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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  17   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  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>mail-transfer-agent.target</filename>,
  72                 <filename>multi-user.target</filename>,
  73                 <filename>network.target</filename>,
  74                 <filename>nss-lookup.target</filename>,
  75                 <filename>nss-user-lookup.target</filename>,
  76                 <filename>poweroff.target</filename>,
  77                 <filename>printer.target</filename>,
  78                 <filename>reboot.target</filename>,
  79                 <filename>remote-fs.target</filename>,
  80                 <filename>remote-fs-pre.target</filename>,
  81                 <filename>rescue.target</filename>,
  82                 <filename>rpcbind.target</filename>,
  83                 <filename>runlevel2.target</filename>,
  84                 <filename>runlevel3.target</filename>,
  85                 <filename>runlevel4.target</filename>,
  86                 <filename>runlevel5.target</filename>,
  87                 <filename>shutdown.target</filename>,
  88                 <filename>sigpwr.target</filename>,
  89                 <filename>sleep.target</filename>,
  90                 <filename>smartcard.target</filename>,
  91                 <filename>sockets.target</filename>,
  92                 <filename>sound.target</filename>,
  93                 <filename>suspend.target</filename>,
  94                 <filename>swap.target</filename>,
  95                 <filename>sysinit.target</filename>,
  96                 <filename>syslog.socket</filename>,
  97                 <filename>syslog.target</filename>,
  98                 <filename>system-update.target</filename>,
  99                 <filename>time-sync.target</filename>,
 100                 <filename>umount.target</filename></para>
 101         </refsynopsisdiv>
 102
 103         <refsect1>
 104                 <title>Description</title>
 105
 106                 <para>A few units are treated specially by
 107                 systemd. They have special internal semantics and
 108                 cannot be renamed.</para>
 109         </refsect1>
 110
 111         <refsect1>
 112                 <title>Special System Units</title>
 113
 114                 <variablelist>
 115                         <varlistentry>
 116                                 <term><filename>basic.target</filename></term>
 117                                 <listitem>
 118                                         <para>A special target unit
 119                                         covering early boot-up.</para>
 120                                         <para>systemd automatically
 121                                         adds dependencies of the types
 122                                         Requires and After for this
 123                                         target unit to all SysV
 124                                         service units configured for
 125                                         runlevel 1 to 5.</para>
 126                                         <para>Usually this should pull-in
 127                                         all sockets, mount points,
 128                                         swap devices and other basic
 129                                         initialization necessary for
 130                                         the general purpose
 131                                         daemons. Most normal daemons
 132                                         should have dependencies of
 133                                         type After and Requires on
 134                                         this unit.</para>
 135                                 </listitem>
 136                         </varlistentry>
 137                         <varlistentry>
 138                                 <term><filename>bluetooth.target</filename></term>
 139                                 <listitem>
 140                                         <para>This target is started
 141                                         automatically as soon as a
 142                                         bluetooth controller is
 143                                         plugged in or becomes
 144                                         available at boot.</para>
 145                                 </listitem>
 146                         </varlistentry>
 147                         <varlistentry>
 148                                 <term><filename>ctrl-alt-del.target</filename></term>
 149                                 <listitem>
 150                                         <para>systemd starts this
 151                                         target whenever
 152                                         Control+Alt+Del is pressed on
 153                                         the console. Usually this
 154                                         should be aliased (symlinked)
 155                                         to
 156                                         <filename>reboot.target</filename>.</para>
 157                                 </listitem>
 158                         </varlistentry>
 159                         <varlistentry>
 160                                 <term><filename>cryptsetup.target</filename></term>
 161                                 <listitem>
 162                                         <para>A target that pulls in
 163                                         setup services for all
 164                                         encrypted block
 165                                         devices.</para>
 166                                 </listitem>
 167                         </varlistentry>
 168                         <varlistentry>
 169                                 <term><filename>dbus.service</filename></term>
 170                                 <listitem>
 171                                         <para>A special unit for the
 172                                         D-Bus system bus. As soon as
 173                                         this service is fully started
 174                                         up systemd will connect to it
 175                                         and register its
 176                                         service.</para>
 177                                 </listitem>
 178                         </varlistentry>
 179                         <varlistentry>
 180                                 <term><filename>dbus.socket</filename></term>
 181                                 <listitem>
 182                                         <para>A special unit for the
 183                                         D-Bus system bus socket. All
 184                                         units with
 185                                         <literal>Type=dbus</literal>
 186                                         automatically gain a
 187                                         dependency on this
 188                                         unit.</para>
 189                                 </listitem>
 190                         </varlistentry>
 191                         <varlistentry>
 192                                 <term><filename>default.target</filename></term>
 193                                 <listitem>
 194                                         <para>The default unit systemd
 195                                         starts at bootup. Usually this
 196                                         should be aliased (symlinked)
 197                                         to
 198                                         <filename>multi-user.target</filename>
 199                                         or
 200                                         <filename>graphical.target</filename>.</para>
 201                                         <para>The default unit systemd
 202                                         starts at bootup can be
 203                                         overridden with the
 204                                         <varname>systemd.unit=</varname>
 205                                         kernel command line option.</para>
 206                                 </listitem>
 207                         </varlistentry>
 208                         <varlistentry>
 209                                 <term><filename>display-manager.service</filename></term>
 210                                 <listitem>
 211                                         <para>The display manager
 212                                         service. Usually this should
 213                                         be aliased (symlinked) to
 214                                         <filename>gdm.service</filename>
 215                                         or a similar display manager
 216                                         service.</para>
 217                                         <para>systemd automatically
 218                                         adds dependencies of type
 219                                         After for this target unit to
 220                                         all SysV init script service
 221                                         units with a LSB header
 222                                         referring to the
 223                                         <literal>$x-display-manager</literal>
 224                                         facility.</para>
 225                                 </listitem>
 226                         </varlistentry>
 227                         <varlistentry>
 228                                 <term><filename>emergency.target</filename></term>
 229                                 <listitem>
 230                                         <para>A special target unit
 231                                         that starts an emergency
 232                                         shell on the main
 233                                         console. This unit is supposed
 234                                         to be used with the kernel
 235                                         command line option
 236                                         <varname>systemd.unit=</varname>
 237                                         and has otherwise little use.
 238                                         </para>
 239                                 </listitem>
 240                         </varlistentry>
 241                         <varlistentry>
 242                                 <term><filename>final.target</filename></term>
 243                                 <listitem>
 244                                         <para>A special target unit
 245                                         that is used during the
 246                                         shutdown logic and may be used
 247                                         to pull in late services after
 248                                         all normal services are
 249                                         already terminated and all
 250                                         mounts unmounted.
 251                                         </para>
 252                                 </listitem>
 253                         </varlistentry>
 254                         <varlistentry>
 255                                 <term><filename>getty.target</filename></term>
 256                                 <listitem>
 257                                         <para>A special target unit
 258                                         that pulls in all local TTY
 259                                         <filename>getty</filename> instances.
 260                                         </para>
 261                                 </listitem>
 262                         </varlistentry>
 263                         <varlistentry>
 264                                 <term><filename>graphical.target</filename></term>
 265                                 <listitem>
 266                                         <para>A special target unit
 267                                         for setting up a graphical
 268                                         login screen. This pulls in
 269                                         <filename>multi-user.target</filename>.</para>
 270
 271                                         <para>Units that are needed
 272                                         for graphical login shall add
 273                                         Wants dependencies for their
 274                                         unit to this unit (or
 275                                         <filename>multi-user.target</filename>)
 276                                         during installation.</para>
 277                                 </listitem>
 278                         </varlistentry>
 279                         <varlistentry>
 280                                 <term><filename>hibernate.target</filename></term>
 281                                 <listitem>
 282                                         <para>A special target unit
 283                                         for hibernating the
 284                                         system. This pulls in
 285                                         <filename>sleep.target</filename>.</para>
 286                                 </listitem>
 287                         </varlistentry>
 288                         <varlistentry>
 289                                 <term><filename>hybrid-sleep.target</filename></term>
 290                                 <listitem>
 291                                         <para>A special target unit
 292                                         for hibernating and suspending the
 293                                         system at the same time. This pulls in
 294                                         <filename>sleep.target</filename>.</para>
 295                                 </listitem>
 296                         </varlistentry>
 297                         <varlistentry>
 298                                 <term><filename>halt.target</filename></term>
 299                                 <listitem>
 300                                         <para>A special target unit
 301                                         for shutting down and halting the system.</para>
 302
 303                                         <para>Applications wanting to
 304                                         halt the system should start
 305                                         this unit.</para>
 306                                 </listitem>
 307                         </varlistentry>
 308                         <varlistentry>
 309                                 <term><filename>kbrequest.target</filename></term>
 310                                 <listitem>
 311                                         <para>systemd starts this
 312                                         target whenever Alt+ArrowUp is
 313                                         pressed on the console. This
 314                                         is a good candidate to be
 315                                         aliased (symlinked) to
 316                                         <filename>rescue.target</filename>.</para>
 317                                 </listitem>
 318                         </varlistentry>
 319                         <varlistentry>
 320                                 <term><filename>kexec.target</filename></term>
 321                                 <listitem>
 322                                         <para>A special target unit
 323                                         for shutting down and rebooting the system via kexec.</para>
 324
 325                                         <para>Applications wanting to
 326                                         reboot the system with kexec should start
 327                                         this unit.</para>
 328                                 </listitem>
 329                         </varlistentry>
 330                         <varlistentry>
 331                                 <term><filename>local-fs.target</filename></term>
 332                                 <listitem>
 333                                         <para>systemd automatically
 334                                         adds dependencies of type
 335                                         After to all mount units that
 336                                         refer to local mount points
 337                                         for this target unit. In
 338                                         addition, systemd adds
 339                                         dependencies of type Wants to
 340                                         this target unit for those
 341                                         mounts listed in
 342                                         <filename>/etc/fstab</filename>
 343                                         that have the
 344                                         <option>auto</option> and
 345                                         <option>comment=systemd.mount</option>
 346                                         mount options set.</para>
 347
 348                                         <para>systemd automatically
 349                                         adds dependencies of type
 350                                         After for this target unit to
 351                                         all SysV init script service
 352                                         units with an LSB header
 353                                         referring to the
 354                                         <literal>$local_fs</literal>
 355                                         facility.</para>
 356                                 </listitem>
 357                         </varlistentry>
 358                         <varlistentry>
 359                                 <term><filename>local-fs-pre.target</filename></term>
 360                                 <listitem>
 361                                         <para>This target unit is
 362                                         automatically ordered before
 363                                         all local mount points marked
 364                                         with <option>auto</option>
 365                                         (see above). It can be used to
 366                                         execute certain units before
 367                                         all local mounts.</para>
 368                                 </listitem>
 369                         </varlistentry>
 370                         <varlistentry>
 371                                 <term><filename>mail-transfer-agent.target</filename></term>
 372                                 <listitem>
 373                                         <para>The mail transfer agent
 374                                         (MTA) service. Usually this
 375                                         should pull-in all units
 376                                         necessary for
 377                                         sending/receiving mails on the
 378                                         local host.</para>
 379
 380                                         <para>systemd automatically
 381                                         adds dependencies of type
 382                                         After for this target unit to
 383                                         all SysV init script service
 384                                         units with an LSB header
 385                                         referring to the
 386                                         <literal>$mail-transfer-agent</literal>.</para>
 387                                 </listitem>
 388                         </varlistentry>
 389                         <varlistentry>
 390                                 <term><filename>multi-user.target</filename></term>
 391                                 <listitem>
 392                                         <para>A special target unit
 393                                         for setting up a multi-user
 394                                         system (non-graphical). This
 395                                         is pulled in by
 396                                         <filename>graphical.target</filename>.</para>
 397
 398                                         <para>Units that are needed
 399                                         for a multi-user system shall
 400                                         add Wants dependencies to
 401                                         this unit for their unit during
 402                                         installation.</para>
 403                                 </listitem>
 404                         </varlistentry>
 405                         <varlistentry>
 406                                 <term><filename>network.target</filename></term>
 407                                 <listitem>
 408                                         <para>systemd automatically
 409                                         adds dependencies of type
 410                                         After for this target unit to
 411                                         all SysV init script service
 412                                         units with an LSB header
 413                                         referring to the
 414                                         <literal>$network</literal>
 415                                         facility.</para>
 416                                 </listitem>
 417                         </varlistentry>
 418                         <varlistentry>
 419                                 <term><filename>nss-lookup.target</filename></term>
 420                                 <listitem>
 421                                         <para>A target that should be
 422                                         used as synchronization point
 423                                         for all host/network name
 424                                         service lookups. Note that
 425                                         this is independent of
 426                                         user/group name lookups for
 427                                         which
 428                                         <filename>nss-user-lookup.target</filename>
 429                                         should be used. systemd
 430                                         automatically adds
 431                                         dependencies of type After for
 432                                         this target unit to all SysV
 433                                         init script service units with
 434                                         an LSB header referring to the
 435                                         <literal>$named</literal>
 436                                         facility.</para>
 437                                 </listitem>
 438                         </varlistentry>
 439                         <varlistentry>
 440                                 <term><filename>nss-user-lookup.target</filename></term>
 441                                 <listitem>
 442                                         <para>A target that should be
 443                                         used as synchronization point
 444                                         for all user/group name
 445                                         service lookups. Note that
 446                                         this is independent of
 447                                         host/network name lookups for
 448                                         which
 449                                         <filename>nss-lookup.target</filename>
 450                                         should be used. </para>
 451                                 </listitem>
 452                         </varlistentry>
 453                         <varlistentry>
 454                                 <term><filename>poweroff.target</filename></term>
 455                                 <listitem>
 456                                         <para>A special target unit
 457                                         for shutting down and powering off the system.</para>
 458
 459                                         <para>Applications wanting to
 460                                         power off the system should start
 461                                         this unit.</para>
 462
 463                                         <para><filename>runlevel0.target</filename>
 464                                         is an alias for this target
 465                                         unit, for compatibility with SysV.</para>
 466                                 </listitem>
 467                         </varlistentry>
 468                         <varlistentry>
 469                                 <term><filename>printer.target</filename></term>
 470                                 <listitem>
 471                                         <para>This target is started
 472                                         automatically as soon as a
 473                                         printer is plugged in or
 474                                         becomes available at
 475                                         boot.</para>
 476                                 </listitem>
 477                         </varlistentry>
 478                         <varlistentry>
 479                                 <term><filename>reboot.target</filename></term>
 480                                 <listitem>
 481                                         <para>A special target unit
 482                                         for shutting down and rebooting the system.</para>
 483
 484                                         <para>Applications wanting to
 485                                         reboot the system should start
 486                                         this unit.</para>
 487
 488                                         <para><filename>runlevel6.target</filename>
 489                                         is an alias for this target
 490                                         unit, for compatibility with SysV.</para>
 491                                 </listitem>
 492                         </varlistentry>
 493                         <varlistentry>
 494                                 <term><filename>remote-fs.target</filename></term>
 495                                 <listitem>
 496                                         <para>Similar to
 497                                         <filename>local-fs.target</filename>,
 498                                         but for remote mount
 499                                         points.</para>
 500
 501                                         <para>systemd automatically
 502                                         adds dependencies of type
 503                                         After for this target unit to
 504                                         all SysV init script service
 505                                         units with an LSB header
 506                                         referring to the
 507                                         <literal>$remote_fs</literal>
 508                                         facility.</para>
 509                                 </listitem>
 510                         </varlistentry>
 511                         <varlistentry>
 512                                 <term><filename>remote-fs-pre.target</filename></term>
 513                                 <listitem>
 514                                         <para>This target unit is
 515                                         automatically ordered before
 516                                         all remote mount points marked
 517                                         with <option>auto</option>
 518                                         (see above). It can be used to
 519                                         execute certain units before
 520                                         all remote mounts.</para>
 521                                 </listitem>
 522                         </varlistentry>
 523                         <varlistentry>
 524                                 <term><filename>rescue.target</filename></term>
 525                                 <listitem>
 526                                         <para>A special target unit
 527                                         for setting up the base system
 528                                         and a rescue shell.</para>
 529
 530                                         <para><filename>runlevel1.target</filename>
 531                                         is an alias for this target
 532                                         unit, for compatibility with SysV.</para>
 533                                 </listitem>
 534                         </varlistentry>
 535                         <varlistentry>
 536                                 <term><filename>rpcbind.target</filename></term>
 537                                 <listitem>
 538                                         <para>systemd automatically
 539                                         adds dependencies of type
 540                                         After for this target unit to
 541                                         all SysV init script service
 542                                         units with an LSB header
 543                                         referring to the
 544                                         <literal>$portmap</literal>
 545                                         facility.</para>
 546                                 </listitem>
 547                         </varlistentry>
 548                         <varlistentry>
 549                                 <term><filename>runlevel2.target</filename></term>
 550                                 <term><filename>runlevel3.target</filename></term>
 551                                 <term><filename>runlevel4.target</filename></term>
 552                                 <term><filename>runlevel5.target</filename></term>
 553                                 <listitem>
 554                                         <para>These are targets that
 555                                         are called whenever the SysV
 556                                         compatibility code asks for
 557                                         runlevel 2, 3, 4, 5,
 558                                         respectively. It is a good
 559                                         idea to make this an alias for
 560                                         (i.e. symlink to)
 561                                         <filename>multi-user.target</filename>
 562                                         (for runlevel 2) or
 563                                         <filename>graphical.target</filename>
 564                                         (the others).</para>
 565                                 </listitem>
 566                         </varlistentry>
 567                         <varlistentry>
 568                                 <term><filename>shutdown.target</filename></term>
 569                                 <listitem>
 570                                         <para>A special target unit
 571                                         that terminates the services
 572                                         on system shutdown.</para>
 573
 574                                         <para>Services that shall be
 575                                         terminated on system shutdown
 576                                         shall add Conflicts
 577                                         dependencies to this unit for
 578                                         their service unit, which is
 579                                         implicitly done when
 580                                         <varname>DefaultDependencies=yes</varname>
 581                                         is set (the default).</para>
 582
 583                                         <para>systemd automatically
 584                                         adds dependencies of type
 585                                         Conflicts to this target unit
 586                                         for all SysV init script
 587                                         service units that shall be
 588                                         terminated in SysV runlevels 0
 589                                         or 6.</para>
 590                                 </listitem>
 591                         </varlistentry>
 592                         <varlistentry>
 593                                 <term><filename>sigpwr.target</filename></term>
 594                                 <listitem>
 595                                         <para>A special target that is
 596                                         started when systemd receives
 597                                         the SIGPWR process signal,
 598                                         which is normally sent by the
 599                                         kernel or UPS daemons when
 600                                         power fails.</para>
 601                                 </listitem>
 602                         </varlistentry>
 603                         <varlistentry>
 604                                 <term><filename>sleep.target</filename></term>
 605                                 <listitem>
 606                                         <para>A special target unit
 607                                         that is pulled in by
 608                                         <filename>suspend.target</filename>,
 609                                         <filename>hibernate.target</filename> and <filename>hybrid-sleep.target</filename>
 610                                         and may be used to hook units
 611                                         into the sleep state
 612                                         logic.</para>
 613                                 </listitem>
 614                         </varlistentry>
 615                         <varlistentry>
 616                                 <term><filename>smartcard.target</filename></term>
 617                                 <listitem>
 618                                         <para>This target is started
 619                                         automatically as soon as a
 620                                         smartcard controller is
 621                                         plugged in or becomes
 622                                         available at boot.</para>
 623                                 </listitem>
 624                         </varlistentry>
 625                         <varlistentry>
 626                                 <term><filename>sockets.target</filename></term>
 627                                 <listitem>
 628                                         <para>A special target unit
 629                                         that sets up all service
 630                                         sockets.</para>
 631
 632                                         <para>Services that can be
 633                                         socket-activated shall add
 634                                         Wants dependencies to this
 635                                         unit for their socket unit
 636                                         during installation.</para>
 637                                 </listitem>
 638                         </varlistentry>
 639                         <varlistentry>
 640                                 <term><filename>sound.target</filename></term>
 641                                 <listitem>
 642                                         <para>This target is started
 643                                         automatically as soon as a
 644                                         sound card is plugged in or
 645                                         becomes available at
 646                                         boot.</para>
 647                                 </listitem>
 648                         </varlistentry>
 649                         <varlistentry>
 650                                 <term><filename>suspend.target</filename></term>
 651                                 <listitem>
 652                                         <para>A special target unit
 653                                         for suspending the
 654                                         system. This pulls in
 655                                         <filename>sleep.target</filename>.</para>
 656                                 </listitem>
 657                         </varlistentry>
 658                         <varlistentry>
 659                                 <term><filename>swap.target</filename></term>
 660                                 <listitem>
 661                                         <para>Similar to
 662                                         <filename>local-fs.target</filename>, but for swap
 663                                         partitions and swap
 664                                         files.</para>
 665                                 </listitem>
 666                         </varlistentry>
 667                         <varlistentry>
 668                                 <term><filename>sysinit.target</filename></term>
 669                                 <listitem>
 670                                         <para>A special target unit
 671                                         covering early boot-up scripts.</para>
 672                                         <para>systemd automatically
 673                                         adds dependencies of the types
 674                                         Wants and After for all
 675                                         SysV service units configured
 676                                         for runlevels that are not 0
 677                                         to 6 to this target unit.
 678                                         This covers the special
 679                                         boot-up runlevels some
 680                                         distributions have, such as S
 681                                         or b.</para>
 682                                 </listitem>
 683                         </varlistentry>
 684                         <varlistentry>
 685                                 <term><filename>syslog.socket</filename></term>
 686                                 <listitem>
 687                                         <para>The socket unit
 688                                         syslog implementations should
 689                                         listen on. All userspace log
 690                                         messages will be made
 691                                         available on this socket. For
 692                                         more information about syslog
 693                                         integration, please consult
 694                                         the <ulink
 695                                         url="http://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog
 696                                         Interface</ulink>
 697                                         document.</para>
 698                                 </listitem>
 699                         </varlistentry>
 700                         <varlistentry>
 701                                 <term><filename>syslog.target</filename></term>
 702                                 <listitem>
 703                                         <para>systemd automatically
 704                                         adds dependencies of type
 705                                         After for this target unit to
 706                                         all SysV init script service
 707                                         units with an LSB header
 708                                         referring to the
 709                                         <literal>$syslog</literal>
 710                                         facility.</para>
 711                                 </listitem>
 712                         </varlistentry>
 713                         <varlistentry>
 714                                 <term><filename>system-update.target</filename></term>
 715                                 <listitem>
 716                                         <para>A special target unit
 717                                         that is used for off-line
 718                                         system updates.
 719                                         <citerefentry><refentrytitle>systemd-system-update-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 720                                         will redirect the boot process
 721                                         to this target if
 722                                         <filename>/system-update</filename>
 723                                         exists. For more information
 724                                         see the <ulink
 725                                         url="http://freedesktop.org/wiki/Software/systemd/SystemUpdates">System
 726                                         Updates
 727                                         Specification</ulink>.</para>
 728                                 </listitem>
 729                         </varlistentry>
 730                         <varlistentry>
 731                                 <term><filename>time-sync.target</filename></term>
 732                                 <listitem>
 733                                         <para>systemd automatically
 734                                         adds dependencies of type
 735                                         After for this target unit to
 736                                         all SysV init script service
 737                                         units with an LSB header
 738                                         referring to the
 739                                         <literal>$time</literal>
 740                                         facility.</para>
 741                                 </listitem>
 742                         </varlistentry>
 743                         <varlistentry>
 744                                 <term><filename>umount.target</filename></term>
 745                                 <listitem>
 746                                         <para>A special target unit
 747                                         that umounts all mount and
 748                                         automount points on system
 749                                         shutdown.</para>
 750
 751                                         <para>Mounts that shall be
 752                                         unmounted on system shutdown
 753                                         shall add Conflicts
 754                                         dependencies to this unit for
 755                                         their mount unit, which is
 756                                         implicitly done when
 757                                         <varname>DefaultDependencies=yes</varname>
 758                                         is set (the default).</para>
 759                                 </listitem>
 760                         </varlistentry>
 761
 762                 </variablelist>
 763         </refsect1>
 764
 765         <refsect1>
 766                 <title>Special User Units</title>
 767
 768                 <para>When systemd runs as a user instance, the
 769                 following special units are available, which have
 770                 similar definitions as their system counterparts:
 771                 <filename>default.target</filename>,
 772                 <filename>shutdown.target</filename>,
 773                 <filename>sockets.target</filename></para>
 774
 775                 <para>In addition the following special unit is
 776                 understood only when systemd runs as service instance:</para>
 777
 778                 <variablelist>
 779                         <varlistentry>
 780                                 <term><filename>exit.target</filename></term>
 781                                 <listitem>
 782                                         <para>A special service unit
 783                                         for shutting down the
 784                                         user service manager.</para>
 785
 786                                         <para>Applications wanting to
 787                                         terminate the user service
 788                                         manager should start this
 789                                         unit. If systemd receives
 790                                         SIGTERM or SIGINT when running
 791                                         as user service daemon it will
 792                                         start this unit.</para>
 793
 794                                         <para>Normally, this pulls in
 795                                         <filename>shutdown.target</filename>
 796                                         which in turn should be
 797                                         conflicted by all units that
 798                                         want to be shut down on
 799                                         user service manager exit.</para>
 800                                 </listitem>
 801                         </varlistentry>
 802                 </variablelist>
 803         </refsect1>
 804
 805         <refsect1>
 806                   <title>See Also</title>
 807                   <para>
 808                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 809                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 810                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 811                           <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 812                           <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 813                           <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 814                   </para>
 815         </refsect1>
 816
 817 </refentry>