NAME

       systemd.special - Special systemd units

SYNOPSIS

       basic.target, bluetooth.target, ctrl-alt-del.target, cryptsetup.target, dbus.service,
       dbus.socket, default.target, display-manager.service, emergency.target, exit.target,
       final.target, getty.target, graphical.target, halt.target, hibernate.target,
       hybrid-sleep.target, initrd-fs.target, kbrequest.target, kexec.target, local-fs.target,
       local-fs-pre.target, multi-user.target, network.target, network-online.target,
       nss-lookup.target, nss-user-lookup.target, paths.target, poweroff.target, printer.target,
       reboot.target, remote-fs.target, remote-fs-pre.target, rescue.target,
       initrd-root-fs.target, rpcbind.target, runlevel2.target, runlevel3.target,
       runlevel4.target, runlevel5.target, shutdown.target, sigpwr.target, sleep.target,
       smartcard.target, sockets.target, sound.target, suspend.target, swap.target,
       sysinit.target, syslog.socket, syslog.target, system-update.target, time-sync.target,
       timers.target, umount.target

DESCRIPTION

       A few units are treated specially by systemd. They have special internal semantics and
       cannot be renamed.

SPECIAL SYSTEM UNITS

       basic.target
           A special target unit covering basic boot-up.

           systemd automatically adds dependencies of the types Requires= and After= for this
           target unit to all services (except for those with DefaultDependencies=no).

           Usually this should pull-in all mount points, swap devices, sockets, timers, and path
           units and other basic initialization necessary for general purpose daemons.

       ctrl-alt-del.target
           systemd starts this target whenever Control+Alt+Del is pressed on the console. Usually
           this should be aliased (symlinked) to reboot.target.

       cryptsetup.target
           A target that pulls in setup services for all encrypted block devices.

       dbus.service
           A special unit for the D-Bus bus daemon. As soon as this service is fully started up
           systemd will connect to it and register its service.

       dbus.socket
           A special unit for the D-Bus system bus socket. All units with Type=dbus automatically
           gain a dependency on this unit.

       default.target
           The default unit systemd starts at bootup. Usually this should be aliased (symlinked)
           to multi-user.target or graphical.target.

           The default unit systemd starts at bootup can be overridden with the systemd.unit=
           kernel command line option.

       display-manager.service
           The display manager service. Usually this should be aliased (symlinked) to gdm.service
           or a similar display manager service.

       emergency.target
           A special target unit that starts an emergency shell on the main console. This unit is
           supposed to be used with the kernel command line option systemd.unit= and has
           otherwise little use.

       final.target
           A special target unit that is used during the shutdown logic and may be used to pull
           in late services after all normal services are already terminated and all mounts
           unmounted.

       getty.target
           A special target unit that pulls in statically configured local TTY getty instances.

       graphical.target
           A special target unit for setting up a graphical login screen. This pulls in
           multi-user.target.

           Units that are needed for graphical logins shall add Wants= dependencies for their
           unit to this unit (or multi-user.target) during installation. This is best configured
           via WantedBy=graphical.target in the unit's [Install] section.

       hibernate.target
           A special target unit for hibernating the system. This pulls in sleep.target.

       hybrid-sleep.target
           A special target unit for hibernating and suspending the system at the same time. This
           pulls in sleep.target.

       halt.target
           A special target unit for shutting down and halting the system. Note that this target
           is distinct from poweroff.target in that it generally really just halts the system
           rather than powering it down.

           Applications wanting to halt the system should start this unit.

       initrd-fs.target
           systemd-fstab-generator(3) automatically adds dependencies of type Before= to
           sysroot-usr.mount and all mount points fround in /etc/fstab that have the auto and
           x-initrd.mount mount options set.

       kbrequest.target
           systemd starts this target whenever Alt+ArrowUp is pressed on the console. This is a
           good candidate to be aliased (symlinked) to rescue.target.

       kexec.target
           A special target unit for shutting down and rebooting the system via kexec.

           Applications wanting to reboot the system with kexec should start this unit.

       local-fs.target
           systemd-fstab-generator(3) automatically adds dependencies of type Before= to all
           mount units that refer to local mount points for this target unit. In addition, it
           adds dependencies of type Wants= to this target unit for those mounts listed in
           /etc/fstab that have the auto mount option set.

           systemd automatically adds dependencies of type After for this target unit to all SysV
           init script service units with an LSB header referring to the $local_fs facility.

       local-fs-pre.target
           This target unit is automatically ordered before all local mount points marked with
           auto (see above). It can be used to execute certain units before all local mounts.

       multi-user.target
           A special target unit for setting up a multi-user system (non-graphical). This is
           pulled in by graphical.target.

           Units that are needed for a multi-user system shall add Wants= dependencies for their
           unit to this unit during installation. This is best configured via
           WantedBy=multi-uer.target in the unit's [Install] section.

       network-online.target
           Units that strictly require a configured network connection should pull in
           network-online.target (via a Wants= type dependency) and order themselves after it.
           This target unit is intended to pull in a service that delays further execution until
           the network is sufficiently set up. What precisely this requires is left to the
           implementation of the network managing service.

           Note the distinction between this unit and network.target. This unit is an active unit
           (i.e. pulled in by the consumer rather than the provider of this functionality) and
           pulls in a service which possibly adds substantial delays to further execution. In
           contrast, network.target is a passive unit (i.e. pulled in by the provider of the
           functionality, rather than the consumer) that usually does not delay execution much.
           Usually, network.target is part of the boot of most systems, while
           network-online.target is not, except when at least one unit requires it. Also see
           Running Services After the Network is up[1] for more information.

           All mount units for remote network file systems automatically pull in this unit, and
           order themselves after it. Note that networking daemons that simply provide
           functionality to other hosts generally don't need to pull this in.

       paths.target
           A special target unit that sets up all path units (see systemd.path(5) for details)
           that shall be active after boot.

           It is recommended that path units installed by applications get pulled in via Wants=
           dependencies from this unit. This is best configured via a WantedBy=paths.target in
           the path unit's [Install] section.

       poweroff.target
           A special target unit for shutting down and powering off the system.

           Applications wanting to power off the system should start this unit.

           runlevel0.target is an alias for this target unit, for compatibility with SysV.

       reboot.target
           A special target unit for shutting down and rebooting the system.

           Applications wanting to reboot the system should start this unit.

           runlevel6.target is an alias for this target unit, for compatibility with SysV.

       remote-fs.target
           Similar to local-fs.target, but for remote mount points.

           systemd automatically adds dependencies of type After= for this target unit to all
           SysV init script service units with an LSB header referring to the $remote_fs
           facility.

       rescue.target
           A special target unit for setting up the base system and a rescue shell.

           runlevel1.target is an alias for this target unit, for compatibility with SysV.

       initrd-root-fs.target
           systemd-fstab-generator(3) automatically adds dependencies of type Before= to the
           sysroot.mount unit, which is generated from the kernel command line.

       runlevel2.target, runlevel3.target, runlevel4.target, runlevel5.target
           These are targets that are called whenever the SysV compatibility code asks for
           runlevel 2, 3, 4, 5, respectively. It is a good idea to make this an alias for (i.e.
           symlink to) multi-user.target (for runlevel 2) or graphical.target (the others).

       shutdown.target
           A special target unit that terminates the services on system shutdown.

           Services that shall be terminated on system shutdown shall add Conflicts= dependencies
           to this unit for their service unit, which is implicitly done when
           DefaultDependencies=yes is set (the default).

       sigpwr.target
           A special target that is started when systemd receives the SIGPWR process signal,
           which is normally sent by the kernel or UPS daemons when power fails.

       sleep.target
           A special target unit that is pulled in by suspend.target, hibernate.target and
           hybrid-sleep.target and may be used to hook units into the sleep state logic.

       sockets.target
           A special target unit that sets up all socket units.(see systemd.socket(5) for
           details) that shall be active after boot.

           Services that can be socket-activated shall add Wants= dependencies to this unit for
           their socket unit during installation. This is best configured via a
           WantedBy=sockets.target in the socket unit's [Install] section.

       suspend.target
           A special target unit for suspending the system. This pulls in sleep.target.

       swap.target
           Similar to local-fs.target, but for swap partitions and swap files.

       sysinit.target
           A special target unit covering early boot-up scripts.

       syslog.socket
           The socket unit syslog implementations should listen on. All userspace log messages
           will be made available on this socket. For more information about syslog integration,
           please consult the Syslog Interface[2] document.

       syslog.target
           systemd automatically adds dependencies of type After for this target unit to all SysV
           init script service units with an LSB header referring to the $syslog facility.

       system-update.target
           A special target unit that is used for off-line system updates.  systemd-system-
           update-generator(8) will redirect the boot process to this target if /system-update
           exists. For more information see the System Updates Specification[3].

       timers.target
           A special target unit that sets up all timer units (see systemd.timer(5) for details)
           that shall be active after boot.

           It is recommended that timer units installed by applications get pulled in via Wants=
           dependencies from this unit. This is best configured via WantedBy=timers.target in the
           timer unit's [Install] section.

       umount.target
           A special target unit that umounts all mount and automount points on system shutdown.

           Mounts that shall be unmounted on system shutdown shall add Conflicts dependencies to
           this unit for their mount unit, which is implicitly done when DefaultDependencies=yes
           is set (the default).

SPECIAL SYSTEM UNITS FOR DEVICES

       Some target units are automatically pulled in as devices of certain kinds show up in the
       system. These may be used to automatically activate various services based on the specific
       type of the available hardware.

       bluetooth.target
           This target is started automatically as soon as a Bluetooth controller is plugged in
           or becomes available at boot.

           This may be used to pull in Bluetooth management daemons dynamically when Bluetooth
           hardware is found.

       printer.target
           This target is started automatically as soon as a printer is plugged in or becomes
           available at boot.

           This may be used to pull in printer management daemons dynamically when printer
           hardware is found.

       smartcard.target
           This target is started automatically as soon as a smartcard controller is plugged in
           or becomes available at boot.

           This may be used to pull in smartcard management daemons dynamically when smartcard
           hardware is found.

       sound.target
           This target is started automatically as soon as a sound card is plugged in or becomes
           available at boot.

           This may be used to pull in audio management daemons dynamically when audio hardware
           is found.

SPECIAL PASSIVE SYSTEM UNITS

       A number of special system targets are defined that can be used to properly order boot-up
       of optional services. These targets are generally not part of the initial boot
       transaction, unless they are explicitly pulled in by one of the implementing services.
       Note specifically, that these passive target units are generally not pulled in by the
       consumer of a service, but by the provider of the service. This means: a consuming service
       should order itself after these targets (as appropriate), but not pull it in. A providing
       service should order itself before these targets (as appropriate) and pull it in (via a
       Wants= type dependency).

       Note that these passive units cannot be started manually, i.e.  systemctl start
       time-sync.target will fail with an error. They can only be pulled in by dependency. This
       is enforced since they exist for ordering purposes only and thus are not useful as only
       unit within a transaction.

       local-fs-pre.target
           This target unit is automatically ordered before all local mount points marked with
           auto (see above). It can be used to execute certain units before all local mounts.

       network.target
           This unit is supposed to indicate when network functionality is available, but it is
           only very weakly defined what that is supposed to mean, with one exception: at
           shutdown, a unit that is ordered after network.target will be stopped before the
           network -- to whatever level it might be set up then -- is shut down. Also see Running
           Services After the Network is up[1] for more information. Also see
           network-online.target described above.

           systemd automatically adds dependencies of type After= for this target unit to all
           SysV init script service units with an LSB header referring to the $network facility.

       nss-lookup.target
           A target that should be used as synchronization point for all host/network name
           service lookups. Note that this is independent of user/group name lookups for which
           nss-user-lookup.target should be used. systemd automatically adds dependencies of type
           After= for this target unit to all SysV init script service units with an LSB header
           referring to the $named facility.

       nss-user-lookup.target
           A target that should be used as synchronization point for all user/group name service
           lookups. Note that this is independent of host/network name lookups for which
           nss-lookup.target should be used.

       remote-fs-pre.target
           This target unit is automatically ordered before all remote mount point units (see
           above). It can be used to run certain units before the remote mounts are established.
           Note that this unit is generally not part of the initial transaction, unless the unit
           that wants to be ordered before all remote mounts pulls it in via a Wants= type
           dependency. If the unit wants to be pulled in by the first remote mount showing up it
           should use network-online.target (see above).

           Again, this target unit is not suitable for pulling in other units, it is only useful
           for ordering.

       rpcbind.target
           systemd automatically adds dependencies of type After= for this target unit to all
           SysV init script service units with an LSB header referring to the $portmap facility.

       time-sync.target
           systemd automatically adds dependencies of type After= for this target unit to all
           SysV init script service units with an LSB header referring to the $time facility.

SPECIAL USER UNITS

       When systemd runs as a user instance, the following special units are available, which
       have similar definitions as their system counterparts: default.target, shutdown.target,
       sockets.target, timers.target, paths.target, bluetooth.target, printer.target,
       smartcard.target, sound.target.

       In addition the following special unit is understood only when systemd runs as service
       instance:

       exit.target
           A special service unit for shutting down the user service manager.

           Applications wanting to terminate the user service manager should start this unit. If
           systemd receives SIGTERM or SIGINT when running as user service daemon it will start
           this unit.

           Normally, this pulls in shutdown.target which in turn should be conflicted by all
           units that want to be shut down on user service manager exit.

SEE ALSO

       systemd(1), systemd.unit(5), systemd.service(5), systemd.socket(5), systemd.target(5),
       bootup(7), systemd-fstab-generator(8)

NOTES

        1. Running Services After the Network is up
           http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget

        2. Syslog Interface
           http://www.freedesktop.org/wiki/Software/systemd/syslog

        3. System Updates Specification
           http://freedesktop.org/wiki/Software/systemd/SystemUpdates