man/systemd.special.html

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  18   </style><a href="index.html">Index </a>·
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  22   <a href="../libudev/index.html">gudev </a><span style="float:right">systemd 217</span><hr><div class="refentry"><a name="systemd.special"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>systemd.special — Special systemd units</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><p><code class="filename">basic.target</code>,
  23                 <code class="filename">bluetooth.target</code>,
  24                 <code class="filename">ctrl-alt-del.target</code>,
  25                 <code class="filename">cryptsetup.target</code>,
  26                 <code class="filename">cryptsetup-pre.target</code>,
  27                 <code class="filename">dbus.service</code>,
  28                 <code class="filename">dbus.socket</code>,
  29                 <code class="filename">default.target</code>,
  30                 <code class="filename">display-manager.service</code>,
  31                 <code class="filename">emergency.target</code>,
  32                 <code class="filename">exit.target</code>,
  33                 <code class="filename">final.target</code>,
  34                 <code class="filename">getty.target</code>,
  35                 <code class="filename">graphical.target</code>,
  36                 <code class="filename">halt.target</code>,
  37                 <code class="filename">hibernate.target</code>,
  38                 <code class="filename">hybrid-sleep.target</code>,
  39                 <code class="filename">initrd-fs.target</code>,
  40                 <code class="filename">kbrequest.target</code>,
  41                 <code class="filename">kexec.target</code>,
  42                 <code class="filename">local-fs.target</code>,
  43                 <code class="filename">local-fs-pre.target</code>,
  44                 <code class="filename">multi-user.target</code>,
  45                 <code class="filename">network.target</code>,
  46                 <code class="filename">network-online.target</code>,
  47                 <code class="filename">network-pre.target</code>,
  48                 <code class="filename">nss-lookup.target</code>,
  49                 <code class="filename">nss-user-lookup.target</code>,
  50                 <code class="filename">paths.target</code>,
  51                 <code class="filename">poweroff.target</code>,
  52                 <code class="filename">printer.target</code>,
  53                 <code class="filename">reboot.target</code>,
  54                 <code class="filename">remote-fs.target</code>,
  55                 <code class="filename">remote-fs-pre.target</code>,
  56                 <code class="filename">rescue.target</code>,
  57                 <code class="filename">initrd-root-fs.target</code>,
  58                 <code class="filename">rpcbind.target</code>,
  59                 <code class="filename">runlevel2.target</code>,
  60                 <code class="filename">runlevel3.target</code>,
  61                 <code class="filename">runlevel4.target</code>,
  62                 <code class="filename">runlevel5.target</code>,
  63                 <code class="filename">shutdown.target</code>,
  64                 <code class="filename">sigpwr.target</code>,
  65                 <code class="filename">sleep.target</code>,
  66                 <code class="filename">smartcard.target</code>,
  67                 <code class="filename">sockets.target</code>,
  68                 <code class="filename">sound.target</code>,
  69                 <code class="filename">suspend.target</code>,
  70                 <code class="filename">swap.target</code>,
  71                 <code class="filename">sysinit.target</code>,
  72                 <code class="filename">syslog.socket</code>,
  73                 <code class="filename">system-update.target</code>,
  74                 <code class="filename">time-sync.target</code>,
  75                 <code class="filename">timers.target</code>,
  76                 <code class="filename">umount.target</code>,
  77                 <code class="filename">-.slice</code>,
  78                 <code class="filename">system.slice</code>,
  79                 <code class="filename">user.slice</code>,
  80                 <code class="filename">machine.slice</code></p></div><div class="refsect1"><a name="idm214170466816"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p>A few units are treated specially by
  81                 systemd. They have special internal semantics and
  82                 cannot be renamed.</p></div><div class="refsect1"><a name="idm214170465472"></a><h2 id="Special System Units">Special System Units<a class="headerlink" title="Permalink to this headline" href="#Special%20System%20Units">¶</a></h2><div class="variablelist"><dl class="variablelist"><dt id="basic.target"><span class="term"><code class="filename">basic.target</code></span><a class="headerlink" title="Permalink to this term" href="#basic.target">¶</a></dt><dd><p>A special target unit
  83                                         covering basic boot-up.</p><p>systemd automatically
  84                                         adds dependencies of the types
  85                                         <code class="varname">Requires=</code>
  86                                         and <code class="varname">After=</code>
  87                                         for this target unit to all
  88                                         services (except for those
  89                                         with
  90                                         <code class="varname">DefaultDependencies=no</code>).</p><p>Usually this should
  91                                         pull-in all mount points, swap
  92                                         devices, sockets, timers, and
  93                                         path units and other basic
  94                                         initialization necessary for
  95                                         general purpose
  96                                         daemons.</p></dd><dt id="ctrl-alt-del.target"><span class="term"><code class="filename">ctrl-alt-del.target</code></span><a class="headerlink" title="Permalink to this term" href="#ctrl-alt-del.target">¶</a></dt><dd><p>systemd starts this
  97                                         target whenever
  98                                         Control+Alt+Del is pressed on
  99                                         the console. Usually this
 100                                         should be aliased (symlinked)
 101                                         to
 102                                         <code class="filename">reboot.target</code>.</p></dd><dt id="cryptsetup.target"><span class="term"><code class="filename">cryptsetup.target</code></span><a class="headerlink" title="Permalink to this term" href="#cryptsetup.target">¶</a></dt><dd><p>A target that pulls in
 103                                         setup services for all
 104                                         encrypted block
 105                                         devices.</p></dd><dt id="dbus.service"><span class="term"><code class="filename">dbus.service</code></span><a class="headerlink" title="Permalink to this term" href="#dbus.service">¶</a></dt><dd><p>A special unit for the
 106                                         D-Bus bus daemon. As soon as
 107                                         this service is fully started
 108                                         up systemd will connect to it
 109                                         and register its
 110                                         service.</p></dd><dt id="dbus.socket"><span class="term"><code class="filename">dbus.socket</code></span><a class="headerlink" title="Permalink to this term" href="#dbus.socket">¶</a></dt><dd><p>A special unit for the
 111                                         D-Bus system bus socket. All
 112                                         units with
 113                                         <code class="varname">Type=dbus</code>
 114                                         automatically gain a
 115                                         dependency on this
 116                                         unit.</p></dd><dt id="default.target"><span class="term"><code class="filename">default.target</code></span><a class="headerlink" title="Permalink to this term" href="#default.target">¶</a></dt><dd><p>The default unit systemd
 117                                         starts at bootup. Usually this
 118                                         should be aliased (symlinked)
 119                                         to
 120                                         <code class="filename">multi-user.target</code>
 121                                         or
 122                                         <code class="filename">graphical.target</code>.</p><p>The default unit systemd
 123                                         starts at bootup can be
 124                                         overridden with the
 125                                         <code class="varname">systemd.unit=</code>
 126                                         kernel command line option.</p></dd><dt id="display-manager.service"><span class="term"><code class="filename">display-manager.service</code></span><a class="headerlink" title="Permalink to this term" href="#display-manager.service">¶</a></dt><dd><p>The display manager
 127                                         service. Usually this should
 128                                         be aliased (symlinked) to
 129                                         <code class="filename">gdm.service</code>
 130                                         or a similar display manager
 131                                         service.</p></dd><dt id="emergency.target"><span class="term"><code class="filename">emergency.target</code></span><a class="headerlink" title="Permalink to this term" href="#emergency.target">¶</a></dt><dd><p>A special target unit
 132                                         that starts an emergency
 133                                         shell on the main
 134                                         console. This unit is supposed
 135                                         to be used with the kernel
 136                                         command line option
 137                                         <code class="varname">systemd.unit=</code>
 138                                         and has otherwise little use.
 139                                         </p></dd><dt id="final.target"><span class="term"><code class="filename">final.target</code></span><a class="headerlink" title="Permalink to this term" href="#final.target">¶</a></dt><dd><p>A special target unit
 140                                         that is used during the
 141                                         shutdown logic and may be used
 142                                         to pull in late services after
 143                                         all normal services are
 144                                         already terminated and all
 145                                         mounts unmounted.
 146                                         </p></dd><dt id="getty.target"><span class="term"><code class="filename">getty.target</code></span><a class="headerlink" title="Permalink to this term" href="#getty.target">¶</a></dt><dd><p>A special target unit
 147                                         that pulls in statically
 148                                         configured local TTY
 149                                         <code class="filename">getty</code>
 150                                         instances.
 151                                         </p></dd><dt id="graphical.target"><span class="term"><code class="filename">graphical.target</code></span><a class="headerlink" title="Permalink to this term" href="#graphical.target">¶</a></dt><dd><p>A special target unit
 152                                         for setting up a graphical
 153                                         login screen. This pulls in
 154                                         <code class="filename">multi-user.target</code>.</p><p>Units that are needed
 155                                         for graphical logins shall add
 156                                         <code class="varname">Wants=</code>
 157                                         dependencies for their unit to
 158                                         this unit (or
 159                                         <code class="filename">multi-user.target</code>)
 160                                         during installation. This is
 161                                         best configured via
 162                                         <code class="varname">WantedBy=graphical.target</code>
 163                                         in the unit's
 164                                         "<code class="literal">[Install]</code>"
 165                                         section.</p></dd><dt id="hibernate.target"><span class="term"><code class="filename">hibernate.target</code></span><a class="headerlink" title="Permalink to this term" href="#hibernate.target">¶</a></dt><dd><p>A special target unit
 166                                         for hibernating the
 167                                         system. This pulls in
 168                                         <code class="filename">sleep.target</code>.</p></dd><dt id="hybrid-sleep.target"><span class="term"><code class="filename">hybrid-sleep.target</code></span><a class="headerlink" title="Permalink to this term" href="#hybrid-sleep.target">¶</a></dt><dd><p>A special target unit
 169                                         for hibernating and suspending the
 170                                         system at the same time. This pulls in
 171                                         <code class="filename">sleep.target</code>.</p></dd><dt id="halt.target"><span class="term"><code class="filename">halt.target</code></span><a class="headerlink" title="Permalink to this term" href="#halt.target">¶</a></dt><dd><p>A special target unit
 172                                         for shutting down and halting
 173                                         the system. Note that this
 174                                         target is distinct from
 175                                         <code class="filename">poweroff.target</code>
 176                                         in that it generally really
 177                                         just halts the system rather
 178                                         than powering it down.</p><p>Applications wanting to
 179                                         halt the system should start
 180                                         this unit.</p></dd><dt id="initrd-fs.target"><span class="term"><code class="filename">initrd-fs.target</code></span><a class="headerlink" title="Permalink to this term" href="#initrd-fs.target">¶</a></dt><dd><p><a href="systemd-fstab-generator.html"><span class="citerefentry"><span class="refentrytitle">systemd-fstab-generator</span>(3)</span></a>
 181                                         automatically adds
 182                                         dependencies of type
 183                                         <code class="varname">Before=</code> to
 184                                         <code class="filename">sysroot-usr.mount</code>
 185                                         and all mount points found in
 186                                         <code class="filename">/etc/fstab</code>
 187                                         that have
 188                                         <code class="option">x-initrd.mount</code>
 189                                         and not have <code class="option">noauto</code>
 190                                         mount options set.</p></dd><dt id="kbrequest.target"><span class="term"><code class="filename">kbrequest.target</code></span><a class="headerlink" title="Permalink to this term" href="#kbrequest.target">¶</a></dt><dd><p>systemd starts this
 191                                         target whenever Alt+ArrowUp is
 192                                         pressed on the console. This
 193                                         is a good candidate to be
 194                                         aliased (symlinked) to
 195                                         <code class="filename">rescue.target</code>.</p></dd><dt id="kexec.target"><span class="term"><code class="filename">kexec.target</code></span><a class="headerlink" title="Permalink to this term" href="#kexec.target">¶</a></dt><dd><p>A special target unit
 196                                         for shutting down and rebooting the system via kexec.</p><p>Applications wanting to
 197                                         reboot the system with kexec should start
 198                                         this unit.</p></dd><dt id="local-fs.target"><span class="term"><code class="filename">local-fs.target</code></span><a class="headerlink" title="Permalink to this term" href="#local-fs.target">¶</a></dt><dd><p><a href="systemd-fstab-generator.html"><span class="citerefentry"><span class="refentrytitle">systemd-fstab-generator</span>(3)</span></a>
 199                                         automatically adds
 200                                         dependencies of type
 201                                         <code class="varname">Before=</code> to
 202                                         all mount units that refer to
 203                                         local mount points for this
 204                                         target unit. In addition, it
 205                                         adds dependencies of type
 206                                         <code class="varname">Wants=</code> to
 207                                         this target unit for those
 208                                         mounts listed in
 209                                         <code class="filename">/etc/fstab</code>
 210                                         that have the
 211                                         <code class="option">auto</code> mount
 212                                         option set.</p></dd><dt id="multi-user.target"><span class="term"><code class="filename">multi-user.target</code></span><a class="headerlink" title="Permalink to this term" href="#multi-user.target">¶</a></dt><dd><p>A special target unit
 213                                         for setting up a multi-user
 214                                         system (non-graphical). This
 215                                         is pulled in by
 216                                         <code class="filename">graphical.target</code>.</p><p>Units that are needed
 217                                         for a multi-user system shall
 218                                         add <code class="varname">Wants=</code>
 219                                         dependencies for their unit to
 220                                         this unit during
 221                                         installation. This is best
 222                                         configured via
 223                                         <code class="varname">WantedBy=multi-user.target</code>
 224                                         in the unit's
 225                                         "<code class="literal">[Install]</code>"
 226                                         section.</p></dd><dt id="network-online.target"><span class="term"><code class="filename">network-online.target</code></span><a class="headerlink" title="Permalink to this term" href="#network-online.target">¶</a></dt><dd><p>Units that strictly
 227                                         require a configured network
 228                                         connection should pull in
 229                                         <code class="filename">network-online.target</code>
 230                                         (via a
 231                                         <code class="varname">Wants=</code> type
 232                                         dependency) and order
 233                                         themselves after it. This
 234                                         target unit is intended to
 235                                         pull in a service that delays
 236                                         further execution until the
 237                                         network is sufficiently set
 238                                         up. What precisely this
 239                                         requires is left to the
 240                                         implementation of the network
 241                                         managing service.</p><p>Note the distinction
 242                                         between this unit and
 243                                         <code class="filename">network.target</code>. This
 244                                         unit is an active unit
 245                                         (i.e. pulled in by the
 246                                         consumer rather than the
 247                                         provider of this
 248                                         functionality) and pulls in a
 249                                         service which possibly adds
 250                                         substantial delays to further
 251                                         execution. In contrast,
 252                                         <code class="filename">network.target</code>
 253                                         is a passive unit (i.e. pulled
 254                                         in by the provider of the
 255                                         functionality, rather than the
 256                                         consumer) that usually does
 257                                         not delay execution
 258                                         much. Usually,
 259                                         <code class="filename">network.target</code>
 260                                         is part of the boot of most
 261                                         systems, while
 262                                         <code class="filename">network-online.target</code>
 263                                         is not, except when at least
 264                                         one unit requires it. Also see
 265                                         <a class="ulink" href="http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget" target="_top">Running
 266                                         Services After the Network is
 267                                         up</a> for more
 268                                         information.</p><p>All mount units for
 269                                         remote network file systems
 270                                         automatically pull in this
 271                                         unit, and order themselves
 272                                         after it. Note that networking
 273                                         daemons that simply provide
 274                                         functionality to other hosts
 275                                         generally do not need to pull
 276                                         this in.</p></dd><dt id="paths.target"><span class="term"><code class="filename">paths.target</code></span><a class="headerlink" title="Permalink to this term" href="#paths.target">¶</a></dt><dd><p>A special target unit
 277                                         that sets up all path units
 278                                         (see
 279                                         <a href="systemd.path.html"><span class="citerefentry"><span class="refentrytitle">systemd.path</span>(5)</span></a>
 280                                         for details) that shall be
 281                                         active after boot.</p><p>It is recommended that
 282                                         path units installed by
 283                                         applications get pulled in via
 284                                         <code class="varname">Wants=</code>
 285                                         dependencies from this
 286                                         unit. This is best configured
 287                                         via a
 288                                         <code class="varname">WantedBy=paths.target</code>
 289                                         in the path unit's
 290                                         "<code class="literal">[Install]</code>"
 291                                         section.</p></dd><dt id="poweroff.target"><span class="term"><code class="filename">poweroff.target</code></span><a class="headerlink" title="Permalink to this term" href="#poweroff.target">¶</a></dt><dd><p>A special target unit
 292                                         for shutting down and powering off the system.</p><p>Applications wanting to
 293                                         power off the system should start
 294                                         this unit.</p><p><code class="filename">runlevel0.target</code>
 295                                         is an alias for this target
 296                                         unit, for compatibility with SysV.</p></dd><dt id="reboot.target"><span class="term"><code class="filename">reboot.target</code></span><a class="headerlink" title="Permalink to this term" href="#reboot.target">¶</a></dt><dd><p>A special target unit
 297                                         for shutting down and rebooting the system.</p><p>Applications wanting to
 298                                         reboot the system should start
 299                                         this unit.</p><p><code class="filename">runlevel6.target</code>
 300                                         is an alias for this target
 301                                         unit, for compatibility with SysV.</p></dd><dt id="remote-fs.target"><span class="term"><code class="filename">remote-fs.target</code></span><a class="headerlink" title="Permalink to this term" href="#remote-fs.target">¶</a></dt><dd><p>Similar to
 302                                         <code class="filename">local-fs.target</code>,
 303                                         but for remote mount
 304                                         points.</p><p>systemd automatically
 305                                         adds dependencies of type
 306                                         <code class="varname">After=</code> for
 307                                         this target unit to all SysV
 308                                         init script service units with
 309                                         an LSB header referring to the
 310                                         "<code class="literal">$remote_fs</code>"
 311                                         facility.</p></dd><dt id="rescue.target"><span class="term"><code class="filename">rescue.target</code></span><a class="headerlink" title="Permalink to this term" href="#rescue.target">¶</a></dt><dd><p>A special target unit
 312                                         for setting up the base system
 313                                         and a rescue shell.</p><p><code class="filename">runlevel1.target</code>
 314                                         is an alias for this target
 315                                         unit, for compatibility with SysV.</p></dd><dt id="initrd-root-fs.target"><span class="term"><code class="filename">initrd-root-fs.target</code></span><a class="headerlink" title="Permalink to this term" href="#initrd-root-fs.target">¶</a></dt><dd><p><a href="systemd-fstab-generator.html"><span class="citerefentry"><span class="refentrytitle">systemd-fstab-generator</span>(3)</span></a>
 316                                         automatically adds
 317                                         dependencies of type
 318                                         <code class="varname">Before=</code> to
 319                                         the
 320                                         <code class="filename">sysroot.mount</code>
 321                                         unit, which is generated from
 322                                         the kernel command line.
 323                                         </p></dd><dt id="runlevel2.target"><span class="term"><code class="filename">runlevel2.target</code>, </span><span class="term"><code class="filename">runlevel3.target</code>, </span><span class="term"><code class="filename">runlevel4.target</code>, </span><span class="term"><code class="filename">runlevel5.target</code></span><a class="headerlink" title="Permalink to this term" href="#runlevel2.target">¶</a></dt><dd><p>These are targets that
 324                                         are called whenever the SysV
 325                                         compatibility code asks for
 326                                         runlevel 2, 3, 4, 5,
 327                                         respectively. It is a good
 328                                         idea to make this an alias for
 329                                         (i.e. symlink to)
 330                                         <code class="filename">multi-user.target</code>
 331                                         (for runlevel 2) or
 332                                         <code class="filename">graphical.target</code>
 333                                         (the others).</p></dd><dt id="shutdown.target"><span class="term"><code class="filename">shutdown.target</code></span><a class="headerlink" title="Permalink to this term" href="#shutdown.target">¶</a></dt><dd><p>A special target unit
 334                                         that terminates the services
 335                                         on system shutdown.</p><p>Services that shall be
 336                                         terminated on system shutdown
 337                                         shall add <code class="varname">Conflicts=</code>
 338                                         dependencies to this unit for
 339                                         their service unit, which is
 340                                         implicitly done when
 341                                         <code class="varname">DefaultDependencies=yes</code>
 342                                         is set (the default).</p></dd><dt id="sigpwr.target"><span class="term"><code class="filename">sigpwr.target</code></span><a class="headerlink" title="Permalink to this term" href="#sigpwr.target">¶</a></dt><dd><p>A special target that is
 343                                         started when systemd receives
 344                                         the SIGPWR process signal,
 345                                         which is normally sent by the
 346                                         kernel or UPS daemons when
 347                                         power fails.</p></dd><dt id="sleep.target"><span class="term"><code class="filename">sleep.target</code></span><a class="headerlink" title="Permalink to this term" href="#sleep.target">¶</a></dt><dd><p>A special target unit
 348                                         that is pulled in by
 349                                         <code class="filename">suspend.target</code>,
 350                                         <code class="filename">hibernate.target</code>
 351                                         and
 352                                         <code class="filename">hybrid-sleep.target</code>
 353                                         and may be used to hook units
 354                                         into the sleep state
 355                                         logic.</p></dd><dt id="sockets.target"><span class="term"><code class="filename">sockets.target</code></span><a class="headerlink" title="Permalink to this term" href="#sockets.target">¶</a></dt><dd><p>A special target unit
 356                                         that sets up all socket
 357                                         units.(see
 358                                         <a href="systemd.socket.html"><span class="citerefentry"><span class="refentrytitle">systemd.socket</span>(5)</span></a>
 359                                         for details) that shall be
 360                                         active after boot.</p><p>Services that can be
 361                                         socket-activated shall add
 362                                         <code class="varname">Wants=</code>
 363                                         dependencies to this unit for
 364                                         their socket unit during
 365                                         installation. This is best
 366                                         configured via a
 367                                         <code class="varname">WantedBy=sockets.target</code>
 368                                         in the socket unit's
 369                                         "<code class="literal">[Install]</code>"
 370                                         section.</p></dd><dt id="suspend.target"><span class="term"><code class="filename">suspend.target</code></span><a class="headerlink" title="Permalink to this term" href="#suspend.target">¶</a></dt><dd><p>A special target unit
 371                                         for suspending the
 372                                         system. This pulls in
 373                                         <code class="filename">sleep.target</code>.</p></dd><dt id="swap.target"><span class="term"><code class="filename">swap.target</code></span><a class="headerlink" title="Permalink to this term" href="#swap.target">¶</a></dt><dd><p>Similar to
 374                                         <code class="filename">local-fs.target</code>, but for swap
 375                                         partitions and swap
 376                                         files.</p></dd><dt id="sysinit.target"><span class="term"><code class="filename">sysinit.target</code></span><a class="headerlink" title="Permalink to this term" href="#sysinit.target">¶</a></dt><dd><p>A special target unit
 377                                         covering early boot-up scripts.</p></dd><dt id="syslog.socket"><span class="term"><code class="filename">syslog.socket</code></span><a class="headerlink" title="Permalink to this term" href="#syslog.socket">¶</a></dt><dd><p>The socket unit
 378                                         syslog implementations should
 379                                         listen on. All userspace log
 380                                         messages will be made
 381                                         available on this socket. For
 382                                         more information about syslog
 383                                         integration, please consult
 384                                         the <a class="ulink" href="http://www.freedesktop.org/wiki/Software/systemd/syslog" target="_top">Syslog
 385                                         Interface</a>
 386                                         document.</p></dd><dt id="system-update.target"><span class="term"><code class="filename">system-update.target</code></span><a class="headerlink" title="Permalink to this term" href="#system-update.target">¶</a></dt><dd><p>A special target unit
 387                                         that is used for off-line
 388                                         system updates.
 389                                         <a href="systemd-system-update-generator.html"><span class="citerefentry"><span class="refentrytitle">systemd-system-update-generator</span>(8)</span></a>
 390                                         will redirect the boot process
 391                                         to this target if
 392                                         <code class="filename">/system-update</code>
 393                                         exists. For more information
 394                                         see the <a class="ulink" href="http://freedesktop.org/wiki/Software/systemd/SystemUpdates" target="_top">System
 395                                         Updates
 396                                         Specification</a>.</p></dd><dt id="timers.target"><span class="term"><code class="filename">timers.target</code></span><a class="headerlink" title="Permalink to this term" href="#timers.target">¶</a></dt><dd><p>A special target unit
 397                                         that sets up all timer
 398                                         units (see
 399                                         <a href="systemd.timer.html"><span class="citerefentry"><span class="refentrytitle">systemd.timer</span>(5)</span></a>
 400                                         for details) that shall be
 401                                         active after boot.</p><p>It is recommended that
 402                                         timer units installed by
 403                                         applications get pulled in via
 404                                         <code class="varname">Wants=</code>
 405                                         dependencies from this
 406                                         unit. This is best configured
 407                                         via
 408                                         <code class="varname">WantedBy=timers.target</code>
 409                                         in the timer unit's
 410                                         "<code class="literal">[Install]</code>"
 411                                         section.</p></dd><dt id="umount.target"><span class="term"><code class="filename">umount.target</code></span><a class="headerlink" title="Permalink to this term" href="#umount.target">¶</a></dt><dd><p>A special target unit
 412                                         that umounts all mount and
 413                                         automount points on system
 414                                         shutdown.</p><p>Mounts that shall be
 415                                         unmounted on system shutdown
 416                                         shall add Conflicts
 417                                         dependencies to this unit for
 418                                         their mount unit, which is
 419                                         implicitly done when
 420                                         <code class="varname">DefaultDependencies=yes</code>
 421                                         is set (the default).</p></dd></dl></div></div><div class="refsect1"><a name="idm214165347792"></a><h2 id="Special System Units for Devices">Special System Units for Devices<a class="headerlink" title="Permalink to this headline" href="#Special%20System%20Units%20for%20Devices">¶</a></h2><p>Some target units are automatically pulled in as
 422                 devices of certain kinds show up in the system. These
 423                 may be used to automatically activate various services
 424                 based on the specific type of the available
 425                 hardware.</p><div class="variablelist"><dl class="variablelist"><dt id="bluetooth.target"><span class="term"><code class="filename">bluetooth.target</code></span><a class="headerlink" title="Permalink to this term" href="#bluetooth.target">¶</a></dt><dd><p>This target is started
 426                                         automatically as soon as a
 427                                         Bluetooth controller is
 428                                         plugged in or becomes
 429                                         available at boot.</p><p>This may be used to pull
 430                                         in Bluetooth management
 431                                         daemons dynamically when
 432                                         Bluetooth hardware is
 433                                         found.</p></dd><dt id="printer.target"><span class="term"><code class="filename">printer.target</code></span><a class="headerlink" title="Permalink to this term" href="#printer.target">¶</a></dt><dd><p>This target is started
 434                                         automatically as soon as a
 435                                         printer is plugged in or
 436                                         becomes available at
 437                                         boot.</p><p>This may be used to pull
 438                                         in printer management
 439                                         daemons dynamically when
 440                                         printer hardware is
 441                                         found.</p></dd><dt id="smartcard.target"><span class="term"><code class="filename">smartcard.target</code></span><a class="headerlink" title="Permalink to this term" href="#smartcard.target">¶</a></dt><dd><p>This target is started
 442                                         automatically as soon as a
 443                                         smartcard controller is
 444                                         plugged in or becomes
 445                                         available at boot.</p><p>This may be used to pull
 446                                         in smartcard management
 447                                         daemons dynamically when
 448                                         smartcard hardware is
 449                                         found.</p></dd><dt id="sound.target"><span class="term"><code class="filename">sound.target</code></span><a class="headerlink" title="Permalink to this term" href="#sound.target">¶</a></dt><dd><p>This target is started
 450                                         automatically as soon as a
 451                                         sound card is plugged in or
 452                                         becomes available at
 453                                         boot.</p><p>This may be used to pull
 454                                         in audio management daemons
 455                                         dynamically when audio
 456                                         hardware is found.</p></dd></dl></div></div><div class="refsect1"><a name="idm214165334640"></a><h2 id="Special Passive System Units ">Special Passive System Units <a class="headerlink" title="Permalink to this headline" href="#Special%20Passive%20System%20Units%20">¶</a></h2><p>A number of special system targets are defined
 457                 that can be used to properly order boot-up of optional
 458                 services. These targets are generally not part of the
 459                 initial boot transaction, unless they are explicitly
 460                 pulled in by one of the implementing services. Note
 461                 specifically that these <span class="emphasis"><em>passive</em></span>
 462                 target units are generally not pulled in by the
 463                 consumer of a service, but by the provider of the
 464                 service. This means: a consuming service should order
 465                 itself after these targets (as appropriate), but not
 466                 pull it in. A providing service should order itself
 467                 before these targets (as appropriate) and pull it in
 468                 (via a <code class="varname">Wants=</code> type
 469                 dependency).</p><p>Note that these passive units cannot be started
 470                 manually, i.e. "<code class="literal">systemctl start
 471                 time-sync.target</code>" will fail with an
 472                 error. They can only be pulled in by dependency. This
 473                 is enforced since they exist for ordering purposes
 474                 only and thus are not useful as only unit within a
 475                 transaction.</p><div class="variablelist"><dl class="variablelist"><dt id="cryptsetup-pre.target"><span class="term"><code class="filename">cryptsetup-pre.target</code></span><a class="headerlink" title="Permalink to this term" href="#cryptsetup-pre.target">¶</a></dt><dd><p>This passive target unit
 476                                         may be pulled in by services
 477                                         that want to run before any
 478                                         encrypted block device is set
 479                                         up. All encrypted block
 480                                         devices are set up after this
 481                                         target has been reached. Since
 482                                         the shutdown order is
 483                                         implicitly the reverse
 484                                         start-up order between units,
 485                                         this target is particularly
 486                                         useful to ensure that a
 487                                         service is shut down only
 488                                         after all encrypted block
 489                                         devices are fully
 490                                         stopped.</p></dd><dt id="local-fs-pre.target"><span class="term"><code class="filename">local-fs-pre.target</code></span><a class="headerlink" title="Permalink to this term" href="#local-fs-pre.target">¶</a></dt><dd><p>This target unit is
 491                                         automatically ordered before
 492                                         all local mount points marked
 493                                         with <code class="option">auto</code>
 494                                         (see above). It can be used to
 495                                         execute certain units before
 496                                         all local mounts.</p></dd><dt id="network.target"><span class="term"><code class="filename">network.target</code></span><a class="headerlink" title="Permalink to this term" href="#network.target">¶</a></dt><dd><p>This unit is supposed to
 497                                         indicate when network
 498                                         functionality is available,
 499                                         but it is only very weakly
 500                                         defined what that is supposed
 501                                         to mean, with one exception:
 502                                         at shutdown, a unit that is
 503                                         ordered after
 504                                         <code class="filename">network.target</code>
 505                                         will be stopped before the
 506                                         network -- to whatever level
 507                                         it might be set up then -- is
 508                                         shut down. It is hence useful
 509                                         when writing service files
 510                                         that require network access on
 511                                         shutdown, which should order
 512                                         themselves after this target,
 513                                         but not pull it in. Also see
 514                                         <a class="ulink" href="http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget" target="_top">Running
 515                                         Services After the Network is
 516                                         up</a> for more
 517                                         information. Also see
 518                                         <code class="filename">network-online.target</code>
 519                                         described above.</p><p>systemd automatically
 520                                         adds dependencies of type
 521                                         <code class="varname">After=</code> for
 522                                         this target unit to all SysV
 523                                         init script service units with
 524                                         an LSB header referring to the
 525                                         "<code class="literal">$network</code>"
 526                                         facility.</p></dd><dt id="network-pre.target"><span class="term"><code class="filename">network-pre.target</code></span><a class="headerlink" title="Permalink to this term" href="#network-pre.target">¶</a></dt><dd><p>This passive target unit
 527                                         may be pulled in by services
 528                                         that want to run before any
 529                                         network is set up, for example
 530                                         for the purpose of setting up a
 531                                         firewall. All network
 532                                         management software orders
 533                                         itself after this target, but
 534                                         does not pull it in.</p></dd><dt id="nss-lookup.target"><span class="term"><code class="filename">nss-lookup.target</code></span><a class="headerlink" title="Permalink to this term" href="#nss-lookup.target">¶</a></dt><dd><p>A target that should be
 535                                         used as synchronization point
 536                                         for all host/network name
 537                                         service lookups. Note that
 538                                         this is independent of
 539                                         user/group name lookups for
 540                                         which
 541                                         <code class="filename">nss-user-lookup.target</code>
 542                                         should be used. All services
 543                                         for which the availability of
 544                                         full host/network name
 545                                         resolution is essential should
 546                                         be ordered after this target,
 547                                         but not pull it in. systemd
 548                                         automatically adds
 549                                         dependencies of type
 550                                         <code class="varname">After=</code> for
 551                                         this target unit to all SysV
 552                                         init script service units with
 553                                         an LSB header referring to the
 554                                         "<code class="literal">$named</code>"
 555                                         facility.</p></dd><dt id="nss-user-lookup.target"><span class="term"><code class="filename">nss-user-lookup.target</code></span><a class="headerlink" title="Permalink to this term" href="#nss-user-lookup.target">¶</a></dt><dd><p>A target that should be
 556                                         used as synchronization point
 557                                         for all user/group name
 558                                         service lookups. Note that
 559                                         this is independent of
 560                                         host/network name lookups for
 561                                         which
 562                                         <code class="filename">nss-lookup.target</code>
 563                                         should be used. All services
 564                                         for which the availability of
 565                                         the full user/group database is
 566                                         essential should be ordered
 567                                         after this target, but not
 568                                         pull it in. Note that system
 569                                         users are always resolvable,
 570                                         and hence do not require any
 571                                         special ordering against this
 572                                         target.</p></dd><dt id="remote-fs-pre.target"><span class="term"><code class="filename">remote-fs-pre.target</code></span><a class="headerlink" title="Permalink to this term" href="#remote-fs-pre.target">¶</a></dt><dd><p>This target unit is
 573                                         automatically ordered before
 574                                         all remote mount point units
 575                                         (see above). It can be used to
 576                                         run certain units before the
 577                                         remote mounts are
 578                                         established. Note that this
 579                                         unit is generally not part of
 580                                         the initial transaction,
 581                                         unless the unit that wants to
 582                                         be ordered before all remote
 583                                         mounts pulls it in via a
 584                                         <code class="varname">Wants=</code> type
 585                                         dependency. If the unit wants
 586                                         to be pulled in by the first
 587                                         remote mount showing up, it
 588                                         should use
 589                                         <code class="filename">network-online.target</code>
 590                                         (see above).</p></dd><dt id="rpcbind.target"><span class="term"><code class="filename">rpcbind.target</code></span><a class="headerlink" title="Permalink to this term" href="#rpcbind.target">¶</a></dt><dd><p>The portmapper/rpcbind
 591                                         pulls in this target and
 592                                         orders itself before it, to
 593                                         indicate its
 594                                         availability. systemd
 595                                         automatically adds
 596                                         dependencies of type
 597                                         <code class="varname">After=</code> for
 598                                         this target unit to all SysV
 599                                         init script service units with
 600                                         an LSB header referring to the
 601                                         "<code class="literal">$portmap</code>"
 602                                         facility.</p></dd><dt id="time-sync.target"><span class="term"><code class="filename">time-sync.target</code></span><a class="headerlink" title="Permalink to this term" href="#time-sync.target">¶</a></dt><dd><p>Services responsible for
 603                                         synchronizing the system clock
 604                                         from a remote source (such as
 605                                         NTP client implementations)
 606                                         should pull in this target and
 607                                         order themselves before
 608                                         it. All services where correct
 609                                         time is essential should be
 610                                         ordered after this unit, but
 611                                         not pull it in. systemd
 612                                         automatically adds
 613                                         dependencies of type
 614                                         <code class="varname">After=</code> for
 615                                         this target unit to all SysV
 616                                         init script service units with
 617                                         an LSB header referring to the
 618                                         "<code class="literal">$time</code>"
 619                                         facility. </p></dd></dl></div></div><div class="refsect1"><a name="idm214165293328"></a><h2 id="Special User Units">Special User Units<a class="headerlink" title="Permalink to this headline" href="#Special%20User%20Units">¶</a></h2><p>When systemd runs as a user instance, the
 620                 following special units are available, which have
 621                 similar definitions as their system counterparts:
 622                 <code class="filename">default.target</code>,
 623                 <code class="filename">shutdown.target</code>,
 624                 <code class="filename">sockets.target</code>,
 625                 <code class="filename">timers.target</code>,
 626                 <code class="filename">paths.target</code>,
 627                 <code class="filename">bluetooth.target</code>,
 628                 <code class="filename">printer.target</code>,
 629                 <code class="filename">smartcard.target</code>,
 630                 <code class="filename">sound.target</code>.</p><p>In addition, the following special unit is
 631                 understood only when systemd runs as service instance:</p><div class="variablelist"><dl class="variablelist"><dt id="exit.target"><span class="term"><code class="filename">exit.target</code></span><a class="headerlink" title="Permalink to this term" href="#exit.target">¶</a></dt><dd><p>A special service unit
 632                                         for shutting down the
 633                                         user service manager.</p><p>Applications wanting to
 634                                         terminate the user service
 635                                         manager should start this
 636                                         unit. If systemd receives
 637                                         <code class="constant">SIGTERM</code> or <code class="constant">SIGINT</code> when running
 638                                         as user service daemon, it will
 639                                         start this unit.</p><p>Normally, this pulls in
 640                                         <code class="filename">shutdown.target</code>
 641                                         which in turn should be
 642                                         conflicted by all units that
 643                                         want to be shut down on
 644                                         user service manager exit.</p></dd></dl></div></div><div class="refsect1"><a name="idm214165280512"></a><h2 id="Special Slice Units">Special Slice Units<a class="headerlink" title="Permalink to this headline" href="#Special%20Slice%20Units">¶</a></h2><p>There are four "<code class="literal">.slice</code>" units
 645                 which form the basis of the hierarchy for assignment
 646                 of resources for services, users, and virtual machines
 647                 or containers.</p><div class="variablelist"><dl class="variablelist"><dt id="-.slice"><span class="term"><code class="filename">-.slice</code></span><a class="headerlink" title="Permalink to this term" href="#-.slice">¶</a></dt><dd><p>The root slice is the
 648                                         root of the hierarchy. It
 649                                         usually does not contain units
 650                                         directly, but may be used to
 651                                         set defaults for the whole
 652                                         tree.</p></dd><dt id="system.slice"><span class="term"><code class="filename">system.slice</code></span><a class="headerlink" title="Permalink to this term" href="#system.slice">¶</a></dt><dd><p>By default, all services
 653                                         services started by
 654                                         <span class="command"><strong>systemd</strong></span> are
 655                                         found in this slice.</p></dd><dt id="user.slice"><span class="term"><code class="filename">user.slice</code></span><a class="headerlink" title="Permalink to this term" href="#user.slice">¶</a></dt><dd><p>By default, all user
 656                                         processes and services started
 657                                         on behalf of the user,
 658                                         including the per-user systemd
 659                                         instance are found in this
 660                                         slice.</p></dd><dt id="machine.slice"><span class="term"><code class="filename">machine.slice</code></span><a class="headerlink" title="Permalink to this term" href="#machine.slice">¶</a></dt><dd><p>By default, all virtual
 661                                         machines and containers
 662                                         registered with
 663                                         <span class="command"><strong>systemd-machined</strong></span>
 664                                         are found in this slice.
 665                                         </p></dd></dl></div></div><div class="refsect1"><a name="idm214165268032"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
 666                           <a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
 667                           <a href="systemd.unit.html"><span class="citerefentry"><span class="refentrytitle">systemd.unit</span>(5)</span></a>,
 668                           <a href="systemd.service.html"><span class="citerefentry"><span class="refentrytitle">systemd.service</span>(5)</span></a>,
 669                           <a href="systemd.socket.html"><span class="citerefentry"><span class="refentrytitle">systemd.socket</span>(5)</span></a>,
 670                           <a href="systemd.target.html"><span class="citerefentry"><span class="refentrytitle">systemd.target</span>(5)</span></a>,
 671                           <a href="systemd.slice.html"><span class="citerefentry"><span class="refentrytitle">systemd.slice</span>(5)</span></a>,
 672                           <a href="http://man7.org/linux/man-pages/man7/bootup.7.html"><span class="citerefentry"><span class="refentrytitle">bootup</span>(7)</span></a>,
 673                           <a href="systemd-fstab-generator.html"><span class="citerefentry"><span class="refentrytitle">systemd-fstab-generator</span>(8)</span></a>
 674                   </p></div></div></body></html>