X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=man%2Fsystemd.special.xml;h=cf76aaf607eb1fddb4ebf00e9198983f96e3e70d;hb=11ea2781eea4b912d2feb26785ece475e504c57b;hp=3f9286d4b4e4a13434007ec7d0af0b889959e873;hpb=9f23530860942a8f94b7c535ead80c38f02424b1;p=elogind.git diff --git a/man/systemd.special.xml b/man/systemd.special.xml index 3f9286d4b..cf76aaf60 100644 --- a/man/systemd.special.xml +++ b/man/systemd.special.xml @@ -1,6 +1,6 @@ + "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> - - systemd.special - systemd - - - - Developer - Lennart - Poettering - lennart@poettering.net - - - - - - systemd.special - 7 - - - - systemd.special - special systemd units - - - - emergency.service - local-fs.target - network.target - nss-lookup.target - remote-fs.target - rpcbind.target - rtc-set.target - shutdown.target - sigpwr.target - sockets.target - swap.target - syslog.target - systemd-initctl.service - systemd-initctl.socket - systemd-logger.service - systemd-logger.socket - - - - Description - - A few units are treated specially by - systemd. They have special internal semantics and - cannot be renamed. - - - - Special System Units - - - - emergency.service - - A special service unit - that starts an emergency - shell on the main - console. This unit is supposed - to be used with the kernel - command line option - systemd.default= - and has otherwise little use. - - - - - local-fs.target - - systemd automatically - adds dependencies of type - After to all mount units that - refer to local mount - points. In addition, systemd - adds dependencies of type - Wants to those mounts listed - in - /etc/fstab - that have the - auto and - comment=systemd.mount - mount options set. - - systemd automatically - adds dependencies of type - After to this target unit for - all SysV init scripts with an - LSB header referring to the - $local_fs - facility. - - - - network.target - - systemd automatically - adds dependencies of type - After to this target unit for - all SysV init scripts with an - LSB header referring to the - $network - facility. - - - - nss-lookup.target - - systemd automatically - adds dependencies of type - After to this target unit for - all SysV init scripts with an - LSB header referring to the - $named - facility. - - - - remote-fs.target - - Similar to local-fs.target, but for remote mount points. - systemd automatically - adds dependencies of type - After to this target unit for - all SysV init scripts with an - LSB header referring to the - $remote-fs - facility. - - - - rpcbind.target - - systemd automatically - adds dependencies of type - After to this target unit for - all SysV init scripts with an - LSB header referring to the - $rpcbind - facility. - - - - rtc-set.target - - systemd automatically - adds dependencies of type - After to this target unit for - all SysV init scripts with an - LSB header referring to the - $time - facility. - - - - shutdown.target - - A special target unit - that terminates the services - on system shutdown. - - Services that shall be - terminated on system shutdown - shall add Wants dependencies - from this unit to their - service unit during - installation. - - systemd automatically - adds dependencies of type - Conflicts to this target unit - for all SysV init scripts that - shall be terminated in SysV - runlevels 0 or 6. - - - - 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 the - power fails. - - - - sockets.target - - A special target unit - that sets up all service - sockets. - - Services that can be - socket-activated shall add - Wants dependencies from this - unit to their socket unit - during installation. - - - - swap.target - - Similar to - local-fs.target, but for swap - partitions and swap - files. - - - - syslog.target - - systemd automatically - adds dependencies of type - After to this target unit for - all SysV init scripts with an - LSB header referring to the - $syslog - facility. - - Administrators should - ensure that this target pulls - in a service unit with the - name or alias of - @SPECIAL_SYSLOG_NAME@ (or a - socket unit that activates - this service). - - - - systemd-initctl.service - - This provides - compatibility with the SysV - /dev/initctl file system FIFO - for communication with the - init system. - This is a - socket-activated service, see - system-initctl.socket. - - - - systemd-initctl.socket - - Socket activation unit - for - system-initctl.service. - - - - systemd-logger.service - - This is used internally - by systemd to provide syslog - logging to started - processes. - This is a - socket-activated service, see - system-logger.socket. - - - - systemd-logger.socket - - Socket activation unit - for - system-logger.service. - - - - - - - Special Session Units - - When systemd runs as a service instance, the - following special units are available, which have - similar definitions as their system counterparts: - local-fs.target, - remote-fs.target, - shutdown.target, - sockets.target, - swap.target. - - - - See Also - - systemd.unit5 - systemd.service5 - systemd.socket5 - systemd.target5 - - + + systemd.special + systemd + + + + Developer + Lennart + Poettering + lennart@poettering.net + + + + + + systemd.special + 7 + + + + systemd.special + Special systemd units + + + + basic.target, + bluetooth.target, + ctrl-alt-del.target, + cryptsetup.target, + cryptsetup-pre.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, + network-pre.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, + system-update.target, + time-sync.target, + timers.target, + umount.target, + -.slice, + system.slice, + user.slice, + machine.slice + + + + 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-generator3 + automatically adds dependencies of type + Before= to + sysroot-usr.mount and all mount points + found in /etc/fstab that have + and not have + 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-generator3 + 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 + mount option set. + + + + 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 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 do not need to pull + this in. + + + + paths.target + + A special target unit that sets up all path units (see + systemd.path5 + 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-generator3 + 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.socket5 + 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 document. + + + + system-update.target + + A special target unit that is used for off-line system + updates. + systemd-system-update-generator8 + will redirect the boot process to this target if + /system-update exists. For more + information see the System + Updates Specification. + + + + timers.target + + A special target unit that sets up all timer units + (see + systemd.timer5 + 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. + + + + 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. + + + + local-fs-pre.target + + This target unit is + automatically ordered before + all local mount points marked + with + (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. 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 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. + + + + 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. + + + + 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. + 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 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. Note that system users are always + resolvable, and hence do not require any special ordering + against this target. + + + + 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). + + + + 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. + + + + time-sync.target + + Services responsible for synchronizing the system + clock from a remote source (such as NTP client + implementations) should pull in this target and order + themselves before it. All services where correct time is + essential should be ordered after this unit, 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 $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. + + + + + + + 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. + + + + -.slice + + The root slice is the root of the hierarchy. It + usually does not contain units directly, but may be used to + set defaults for the whole tree. + + + + + system.slice + + By default, all services services started by + systemd are found in this slice. + + + + + 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. + + + + + machine.slice + + By default, all virtual machines and containers + registered with systemd-machined are + found in this slice. + + + + + + + + See Also + + systemd1, + systemd.unit5, + systemd.service5, + systemd.socket5, + systemd.target5, + systemd.slice5, + bootup7, + systemd-fstab-generator8 + +