# systemd.special

## NAME



           systemd.special - Special systemd units
    


## SYNOPSIS



           basic.target, bluetooth.target, cryptsetup-pre.target,
           cryptsetup.target, veritysetup-pre.target, veritysetup.target,
           ctrl-alt-del.target, blockdev@.target, boot-complete.target,
           default.target, emergency.target, exit.target,
           factory-reset.target, factory-reset-now.target, final.target,
           first-boot-complete.target, getty.target, getty-pre.target,
           graphical.target, halt.target, hibernate.target,
           hybrid-sleep.target, suspend-then-hibernate.target, initrd.target,
           initrd-fs.target, initrd-root-device.target,
           initrd-root-fs.target, initrd-usr-fs.target,
           integritysetup-pre.target, integritysetup.target,
           kbrequest.target, kexec.target, local-fs-pre.target,
           local-fs.target, machines.target multi-user.target,
           network-online.target, network-pre.target, network.target,
           nss-lookup.target, nss-user-lookup.target, paths.target,
           poweroff.target, printer.target, reboot.target,
           remote-cryptsetup.target, remote-integritysetup.target,
           remote-veritysetup.target, remote-fs-pre.target, remote-fs.target,
           rescue.target, rpcbind.target, shutdown.target, sigpwr.target,
           sleep.target, slices.target, smartcard.target, sockets.target,
           soft-reboot.target, sound.target, ssh-access.target,
           storage-target-mode.target, suspend.target, swap.target,
           sysinit.target, system-update.target, system-update-pre.target,
           time-set.target, time-sync.target, timers.target, tpm2.target,
           umount.target, usb-gadget.target, -.slice, capsule.slice,
           machine.slice, system.slice, user.slice, -.mount, dbus.service,
           dbus.socket, display-manager.service, init.scope, syslog.socket,
           system-update-cleanup.service
    


## DESCRIPTION



           A few units are treated specially by systemd. Many of them have
           special internal semantics and cannot be renamed, while others
           simply have a standard meaning and should be present on all
           systems.
    


## UNITS MANAGED BY THE SYSTEM SERVICE MANAGER



       **Special System Units**
           -.mount
               The root mount point, i.e. the mount unit for the / path. This
               unit is unconditionally active, during the entire time the
               system is up, as this mount point is where the basic userspace
               is running from.
    
               Added in version 235.
    
           basic.target
               A special target unit covering basic boot-up.
    
               systemd automatically adds dependency of the type _After=_ for
               this target unit to all services (except for those with
               _DefaultDependencies=no_).
    
               Usually, this should pull-in all local mount points plus
               /var/, /tmp/ and /var/tmp/, swap devices, sockets, timers,
               path units and other basic initialization necessary for
               general purpose daemons. The mentioned mount points are
               special cased to allow them to be remote.
    
               This target usually does not pull in any non-target units
               directly, but rather does so indirectly via other early boot
               targets. It is instead meant as a synchronization point for
               late boot services. Refer to bootup(7) for details on the
               targets involved.
    
           boot-complete.target
               This target is intended as generic synchronization point for
               services that shall determine or act on whether the boot
               process completed successfully. Order units that are required
               to succeed for a boot process to be considered successful
               before this unit, and add a _Requires=_ dependency from the
               target unit to them. Order units that shall only run when the
               boot process is considered successful after the target unit
               and pull in the target from it, also with _Requires=_. Note that
               by default this target unit is not part of the initial boot
               transaction, but is supposed to be pulled in only if required
               by units that want to run only on successful boots.
    
               See systemd-boot-check-no-failures.service(8) for a service
               that implements a generic system health check and orders
               itself before boot-complete.target.
    
               See systemd-bless-boot.service(8) for a service that
               propagates boot success information to the boot loader, and
               orders itself after boot-complete.target.
    
               Added in version 240.
    
           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.
    
           veritysetup.target
               A target that pulls in setup services for all verity integrity
               protected block devices.
    
               Added in version 248.
    
           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. See bootup(7) for more discussion.
    
               The default unit systemd starts at bootup can be overridden
               with the _systemd.unit=_ kernel command line option, or more
               conveniently, with the short names like _single_ , _rescue_ , _1_ , _3_ ,
               _5_ , ...; see systemd(1).
    
               For typical unit files please set "WantedBy=" to a regular
               target (like multi-user.target or graphical.target), instead
               of default.target, since such a service will also be run on
               special boots like on system update, emergency boot...
    
           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 target does not pull in other services or
               mounts. It is the most minimal version of starting the system
               in order to acquire an interactive shell; the only processes
               running are usually just the system manager (PID 1) and the
               shell process. This unit may be used by specifying _emergency_
               on the kernel command line; it is also used when a file system
               check on a required file system fails and boot-up cannot
               continue. Compare with rescue.target, which serves a similar
               purpose, but also starts the most basic services and mounts
               all file systems.
    
               In many ways booting into emergency.target is similar to the
               effect of booting with "init=/bin/sh" on the kernel command
               line, except that emergency mode provides you with the full
               system and service manager, and allows starting individual
               units in order to continue the boot process in steps.
    
               Note that depending on how emergency.target is reached, the
               root file system might be mounted read-only or read-write (no
               remounting is done specially for this target). For example,
               the system may boot with root mounted read-only when _ro_ is
               used on the kernel command line and remain this way for
               emergency.target, or the system may transition to
               emergency.target after the system has been partially booted
               and disks have already been remounted read-write.
    
           exit.target
               A special service unit for shutting down the system or user
               service manager. It is equivalent to poweroff.target on
               non-container systems, and also works in containers.
    
               systemd will start this unit when it receives the **SIGTERM** or
               **SIGINT** signal when running as user service daemon.
    
               Normally, this (indirectly) pulls in shutdown.target, which in
               turn should be conflicted by all units that want to be
               scheduled for shutdown when the service manager starts to
               exit.
    
               Added in version 186.
    
           factory-reset.target
               A special target to request a factory reset operation. This
               will typically persistently store a request flag for the next
               boot and then reboot in order to reset the system to factory
               state.
    
               See **Factory Reset******[1] for more information.
    
               Added in version 250.
    
           factory-reset-now.target
               A special target that is started on boots that shall execute a
               factory reset. It may be used to pull in additional services
               that shall be invoked during a factory reset operation. It
               also acts as ordering barrier: once the target is reached the
               factory reset state is marked as "completed".
    
               See**Factory Reset******[1] for more information.
    
               Added in version 258.
    
           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.
    
               Added in version 196.
    
           suspend-then-hibernate.target
               A special target unit for suspending the system for a period
               of time, waking it and putting it into hibernate. This pulls
               in sleep.target.
    
               Added in version 239.
    
           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 not start this
               unit directly, but should instead execute **systemctl halt**
               (possibly with the **--no-block** option) or call systemd(1)'s
               **org.freedesktop.systemd1.Manager.Halt** D-Bus method directly.
    
           imports.target
               A target unit that pulls in all disk image download jobs to
               execute on system boot. This is used by
               systemd-import-generator(8).
    
               Added in version 258.
    
           init.scope
               This scope unit is where the system and service manager (PID
               1) itself resides. It is active as long as the system is
               running.
    
               Added in version 235.
    
           initrd.target
               This is the default target in the initrd, similar to
               default.target in the main system. It is used to mount the
               real root and transition to it. See bootup(7) for more
               discussion.
    
               Added in version 245.
    
           initrd-fs.target
               systemd-fstab-generator(8) automatically adds dependencies of
               type _Before=_ to sysroot-usr.mount and all mount points found
               in /etc/fstab that have the **x-initrd.mount** mount option set
               and do not have the **noauto** mount option set. It is also
               indirectly ordered after sysroot.mount. Thus, once this target
               is reached the /sysroot/ hierarchy is fully set up, in
               preparation for the transition to the host OS.
    
               Added in version 199.
    
           initrd-root-device.target
               A special initrd target unit that is reached when the root
               filesystem device is available, but before it has been
               mounted.  systemd-fstab-generator(8) and
               systemd-gpt-auto-generator(8) automatically set up the
               appropriate dependencies to make this happen.
    
               Added in version 230.
    
           initrd-root-fs.target
               systemd-fstab-generator(8) automatically adds dependencies of
               type _Before=_ to the sysroot.mount unit, which is generated
               from the kernel command line's _root=_ setting (or equivalent).
    
               Added in version 199.
    
           initrd-usr-fs.target
               systemd-fstab-generator(8) automatically adds dependencies of
               type _Before=_ to the sysusr-usr.mount unit, which is generated
               from the kernel command line's _usr=_ switch. Services may order
               themselves after this target unit in order to run once the
               /sysusr/ hierarchy becomes available, on systems that come up
               initially without a root file system, but with an initialized
               /usr/ and need to access that before setting up the root file
               system to ultimately switch to. On systems where _usr=_ is not
               used this target is ordered after sysroot.mount and thus
               mostly equivalent to initrd-root-fs.target. In effect on any
               system once this target is reached the file system backing
               /usr/ is mounted, though possibly at two different locations,
               either below the /sysusr/ or the /sysroot/ hierarchies.
    
               Added in version 249.
    
           kbrequest.target
               systemd starts this target whenever Alt+ArrowUp is pressed on
               the console. Note that any user with physical access to the
               machine will be able to do this, without authentication, so
               this should be used carefully.
    
           kexec.target
               A special target unit for shutting down and rebooting the
               system via kexec.
    
               Applications wanting to reboot the system should not start
               this unit directly, but should instead execute **systemctl kexec**
               (possibly with the **--no-block** option) or call
               systemd-logind(8)'s
               **org.freedesktop.login1.Manager.RebootWithFlags()** D-Bus method
               directly.
    
               See systemd-kexec.service(8) for further details of the
               operation this target pulls in.
    
           local-fs.target
               systemd-fstab-generator(8) 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.
    
           machines.target
               A standard target unit for starting all the containers and
               other virtual machines. See systemd-nspawn@.service for an
               example.
    
               Added in version 233.
    
           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-user.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******[2] 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 (as opposed to _consume_ functionality of other hosts)
               generally do not need to pull this in.
    
               systemd automatically adds dependencies of type _Wants=_ and
               _After=_ for this target unit to all SysV init script service
               units with an LSB header referring to the "$network" facility.
    
               Note that this unit is only useful during the original system
               start-up logic. After the system has completed booting up, it
               will not track the online state of the system anymore. Due to
               this it cannot be used as a network connection monitor
               concept, it is purely a one-time system start-up concept.
    
               Added in version 200.
    
           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.
    
               Added in version 199.
    
           poweroff.target
               A special target unit for shutting down and powering off the
               system.
    
               Applications wanting to power off the system should not start
               this unit directly, but should instead execute **systemctl**
               **poweroff**(possibly with the **--no-block** option) or call
               systemd-logind(8)'s **org.freedesktop.login1.Manager.PowerOff**
               D-Bus method directly.
    
           reboot.target
               A special target unit for shutting down and rebooting the
               system.
    
               Applications wanting to reboot the system should not start
               this unit directly, but should instead execute **systemctl**
               **reboot**(possibly with the **--no-block** option) or call
               systemd-logind(8)'s **org.freedesktop.login1.Manager.Reboot()**
               D-Bus method directly.
    
               See systemd-reboot.service(8) for further details of the
               operation this target pulls in.
    
           remote-cryptsetup.target
               Similar to cryptsetup.target, but for encrypted devices which
               are accessed over the network. It is used for crypttab(5)
               entries marked with **_netdev**.
    
               Added in version 235.
    
           remote-integritysetup.target
               Similar to integritysetup.target, but for integrity protected
               devices which are accessed over the network. It is used for
               integritytab(5) entries marked with **_netdev**.
    
               Added in version 258.
    
           remote-veritysetup.target
               Similar to veritysetup.target, but for verity protected
               devices which are accessed over the network. It is used for
               veritytab(5) entries marked with **_netdev**.
    
               Added in version 248.
    
           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 that pulls in the base system (including
               system mounts) and spawns a rescue shell. Isolate to this
               target in order to administer the system in single-user mode
               with all file systems mounted but with no services running,
               except for the most basic. Compare with emergency.target,
               which is much more reduced and does not provide the file
               systems or most basic services. Compare with
               multi-user.target, this target could be seen as
               single-user.target.
    
               Use the "systemd.unit=rescue.target" kernel command line
               option to boot into this mode. A short alias for this kernel
               command line option is "1", for compatibility with SysV.
    
           shutdown.target
               A special target unit that terminates the services on system
               shutdown.
    
               Services that shall be terminated on system shutdown shall add
               _Conflicts=_ and _Before=_ 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, suspend-then-hibernate.target, and
               hybrid-sleep.target and may be used to hook units into the
               sleep state logic.
    
               In order to hook external programs _before_ the actual system
               sleep operation, place their command line in a service unit
               file's _ExecStart=_ line (use _Type=oneshot_), and ensure the unit
               is pulled in by sleep.target and ordered before it. In order
               to hook program code _after_ the actual system sleep operation
               (i.e. to be run after the system woke up again), place the
               command in _ExecStop=_ instead, and make sure to enable
               _StopWhenUnneeded=_ and _RemainAfterExit=_. Both approaches can be
               combined into one unit file in order to run programs both
               before and after the sleep operation.
    
               **Example 1. Combined Example**
    
                   [Unit]
                   DefaultDependencies=no
                   StopWhenUnneeded=yes
                   Before=sleep.target
    
                   [Service]
                   Type=oneshot
                   RemainAfterExit=yes
                   ExecStart=/usr/bin/some-before-command
                   ExecStop=/Usr/bin/some-after-command
    
                   [Install]
                   WantedBy=sleep.target
    
           slices.target
               A special target unit that sets up all slice units (see
               systemd.slice(5) for details) that shall always be active
               after boot. By default, the generic system.slice slice unit as
               well as the root slice unit -.slice are pulled in and ordered
               before this unit (see below).
    
               Adding slice units to slices.target is generally not
               necessary. Instead, when some unit that uses _Slice=_ is
               started, the specified slice will be started automatically.
               Adding _WantedBy=slices.target_ lines to the [Install] section
               should only be done for units that need to be always active.
               In that case care needs to be taken to avoid creating a loop
               through the automatic dependencies on "parent" slices.
    
               Added in version 229.
    
           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.
    
           soft-reboot.target
               A special target unit for shutting down and rebooting the
               userspace of the system (leaving the kernel running).
    
               Applications wanting to reboot the system should not start
               this unit directly, but should instead execute **systemctl**
               **soft-reboot**(possibly with the **--no-block** option) or call
               systemd-logind(8)'s
               **org.freedesktop.login1.Manager.RebootWithFlags()** D-Bus method
               directly.
    
               See systemd-soft-reboot.service(8) for further details of the
               operation this target pulls in.
    
               Added in version 254.
    
           storage-target-mode.target
               A special target unit that can be booted into that selects the
               "Storage Target Mode" for the OS. In this mode all local
               storage disks are exposed to external systems as block
               devices. This invokes systemd-storagetm.service(8) which
               exposes all local disks as NVMe-TCP devices for access over
               the network. It might as well invoke other services too that
               make local disks available via other mechanisms.
    
               Added in version 255.
    
           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
               systemd automatically adds dependencies of the types _Requires=_
               and _After=_ for this target unit to all services (except for
               those with _DefaultDependencies=no_).
    
               This target pulls in the services required for system
               initialization. System services pulled in by this target
               should declare _DefaultDependencies=no_ and specify all their
               dependencies manually, including access to anything more than
               a read only root filesystem. For details on the dependencies
               of this target, refer to bootup(7).
    
           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******[3] document.
    
           system-update.target, system-update-pre.target,
           system-update-cleanup.service
               A special target unit that is used for offline system updates.systemd-system-update-generator(8) will redirect the boot
               process to this target if /system-update or /etc/system-update
               exists. For more information see systemd.offline-updates(7).
    
               Updates should happen before the system-update.target is
               reached, and the services which implement them should cause
               the machine to reboot. The main units executing the update
               should order themselves after system-update-pre.target but not
               pull it in. Services which want to run during system updates
               only, but before the actual system update is executed should
               order themselves before this unit and pull it in. As a safety
               measure, if this does not happen, and /system-update or
               /etc/system-update still exists after system-update.target is
               reached, system-update-cleanup.service will remove the
               symlinks and reboot the machine.
    
               Added in version 186.
    
           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.
    
               Added in version 199.
    
           umount.target
               A special target unit that unmounts 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.
    
           usb-gadget.target
               This target is started automatically as soon as a USB Device
               Controller becomes available at boot.
    
               This may be used to pull in usb gadget dynamically when UDC
               hardware is found.
    
               Added in version 242.
    
           tpm2.target
               This target is started automatically if a TPM2 device is
               discovered, either by the OS or by the firmware. It acts as
               synchronization point for services that require TPM2 device
               access. The target unit is enqueued by
               systemd-tpm2-generator(8) if it detects that the firmware has
               discovered a TPM2 device but the OS kernel has not activated a
               driver for it yet. It is also pulled in whenever
               systemd-udevd.service(8) discovers a TPM2 device. The target
               unit is ordered after the /dev/tpmrm0 device node, so that it
               only becomes active once the TPM2 device is actually
               accessible. Early boot programs that intend to access the TPM2
               device should hence order themselves after this target unit,
               but not pull it in.
    
               Added in version 256.
    
       **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.
    
           blockdev@.target
               This template unit is used to order mount units and other
               consumers of block devices after services that synthesize
               these block devices. In particular, this is intended to be
               used with storage services (such as
               **systemd-cryptsetup** @.service(5)/
               systemd-veritysetup@.service(8)) that allocate and manage a
               virtual block device. Storage services are ordered before an
               instance of blockdev@.target, and the consumer units after it.
               The ordering is particularly relevant during shutdown, as it
               ensures that the mount is deactivated first and the service
               backing the mount later. The blockdev@.target instance should
               be pulled in via a **Wants=** dependency of the storage daemon and
               thus generally not be part of any transaction unless a storage
               daemon is used. The instance name for instances of this
               template unit must be a properly escaped block device node
               path, e.g.  blockdev@dev-mapper-foobar.target for the storage
               device /dev/mapper/foobar.
    
               Added in version 245.
    
           cryptsetup-pre.target
               This passive target unit may be pulled in by services that
               want to run before any encrypted block device is set up. All
               encrypted block devices are set up after this target has been
               reached. Since the shutdown order is implicitly the reverse
               start-up order between units, this target is particularly
               useful to ensure that a service is shut down only after all
               encrypted block devices are fully stopped.
    
               Added in version 215.
    
           veritysetup-pre.target
               This passive target unit may be pulled in by services that
               want to run before any verity integrity protected block device
               is set up. All verity integrity protected block devices are
               set up after this target has been reached. Since the shutdown
               order is implicitly the reverse start-up order between units,
               this target is particularly useful to ensure that a service is
               shut down only after all verity integrity protected block
               devices are fully stopped.
    
               Added in version 248.
    
           first-boot-complete.target
               This passive target is intended as a synchronization point for
               units that need to run once during the first boot. Only after
               all units ordered before this target have finished, will the
               machine-id(5) be committed to disk, marking the first boot as
               completed. If the boot is aborted at any time before that, the
               next boot will re-run any units with _ConditionFirstBoot=yes_.
    
               Added in version 247.
    
           getty-pre.target
               A special passive target unit. Users of this target are
               expected to pull it in the boot transaction via a dependency
               (e.g.  _Wants=_). Order your unit before this unit if you want
               to make use of the console just before getty is started.
    
               Added in version 235.
    
           imports-pre.target
               A passive unit that is ordered before all disk image download
               jobs to execute on system boot. This is used by
               systemd-import-generator(8).
    
               Added in version 258.
    
           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. However, the following should apply at
               minimum:
    
               •   At start-up, any configured synthetic network devices
                   (i.e. not physical ones that require hardware to show up
                   and be probed, but virtual ones like bridge devices and
                   similar which are created programmatically) that do not
                   depend on any underlying hardware should be allocated by
                   the time this target is reached. It is not necessary for
                   these interfaces to also have completed IP level
                   configuration by the time network.target is reached.
    
               •   At shutdown, a unit that is ordered after network.target
                   will be stopped before the network — to whatever level it
                   might be set up by then — is shut down. It is hence useful
                   when writing service files that require network access on
                   shutdown, which should order themselves after this target,
                   but not pull it in. Also see **Running Services After the**
                   **Network Is Up******[2] for more information.
    
               It must emphasized that at start-up there's no guarantee that
               hardware-based devices have shown up by the time this target
               is reached, or even acquired complete IP configuration. For
               that purpose use network-online.target as described above.
    
           network-pre.target
               This passive target unit may be pulled in by services that
               want to run before any network is set up, for example for the
               purpose of setting up a firewall. All network management
               software orders itself after this target, but does not pull it
               in. Also see**Running Services After the Network Is Up******[2] for
               more information.
    
               Added in version 214.
    
           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 UNIX user/group name lookups for which
               nss-user-lookup.target should be used. All services for which
               the availability of full host/network name resolution is
               essential should be ordered after this target, but not pull it
               in. 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
               regular UNIX user/group name service lookups. Note that this
               is independent of host/network name lookups for which
               nss-lookup.target should be used. All services for which the
               availability of the full user/group database is essential
               should be ordered after this target, but not pull it in. All
               services which provide parts of the user/group database should
               be ordered before this target, and pull it in. Note that this
               unit is only relevant for regular users and groups — system
               users and groups are required to be resolvable during earliest
               boot already, and hence do not need any special ordering
               against this target.
    
           remote-fs-pre.target
               This target unit is automatically ordered before all mount
               point units (see above) and cryptsetup/veritysetup devices
               marked with the **_netdev**. It can be used to run certain units
               before remote encrypted devices and 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).
    
           rpcbind.target
               The portmapper/rpcbind pulls in this target and orders itself
               before it, to indicate its availability. 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.
    
           ssh-access.target
               Service and socket units that provide remote SSH secure shell
               access to the local system should pull in this unit and order
               themselves before this unit. It's supposed to act as a
               milestone indicating if and when SSH access into the system is
               available. It should only become active when an SSH port is
               bound for remote clients (i.e. if SSH is used as a local
               privilege escalation mechanism, it should _not_ involve this
               target unit), regardless of the protocol choices, i.e.
               regardless of whether IPv4, IPv6 or **AF_VSOCK** is used.
    
               Added in version 256.
    
           time-set.target
               Services responsible for setting the system clock
               (**CLOCK_REALTIME**) from a local source (such as a maintained
               timestamp file or imprecise real-time clock) should pull in
               this target and order themselves before it. Services where
               approximate, roughly monotonic time is desired should be
               ordered after this unit, but not pull it in.
    
               This target does not provide the accuracy guarantees of
               time-sync.target (see below), however does not depend on
               remote clock sources to be reachable, i.e. the target is
               typically not delayed by network problems and similar. Use of
               this target is recommended for services where approximate
               clock accuracy and rough monotonicity is desired but
               activation shall not be delayed for possibly unreliable
               network communication.
    
               The service manager automatically adds dependencies of type
               _After=_ for this target unit to all timer units with at least
               one _OnCalendar=_ directive.
    
               The systemd-timesyncd.service(8) service is a simple daemon
               that pulls in this target and orders itself before it. Besides
               implementing the SNTP network protocol it maintains a
               timestamp file on disk whose modification time is regularly
               updated. At service start-up the local system clock is set
               from that modification time, ensuring it increases roughly
               monotonically.
    
               Note that ordering a unit after time-set.target only has
               effect if there's actually a service ordered before it that
               delays it until the clock is adjusted for rough monotonicity.
               Otherwise, this target might get reached before the clock is
               adjusted to be roughly monotonic. Enable
               systemd-timesyncd.service(8), or an alternative NTP
               implementation to delay the target.
    
               Added in version 242.
    
           time-sync.target
               Services indicating completed synchronization of the system
               clock (**CLOCK_REALTIME**) to a remote source should pull in this
               target and order themselves before it. Services where accurate
               time is essential should be ordered after this unit, but not
               pull it in.
    
               The service manager 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, as
               well to all timer units with at least one _OnCalendar=_
               directive.
    
               This target provides stricter clock accuracy guarantees than
               time-set.target (see above), but likely requires network
               communication and thus introduces unpredictable delays.
               Services that require clock accuracy and where network
               communication delays are acceptable should use this target.
               Services that require a less accurate clock, and only
               approximate and roughly monotonic clock behaviour should use
               time-set.target instead.
    
               Note that ordering a unit after time-sync.target only has
               effect if there's actually a service ordered before it that
               delays it until clock synchronization is reached. Otherwise,
               this target might get reached before the clock is synchronized
               to any remote accurate reference clock. When using
               systemd-timesyncd.service(8), enable
               systemd-time-wait-sync.service(8) to delay the target; or use
               an equivalent service for other NTP implementations.
    
               **Table 1. Comparison**
               ┌───────────────────────────┬────────────────────────────────┐
               │ **time-set.target** │ **time-sync.target** │
               ├───────────────────────────┼────────────────────────────────┤
               │ "quick" to reach          │ "slow" to reach                │
               ├───────────────────────────┼────────────────────────────────┤
               │ typically uses local      │ typically uses remote          │
               │ clock sources, boot       │ clock sources, inserts         │
               │ process not affected by   │ dependencies on remote         │
               │ availability of external  │ resources into boot            │
               │ resources                 │ process                        │
               ├───────────────────────────┼────────────────────────────────┤
               │ reliable, because local   │ unreliable, because            │
               │                           │ typically network              │
               │                           │ involved                       │
               ├───────────────────────────┼────────────────────────────────┤
               │ typically guarantees an   │ typically guarantees an        │
               │ approximate and roughly   │ accurate clock                 │
               │ monotonic clock only      │                                │
               ├───────────────────────────┼────────────────────────────────┤
               │ implemented by            │ implemented by                 │
               │ systemd-timesyncd.service │ systemd-time-wait-sync.service │
               └───────────────────────────┴────────────────────────────────┘
    
       **Special Slice Units**
           There are four ".slice" units which form the basis of the
           hierarchy for assignment of resources for services, users, and
           virtual machines or containers. See systemd.slice(5) for details
           about slice units.
    
           -.slice
               The root slice is the root of the slice hierarchy. It usually
               does not contain units directly, but may be used to set
               defaults for the whole tree.
    
               Added in version 206.
    
           machine.slice
               By default, all virtual machines and containers registered
               with **systemd-machined** are found in this slice. This is pulled
               in by systemd-machined.service.
    
               Added in version 206.
    
           capsule.slice
               By default, all capsules encapsulated in capsule@.service are
               found in this slice.
    
               Added in version 255.
    
           system.slice
               By default, all system services started by **systemd** are found
               in this slice.
    
               Added in version 206.
    
           user.slice
               By default, all user processes and services started on behalf
               of the user, including the per-user systemd instance are found
               in this slice. This is pulled in by systemd-logind.service.
    
               Added in version 206.
    


## UNITS MANAGED BY THE USER SERVICE MANAGER



       **Special User Units**
           When systemd runs as a user instance, the following special units
           are available:
    
           default.target
               This is the main target of the user service manager, started
               by default when the service manager is invoked. Various
               services that compose the normal user session should be pulled
               into this target. In this regard, default.target is similar to
               multi-user.target in the system instance, but it is a real
               unit, not an alias.
    
               Added in version 242.
    
           capsule@.target
               This is the main target of capsule service managers, started
               by default, instantiated with the capsule name. This may be
               used to define different sets of units that are started for
               different capsules via generic unit definitions. For details
               about capsules see capsule@.service(5).
    
               Added in version 255.
    
           In addition, the following units are available which have
           definitions similar to their system counterparts: exit.target,
           shutdown.target, sockets.target, timers.target, paths.target,
           bluetooth.target, printer.target, smartcard.target, sound.target.
    
       **Special Passive User Units**
           graphical-session.target
               This target is active whenever any graphical session is
               running. It is used to stop user services which only apply to
               a graphical (X, Wayland, etc.) session when the session is
               terminated. Such services should have
               "PartOf=graphical-session.target" in their [Unit] section. A
               target for a particular session (e. g.  gnome-session.target)
               starts and stops "graphical-session.target" with
               "BindsTo=graphical-session.target".
    
               Which services are started by a session target is determined
               by the "Wants=" and "Requires=" dependencies. For services
               that can be enabled independently, symlinks in ".wants/" and
               ".requires/" should be used, see systemd.unit(5). Those
               symlinks should either be shipped in packages, or should be
               added dynamically after installation, for example using
               "systemctl add-wants", see systemctl(1).
    
               **Example 2. Nautilus as part of a GNOME session**
               "gnome-session.target" pulls in Nautilus as top-level service:
    
                   [Unit]
                   Description=User systemd services for GNOME graphical session
                   Wants=nautilus.service
                   BindsTo=graphical-session.target
    
               "nautilus.service" gets stopped when the session stops:
    
                   [Unit]
                   Description=Render the desktop icons with Nautilus
                   PartOf=graphical-session.target
    
                   [Service]
                   ...
    
               Added in version 234.
    
           graphical-session-pre.target
               This target contains services which set up the environment or
               global configuration of a graphical session, such as SSH/GPG
               agents (which need to export an environment variable into all
               desktop processes) or migration of obsolete d-conf keys after
               an OS upgrade (which needs to happen before starting any
               process that might use them). This target must be started
               before starting a graphical session like gnome-session.target.
    
               Added in version 234.
    
           xdg-desktop-autostart.target
               The XDG specification defines a way to autostart applications
               using XDG desktop files. systemd ships
               systemd-xdg-autostart-generator(8) for the XDG desktop files
               in autostart directories. Desktop Environments can opt-in to
               use this service by adding a _Wants=_ dependency on
               xdg-desktop-autostart.target.
    
               Added in version 246.
    
       **Special User Slice Units**
           There are four ".slice" units which form the basis of the user
           hierarchy for assignment of resources for user applications and
           services. See systemd.slice(5) for details about slice units and
           the documentation about **Desktop Environments******[4] for further
           information.
    
           -.slice
               The root slice is the root of the user's slice hierarchy. It
               usually does not contain units directly, but may be used to
               set defaults for the whole tree.
    
               Added in version 247.
    
           app.slice
               By default, all user services and applications managed by**systemd** are found in this slice. All interactively launched
               applications like web browsers and text editors as well as
               non-critical services should be placed into this slice.
    
               Added in version 247.
    
           session.slice
               All essential services and applications required for the
               session should use this slice. These are services that either
               cannot be restarted easily or where latency issues may affect
               the interactivity of the system and applications. This
               includes the display server, screen readers and other services
               such as DBus or XDG portals. Such services should be
               configured to be part of this slice by adding
               _Slice=session.slice_ to their unit files.
    
               Added in version 247.
    
           background.slice
               All services running low-priority background tasks should use
               this slice. This permits resources to be preferentially
               assigned to the other slices. Examples include non-interactive
               tasks like file indexing or backup operations where latency is
               not important.
    
               Added in version 247.
    


## NOTES



            1. Factory Reset
               https://systemd.io/FACTORY_RESET
    
            2. Running Services After the Network Is Up
               https://systemd.io/NETWORK_ONLINE
    
            3. Syslog Interface
               https://systemd.io/SYSLOG
    
            4. Desktop Environments
               https://systemd.io/DESKTOP_ENVIRONMENTS
    


* * *