systemd service

Man page
systemd.unit

SYSTEMD.UNIT(5)                  systemd.unit                  SYSTEMD.UNIT(5)NAME       systemd.unit - Unit configurationSYNOPSIS       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 [e-mail] 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)