Man page
systemd.unit

SYSTEMD.UNIT(5)                  systemd.unit                  SYSTEMD.UNIT(5)

NAME
       systemd.unit - Unit configuration

SYNOPSIS
       service.service, socket.socket, device.device, mount.mount,
       automount.automount, swap.swap, target.target, path.path, timer.timer,
       snapshot.snapshot

       /etc/systemd/system/*
       /run/systemd/system/*
       /usr/lib/systemd/system/*
       ...

       /etc/systemd/user/*
       /run/systemd/user/*
       /usr/lib/systemd/user/*
       ...

DESCRIPTION
       A unit configuration file encodes information about a service, a
       socket, a device, a mount point, an automount point, a swap file or
       partition, a start-up target, a file system path, or a timer controlled
       and supervised by systemd(1). The syntax is inspired by XDG Desktop
       Entry Specification[1].desktop files, which are in turn inspired by
       Microsoft Windows .ini files.

       This man page lists the common configuration options of all the unit
       types. These options need to be configured in the [Unit] or [Install]
       sections of the unit files.

       In addition to the generic [Unit] and [Install] sections described
       here, each unit may have a type-specific section, e.g. [Service] for a
       service unit. See the respective man pages for more information:
       systemd.service(5), systemd.socket(5), systemd.device(5),
       systemd.mount(5), systemd.automount(5), systemd.swap(5),
       systemd.target(5), systemd.path(5), systemd.timer(5),
       systemd.snapshot(5).

       Unit files are loaded from a set of paths determined during
       compilation, described in the next section.

       Unit files may contain additional options on top of those listed here.
       If systemd encounters an unknown option it will write a warning log
       message but continue loading the unit. If an option is prefixed with X-
       it is ignored completely by systemd. Applications may use this to
       include additional information in the unit files.

       Boolean arguments used in unit files can be written in various formats.
       For positive settings the strings 1, yes, true and on are equivalent.
       For negative settings the strings 0, no, false and off are equivalent.

       Time span values encoded in unit files can be written in various
       formats. A stand-alone number specifies a time in seconds. If suffixed
       with a time unit, the unit is honored. A concatenation of multiple
       values with units is supported, in which case the values are added up.
       Example: "50" refers to 50 seconds; "2min 200ms" refers to 2 minutes
       plus 200 milliseconds, i.e. 120200ms. The following time units are
       understood: s, min, h, d, w, ms, us. For details see systemd.time(7).

       Empty lines and lines starting with # or ; are ignored. This may be
       used for commenting. Lines ending in a backslash are concatenated with
       the following line while reading and the backslash is replaced by a
       space character. This may be used to wrap long lines.

       Along with a unit file foo.service the directory foo.service.wants/ may
       exist. All unit files symlinked from such a directory are implicitly
       added as dependencies of type Wanted= to the unit. This is useful to
       hook units into the start-up of other units, without having to modify
       their unit files. For details about the semantics of Wanted= see below.
       The preferred way to create symlinks in the .wants/ directory of a unit
       file is with the enable command of the systemctl(1) tool which reads
       information from the [Install] section of unit files (see below). A
       similar functionality exists for Requires= type dependencies as well,
       the directory suffix is .requires/ in this case.

       Along with a unit file foo.service a directory foo.service.d/ may
       exist. All files with the suffix .conf from this directory will be
       parsed after the file itself is parsed. This is useful to alter or add
       configuration settings to a unit, without having to modify their unit
       files. Make sure that the file that is included has the appropriate
       section headers before any directive.

       If a line starts with .include followed by a file name, the specified
       file will be parsed at this point. Make sure that the file that is
       included has the appropriate section headers before any directives.

       Note that while systemd offers a flexible dependency system between
       units it is recommended to use this functionality only sparingly and
       instead rely on techniques such as bus-based or socket-based activation
       which make dependencies implicit, resulting in a both simpler and more
       flexible system.

       Some unit names reflect paths existing in the file system name space.
       Example: a device unit dev-sda.device refers to a device with the
       device node /dev/sda in the file system namespace. If this applies a
       special way to escape the path name is used, so that the result is
       usable as part of a file name. Basically, given a path, "/" is replaced
       by "-", and all unprintable characters and the "-" are replaced by
       C-style "\x20" escapes. The root directory "/" is encoded as single
       dash, while otherwise the initial and ending "/" is removed from all
       paths during transformation. This escaping is reversible.

       Optionally, units may be instantiated from a template file at runtime.
       This allows creation of multiple units from a single configuration
       file. If systemd looks for a unit configuration file it will first
       search for the literal unit name in the filesystem. If that yields no
       success and the unit name contains an @ character, systemd will look
       for a unit template that shares the same name but with the instance
       string (i.e. the part between the @ character and the suffix) removed.
       Example: if a service getty@tty3.service is requested and no file by
       that name is found, systemd will look for getty@.service and
       instantiate a service from that configuration file if it is found.

       To refer to the instance string from within the configuration file you
       may use the special %i specifier in many of the configuration options.
       See below for details.

       If a unit file is empty (i.e. has the file size 0) or is symlinked to
       /dev/null its configuration will not be loaded and it appears with a
       load state of masked, and cannot be activated. Use this as an effective
       way to fully disable a unit, making it impossible to start it even
       manually.

       The unit file format is covered by the Interface Stability Promise[2].

UNIT LOAD PATH
       Unit files are loaded from a set of paths determined during
       compilation, described in the two tables below. Unit files found in
       directories higher in the hierarchy override files with the same name
       lower in the hierarchy, thus allowing overrides.

       When systemd is running in user mode (--user) and the variable
       $SYSTEMD_UNIT_PATH is set, this contents of this variable overrides the
       unit load path.

       Table 1.  Load path when running in system mode (--system).
       +------------------------------+--------------------------+
       |Path                          | Description              |
       +------------------------------+--------------------------+
       |/run/systemd/generator.early  | Generated units (early)  |
       +------------------------------+--------------------------+
       |/etc/systemd/system           | Local configuration      |
       +------------------------------+--------------------------+
       |/run/systemd/systemd          | Volatile units           |
       +------------------------------+--------------------------+
       |/run/systemd/generator        | Generated units (middle) |
       +------------------------------+--------------------------+
       |/usr/local/lib/systemd/system | Units for local packages |
       +------------------------------+--------------------------+
       |/usr/lib/systemd/system       | Units for installed      |
       |                              | packages                 |
       +------------------------------+--------------------------+
       |/run/systemd/generator.late   | Generated units (late)   |
       +------------------------------+--------------------------+

       Table 2.  Load path when running in session mode (--user).
       +------------------------------------+--------------------------+
       |Path                                | Description              |
       +------------------------------------+--------------------------+
       |/tmp/systemd-generator.early.XXXXXX | Generated units (early)  |
       +------------------------------------+--------------------------+
       |/etc/systemd/user                   | Local configuration      |
       +------------------------------------+--------------------------+
       |/run/systemd/user                   | Volatile units           |
       +------------------------------------+--------------------------+
       |/tmp/systemd-generator.XXXXXX       | Generated units (middle) |
       +------------------------------------+--------------------------+
       |/usr/local/lib/systemd/user         | Units for local packages |
       +------------------------------------+--------------------------+
       |/usr/lib/systemd/user               | Units for installed      |
       |                                    | packages                 |
       +------------------------------------+--------------------------+
       |/tmp/systemd-generator.late.XXXXXX  | Generated units (late)   |
       +------------------------------------+--------------------------+

       Additional units might be loaded into systemd ("linked") from
       directories not on the unit load path. See the link command for
       systemctl(1).

OPTIONS
       Unit file may include a [Unit] section, which carries generic
       information about the unit that is not dependent on the type of unit:

       Description=
           A free-form string describing the unit. This is intended for use in
           UIs to show descriptive information along with the unit name.

       Documentation=
           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.

       Requires=
           Configures requirement dependencies on other units. If this unit
           gets activated, the units listed here will be activated as well. If
           one of the other units gets deactivated or its activation fails,
           this unit will be deactivated. This option may be specified more
           than once, in which case requirement dependencies for all listed
           names are created. 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 a unit foo.service requires a unit bar.service as
           configured with Requires= 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. 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 dependencies of this type may also be configured outside
           of the unit configuration file by adding a symlink to a .requires/
           directory accompanying the unit file. For details see above.

       RequiresOverridable=
           Similar to Requires=. Dependencies listed in RequiresOverridable=
           which cannot be fulfilled or fail to start are ignored if the
           startup was explicitly requested by the user. If the start-up was
           pulled in indirectly by some dependency or automatic start-up of
           units that is not requested by the user this dependency must be
           fulfilled and otherwise the transaction fails. Hence, this option
           may be used to configure dependencies that are normally honored
           unless the user explicitly starts up the unit, in which case
           whether they failed or not is irrelevant.

       Requisite=, RequisiteOverridable=
           Similar to Requires= and RequiresOverridable=, respectively.
           However, if a unit listed here is not started already it will not
           be started and the transaction fails immediately.

       Wants=
           A weaker version of Requires=. A unit listed in this option will be
           started if the configuring unit is. However, if the listed unit
           fails to start up or cannot be added to the transaction this has no
           impact on the validity of the transaction as a whole. This is the
           recommended way to hook start-up of one unit to the start-up of
           another unit.

           Note that 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.

       BindsTo=
           Configures requirement dependencies, very similar in style to
           Requires=, however in addition to this behavior it also declares
           that this unit is stopped when any of the units listed suddenly
           disappears. Units can suddenly, unexpectedly disappear if a service
           terminates on its own choice, a device is unplugged or a mount
           point unmounted without involvement of systemd.

       PartOf=
           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.

       Conflicts=
           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 is independent of
           and orthogonal to the After= and Before= ordering dependencies.

           If a unit A that conflicts with a unit B is scheduled to be started
           at the same time as B, the transaction will either fail (in case
           both are required part 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 the 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.

       Before=, After=
           Configures ordering dependencies between units. If a unit
           foo.service contains a setting Before=bar.service and both units
           are being started, bar.service‘s start-up is delayed until
           foo.service is started up. Note that this setting is independent of
           and orthogonal to the requirement dependencies as configured by
           Requires=. It is a common pattern to include a unit name in both
           the After= and Requires= option in which case the unit listed will
           be started before the unit that is configured with these options.
           This option may be specified more than once, in which case ordering
           dependencies for all listed names are created.  After= is the
           inverse of Before=, i.e. while After= ensures that the configured
           unit is started after the listed unit finished starting up, Before=
           ensures the opposite, i.e. that the configured unit is fully
           started up before the listed unit is started. Note that 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. If one unit with an
           ordering dependency on another unit is shut down while the latter
           is started up, the shut down is ordered before the start-up
           regardless whether the ordering dependency is actually of type
           After= or Before=. If two units have no ordering dependencies
           between them they are shut down or started up simultaneously, and
           no ordering takes place.

       OnFailure=
           Lists one or more units that are activated when this unit enters
           the ‘failed‘ state.

       PropagatesReloadTo=, ReloadPropagatedFrom=
           Lists one or more units where reload requests on the unit will be
           propagated to/on the other unit will be propagated from. Issuing a
           reload request on a unit will automatically also enqueue a reload
           request on all units that the reload request shall be propagated to
           via these two settings.

       RequiresMountsFor=
           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.

       OnFailureIsolate=
           Takes a boolean argument. If true the unit listed in OnFailure=
           will be enqueued in isolation mode, i.e. all units that are not its
           dependency will be stopped. If this is set only a single unit may
           be listed in OnFailure=. Defaults to false.

       IgnoreOnIsolate=
           Takes a boolean argument. If true this unit will not be stopped
           when isolating another unit. Defaults to false.

       IgnoreOnSnapshot=
           Takes a boolean argument. If true this unit will not be included in
           snapshots. Defaults to true for device and snapshot units, false
           for the others.

       StopWhenUnneeded=
           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.

       RefuseManualStart=, RefuseManualStop=
           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.

       AllowIsolate=
           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.

       DefaultDependencies=
           Takes a boolean argument. If true (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 false. It is highly
           recommended to leave this option enabled for the majority of common
           units. If set to false this option does not disable all implicit
           dependencies, just non-essential ones.

       JobTimeoutSec=
           When clients are waiting for a job of this unit to complete, time
           out after the specified time. If this time limit is reached the job
           will be cancelled, the unit however will not change state or even
           enter the ‘failed‘ mode. This value defaults to 0 (job timeouts
           disabled), except for device units. NB: this timeout is independent
           from any unit-specific timeout (for example, the timeout set with
           Timeout= in service units) as the job timeout has no effect on the
           unit itself, only on the job that might be pending for it. 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.

       ConditionPathExists=, ConditionPathExistsGlob=,
       ConditionPathIsDirectory=, ConditionPathIsSymbolicLink=,
       ConditionPathIsMountPoint=, ConditionPathIsReadWrite=,
       ConditionDirectoryNotEmpty=, ConditionFileNotEmpty=,
       ConditionFileIsExecutable=, ConditionKernelCommandLine=,
       ConditionVirtualization=, ConditionSecurity=, ConditionCapability=,
       ConditionHost=, ConditionACPower=, ConditionNull=
           Before starting a unit verify that the specified condition is true.
           If it is not true the starting of the unit will be skipped, however
           all ordering dependencies of it are still respected. A failing
           condition will not result in the unit being moved into a failure
           state. The condition is checked at the time the queued start job is
           to be executed.

           With ConditionPathExists= a file existence condition is checked
           before a unit is started. If the specified absolute path name does
           not exist the condition will fail. If the absolute path name passed
           to ConditionPathExists= is prefixed with an exclamation mark (‘!‘),
           the test is negated, and the unit is only started if the path does
           not exist.

           ConditionPathExistsGlob= is similar to ConditionPathExists=, but
           checks for the existence of at least one file or directory matching
           the specified globbing pattern.

           ConditionPathIsDirectory= is similar to ConditionPathExists= but
           verifies whether a certain path exists and is a directory.

           ConditionPathIsSymbolicLink= is similar to ConditionPathExists= but
           verifies whether a certain path exists and is a symbolic link.

           ConditionPathIsMountPoint= is similar to ConditionPathExists= but
           verifies whether a certain path exists and is a mount point.

           ConditionPathIsReadWrite= is similar to ConditionPathExists= but
           verifies whether the underlying file system is readable and
           writable (i.e. not mounted read-only).

           ConditionDirectoryNotEmpty= is similar to ConditionPathExists= but
           verifies whether a certain path exists and is a non-empty
           directory.

           ConditionFileNotEmpty= is similar to ConditionPathExists= but
           verifies whether a certain path exists and refers to a regular file
           with a non-zero size.

           ConditionFileIsExecutable= is similar to ConditionPathExists= but
           verifies whether a certain path exists, is a regular file and
           marked executable.

           Similar, ConditionKernelCommandLine= may be used to check whether a
           specific kernel command line option is set (or if prefixed with the
           exclamation mark unset). The argument must either be a single word,
           or an assignment (i.e. two words, separated ‘=‘). In the former
           case the kernel command line is searched for the word appearing as
           is, or as left hand side of an assignment. In the latter case the
           exact assignment is looked for with right and left hand side
           matching.

           ConditionVirtualization= may be used to check whether the system is
           executed in a virtualized environment and optionally test whether
           it is a specific implementation. Takes either boolean value to
           check if being executed in any virtualized environment, or one of
           vm and container to test against a generic type of virtualization
           solution, or one of qemu, kvm, vmware, microsoft, oracle, xen,
           bochs, chroot, openvz, lxc, lxc-libvirt, systemd-nspawn to test
           against a specific implementation. If multiple virtualization
           technologies are nested only the innermost is considered. The test
           may be negated by prepending an exclamation mark.

           ConditionSecurity= may be used to check whether the given security
           module is enabled on the system. Currently the only recognized
           values are selinux, apparmor, and smack. The test may be negated by
           prepending an exclamation mark.

           ConditionCapability= may be used to check whether the given
           capability exists in the capability bounding set of the service
           manager (i.e. this does not check whether capability is actually
           available in the permitted or effective sets, see capabilities(7)
           for details). Pass a capability name such as CAP_MKNOD, possibly
           prefixed with an exclamation mark to negate the check.

           ConditionHost= may be used to match against the host name or
           machine ID of the host. This either takes a host name string
           (optionally with shell style globs) which is tested against the
           locally set host name as returned by gethostname(2), or a machine
           ID formatted as string (see machine-id(5)). The test may be negated
           by prepending an exclamation mark.

           ConditionACPower= may be used to check whether the system has AC
           power, or is exclusively battery powered at the time of activation
           of the unit. This takes a boolean argument. If set to true the
           condition will hold only if at least one AC connector of the system
           is connected to a power source, or if no AC connectors are known.
           Conversely, if set to false the condition will hold only if there
           is at least one AC connector known and all AC connectors are
           disconnected from a power source.

           Finally, ConditionNull= may be used to add a constant condition
           check value to the unit. It takes a boolean argument. If set to
           false the condition will always fail, otherwise succeed.

           If multiple conditions are specified the unit will be executed if
           all of them apply (i.e. a logical AND is applied). Condition checks
           can be prefixed with a pipe symbol (|) in which case a condition
           becomes a triggering condition. If at least one triggering
           condition is defined for a unit then the unit will be executed if
           at least one of the triggering conditions apply and all of the
           non-triggering conditions. If you prefix an argument with the pipe
           symbol and an exclamation mark the pipe symbol must be passed
           first, the exclamation second. Except for
           ConditionPathIsSymbolicLink=, all path checks follow symlinks. If
           any of these options is assigned the empty string the list of
           conditions is reset completely, all previous condition settings (of
           any kind) will have no effect.

       SourcePath=
           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. Thus functionality should not be used in
           normal units.

       Unit file may include a [Install] section, which carries installation
       information for the unit. This section is not interpreted by systemd(1)
       during runtime. It is used exclusively by the enable and disable
       commands of the systemctl(1) tool during installation of a unit:

       Alias=
           Additional names this unit shall be installed under. The names
           listed here must have the same suffix (i.e. type) as the unit file
           name. 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 file name.

       WantedBy=, RequiredBy=
           Installs a symlink in the .wants/ or .requires/ subdirectory for a
           unit, respectively. This has the effect that when the listed unit
           name is activated the unit listing it is activated too.
           WantedBy=foo.service in a service bar.service is mostly equivalent
           to Alias=foo.service.wants/bar.service in the same file.

       Also=
           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.

       The following specifiers are interpreted in the Install section: %n,
       %N, %p, %i, %U, %u, %m, %H, %b. For their meaning see the next section.

SPECIFIERS
       Many settings resolve specifiers which may be used to write generic
       unit files referring to runtime or unit parameters that are replaced
       when the unit files are loaded. The following specifiers are
       understood:

       Table 3. Specifiers available in unit files
       +----------+---------------------+---------------------+
       |Specifier | Meaning             | Details             |
       +----------+---------------------+---------------------+
       |%n        | Full unit name      |                     |
       +----------+---------------------+---------------------+
       |%N        | Unescaped full unit |                     |
       |          | name                |                     |
       +----------+---------------------+---------------------+
       |%p        | Prefix name         | For instantiated    |
       |          |                     | units this refers   |
       |          |                     | to the string       |
       |          |                     | before the @. For   |
       |          |                     | non-instantiated    |
       |          |                     | units this refers   |
       |          |                     | to to the name of   |
       |          |                     | the unit with the   |
       |          |                     | type suffix         |
       |          |                     | removed.            |
       +----------+---------------------+---------------------+
       |%P        | Unescaped prefix    |                     |
       |          | name                |                     |
       +----------+---------------------+---------------------+
       |%i        | Instance name       | For instantiated    |
       |          |                     | units: this is the  |
       |          |                     | string between the  |
       |          |                     | @ character and the |
       |          |                     | suffix.             |
       +----------+---------------------+---------------------+
       |%I        | Unescaped instance  |                     |
       |          | name                |                     |
       +----------+---------------------+---------------------+
       |%f        | Unescaped file name | This is either the  |
       |          |                     | unescaped instance  |
       |          |                     | name (if            |
       |          |                     | applicable) with /  |
       |          |                     | prepended (if       |
       |          |                     | applicable), or the |
       |          |                     | prefix name         |
       |          |                     | similarly prepended |
       |          |                     | with /.             |
       +----------+---------------------+---------------------+
       |%c        | Control group path  |                     |
       |          | of the unit         |                     |
       +----------+---------------------+---------------------+
       |%r        | Root control group  | For system          |
       |          | path where units    | instances this      |
       |          | are placed.         | usually resolves to |
       |          |                     | /system, except in  |
       |          |                     | containers, where   |
       |          |                     | the path might be   |
       |          |                     | prefixed with the   |
       |          |                     | container‘s root    |
       |          |                     | control group.      |
       +----------+---------------------+---------------------+
       |%R        | Parent directory of | For system          |
       |          | the control group   | instances this      |
       |          | path where units    | usually resolves to |
       |          | are placed.         | /, except in        |
       |          |                     | containers, where   |
       |          |                     | this resolves to    |
       |          |                     | the container‘s     |
       |          |                     | root directory.     |
       |          |                     | This specifier is   |
       |          |                     | particularly useful |
       |          |                     | in the              |
       |          |                     | ControlGroup=       |
       |          |                     | setting (see        |
       |          |                     | systemd.exec(5)).   |
       +----------+---------------------+---------------------+
       |%t        | Runtime socket dir  | This is either /run |
       |          |                     | (for the system     |
       |          |                     | manager) or         |
       |          |                     | $XDG_RUNTIME_DIR    |
       |          |                     | (for user           |
       |          |                     | managers).          |
       +----------+---------------------+---------------------+
       |%u        | User name           | This is the name of |
       |          |                     | the configured user |
       |          |                     | of the unit, or (if |
       |          |                     | none is set) the    |
       |          |                     | user running the    |
       |          |                     | systemd instance.   |
       +----------+---------------------+---------------------+
       |%U        | User UID            | This is the UID of  |
       |          |                     | the configured user |
       |          |                     | of the unit, or (if |
       |          |                     | none is set) the    |
       |          |                     | user running the    |
       |          |                     | systemd instance.   |
       +----------+---------------------+---------------------+
       |%h        | User home directory | This is the home    |
       |          |                     | directory of the    |
       |          |                     | configured user of  |
       |          |                     | the unit, or (if    |
       |          |                     | none is set) the    |
       |          |                     | user running the    |
       |          |                     | systemd instance.   |
       +----------+---------------------+---------------------+
       |%s        | User shell          | This is the shell   |
       |          |                     | of the configured   |
       |          |                     | user of the unit,   |
       |          |                     | or (if none is set) |
       |          |                     | the user running    |
       |          |                     | the systemd         |
       |          |                     | instance.  If the   |
       |          |                     | user is root (UID   |
       |          |                     | equal to 0), the    |
       |          |                     | shell configured in |
       |          |                     | account database is |
       |          |                     | ignored and /bin/sh |
       |          |                     | is always used.     |
       +----------+---------------------+---------------------+
       |%m        | Machine ID          | The machine ID of   |
       |          |                     | the running system, |
       |          |                     | formatted as        |
       |          |                     | string. See         |
       |          |                     | machine-id(5) for   |
       |          |                     | more information.   |
       +----------+---------------------+---------------------+
       |%b        | Boot ID             | The boot ID of the  |
       |          |                     | running system,     |
       |          |                     | formatted as        |
       |          |                     | string. See         |
       |          |                     | random(4) for more  |
       |          |                     | information.        |
       +----------+---------------------+---------------------+
       |%H        | Host name           | The host name of    |
       |          |                     | the running system. |
       +----------+---------------------+---------------------+
       |%%        | Escaped %           | Single percent      |
       |          |                     | sign.               |
       +----------+---------------------+---------------------+

SEE ALSO
       systemd(1), systemctl(8), systemd.special(7), systemd.service(5),
       systemd.socket(5), systemd.device(5), systemd.mount(5),
       systemd.automount(5), systemd.swap(5), systemd.target(5),
       systemd.path(5), systemd.timer(5), systemd.snapshot(5),
       systemd.time(7), capabilities(7), systemd.directives(7)

NOTES
        1. XDG Desktop Entry Specification
           http://standards.freedesktop.org/desktop-entry-spec/latest/

        2. Interface Stability Promise
           http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise
(http://www.dsm.fordham.edu/cgi-bin/man-cgi.pl?topic=systemd.unit&ampsect=5)