man/systemd.special.xml.in

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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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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  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
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  23
  24 <refentry id="systemd.special">
  25
  26         <refentryinfo>
  27                 <title>systemd.special</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>systemd.special</refentrytitle>
  42                 <manvolnum>7</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>systemd.special</refname>
  47                 <refpurpose>special systemd units</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <para><filename>basic.target</filename>,
  52                 <filename>ctrl-alt-del.target</filename>,
  53                 <filename>dbus.service</filename>,
  54                 <filename>dbus.target</filename>,
  55                 <filename>default.target</filename>,
  56                 <filename>display-manager.service</filename>,
  57                 <filename>emergency.target</filename>,
  58                 <filename>exit.service</filename>,
  59                 <filename>graphical.target</filename>,
  60                 <filename>halt.target</filename>,
  61                 <filename>kbrequest.target</filename>,
  62                 <filename>local-fs.target</filename>,
  63                 <filename>mail-transfer-agent.target</filename>,
  64                 <filename>multi-user.target</filename>,
  65                 <filename>network.target</filename>,
  66                 <filename>nss-lookup.target</filename>,
  67                 <filename>poweroff.target</filename>,
  68                 <filename>reboot.target</filename>,
  69                 <filename>remote-fs.target</filename>,
  70                 <filename>rescue.target</filename>,
  71                 <filename>rpcbind.target</filename>,
  72                 <filename>rtc-set.target</filename>,
  73                 <filename>runlevel2.target</filename>,
  74                 <filename>runlevel3.target</filename>,
  75                 <filename>runlevel4.target</filename>,
  76                 <filename>runlevel5.target</filename>,
  77                 <filename>shutdown.target</filename>,
  78                 <filename>sigpwr.target</filename>,
  79                 <filename>sockets.target</filename>,
  80                 <filename>swap.target</filename>,
  81                 <filename>sysinit.target</filename>,
  82                 <filename>@SPECIAL_SYSLOG_SERVICE@</filename>,
  83                 <filename>syslog.target</filename>,
  84                 <filename>systemd-initctl.service</filename>,
  85                 <filename>systemd-initctl.socket</filename>,
  86                 <filename>systemd-logger.service</filename>,
  87                 <filename>systemd-logger.socket</filename>,
  88                 <filename>umount.target</filename></para>
  89         </refsynopsisdiv>
  90
  91         <refsect1>
  92                 <title>Description</title>
  93
  94                 <para>A few units are treated specially by
  95                 systemd. They have special internal semantics and
  96                 cannot be renamed.</para>
  97         </refsect1>
  98
  99         <refsect1>
 100                 <title>Special System Units</title>
 101
 102                 <variablelist>
 103                         <varlistentry>
 104                                 <term><filename>basic.target</filename></term>
 105                                 <listitem>
 106                                         <para>A special target unit
 107                                         covering early boot-up.</para>
 108                                         <para>systemd automatically
 109                                         adds dependencies of the types
 110                                         Requires and After for this
 111                                         target unit to all SysV
 112                                         service units configured for
 113                                         runlevel 1 to 5.</para>
 114                                         <para>Usually this should pull-in
 115                                         all sockets, mount points,
 116                                         swap devices and other basic
 117                                         initialization necessary for
 118                                         the general purpose
 119                                         daemons. Most normal daemons
 120                                         should have dependencies of
 121                                         type After and Requires on
 122                                         this unit.</para>
 123                                 </listitem>
 124                         </varlistentry>
 125                         <varlistentry>
 126                                 <term><filename>ctrl-alt-del.target</filename></term>
 127                                 <listitem>
 128                                         <para>systemd starts this
 129                                         target whenever
 130                                         Control+Alt+Del is pressed on
 131                                         the console. Usually this
 132                                         should be aliased (symlinked)
 133                                         to
 134                                         <filename>reboot.target</filename>.</para>
 135                                 </listitem>
 136                         </varlistentry>
 137                         <varlistentry>
 138                                 <term><filename>dbus.service</filename></term>
 139                                 <listitem>
 140                                         <para>A special unit for the
 141                                         D-Bus system bus. As soon as
 142                                         this service is fully started
 143                                         up systemd will connect to it
 144                                         and register its
 145                                         service.</para>
 146
 147                                         <para>Units should generally
 148                                         avoid depending on this unit
 149                                         directly and instead refer to
 150                                         the
 151                                         <filename>dbus.target</filename>
 152                                         unit instead, which pulls this
 153                                         one in directly or indirectly
 154                                         via socket-based activation.</para>
 155                                 </listitem>
 156                         </varlistentry>
 157                         <varlistentry>
 158                                 <term><filename>dbus.target</filename></term>
 159                                 <listitem>
 160                                         <para>Administrators should
 161                                         ensure that this target pulls
 162                                         in a service unit with the
 163                                         name or alias of
 164                                         <filename>dbus.service</filename>
 165                                         (or a socket unit that
 166                                         activates this
 167                                         service).</para>
 168                                 </listitem>
 169                         </varlistentry>
 170                         <varlistentry>
 171                                 <term><filename>default.target</filename></term>
 172                                 <listitem>
 173                                         <para>The default unit systemd
 174                                         starts at bootup. Usually this
 175                                         should be aliased (symlinked)
 176                                         to
 177                                         <filename>multi-user.target</filename>
 178                                         or
 179                                         <filename>graphical.target</filename>.</para>
 180                                         <para>The default unit systemd
 181                                         starts at bootup can be
 182                                         overriden with the
 183                                         <varname>systemd.default=</varname>
 184                                         kernel command line option.</para>
 185                                 </listitem>
 186                         </varlistentry>
 187                         <varlistentry>
 188                                 <term><filename>display-manager.service</filename></term>
 189                                 <listitem>
 190                                         <para>The display manager
 191                                         service. Usually this should
 192                                         be aliased (symlinked) to
 193                                         <filename>xdm.service</filename>
 194                                         or a similar display manager
 195                                         service.</para>
 196                                         <para>systemd automatically
 197                                         adds dependencies of type
 198                                         After for this target unit to
 199                                         all SysV init script service
 200                                         units with a LSB header
 201                                         referring to the
 202                                         <literal>$x-display-manager</literal>
 203                                         facility, for compatibility
 204                                         with Debian.</para>
 205                                 </listitem>
 206                         </varlistentry>
 207                         <varlistentry>
 208                                 <term><filename>emergency.target</filename></term>
 209                                 <listitem>
 210                                         <para>A special target unit
 211                                         that starts an emergency
 212                                         shell on the main
 213                                         console. This unit is supposed
 214                                         to be used with the kernel
 215                                         command line option
 216                                         <varname>systemd.default=</varname>
 217                                         and has otherwise little use.
 218                                         </para>
 219                                 </listitem>
 220                         </varlistentry>
 221                         <varlistentry>
 222                                 <term><filename>graphical.target</filename></term>
 223                                 <listitem>
 224                                         <para>A special target unit
 225                                         for setting up a graphical
 226                                         login screen. This pulls in
 227                                         <filename>multi-user.target</filename>.</para>
 228
 229                                         <para>Units that are needed
 230                                         for graphical login shall add
 231                                         Wants dependencies for their
 232                                         unit to this unit (or
 233                                         <filename>multi-user.target</filename>)
 234                                         during installation.</para>
 235                                 </listitem>
 236                         </varlistentry>
 237                         <varlistentry>
 238                                 <term><filename>halt.target</filename></term>
 239                                 <listitem>
 240                                         <para>A special target unit
 241                                         for shutting down and halting the system.</para>
 242
 243                                         <para>Applications wanting to
 244                                         halt the system should start
 245                                         this unit.</para>
 246                                 </listitem>
 247                         </varlistentry>
 248                         <varlistentry>
 249                                 <term><filename>kbrequest.target</filename></term>
 250                                 <listitem>
 251                                         <para>systemd starts this
 252                                         target whenever Alt+ArrowUp is
 253                                         pressed on the console. This
 254                                         is a good candidate to be
 255                                         aliased (symlinked) to
 256                                         <filename>rescue.target</filename>.</para>
 257                                 </listitem>
 258                         </varlistentry>
 259                         <varlistentry>
 260                                 <term><filename>local-fs.target</filename></term>
 261                                 <listitem>
 262                                         <para>systemd automatically
 263                                         adds dependencies of type
 264                                         After to all mount units that
 265                                         refer to local mount points
 266                                         for this target unit. In
 267                                         addition, systemd adds
 268                                         dependencies of type Wants to
 269                                         this target unit for those
 270                                         mounts listed in
 271                                         <filename>/etc/fstab</filename>
 272                                         that have the
 273                                         <option>auto</option> and
 274                                         <option>comment=systemd.mount</option>
 275                                         mount options set.</para>
 276
 277                                         <para>systemd automatically
 278                                         adds dependencies of type
 279                                         After for this target unit to
 280                                         all SysV init script service
 281                                         units with an LSB header
 282                                         referring to the
 283                                         <literal>$local_fs</literal>
 284                                         facility.</para>
 285                                 </listitem>
 286                         </varlistentry>
 287                         <varlistentry>
 288                                 <term><filename>mail-transfer-agent.target</filename></term>
 289                                 <listitem>
 290                                         <para>The mail transfer agent
 291                                         (MTA) service. Usually this
 292                                         should pull-in all units
 293                                         necessary for
 294                                         sending/receiving mails on the
 295                                         local host.</para>
 296
 297                                         <para>systemd automatically
 298                                         adds dependencies of type
 299                                         After for this target unit to
 300                                         all SysV init script service
 301                                         units with an LSB header
 302                                         referring to the
 303                                         <literal>$mail-transfer-argent</literal>
 304                                         or
 305                                         <literal>$mail-transport-agent</literal>
 306                                         facilities, for compatibility
 307                                         with Debian.</para>
 308                                 </listitem>
 309                         </varlistentry>
 310                         <varlistentry>
 311                                 <term><filename>multi-user.target</filename></term>
 312                                 <listitem>
 313                                         <para>A special target unit
 314                                         for setting up a multi-user
 315                                         system (non-graphical). This
 316                                         is pulled in by
 317                                         <filename>graphical.target</filename>.</para>
 318
 319                                         <para>Units that are needed
 320                                         for a multi-user system shall
 321                                         add Wants dependencies to
 322                                         this unit for their unit during
 323                                         installation.</para>
 324                                 </listitem>
 325                         </varlistentry>
 326                         <varlistentry>
 327                                 <term><filename>network.target</filename></term>
 328                                 <listitem>
 329                                         <para>systemd automatically
 330                                         adds dependencies of type
 331                                         After for this target unit to
 332                                         all SysV init script service
 333                                         units with an LSB header
 334                                         referring to the
 335                                         <literal>$network</literal>
 336                                         facility.</para>
 337                                 </listitem>
 338                         </varlistentry>
 339                         <varlistentry>
 340                                 <term><filename>nss-lookup.target</filename></term>
 341                                 <listitem>
 342                                         <para>systemd automatically
 343                                         adds dependencies of type
 344                                         After for this target unit to
 345                                         all SysV init script service
 346                                         units with an LSB header
 347                                         referring to the
 348                                         <literal>$named</literal>
 349                                         facility.</para>
 350                                 </listitem>
 351                         </varlistentry>
 352                         <varlistentry>
 353                                 <term><filename>poweroff.target</filename></term>
 354                                 <listitem>
 355                                         <para>A special target unit
 356                                         for shutting down and powering off the system.</para>
 357
 358                                         <para>Applications wanting to
 359                                         power off the system should start
 360                                         this unit.</para>
 361
 362                                         <para><filename>runlevel0.target</filename>
 363                                         is an alias for this target
 364                                         unit, for compatibility with SysV.</para>
 365                                 </listitem>
 366                         </varlistentry>
 367                         <varlistentry>
 368                                 <term><filename>reboot.target</filename></term>
 369                                 <listitem>
 370                                         <para>A special target unit
 371                                         for shutting down and rebooting the system.</para>
 372
 373                                         <para>Applications wanting to
 374                                         reboot the system should start
 375                                         this unit.</para>
 376
 377                                         <para><filename>runlevel6.target</filename>
 378                                         is an alias for this target
 379                                         unit, for compatibility with SysV.</para>
 380                                 </listitem>
 381                         </varlistentry>
 382                         <varlistentry>
 383                                 <term><filename>remote-fs.target</filename></term>
 384                                 <listitem>
 385                                         <para>Similar to
 386                                         <filename>local-fs.target</filename>,
 387                                         but for remote mount
 388                                         points.</para>
 389
 390                                         <para>systemd automatically
 391                                         adds dependencies of type
 392                                         After for this target unit to
 393                                         all SysV init script service
 394                                         units with an LSB header
 395                                         referring to the
 396                                         <literal>$remote_fs</literal>
 397                                         facility.</para>
 398                                 </listitem>
 399                         </varlistentry>
 400                         <varlistentry>
 401                                 <term><filename>rescue.target</filename></term>
 402                                 <listitem>
 403                                         <para>A special target unit
 404                                         for setting up the base system
 405                                         and a rescue shell.</para>
 406
 407                                         <para><filename>runlevel1.target</filename>
 408                                         is an alias for this target
 409                                         unit, for compatibility with SysV.</para>
 410                                 </listitem>
 411                         </varlistentry>
 412                         <varlistentry>
 413                                 <term><filename>rpcbind.target</filename></term>
 414                                 <listitem>
 415                                         <para>systemd automatically
 416                                         adds dependencies of type
 417                                         After for this target unit to
 418                                         all SysV init script service
 419                                         units with an LSB header
 420                                         referring to the
 421                                         <literal>$rpcbind</literal>
 422                                         facility.</para>
 423                                 </listitem>
 424                         </varlistentry>
 425                         <varlistentry>
 426                                 <term><filename>rtc-set.target</filename></term>
 427                                 <listitem>
 428                                         <para>systemd automatically
 429                                         adds dependencies of type
 430                                         After for this target unit to
 431                                         all SysV init script service
 432                                         units with an LSB header
 433                                         referring to the
 434                                         <literal>$time</literal>
 435                                         facility.</para>
 436                                 </listitem>
 437                         </varlistentry>
 438                         <varlistentry>
 439                                 <term><filename>runlevel2.target</filename></term>
 440                                 <listitem>
 441                                         <para>This is a target that is
 442                                         called whever the SysV
 443                                         compatibility code asks for
 444                                         runlevel 2. It is a good idea
 445                                         to make this an alias for
 446                                         (i.e. symlink to)
 447                                         <filename>multi-user.target</filename>.</para>
 448                                 </listitem>
 449                         </varlistentry>
 450                         <varlistentry>
 451                                 <term><filename>runlevel3.target</filename></term>
 452                                 <listitem>
 453                                         <para>This is a target that is
 454                                         called whever the SysV
 455                                         compatibility code asks for
 456                                         runlevel 3. It is a good idea
 457                                         to make this an alias for
 458                                         (i.e. symlink to)
 459                                         <filename>multi-user.target</filename>
 460                                         or
 461                                         <filename>graphical.target</filename>.</para>
 462                                 </listitem>
 463                         </varlistentry>
 464                         <varlistentry>
 465                                 <term><filename>runlevel4.target</filename></term>
 466                                 <listitem>
 467                                         <para>This is a target that is
 468                                         called whever the SysV
 469                                         compatibility code asks for
 470                                         runlevel 4. It is a good idea
 471                                         to make this an alias for
 472                                         (i.e. symlink to)
 473                                         <filename>multi-user.target</filename>
 474                                         or
 475                                         <filename>graphical.target</filename>.</para>
 476                                 </listitem>
 477                         </varlistentry>
 478                         <varlistentry>
 479                                 <term><filename>runlevel5.target</filename></term>
 480                                 <listitem>
 481                                         <para>This is a target that is
 482                                         called whever the SysV
 483                                         compatibility code asks for
 484                                         runlevel 5. It is a good idea
 485                                         to make this an alias for
 486                                         (i.e. symlink to)
 487                                         <filename>multi-user.target</filename>
 488                                         or
 489                                         <filename>graphical.target</filename>.</para>
 490                                 </listitem>
 491                         </varlistentry>
 492                         <varlistentry>
 493                                 <term><filename>shutdown.target</filename></term>
 494                                 <listitem>
 495                                         <para>A special target unit
 496                                         that terminates the services
 497                                         on system shutdown.</para>
 498
 499                                         <para>Services that shall be
 500                                         terminated on system shutdown
 501                                         shall add Conflicts
 502                                         dependencies to this unit for
 503                                         their service unit, which is
 504                                         implicitly done when
 505                                         <varname>DefaultDependencies=yes</varname>
 506                                         is set (the default).</para>
 507
 508                                         <para>systemd automatically
 509                                         adds dependencies of type
 510                                         Conflicts to this target unit
 511                                         for all SysV init script
 512                                         service units that shall be
 513                                         terminated in SysV runlevels 0
 514                                         or 6.</para>
 515                                 </listitem>
 516                         </varlistentry>
 517                         <varlistentry>
 518                                 <term><filename>sigpwr.target</filename></term>
 519                                 <listitem>
 520                                         <para>A special target that is
 521                                         started when systemd receives
 522                                         the SIGPWR process signal,
 523                                         which is normally sent by the
 524                                         kernel or UPS daemons when
 525                                         power fails.</para>
 526                                 </listitem>
 527                         </varlistentry>
 528                         <varlistentry>
 529                                 <term><filename>sockets.target</filename></term>
 530                                 <listitem>
 531                                         <para>A special target unit
 532                                         that sets up all service
 533                                         sockets.</para>
 534
 535                                         <para>Services that can be
 536                                         socket-activated shall add
 537                                         Wants dependencies to this
 538                                         unit for their socket unit
 539                                         during installation.</para>
 540                                 </listitem>
 541                         </varlistentry>
 542                         <varlistentry>
 543                                 <term><filename>swap.target</filename></term>
 544                                 <listitem>
 545                                         <para>Similar to
 546                                         <filename>local-fs.target</filename>, but for swap
 547                                         partitions and swap
 548                                         files.</para>
 549                                 </listitem>
 550                         </varlistentry>
 551                         <varlistentry>
 552                                 <term><filename>sysinit.target</filename></term>
 553                                 <listitem>
 554                                         <para>A special target unit
 555                                         covering early boot-up scripts.</para>
 556                                         <para>systemd automatically
 557                                         adds dependencies of the types
 558                                         Wants and After for all
 559                                         SysV service units configured
 560                                         for runlevels that are not 0
 561                                         to 6 to this target unit.
 562                                         This covers the special
 563                                         boot-up runlevels some
 564                                         distributions have, such as S
 565                                         or b.</para>
 566                                 </listitem>
 567                         </varlistentry>
 568                         <varlistentry>
 569                                 <term><filename>@SPECIAL_SYSLOG_SERVICE@</filename></term>
 570                                 <listitem>
 571                                         <para>A special unit for the
 572                                         syslog daemon. As soon as
 573                                         this service is fully started
 574                                         up systemd will connect to it
 575                                         and use it for logging if it
 576                                         has been configured for
 577                                         that.</para>
 578
 579                                         <para>Units should generally
 580                                         avoid depending on this unit
 581                                         directly and instead refer to
 582                                         the
 583                                         <filename>syslog.target</filename>
 584                                         unit instead, which pulls this
 585                                         one in directly or indirectly
 586                                         via socket-based activation.</para>
 587                                 </listitem>
 588                         </varlistentry>
 589                         <varlistentry>
 590                                 <term><filename>syslog.target</filename></term>
 591                                 <listitem>
 592                                         <para>systemd automatically
 593                                         adds dependencies of type
 594                                         After for this target unit to
 595                                         all SysV init script service
 596                                         units with an LSB header
 597                                         referring to the
 598                                         <literal>$syslog</literal>
 599                                         facility.</para>
 600
 601                                         <para>Administrators should
 602                                         ensure that this target pulls
 603                                         in a service unit with the
 604                                         name or alias of
 605                                         <filename>@SPECIAL_SYSLOG_SERVICE@</filename>
 606                                         (or a socket unit that
 607                                         activates this
 608                                         service).</para>
 609                                 </listitem>
 610                         </varlistentry>
 611                         <varlistentry>
 612                                 <term><filename>systemd-initctl.service</filename></term>
 613                                 <listitem>
 614                                         <para>This provides
 615                                         compatibility with the SysV
 616                                         /dev/initctl file system FIFO
 617                                         for communication with the
 618                                         init system.</para>
 619                                         <para>This is a
 620                                         socket-activated service, see
 621                                         <filename>system-initctl.socket</filename>.</para>
 622                                 </listitem>
 623                         </varlistentry>
 624                         <varlistentry>
 625                                 <term><filename>systemd-initctl.socket</filename></term>
 626                                 <listitem>
 627                                         <para>Socket activation unit
 628                                         for
 629                                         <filename>system-initctl.service</filename>.</para>
 630                                 </listitem>
 631                         </varlistentry>
 632                         <varlistentry>
 633                                 <term><filename>systemd-logger.service</filename></term>
 634                                 <listitem>
 635                                         <para>This is internally used
 636                                         by systemd to provide syslog
 637                                         logging to the processes it
 638                                         maintains.</para>
 639                                         <para>This is a
 640                                         socket-activated service, see
 641                                         <filename>system-logger.socket</filename>.</para>
 642                                 </listitem>
 643                         </varlistentry>
 644                         <varlistentry>
 645                                 <term><filename>systemd-logger.socket</filename></term>
 646                                 <listitem>
 647                                         <para>Socket activation unit
 648                                         for
 649                                         <filename>system-logger.service</filename>. systemd
 650                                         will automatically add
 651                                         dependencies of types Requires
 652                                         and After to all units that
 653                                         have been configured for
 654                                         stdout or stderr to be
 655                                         connected to syslog or the
 656                                         kernel log buffer.</para>
 657                                 </listitem>
 658                         </varlistentry>
 659                          <varlistentry>
 660                                 <term><filename>systemd-shutdownd.service</filename></term>
 661                                 <listitem>
 662                                         <para>This is internally used
 663                                         by
 664                                         <citerefentry><refentrytitle>shutdown</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 665                                         to implement delayed shutdowns.</para>
 666                                         <para>This is a
 667                                         socket-activated service, see
 668                                         <filename>system-shutdownd.socket</filename>.</para>
 669                                 </listitem>
 670                         </varlistentry>
 671                         <varlistentry>
 672                                 <term><filename>systemd-shutdownd.socket</filename></term>
 673                                 <listitem>
 674                                         <para>Socket activation unit
 675                                         for
 676                                         <filename>system-shutdownd.service</filename>.</para>
 677                                 </listitem>
 678                         </varlistentry>
 679                         <varlistentry>
 680                                 <term><filename>umount.target</filename></term>
 681                                 <listitem>
 682                                         <para>A special target unit
 683                                         that umounts all mount and
 684                                         automount points on system
 685                                         shutdown.</para>
 686
 687                                         <para>Mounts that shall be
 688                                         unmounted on system shutdown
 689                                         shall add Conflicts
 690                                         dependencies to this unit for
 691                                         their mount unit, which is
 692                                         implicitly done when
 693                                         <varname>DefaultDependencies=yes</varname>
 694                                         is set (the default).</para>
 695                                 </listitem>
 696                         </varlistentry>
 697                 </variablelist>
 698         </refsect1>
 699
 700         <refsect1>
 701                 <title>Special Session Units</title>
 702
 703                 <para>When systemd runs as a service instance, the
 704                 following special units are available, which have
 705                 similar definitions as their system counterparts:
 706                 <filename>default.target</filename>,
 707                 <filename>local-fs.target</filename>,
 708                 <filename>remote-fs.target</filename>,
 709                 <filename>shutdown.target</filename>,
 710                 <filename>sockets.target</filename>,
 711                 <filename>swap.target</filename>.</para>
 712
 713                 <para>In addition the following special unit is
 714                 understood only when systemd runs as service instance:</para>
 715
 716                 <variablelist>
 717                         <varlistentry>
 718                                 <term><filename>exit.service</filename></term>
 719                                 <listitem>
 720                                         <para>A special service unit
 721                                         for shutting down the
 722                                         session.</para>
 723
 724                                         <para>Applications wanting to
 725                                         terminate the session should
 726                                         start this unit. If systemd
 727                                         receives SIGTERM or SIGINT
 728                                         when running as session daemon
 729                                         it will start this
 730                                         unit.</para>
 731
 732                                         <para>Normally, this pulls in
 733                                         <filename>shutdown.target</filename>
 734                                         which in turn should be
 735                                         conflicted by all units that
 736                                         want to be shut down on
 737                                         session exit.</para>
 738                                 </listitem>
 739                         </varlistentry>
 740                 </variablelist>
 741         </refsect1>
 742
 743         <refsect1>
 744                   <title>See Also</title>
 745                   <para>
 746                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 747                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 748                           <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 749                           <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 750                   </para>
 751         </refsect1>
 752
 753 </refentry>