man/systemd.special.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
   5 <!--
   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 Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
  15   systemd is distributed in the hope that it will be useful, but
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  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 -->
  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>bluetooth.target</filename>,
  53                 <filename>ctrl-alt-del.target</filename>,
  54                 <filename>cryptsetup.target</filename>,
  55                 <filename>dbus.service</filename>,
  56                 <filename>dbus.socket</filename>,
  57                 <filename>default.target</filename>,
  58                 <filename>display-manager.service</filename>,
  59                 <filename>emergency.target</filename>,
  60                 <filename>exit.target</filename>,
  61                 <filename>final.target</filename>,
  62                 <filename>getty.target</filename>,
  63                 <filename>graphical.target</filename>,
  64                 <filename>halt.target</filename>,
  65                 <filename>hibernate.target</filename>,
  66                 <filename>hybrid-sleep.target</filename>,
  67                 <filename>kbrequest.target</filename>,
  68                 <filename>kexec.target</filename>,
  69                 <filename>local-fs.target</filename>,
  70                 <filename>local-fs-pre.target</filename>,
  71                 <filename>multi-user.target</filename>,
  72                 <filename>network.target</filename>,
  73                 <filename>nss-lookup.target</filename>,
  74                 <filename>nss-user-lookup.target</filename>,
  75                 <filename>poweroff.target</filename>,
  76                 <filename>printer.target</filename>,
  77                 <filename>reboot.target</filename>,
  78                 <filename>remote-fs.target</filename>,
  79                 <filename>remote-fs-pre.target</filename>,
  80                 <filename>rescue.target</filename>,
  81                 <filename>rpcbind.target</filename>,
  82                 <filename>runlevel2.target</filename>,
  83                 <filename>runlevel3.target</filename>,
  84                 <filename>runlevel4.target</filename>,
  85                 <filename>runlevel5.target</filename>,
  86                 <filename>shutdown.target</filename>,
  87                 <filename>sigpwr.target</filename>,
  88                 <filename>sleep.target</filename>,
  89                 <filename>smartcard.target</filename>,
  90                 <filename>sockets.target</filename>,
  91                 <filename>sound.target</filename>,
  92                 <filename>suspend.target</filename>,
  93                 <filename>swap.target</filename>,
  94                 <filename>sysinit.target</filename>,
  95                 <filename>syslog.socket</filename>,
  96                 <filename>system-update.target</filename>,
  97                 <filename>time-sync.target</filename>,
  98                 <filename>umount.target</filename></para>
  99         </refsynopsisdiv>
 100
 101         <refsect1>
 102                 <title>Description</title>
 103
 104                 <para>A few units are treated specially by
 105                 systemd. They have special internal semantics and
 106                 cannot be renamed.</para>
 107         </refsect1>
 108
 109         <refsect1>
 110                 <title>Special System Units</title>
 111
 112                 <variablelist>
 113                         <varlistentry>
 114                                 <term><filename>basic.target</filename></term>
 115                                 <listitem>
 116                                         <para>A special target unit
 117                                         covering early boot-up.</para>
 118                                         <para>systemd automatically
 119                                         adds dependencies of the types
 120                                         Requires and After for this
 121                                         target unit to all SysV
 122                                         service units configured for
 123                                         runlevel 1 to 5.</para>
 124                                         <para>Usually this should pull-in
 125                                         all sockets, mount points,
 126                                         swap devices and other basic
 127                                         initialization necessary for
 128                                         the general purpose
 129                                         daemons. Most normal daemons
 130                                         should have dependencies of
 131                                         type After and Requires on
 132                                         this unit.</para>
 133                                 </listitem>
 134                         </varlistentry>
 135                         <varlistentry>
 136                                 <term><filename>bluetooth.target</filename></term>
 137                                 <listitem>
 138                                         <para>This target is started
 139                                         automatically as soon as a
 140                                         bluetooth controller is
 141                                         plugged in or becomes
 142                                         available at boot.</para>
 143                                 </listitem>
 144                         </varlistentry>
 145                         <varlistentry>
 146                                 <term><filename>ctrl-alt-del.target</filename></term>
 147                                 <listitem>
 148                                         <para>systemd starts this
 149                                         target whenever
 150                                         Control+Alt+Del is pressed on
 151                                         the console. Usually this
 152                                         should be aliased (symlinked)
 153                                         to
 154                                         <filename>reboot.target</filename>.</para>
 155                                 </listitem>
 156                         </varlistentry>
 157                         <varlistentry>
 158                                 <term><filename>cryptsetup.target</filename></term>
 159                                 <listitem>
 160                                         <para>A target that pulls in
 161                                         setup services for all
 162                                         encrypted block
 163                                         devices.</para>
 164                                 </listitem>
 165                         </varlistentry>
 166                         <varlistentry>
 167                                 <term><filename>dbus.service</filename></term>
 168                                 <listitem>
 169                                         <para>A special unit for the
 170                                         D-Bus system bus. As soon as
 171                                         this service is fully started
 172                                         up systemd will connect to it
 173                                         and register its
 174                                         service.</para>
 175                                 </listitem>
 176                         </varlistentry>
 177                         <varlistentry>
 178                                 <term><filename>dbus.socket</filename></term>
 179                                 <listitem>
 180                                         <para>A special unit for the
 181                                         D-Bus system bus socket. All
 182                                         units with
 183                                         <literal>Type=dbus</literal>
 184                                         automatically gain a
 185                                         dependency on this
 186                                         unit.</para>
 187                                 </listitem>
 188                         </varlistentry>
 189                         <varlistentry>
 190                                 <term><filename>default.target</filename></term>
 191                                 <listitem>
 192                                         <para>The default unit systemd
 193                                         starts at bootup. Usually this
 194                                         should be aliased (symlinked)
 195                                         to
 196                                         <filename>multi-user.target</filename>
 197                                         or
 198                                         <filename>graphical.target</filename>.</para>
 199                                         <para>The default unit systemd
 200                                         starts at bootup can be
 201                                         overridden with the
 202                                         <varname>systemd.unit=</varname>
 203                                         kernel command line option.</para>
 204                                 </listitem>
 205                         </varlistentry>
 206                         <varlistentry>
 207                                 <term><filename>display-manager.service</filename></term>
 208                                 <listitem>
 209                                         <para>The display manager
 210                                         service. Usually this should
 211                                         be aliased (symlinked) to
 212                                         <filename>gdm.service</filename>
 213                                         or a similar display manager
 214                                         service.</para>
 215                                 </listitem>
 216                         </varlistentry>
 217                         <varlistentry>
 218                                 <term><filename>emergency.target</filename></term>
 219                                 <listitem>
 220                                         <para>A special target unit
 221                                         that starts an emergency
 222                                         shell on the main
 223                                         console. This unit is supposed
 224                                         to be used with the kernel
 225                                         command line option
 226                                         <varname>systemd.unit=</varname>
 227                                         and has otherwise little use.
 228                                         </para>
 229                                 </listitem>
 230                         </varlistentry>
 231                         <varlistentry>
 232                                 <term><filename>final.target</filename></term>
 233                                 <listitem>
 234                                         <para>A special target unit
 235                                         that is used during the
 236                                         shutdown logic and may be used
 237                                         to pull in late services after
 238                                         all normal services are
 239                                         already terminated and all
 240                                         mounts unmounted.
 241                                         </para>
 242                                 </listitem>
 243                         </varlistentry>
 244                         <varlistentry>
 245                                 <term><filename>getty.target</filename></term>
 246                                 <listitem>
 247                                         <para>A special target unit
 248                                         that pulls in all local TTY
 249                                         <filename>getty</filename> instances.
 250                                         </para>
 251                                 </listitem>
 252                         </varlistentry>
 253                         <varlistentry>
 254                                 <term><filename>graphical.target</filename></term>
 255                                 <listitem>
 256                                         <para>A special target unit
 257                                         for setting up a graphical
 258                                         login screen. This pulls in
 259                                         <filename>multi-user.target</filename>.</para>
 260
 261                                         <para>Units that are needed
 262                                         for graphical login shall add
 263                                         Wants dependencies for their
 264                                         unit to this unit (or
 265                                         <filename>multi-user.target</filename>)
 266                                         during installation.</para>
 267                                 </listitem>
 268                         </varlistentry>
 269                         <varlistentry>
 270                                 <term><filename>hibernate.target</filename></term>
 271                                 <listitem>
 272                                         <para>A special target unit
 273                                         for hibernating the
 274                                         system. This pulls in
 275                                         <filename>sleep.target</filename>.</para>
 276                                 </listitem>
 277                         </varlistentry>
 278                         <varlistentry>
 279                                 <term><filename>hybrid-sleep.target</filename></term>
 280                                 <listitem>
 281                                         <para>A special target unit
 282                                         for hibernating and suspending the
 283                                         system at the same time. This pulls in
 284                                         <filename>sleep.target</filename>.</para>
 285                                 </listitem>
 286                         </varlistentry>
 287                         <varlistentry>
 288                                 <term><filename>halt.target</filename></term>
 289                                 <listitem>
 290                                         <para>A special target unit
 291                                         for shutting down and halting the system.</para>
 292
 293                                         <para>Applications wanting to
 294                                         halt the system should start
 295                                         this unit.</para>
 296                                 </listitem>
 297                         </varlistentry>
 298                         <varlistentry>
 299                                 <term><filename>kbrequest.target</filename></term>
 300                                 <listitem>
 301                                         <para>systemd starts this
 302                                         target whenever Alt+ArrowUp is
 303                                         pressed on the console. This
 304                                         is a good candidate to be
 305                                         aliased (symlinked) to
 306                                         <filename>rescue.target</filename>.</para>
 307                                 </listitem>
 308                         </varlistentry>
 309                         <varlistentry>
 310                                 <term><filename>kexec.target</filename></term>
 311                                 <listitem>
 312                                         <para>A special target unit
 313                                         for shutting down and rebooting the system via kexec.</para>
 314
 315                                         <para>Applications wanting to
 316                                         reboot the system with kexec should start
 317                                         this unit.</para>
 318                                 </listitem>
 319                         </varlistentry>
 320                         <varlistentry>
 321                                 <term><filename>local-fs.target</filename></term>
 322                                 <listitem>
 323                                         <para>systemd automatically
 324                                         adds dependencies of type
 325                                         After to all mount units that
 326                                         refer to local mount points
 327                                         for this target unit. In
 328                                         addition, systemd adds
 329                                         dependencies of type Wants to
 330                                         this target unit for those
 331                                         mounts listed in
 332                                         <filename>/etc/fstab</filename>
 333                                         that have the
 334                                         <option>auto</option> and
 335                                         <option>comment=systemd.mount</option>
 336                                         mount options set.</para>
 337                                 </listitem>
 338                         </varlistentry>
 339                         <varlistentry>
 340                                 <term><filename>local-fs-pre.target</filename></term>
 341                                 <listitem>
 342                                         <para>This target unit is
 343                                         automatically ordered before
 344                                         all local mount points marked
 345                                         with <option>auto</option>
 346                                         (see above). It can be used to
 347                                         execute certain units before
 348                                         all local mounts.</para>
 349                                 </listitem>
 350                         </varlistentry>
 351                         <varlistentry>
 352                                 <term><filename>multi-user.target</filename></term>
 353                                 <listitem>
 354                                         <para>A special target unit
 355                                         for setting up a multi-user
 356                                         system (non-graphical). This
 357                                         is pulled in by
 358                                         <filename>graphical.target</filename>.</para>
 359
 360                                         <para>Units that are needed
 361                                         for a multi-user system shall
 362                                         add Wants dependencies to
 363                                         this unit for their unit during
 364                                         installation.</para>
 365                                 </listitem>
 366                         </varlistentry>
 367                         <varlistentry>
 368                                 <term><filename>network.target</filename></term>
 369                                 <listitem>
 370                                         <para>systemd automatically
 371                                         adds dependencies of type
 372                                         After for this target unit to
 373                                         all SysV init script service
 374                                         units with an LSB header
 375                                         referring to the
 376                                         <literal>$network</literal>
 377                                         facility.</para>
 378
 379                                         <para>This unit is supposed to
 380                                         indicate when the network is
 381                                         "up", but it is only very
 382                                         loosely defined what that is
 383                                         supposed to mean. Also see <ulink
 384                                         url="http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
 385                                         Services After the Network is
 386                                         up</ulink> for more
 387                                         information.</para>
 388                                 </listitem>
 389                         </varlistentry>
 390                         <varlistentry>
 391                                 <term><filename>nss-lookup.target</filename></term>
 392                                 <listitem>
 393                                         <para>A target that should be
 394                                         used as synchronization point
 395                                         for all host/network name
 396                                         service lookups. Note that
 397                                         this is independent of
 398                                         user/group name lookups for
 399                                         which
 400                                         <filename>nss-user-lookup.target</filename>
 401                                         should be used. systemd
 402                                         automatically adds
 403                                         dependencies of type After for
 404                                         this target unit to all SysV
 405                                         init script service units with
 406                                         an LSB header referring to the
 407                                         <literal>$named</literal>
 408                                         facility.</para>
 409                                 </listitem>
 410                         </varlistentry>
 411                         <varlistentry>
 412                                 <term><filename>nss-user-lookup.target</filename></term>
 413                                 <listitem>
 414                                         <para>A target that should be
 415                                         used as synchronization point
 416                                         for all user/group name
 417                                         service lookups. Note that
 418                                         this is independent of
 419                                         host/network name lookups for
 420                                         which
 421                                         <filename>nss-lookup.target</filename>
 422                                         should be used. </para>
 423                                 </listitem>
 424                         </varlistentry>
 425                         <varlistentry>
 426                                 <term><filename>poweroff.target</filename></term>
 427                                 <listitem>
 428                                         <para>A special target unit
 429                                         for shutting down and powering off the system.</para>
 430
 431                                         <para>Applications wanting to
 432                                         power off the system should start
 433                                         this unit.</para>
 434
 435                                         <para><filename>runlevel0.target</filename>
 436                                         is an alias for this target
 437                                         unit, for compatibility with SysV.</para>
 438                                 </listitem>
 439                         </varlistentry>
 440                         <varlistentry>
 441                                 <term><filename>printer.target</filename></term>
 442                                 <listitem>
 443                                         <para>This target is started
 444                                         automatically as soon as a
 445                                         printer is plugged in or
 446                                         becomes available at
 447                                         boot.</para>
 448                                 </listitem>
 449                         </varlistentry>
 450                         <varlistentry>
 451                                 <term><filename>reboot.target</filename></term>
 452                                 <listitem>
 453                                         <para>A special target unit
 454                                         for shutting down and rebooting the system.</para>
 455
 456                                         <para>Applications wanting to
 457                                         reboot the system should start
 458                                         this unit.</para>
 459
 460                                         <para><filename>runlevel6.target</filename>
 461                                         is an alias for this target
 462                                         unit, for compatibility with SysV.</para>
 463                                 </listitem>
 464                         </varlistentry>
 465                         <varlistentry>
 466                                 <term><filename>remote-fs.target</filename></term>
 467                                 <listitem>
 468                                         <para>Similar to
 469                                         <filename>local-fs.target</filename>,
 470                                         but for remote mount
 471                                         points.</para>
 472
 473                                         <para>systemd automatically
 474                                         adds dependencies of type
 475                                         After for this target unit to
 476                                         all SysV init script service
 477                                         units with an LSB header
 478                                         referring to the
 479                                         <literal>$remote_fs</literal>
 480                                         facility.</para>
 481                                 </listitem>
 482                         </varlistentry>
 483                         <varlistentry>
 484                                 <term><filename>remote-fs-pre.target</filename></term>
 485                                 <listitem>
 486                                         <para>This target unit is
 487                                         automatically ordered before
 488                                         all remote mount points marked
 489                                         with <option>auto</option>
 490                                         (see above). It can be used to
 491                                         execute certain units before
 492                                         all remote mounts.</para>
 493                                 </listitem>
 494                         </varlistentry>
 495                         <varlistentry>
 496                                 <term><filename>rescue.target</filename></term>
 497                                 <listitem>
 498                                         <para>A special target unit
 499                                         for setting up the base system
 500                                         and a rescue shell.</para>
 501
 502                                         <para><filename>runlevel1.target</filename>
 503                                         is an alias for this target
 504                                         unit, for compatibility with SysV.</para>
 505                                 </listitem>
 506                         </varlistentry>
 507                         <varlistentry>
 508                                 <term><filename>rpcbind.target</filename></term>
 509                                 <listitem>
 510                                         <para>systemd automatically
 511                                         adds dependencies of type
 512                                         After for this target unit to
 513                                         all SysV init script service
 514                                         units with an LSB header
 515                                         referring to the
 516                                         <literal>$portmap</literal>
 517                                         facility.</para>
 518                                 </listitem>
 519                         </varlistentry>
 520                         <varlistentry>
 521                                 <term><filename>runlevel2.target</filename></term>
 522                                 <term><filename>runlevel3.target</filename></term>
 523                                 <term><filename>runlevel4.target</filename></term>
 524                                 <term><filename>runlevel5.target</filename></term>
 525                                 <listitem>
 526                                         <para>These are targets that
 527                                         are called whenever the SysV
 528                                         compatibility code asks for
 529                                         runlevel 2, 3, 4, 5,
 530                                         respectively. It is a good
 531                                         idea to make this an alias for
 532                                         (i.e. symlink to)
 533                                         <filename>multi-user.target</filename>
 534                                         (for runlevel 2) or
 535                                         <filename>graphical.target</filename>
 536                                         (the others).</para>
 537                                 </listitem>
 538                         </varlistentry>
 539                         <varlistentry>
 540                                 <term><filename>shutdown.target</filename></term>
 541                                 <listitem>
 542                                         <para>A special target unit
 543                                         that terminates the services
 544                                         on system shutdown.</para>
 545
 546                                         <para>Services that shall be
 547                                         terminated on system shutdown
 548                                         shall add Conflicts
 549                                         dependencies to this unit for
 550                                         their service unit, which is
 551                                         implicitly done when
 552                                         <varname>DefaultDependencies=yes</varname>
 553                                         is set (the default).</para>
 554
 555                                         <para>systemd automatically
 556                                         adds dependencies of type
 557                                         Conflicts to this target unit
 558                                         for all SysV init script
 559                                         service units that shall be
 560                                         terminated in SysV runlevels 0
 561                                         or 6.</para>
 562                                 </listitem>
 563                         </varlistentry>
 564                         <varlistentry>
 565                                 <term><filename>sigpwr.target</filename></term>
 566                                 <listitem>
 567                                         <para>A special target that is
 568                                         started when systemd receives
 569                                         the SIGPWR process signal,
 570                                         which is normally sent by the
 571                                         kernel or UPS daemons when
 572                                         power fails.</para>
 573                                 </listitem>
 574                         </varlistentry>
 575                         <varlistentry>
 576                                 <term><filename>sleep.target</filename></term>
 577                                 <listitem>
 578                                         <para>A special target unit
 579                                         that is pulled in by
 580                                         <filename>suspend.target</filename>,
 581                                         <filename>hibernate.target</filename> and <filename>hybrid-sleep.target</filename>
 582                                         and may be used to hook units
 583                                         into the sleep state
 584                                         logic.</para>
 585                                 </listitem>
 586                         </varlistentry>
 587                         <varlistentry>
 588                                 <term><filename>smartcard.target</filename></term>
 589                                 <listitem>
 590                                         <para>This target is started
 591                                         automatically as soon as a
 592                                         smartcard controller is
 593                                         plugged in or becomes
 594                                         available at boot.</para>
 595                                 </listitem>
 596                         </varlistentry>
 597                         <varlistentry>
 598                                 <term><filename>sockets.target</filename></term>
 599                                 <listitem>
 600                                         <para>A special target unit
 601                                         that sets up all service
 602                                         sockets.</para>
 603
 604                                         <para>Services that can be
 605                                         socket-activated shall add
 606                                         Wants dependencies to this
 607                                         unit for their socket unit
 608                                         during installation.</para>
 609                                 </listitem>
 610                         </varlistentry>
 611                         <varlistentry>
 612                                 <term><filename>sound.target</filename></term>
 613                                 <listitem>
 614                                         <para>This target is started
 615                                         automatically as soon as a
 616                                         sound card is plugged in or
 617                                         becomes available at
 618                                         boot.</para>
 619                                 </listitem>
 620                         </varlistentry>
 621                         <varlistentry>
 622                                 <term><filename>suspend.target</filename></term>
 623                                 <listitem>
 624                                         <para>A special target unit
 625                                         for suspending the
 626                                         system. This pulls in
 627                                         <filename>sleep.target</filename>.</para>
 628                                 </listitem>
 629                         </varlistentry>
 630                         <varlistentry>
 631                                 <term><filename>swap.target</filename></term>
 632                                 <listitem>
 633                                         <para>Similar to
 634                                         <filename>local-fs.target</filename>, but for swap
 635                                         partitions and swap
 636                                         files.</para>
 637                                 </listitem>
 638                         </varlistentry>
 639                         <varlistentry>
 640                                 <term><filename>sysinit.target</filename></term>
 641                                 <listitem>
 642                                         <para>A special target unit
 643                                         covering early boot-up scripts.</para>
 644                                 </listitem>
 645                         </varlistentry>
 646                         <varlistentry>
 647                                 <term><filename>syslog.socket</filename></term>
 648                                 <listitem>
 649                                         <para>The socket unit
 650                                         syslog implementations should
 651                                         listen on. All userspace log
 652                                         messages will be made
 653                                         available on this socket. For
 654                                         more information about syslog
 655                                         integration, please consult
 656                                         the <ulink
 657                                         url="http://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog
 658                                         Interface</ulink>
 659                                         document.</para>
 660                                 </listitem>
 661                         </varlistentry>
 662                         <varlistentry>
 663                                 <term><filename>system-update.target</filename></term>
 664                                 <listitem>
 665                                         <para>A special target unit
 666                                         that is used for off-line
 667                                         system updates.
 668                                         <citerefentry><refentrytitle>systemd-system-update-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 669                                         will redirect the boot process
 670                                         to this target if
 671                                         <filename>/system-update</filename>
 672                                         exists. For more information
 673                                         see the <ulink
 674                                         url="http://freedesktop.org/wiki/Software/systemd/SystemUpdates">System
 675                                         Updates
 676                                         Specification</ulink>.</para>
 677                                 </listitem>
 678                         </varlistentry>
 679                         <varlistentry>
 680                                 <term><filename>time-sync.target</filename></term>
 681                                 <listitem>
 682                                         <para>systemd automatically
 683                                         adds dependencies of type
 684                                         After for this target unit to
 685                                         all SysV init script service
 686                                         units with an LSB header
 687                                         referring to the
 688                                         <literal>$time</literal>
 689                                         facility.</para>
 690                                 </listitem>
 691                         </varlistentry>
 692                         <varlistentry>
 693                                 <term><filename>umount.target</filename></term>
 694                                 <listitem>
 695                                         <para>A special target unit
 696                                         that umounts all mount and
 697                                         automount points on system
 698                                         shutdown.</para>
 699
 700                                         <para>Mounts that shall be
 701                                         unmounted on system shutdown
 702                                         shall add Conflicts
 703                                         dependencies to this unit for
 704                                         their mount unit, which is
 705                                         implicitly done when
 706                                         <varname>DefaultDependencies=yes</varname>
 707                                         is set (the default).</para>
 708                                 </listitem>
 709                         </varlistentry>
 710
 711                 </variablelist>
 712         </refsect1>
 713
 714         <refsect1>
 715                 <title>Special User Units</title>
 716
 717                 <para>When systemd runs as a user instance, the
 718                 following special units are available, which have
 719                 similar definitions as their system counterparts:
 720                 <filename>default.target</filename>,
 721                 <filename>shutdown.target</filename>,
 722                 <filename>sockets.target</filename></para>
 723
 724                 <para>In addition the following special unit is
 725                 understood only when systemd runs as service instance:</para>
 726
 727                 <variablelist>
 728                         <varlistentry>
 729                                 <term><filename>exit.target</filename></term>
 730                                 <listitem>
 731                                         <para>A special service unit
 732                                         for shutting down the
 733                                         user service manager.</para>
 734
 735                                         <para>Applications wanting to
 736                                         terminate the user service
 737                                         manager should start this
 738                                         unit. If systemd receives
 739                                         SIGTERM or SIGINT when running
 740                                         as user service daemon it will
 741                                         start this unit.</para>
 742
 743                                         <para>Normally, this pulls in
 744                                         <filename>shutdown.target</filename>
 745                                         which in turn should be
 746                                         conflicted by all units that
 747                                         want to be shut down on
 748                                         user service manager exit.</para>
 749                                 </listitem>
 750                         </varlistentry>
 751                 </variablelist>
 752         </refsect1>
 753
 754         <refsect1>
 755                   <title>See Also</title>
 756                   <para>
 757                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 758                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 759                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 760                           <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 761                           <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 762                           <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 763                   </para>
 764         </refsect1>
 765
 766 </refentry>