A short human readable title of the unit. This may be used by systemd (and other UIs) as a user-visible label for the unit, so this string should identify the unit rather than describe it, despite the name. This string also shouldn't just repeat the unit name. "Apache2 Web Server" is a good example. Bad examples are "high-performance light-weight HTTP server" (too generic) or "Apache2" (meaningless for people who do not know Apache, duplicates the unit name). systemd may use this string as a noun in status messages ("Starting description...", "Started description.", "Reached target description.", "Failed to start description."), so it should be capitalized, and should not be a full sentence, or a phrase with a continuous verb. Bad examples include "exiting the container" or "updating the database once per day.".

A space-separated list of URIs referencing documentation for this unit or its configuration. Accepted are only URIs of the types "http://", "https://", "file:", "info:", "man:". For more information about the syntax of these URIs, see uri(7). The URIs should be listed in order of relevance, starting with the most relevant. It is a good idea to first reference documentation that explains what the unit's purpose is, followed by how it is configured, followed by any other related documentation. This option may be specified more than once, in which case the specified list of URIs is merged. If the empty string is assigned to this option, the list is reset and all prior assignments will have no effect.

Configures (weak) requirement dependencies on other units. This option may be specified more than once or multiple space-separated units may be specified in one option in which case dependencies for all listed names will be created. Dependencies of this type may also be configured outside of the unit configuration file by adding a symlink to a .wants/ directory accompanying the unit file. For details, see above.

Units listed in this option will be started if the configuring unit is. However, if the listed units fail to start or cannot be added to the transaction, this has no impact on the validity of the transaction as a whole, and this unit will still be started. This is the recommended way to hook the start-up of one unit to the start-up of another unit.

Note that requirement dependencies do not influence the order in which services are started or stopped. This has to be configured independently with the After= or Before= options. If unit foo.service pulls in unit bar.service as configured with Wants= and no ordering is configured with After= or Before=, then both units will be started simultaneously and without any delay between them if foo.service is activated.

Similar to Wants=, but declares a stronger requirement dependency. Dependencies of this type may also be configured by adding a symlink to a .requires/ directory accompanying the unit file.

If this unit gets activated, the units listed will be activated as well. If one of the other units fails to activate, and an ordering dependency After= on the failing unit is set, this unit will not be started. Besides, with or without specifying After=, this unit will be stopped if one of the other units is explicitly stopped.

Often, it is a better choice to use Wants= instead of Requires= in order to achieve a system that is more robust when dealing with failing services.

Note that this dependency type does not imply that the other unit always has to be in active state when this unit is running. Specifically: failing condition checks (such as ConditionPathExists=, ConditionPathIsSymbolicLink=, … — see below) do not cause the start job of a unit with a Requires= dependency on it to fail. Also, some unit types may deactivate on their own (for example, a service process may decide to exit cleanly, or a device may be unplugged by the user), which is not propagated to units having a Requires= dependency. Use the BindsTo= dependency type together with After= to ensure that a unit may never be in active state without a specific other unit also in active state (see below).

Similar to Requires=. However, if the units listed here are not started already, they will not be started and the starting of this unit will fail immediately. Requisite= does not imply an ordering dependency, even if both units are started in the same transaction. Hence this setting should usually be combined with After=, to ensure this unit is not started before the other unit.

When Requisite=b.service is used on a.service, this dependency will show as RequisiteOf=a.service in property listing of b.service. RequisiteOf= dependency cannot be specified directly.

Configures requirement dependencies, very similar in style to Requires=. However, this dependency type is stronger: in addition to the effect of Requires= it declares that if the unit bound to is stopped, this unit will be stopped too. This means a unit bound to another unit that suddenly enters inactive state will be stopped too. Units can suddenly, unexpectedly enter inactive state for different reasons: the main process of a service unit might terminate on its own choice, the backing device of a device unit might be unplugged or the mount point of a mount unit might be unmounted without involvement of the system and service manager.

When used in conjunction with After= on the same unit the behaviour of BindsTo= is even stronger. In this case, the unit bound to strictly has to be in active state for this unit to also be in active state. This not only means a unit bound to another unit that suddenly enters inactive state, but also one that is bound to another unit that gets skipped due to a failed condition check (such as ConditionPathExists=, ConditionPathIsSymbolicLink=, … — see below) will be stopped, should it be running. Hence, in many cases it is best to combine BindsTo= with After=.

When BindsTo=b.service is used on a.service, this dependency will show as BoundBy=a.service in property listing of b.service. BoundBy= dependency cannot be specified directly.

Configures dependencies similar to Requires=, but limited to stopping and restarting of units. When systemd stops or restarts the units listed here, the action is propagated to this unit. Note that this is a one-way dependency — changes to this unit do not affect the listed units.

When PartOf=b.service is used on a.service, this dependency will show as ConsistsOf=a.service in property listing of b.service. ConsistsOf= dependency cannot be specified directly.

Configures dependencies similar to Wants=, but as long a this unit is up, all units listed in Upholds= are started whenever found to be inactive or failed, and no job is queued for them. While a Wants= dependency on another unit has a one-time effect when this units started, a Upholds= dependency on it has a continuous effect, constantly restarting the unit if necessary. This is an alternative to the Restart= setting of service units, to ensure they are kept running whatever happens.

When Upholds=b.service is used on a.service, this dependency will show as UpheldBy=a.service in the property listing of b.service. The UpheldBy= dependency cannot be specified directly.

A space-separated list of unit names. Configures negative requirement dependencies. If a unit has a Conflicts= setting on another unit, starting the former will stop the latter and vice versa.

Note that this setting does not imply an ordering dependency, similarly to the Wants= and Requires= dependencies described above. This means that to ensure that the conflicting unit is stopped before the other unit is started, an After= or Before= dependency must be declared. It doesn't matter which of the two ordering dependencies is used, because stop jobs are always ordered before start jobs, see the discussion in Before=/After= below.

If unit A that conflicts with unit B is scheduled to be started at the same time as B, the transaction will either fail (in case both are required parts of the transaction) or be modified to be fixed (in case one or both jobs are not a required part of the transaction). In the latter case, the job that is not required will be removed, or in case both are not required, the unit that conflicts will be started and the unit that is conflicted is stopped.

These two settings expect a space-separated list of unit names. They may be specified more than once, in which case dependencies for all listed names are created.

Those two settings configure ordering dependencies between units. If unit foo.service contains the setting Before=bar.service and both units are being started, bar.service's start-up is delayed until foo.service has finished starting up. After= is the inverse of Before=, i.e. while Before= ensures that the configured unit is started before the listed unit begins starting up, After= ensures the opposite, that the listed unit is fully started up before the configured unit is started.

When two units with an ordering dependency between them are shut down, the inverse of the start-up order is applied. I.e. if a unit is configured with After= on another unit, the former is stopped before the latter if both are shut down. Given two units with any ordering dependency between them, if one unit is shut down and the other is started up, the shutdown is ordered before the start-up. It doesn't matter if the ordering dependency is After= or Before=, in this case. It also doesn't matter which of the two is shut down, as long as one is shut down and the other is started up; the shutdown is ordered before the start-up in all cases. If two units have no ordering dependencies between them, they are shut down or started up simultaneously, and no ordering takes place. It depends on the unit type when precisely a unit has finished starting up. Most importantly, for service units start-up is considered completed for the purpose of Before=/After= when all its configured start-up commands have been invoked and they either failed or reported start-up success. Note that this does includes ExecStartPost= (or ExecStopPost= for the shutdown case).

Note that those settings are independent of and orthogonal to the requirement dependencies as configured by Requires=, Wants=, Requisite=, or BindsTo=. It is a common pattern to include a unit name in both the After= and Wants= options, in which case the unit listed will be started before the unit that is configured with these options.

Note that Before= dependencies on device units have no effect and are not supported. Devices generally become available as a result of an external hotplug event, and systemd creates the corresponding device unit without delay.

A space-separated list of one or more units that are activated when this unit enters the "failed" state. A service unit using Restart= enters the failed state only after the start limits are reached.

A space-separated list of one or more units that are activated when this unit enters the "inactive" state.

A space-separated list of one or more units to which reload requests from this unit shall be propagated to, or units from which reload requests shall be propagated to this unit, respectively. Issuing a reload request on a unit will automatically also enqueue reload requests on all units that are linked to it using these two settings.

A space-separated list of one or more units to which stop requests from this unit shall be propagated to, or units from which stop requests shall be propagated to this unit, respectively. Issuing a stop request on a unit will automatically also enqueue stop requests on all units that are linked to it using these two settings.

For units that start processes (such as service units), lists one or more other units whose network and/or temporary file namespace to join. This only applies to unit types which support the PrivateNetwork=, NetworkNamespacePath=, PrivateIPC=, IPCNamespacePath=, and PrivateTmp= directives (see systemd.exec(5) for details). If a unit that has this setting set is started, its processes will see the same /tmp/, /var/tmp/, IPC namespace and network namespace as one listed unit that is started. If multiple listed units are already started, it is not defined which namespace is joined. Note that this setting only has an effect if PrivateNetwork=/NetworkNamespacePath=, PrivateIPC=/IPCNamespacePath= and/or PrivateTmp= is enabled for both the unit that joins the namespace and the unit whose namespace is joined.

Takes a space-separated list of absolute paths. Automatically adds dependencies of type Requires= and After= for all mount units required to access the specified path.

Mount points marked with noauto are not mounted automatically through local-fs.target, but are still honored for the purposes of this option, i.e. they will be pulled in by this unit.

Takes a value of "fail", "replace", "replace-irreversibly", "isolate", "flush", "ignore-dependencies" or "ignore-requirements". Defaults to "replace". Specifies how the units listed in OnFailure= will be enqueued. See systemctl(1)'s --job-mode= option for details on the possible values. If this is set to "isolate", only a single unit may be listed in OnFailure=.

Takes a boolean argument. If true, this unit will not be stopped when isolating another unit. Defaults to false for service, target, socket, timer, and path units, and true for slice, scope, device, swap, mount, and automount units.

Takes a boolean argument. If true, this unit will be stopped when it is no longer used. Note that, in order to minimize the work to be executed, systemd will not stop units by default unless they are conflicting with other units, or the user explicitly requested their shut down. If this option is set, a unit will be automatically cleaned up if no other active unit requires it. Defaults to false.

Takes a boolean argument. If true, this unit can only be activated or deactivated indirectly. In this case, explicit start-up or termination requested by the user is denied, however if it is started or stopped as a dependency of another unit, start-up or termination will succeed. This is mostly a safety feature to ensure that the user does not accidentally activate units that are not intended to be activated explicitly, and not accidentally deactivate units that are not intended to be deactivated. These options default to false.

Takes a boolean argument. If true, this unit may be used with the systemctl isolate command. Otherwise, this will be refused. It probably is a good idea to leave this disabled except for target units that shall be used similar to runlevels in SysV init systems, just as a precaution to avoid unusable system states. This option defaults to false.

Takes a boolean argument. If yes, (the default), a few default dependencies will implicitly be created for the unit. The actual dependencies created depend on the unit type. For example, for service units, these dependencies ensure that the service is started only after basic system initialization is completed and is properly terminated on system shutdown. See the respective man pages for details. Generally, only services involved with early boot or late shutdown should set this option to no. It is highly recommended to leave this option enabled for the majority of common units. If set to no, this option does not disable all implicit dependencies, just non-essential ones.

Tweaks the "garbage collection" algorithm for this unit. Takes one of inactive or inactive-or-failed. If set to inactive the unit will be unloaded if it is in the inactive state and is not referenced by clients, jobs or other units — however it is not unloaded if it is in the failed state. In failed mode, failed units are not unloaded until the user invoked systemctl reset-failed on them to reset the failed state, or an equivalent command. This behaviour is altered if this option is set to inactive-or-failed: in this case the unit is unloaded even if the unit is in a failed state, and thus an explicitly resetting of the failed state is not necessary. Note that if this mode is used unit results (such as exit codes, exit signals, consumed resources, …) are flushed out immediately after the unit completed, except for what is stored in the logging subsystem. Defaults to inactive.

Configure the action to take when the unit stops and enters a failed state or inactive state. Takes one of none, reboot, reboot-force, reboot-immediate, poweroff, poweroff-force, poweroff-immediate, exit, and exit-force. In system mode, all options are allowed. In user mode, only none, exit, and exit-force are allowed. Both options default to none.

If none is set, no action will be triggered. reboot causes a reboot following the normal shutdown procedure (i.e. equivalent to systemctl reboot). reboot-force causes a forced reboot which will terminate all processes forcibly but should cause no dirty file systems on reboot (i.e. equivalent to systemctl reboot -f) and reboot-immediate causes immediate execution of the reboot(2) system call, which might result in data loss (i.e. equivalent to systemctl reboot -ff). Similarly, poweroff, poweroff-force, poweroff-immediate have the effect of powering down the system with similar semantics. exit causes the manager to exit following the normal shutdown procedure, and exit-force causes it terminate without shutting down services. When exit or exit-force is used by default the exit status of the main process of the unit (if this applies) is returned from the service manager. However, this may be overridden with FailureActionExitStatus=/SuccessActionExitStatus=, see below.

Controls the exit status to propagate back to an invoking container manager (in case of a system service) or service manager (in case of a user manager) when the FailureAction=/SuccessAction= are set to exit or exit-force and the action is triggered. By default the exit status of the main process of the triggering unit (if this applies) is propagated. Takes a value in the range 0…255 or the empty string to request default behaviour.

JobTimeoutSec= specifies a timeout for the whole job that starts running when the job is queued. JobRunningTimeoutSec= specifies a timeout that starts running when the queued job is actually started. If either limit is reached, the job will be cancelled, the unit however will not change state or even enter the "failed" mode.

Both settings take a time span with the default unit of seconds, but other units may be specified, see systemd.time(5). The default is "infinity" (job timeouts disabled), except for device units where JobRunningTimeoutSec= defaults to DefaultTimeoutStartSec=.

Note: these timeouts are independent from any unit-specific timeouts (for example, the timeout set with TimeoutStartSec= in service units). The job timeout has no effect on the unit itself. Or in other words: unit-specific timeouts are useful to abort unit state changes, and revert them. The job timeout set with this option however is useful to abort only the job waiting for the unit state to change.

JobTimeoutAction= optionally configures an additional action to take when the timeout is hit, see description of JobTimeoutSec= and JobRunningTimeoutSec= above. It takes the same values as StartLimitAction=. Defaults to none.

JobTimeoutRebootArgument= configures an optional reboot string to pass to the reboot(2) system call.

Configure unit start rate limiting. Units which are started more than burst times within an interval time span are not permitted to start any more. Use StartLimitIntervalSec= to configure the checking interval and StartLimitBurst= to configure how many starts per interval are allowed.

interval is a time span with the default unit of seconds, but other units may be specified, see systemd.time(5). Defaults to DefaultStartLimitIntervalSec= in manager configuration file, and may be set to 0 to disable any kind of rate limiting. burst is a number and defaults to DefaultStartLimitBurst= in manager configuration file.

These configuration options are particularly useful in conjunction with the service setting Restart= (see systemd.service(5)); however, they apply to all kinds of starts (including manual), not just those triggered by the Restart= logic.

Note that units which are configured for Restart=, and which reach the start limit are not attempted to be restarted anymore; however, they may still be restarted manually or from a timer or socket at a later point, after the interval has passed. From that point on, the restart logic is activated again. systemctl reset-failed will cause the restart rate counter for a service to be flushed, which is useful if the administrator wants to manually start a unit and the start limit interferes with that. Rate-limiting is enforced after any unit condition checks are executed, and hence unit activations with failing conditions do not count towards the rate limit.

When a unit is unloaded due to the garbage collection logic (see above) its rate limit counters are flushed out too. This means that configuring start rate limiting for a unit that is not referenced continuously has no effect.

This setting does not apply to slice, target, device, and scope units, since they are unit types whose activation may either never fail, or may succeed only a single time.

Configure an additional action to take if the rate limit configured with StartLimitIntervalSec= and StartLimitBurst= is hit. Takes the same values as the FailureAction=/SuccessAction= settings. If none is set, hitting the rate limit will trigger no action except that the start will not be permitted. Defaults to none.

Configure the optional argument for the reboot(2) system call if StartLimitAction= or FailureAction= is a reboot action. This works just like the optional argument to systemctl reboot command.

A path to a configuration file this unit has been generated from. This is primarily useful for implementation of generator tools that convert configuration from an external configuration file format into native unit files. This functionality should not be used in normal units.

A space-separated list of additional names this unit shall be installed under. The names listed here must have the same suffix (i.e. type) as the unit filename. This option may be specified more than once, in which case all listed names are used. At installation time, systemctl enable will create symlinks from these names to the unit filename. Note that not all unit types support such alias names, and this setting is not supported for them. Specifically, mount, slice, swap, and automount units do not support aliasing.

This option may be used more than once, or a space-separated list of unit names may be given. A symbolic link is created in the .wants/ or .requires/ directory of each of the listed units when this unit is installed by systemctl enable. This has the effect that a dependency of type Wants= or Requires= is added from the listed unit to the current unit. The primary result is that the current unit will be started when the listed unit is started. See the description of Wants= and Requires= in the [Unit] section for details.

WantedBy=foo.service in a service bar.service is mostly equivalent to Alias=foo.service.wants/bar.service in the same file. In case of template units, systemctl enable must be called with an instance name, and this instance will be added to the .wants/ or .requires/ list of the listed unit. E.g. WantedBy=getty.target in a service getty@.service will result in systemctl enable getty@tty2.service creating a getty.target.wants/getty@tty2.service link to getty@.service.

Additional units to install/deinstall when this unit is installed/deinstalled. If the user requests installation/deinstallation of a unit with this option configured, systemctl enable and systemctl disable will automatically install/uninstall units listed in this option as well.

This option may be used more than once, or a space-separated list of unit names may be given.

In template unit files, this specifies for which instance the unit shall be enabled if the template is enabled without any explicitly set instance. This option has no effect in non-template unit files. The specified string must be usable as instance identifier.