                                 shutdown of all running services is
 878                                 skipped, however all processes killed
 879                                 and all file systems unmounted or
 880                                 mounted read-only, immediately
 881                                 followed by the
 882                                 powering off.</para></listitem>
 883                         </varlistentry>
 884                         <varlistentry>
 885                                 <term><command>reboot</command></term>
 886
 887                                 <listitem><para>Shut down and
 888                                 reboot the system. This is mostly
 889                                 equivalent to <command>start
 890                                 reboot.target</command> but also
 891                                 prints a wall message to all
 892                                 users. If
 893                                 combined with <option>--force</option>
 894                                 shutdown of all running services is
 895                                 skipped, however all processes killed
 896                                 and all file systems unmounted or
 897                                 mounted read-only, immediately
 898                                 followed by the
 899                                 reboot.</para></listitem>
 900                         </varlistentry>
 901                         <varlistentry>
 902                                 <term><command>kexec</command></term>
 903
 904                                 <listitem><para>Shut down and reboot
 905                                 the system via kexec. This is mostly
 906                                 equivalent to <command>start
 907                                 kexec.target</command> but also prints
 908                                 a wall message to all users. If
 909                                 combined with <option>--force</option>
 910                                 shutdown of all running services is
 911                                 skipped, however all processes killed
 912                                 and all file systems unmounted or
 913                                 mounted read-only, immediately
 914                                 followed by the
 915                                 reboot.</para></listitem>
 916                         </varlistentry>
 917                         <varlistentry>
 918                                 <term><command>exit</command></term>
 919
 920                                 <listitem><para>Ask the systemd
 921                                 manager to quit. This is only
 922                                 supported for session managers
 923                                 (i.e. in conjunction with the
 924                                 <option>--session</option> option) and
 925                                 will fail otherwise.</para></listitem>
 926                         </varlistentry>
 927                 </variablelist>
 928
 929         </refsect1>
 930
 931         <refsect1>
 932                 <title>Exit status</title>
 933
 934                 <para>On success 0 is returned, a non-zero failure
 935                 code otherwise.</para>
 936         </refsect1>
 937
 938         <refsect1>
 939                 <title>See Also</title>
 940                 <para>
 941                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 942                         <citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 943                         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 944                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 945                         <citerefentry><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 946                 </para>
 947         </refsect1>
 948
 949 </refentry>