X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=man%2Fsystemd.unit.xml;h=09e11b4711f5bc886941837b482b8aea0f1f76db;hp=dcdfc1e5d6087ec3d0942cb3d56a213af679086b;hb=e2acdb6b0f68d9b4152708a9f21bf9e11f8b9e7e;hpb=ccc9a4f9ffdab069b0b785627c48962fdadf6d46;ds=sidebyside
diff --git a/man/systemd.unit.xml b/man/systemd.unit.xml
index dcdfc1e5d..09e11b471 100644
--- a/man/systemd.unit.xml
+++ b/man/systemd.unit.xml
@@ -1,6 +1,9 @@
+ "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
+
+%entities;
+]>
+
+ 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
+ namespace. 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
+ filename. Basically, given a path, "/" is replaced by "-" and all
+ other characters which are not ASCII alphanumerics are replaced by
+ C-style "\x2d" escapes (except that "_" is never replaced and "."
+ is only replaced when it would be the first character in the
+ escaped path). The root directory "/" is encoded as single dash,
+ while otherwise the initial and ending "/" are removed from all
+ paths during transformation. This escaping is reversible. Properly
+ escaped paths can be generated using the
+ systemd-escape1
+ command.
+
+ 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
+ file system. 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.
+
+
+
+
+ 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 listed earlier override files with the same name in
+ directories lower in the list.
+
+ When systemd is running in user mode
+ () and the variable
+ $SYSTEMD_UNIT_PATH is set, the contents of this
+ variable overrides the unit load path. If
+ $SYSTEMD_UNIT_PATH ends with an empty component
+ (:), the usual unit load path will be appended
+ to the contents of the variable.
+
+
+
+ Load path when running in system mode (<option>--system</option>).
+
+
+
+
+
+
+
+ Path
+ Description
+
+
+
+
+ /etc/systemd/system
+ Local configuration
+
+
+ /run/systemd/system
+ Runtime units
+
+
+ /usr/lib/systemd/system
+ Units of installed packages
+
+
+
+
+
+
+
+ Load path when running in user mode (<option>--user</option>).
+
+
+
+
+
+
+
+ Path
+ Description
+
+
+
+
+ $XDG_CONFIG_HOME/systemd/user
+ User configuration (only used when $XDG_CONFIG_HOME is set)
+
+
+ $HOME/.config/systemd/user
+ User configuration (only used when $XDG_CONFIG_HOME is not set)
+
+
+ /etc/systemd/user
+ Local configuration
+
+
+ $XDG_RUNTIME_DIR/systemd/user
+ Runtime units (only used when $XDG_RUNTIME_DIR is set)
+
+
+ /run/systemd/user
+ Runtime units
+
+
+ $XDG_DATA_HOME/systemd/user
+ Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is set)
+
+
+ $HOME/.local/share/systemd/user
+ Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is not set)
+
+
+ /usr/lib/systemd/user
+ Units of packages that have been installed system-wide
+
+
+
+
+
+ Additional units might be loaded into systemd ("linked")
+ from directories not on the unit load path. See the
+ link command for
+ systemctl1.
+ Also, some units are dynamically created via generators Generators.
+
+
+
+
+ [Unit] Section 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. The description should contain a
+ name that means something to the end user. Apache2
+ Web Server is a good example. Bad examples are
+ high-performance light-weight HTTP server
+ (too generic) or Apache2 (too specific and
+ meaningless for people who do not know
+ Apache).
+
+
+
+ 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 uri7.
+ 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 or
+ multiple space-separated units may be specified in one option
+ in which case requirement dependencies for all listed names
+ will be 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 the units listed here are not started already,
+ they will not be started and the transaction will fail
+ immediately.
+
+
+
+ Wants=
+
+ A weaker version of
+ Requires=. 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. 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
+ symlinks 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 â changes to this unit do not
+ affect the listed units.
+
+
+
+ Conflicts=
+
+ 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 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=
+
+ A space-separated list of unit names.
+ Configures ordering dependencies between units. If a unit
+ foo.service contains a setting
+ 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 of 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=
+
+ A space-separated list of one or more units
+ that are activated when this unit enters the
+ failed state.
+
+
+
+ PropagatesReloadTo=
+ ReloadPropagatedFrom=
+
+ A space-separated list of one or more units
+ where reload requests on this unit will be propagated to, or
+ reload requests on the other unit will be propagated to this
+ unit, respectively. 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.
+
+
+
+ JoinsNamespaceOf=
+
+ 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= and
+ PrivateTmp= directives (see
+ systemd.exec5
+ for details). If a unit that has this setting set is started,
+ its processes will see the same /tmp,
+ /tmp/var 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= and/or
+ PrivateTmp= is enabled for both the unit
+ that joins the namespace and the unit whose namespace is
+ joined.
+
+
+
+ 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.
+
+ Mount points marked with are not
+ mounted automatically and will be ignored for the purposes of
+ this option. If such a mount should be a requirement for this
+ unit, direct dependencies on the mount units may be added
+ (Requires= and After= or
+ some other combination).
+
+
+
+ OnFailureJobMode=
+
+ 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
+ systemctl1's
+ option for details on the
+ possible values. If this is set to isolate,
+ only a single unit may be listed in
+ OnFailure=..
+
+
+
+ IgnoreOnIsolate=
+
+ Takes a boolean argument. If
+ , this unit will not be stopped when
+ isolating another unit. Defaults to
+ .
+
+
+
+ IgnoreOnSnapshot=
+
+ Takes a boolean argument. If
+ , this unit will not be included in
+ snapshots. Defaults to for device and
+ snapshot units, for the
+ others.
+
+
+
+ StopWhenUnneeded=
+
+ Takes a boolean argument. If
+ , 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 .
+
+
+
+ RefuseManualStart=
+ RefuseManualStop=
+
+ Takes a boolean argument. If
+ , 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
+ .
+
+
+
+ AllowIsolate=
+
+ Takes a boolean argument. If
+ , 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
+ .
+
+
+
+ DefaultDependencies=
+
+ Takes a boolean argument. If
+ , (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 . It is highly recommended to
+ leave this option enabled for the majority of common units. If
+ set to , this option does not disable
+ all implicit dependencies, just non-essential
+ ones.
+
+
+
+ JobTimeoutSec=
+ JobTimeoutAction=
+ JobTimeoutRebootArgument=
+
+ When a job for this unit is queued a time-out
+ may be configured. 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
+ StartTimeoutSec= 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.
+
+ JobTimeoutAction=
+ optionally configures an additional
+ action to take when the time-out is
+ hit. It takes the same values as the
+ per-service
+ StartLimitAction=
+ setting, see
+ systemd.service5
+ for details. Defaults to
+ . JobTimeoutRebootArgument=
+ configures an optional reboot string
+ to pass to the
+ reboot2
+ system call.
+
+
+
+ ConditionArchitecture=
+ ConditionVirtualization=
+ ConditionHost=
+ ConditionKernelCommandLine=
+ ConditionSecurity=
+ ConditionCapability=
+ ConditionACPower=
+ ConditionNeedsUpdate=
+ ConditionFirstBoot=
+ ConditionPathExists=
+ ConditionPathExistsGlob=
+ ConditionPathIsDirectory=
+ ConditionPathIsSymbolicLink=
+ ConditionPathIsMountPoint=
+ ConditionPathIsReadWrite=
+ ConditionDirectoryNotEmpty=
+ ConditionFileNotEmpty=
+ ConditionFileIsExecutable=
+
+
+
+ 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.
+
+ ConditionArchitecture= may be used to
+ check whether the system is running on a specific
+ architecture. Takes one of
+ x86,
+ x86-64,
+ ppc,
+ ppc-le,
+ ppc64,
+ ppc64-le,
+ ia64,
+ parisc,
+ parisc64,
+ s390,
+ s390x,
+ sparc,
+ sparc64,
+ mips,
+ mips-le,
+ mips64,
+ mips64-le,
+ alpha,
+ arm,
+ arm-be,
+ arm64,
+ arm64-be,
+ sh,
+ sh64,
+ m86k,
+ tilegx,
+ cris to test
+ against a specific architecture. The architecture is
+ determined from the information returned by
+ uname2
+ and is thus subject to
+ personality2.
+ Note that a Personality= setting in the
+ same unit file has no effect on this condition. A special
+ architecture name native is mapped to the
+ architecture the system manager itself is compiled for. The
+ test may be negated by prepending an exclamation mark.
+
+ 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,
+ zvm,
+ vmware,
+ microsoft,
+ oracle,
+ xen,
+ bochs,
+ uml,
+ openvz,
+ lxc,
+ lxc-libvirt,
+ systemd-nspawn,
+ docker to test
+ against a specific implementation. See
+ systemd-detect-virt1
+ for a full list of known virtualization technologies and their
+ identifiers. If multiple virtualization technologies are
+ nested, only the innermost is considered. The test may be
+ negated by prepending an exclamation mark.
+
+ ConditionHost= may be used to match
+ against the hostname or machine ID of the host. This either
+ takes a hostname string (optionally with shell style globs)
+ which is tested against the locally set hostname as returned
+ by
+ gethostname2,
+ or a machine ID formatted as string (see
+ machine-id5).
+ The test may be negated by prepending an exclamation
+ mark.
+
+ 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.
+
+ ConditionSecurity= may be used to
+ check whether the given security module is enabled on the
+ system. Currently the recognized values values are
+ selinux,
+ apparmor,
+ ima,
+ smack and
+ audit. 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
+ capabilities7
+ for details). Pass a capability name such as
+ CAP_MKNOD, possibly prefixed with an
+ exclamation mark to negate the check.
+
+ 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.
+
+ ConditionNeedsUpdate= takes one of
+ /var or /etc as
+ argument, possibly prefixed with a ! (for
+ inverting the condition). This condition may be used to
+ conditionalize units on whether the specified directory
+ requires an update because /usr's
+ modification time is newer than the stamp file
+ .updated in the specified directory. This
+ is useful to implement offline updates of the vendor operating
+ system resources in /usr that require
+ updating of /etc or
+ /var on the next following boot. Units
+ making use of this condition should order themselves before
+ systemd-update-done.service8,
+ to make sure they run before the stamp files's modification
+ time gets reset indicating a completed update.
+
+ ConditionFirstBoot= takes a boolean
+ argument. This condition may be used to conditionalize units
+ on whether the system is booting up with an unpopulated
+ /etc directory. This may be used to
+ populate /etc on the first boot after
+ factory reset, or when a new system instances boots up for the
+ first time.
+
+ 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.
+
+ 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.
+
+
+
+ AssertArchitecture=
+ AssertVirtualization=
+ AssertHost=
+ AssertKernelCommandLine=
+ AssertSecurity=
+ AssertCapability=
+ AssertACPower=
+ AssertNeedsUpdate=
+ AssertFirstBoot=
+ AssertPathExists=
+ AssertPathExistsGlob=
+ AssertPathIsDirectory=
+ AssertPathIsSymbolicLink=
+ AssertPathIsMountPoint=
+ AssertPathIsReadWrite=
+ AssertDirectoryNotEmpty=
+ AssertFileNotEmpty=
+ AssertFileIsExecutable=
+
+ Similar to the
+ ConditionArchitecture=,
+ ConditionVirtualization=, ... condition
+ settings described above these settings add assertion checks
+ to the start-up of the unit. However, unlike the conditions
+ settings any assertion setting that is not met results in
+ failure of the start job it was triggered
+ by.
+
+
+
+ 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. This functionality should not be used in normal
+ units.
+
+
+
+
+
+
+ [Install] Section Options
+
+ Unit file may include an [Install]
+ section, which carries installation information for the unit. This
+ section is not interpreted by
+ systemd1
+ during runtime. It is used exclusively by the
+ enable and disable commands
+ of the
+ systemctl1
+ tool during installation of a unit:
+
+
+
+ Alias=
+
+ 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 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 filename.
+
+
+
+ WantedBy=
+ RequiredBy=
+
+ 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.
+
+
+
+
+ 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.
+
+ This option may be used more than once, or a
+ space-separated list of unit names may be
+ given.
+
+
+
+ DefaultInstance=
+
+ 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.
+
+
+
+ The following specifiers are interpreted in the Install
+ section: %n, %N, %p, %i, %U, %u, %m, %H, %b, %v. 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:
+
+
+ Specifiers available in unit files
+
+
+
+
+
+
+ Specifier
+ Meaning
+ Details
+
+
+
+
+ %n
+ Full unit name
+
+
+
+ %N
+ Unescaped full unit name
+ Same as %n, but with escaping undone
+
+
+ %p
+ Prefix name
+ For instantiated units, this refers to the string before the @ character of the unit name. For non-instantiated units, this refers to the name of the unit with the type suffix removed.
+
+
+ %P
+ Unescaped prefix name
+ Same as %p, but with escaping undone
+
+
+ %i
+ Instance name
+ For instantiated units: this is the string between the @ character and the suffix of the unit name.
+
+
+ %I
+ Unescaped instance name
+ Same as %i, but with escaping undone
+
+
+ %f
+ Unescaped filename
+ This is either the unescaped instance name (if applicable) with / prepended (if applicable), or the prefix name prepended with /.
+
+
+ %c
+ Control group path of the unit
+ This path does not include the /sys/fs/cgroup/systemd/ prefix.
+
+
+ %r
+ Control group path of the slice the unit is placed in
+ This usually maps to the parent cgroup path of %c.
+
+
+ %R
+ Root control group path below which slices and units are placed
+ For system instances, this resolves to /, except in containers, where this maps to the container's root control group path.
+
+
+ %t
+ Runtime directory
+ This is either /run (for the system manager) or the path $XDG_RUNTIME_DIR resolves to (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 numeric UID of the configured user of the unit, or (if none is set) the user running the systemd user instance. Note that this specifier is not available for units run by the systemd system instance (as opposed to those run by a systemd user instance), unless the user has been configured as a numeric UID in the first place or the configured user is the root user.
+
+
+ %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 user instance. Similar to %U, this specifier is not available for units run by the systemd system instance, unless the configured user is the root user.
+
+
+ %s
+ User shell
+ This is the shell of the configured user of the unit, or (if none is set) the user running the systemd user instance. Similar to %U, this specifier is not available for units run by the systemd system instance, unless the configured user is the root user.
+
+
+ %m
+ Machine ID
+ The machine ID of the running system, formatted as string. See machine-id5 for more information.
+
+
+ %b
+ Boot ID
+ The boot ID of the running system, formatted as string. See random4 for more information.
+
+
+ %H
+ Host name
+ The hostname of the running system at the point in time the unit configuation is loaded.
+
+
+ %v
+ Kernel release
+ Identical to uname -r output
+
+
+ %%
+ Single percent sign
+ Use %% in place of % to specify a single percent sign.
+
+
+
+
+
+ Please note that specifiers %U,
+ %h, %s are mostly useless
+ when systemd is running in system mode. PID 1 cannot query the
+ user account database for information, so the specifiers only work
+ as shortcuts for things which are already specified in a different
+ way in the unit file. They are fully functional when systemd is
+ running in mode.
+
+
+
+ Examples
+
+
+ Allowing units to be enabled
+
+ The following snippet (highlighted) allows a unit (e.g.
+ foo.service) to be enabled via
+ systemctl enable:
+
+ [Unit]
+Description=Foo
+
+[Service]
+ExecStart=/usr/sbin/foo-daemon
+
+[Install]
+WantedBy=multi-user.target
+
+ After running systemctl enable, a
+ symlink
+ /etc/systemd/system/multi-user.target.wants/foo.service
+ linking to the actual unit will be created. It tells systemd to
+ pull in the unit when starting
+ multi-user.target. The inverse
+ systemctl disable will remove that symlink
+ again.
+
+
+
+ Overriding vendor settings
+
+ There are two methods of overriding vendor settings in
+ unit files: copying the unit file from
+ /usr/lib/systemd/system to
+ /etc/systemd/system and modifying the
+ chosen settings. Alternatively, one can create a directory named
+ unit.d/ within
+ /etc/systemd/system and place a drop-in
+ file name.conf
+ there that only changes the specific settings one is interested
+ in. Note that multiple such drop-in files are read if
+ present.
+
+ The advantage of the first method is that one easily
+ overrides the complete unit, the vendor unit is not parsed at
+ all anymore. It has the disadvantage that improvements to the
+ unit file by the vendor are not automatically incorporated on
+ updates.
+
+ The advantage of the second method is that one only
+ overrides the settings one specifically wants, where updates to
+ the unit by the vendor automatically apply. This has the
+ disadvantage that some future updates by the vendor might be
+ incompatible with the local changes.
+
+ Note that for drop-in files, if one wants to remove
+ entries from a setting that is parsed as a list (and is not a
+ dependency), such as ConditionPathExists= (or
+ e.g. ExecStart= in service units), one needs
+ to first clear the list before re-adding all entries except the
+ one that is to be removed. See below for an example.
+
+ This also applies for user instances of systemd, but with
+ different locations for the unit files. See the section on unit
+ load paths for further details.
+
+ Suppose there is a vendor-supplied unit
+ /usr/lib/systemd/system/httpd.service with
+ the following contents:
+
+ [Unit]
+Description=Some HTTP server
+After=remote-fs.target sqldb.service
+Requires=sqldb.service
+AssertPathExists=/srv/webserver
+
+[Service]
+Type=notify
+ExecStart=/usr/sbin/some-fancy-httpd-server
+Nice=5
+
+[Install]
+WantedBy=multi-user.target
+
+ Now one wants to change some settings as an administrator:
+ firstly, in the local setup, /srv/webserver
+ might not exist, because the HTTP server is configured to use
+ /srv/www instead. Secondly, the local
+ configuration makes the HTTP server also depend on a memory
+ cache service, memcached.service, that
+ should be pulled in (Requires=) and also be
+ ordered appropriately (After=). Thirdly, in
+ order to harden the service a bit more, the administrator would
+ like to set the PrivateTmp= setting (see
+ systemd.service5
+ for details). And lastly, the administrator would like to reset
+ the niceness of the service to its default value of 0.
+
+ The first possibility is to copy the unit file to
+ /etc/systemd/system/httpd.service and
+ change the chosen settings:
+
+ [Unit]
+Description=Some HTTP server
+After=remote-fs.target sqldb.service memcached.service
+Requires=sqldb.service memcached.service
+AssertPathExists=/srv/www
+
+[Service]
+Type=notify
+ExecStart=/usr/sbin/some-fancy-httpd-server
+Nice=0
+PrivateTmp=yes
+
+[Install]
+WantedBy=multi-user.target
+
+ Alternatively, the administrator could create a drop-in
+ file
+ /etc/systemd/system/httpd.service.d/local.conf
+ with the following contents:
+
+ [Unit]
+After=memcached.service
+Requires=memcached.service
+# Reset all assertions and then re-add the condition we want
+AssertPathExists=
+AssertPathExists=/srv/www
+
+[Service]
+Nice=0
+PrivateTmp=yes
+
+ Note that dependencies (After=, etc.)
+ cannot be reset to an empty list, so dependencies can only be
+ added in drop-ins. If you want to remove dependencies, you have
+ to override the entire unit.
+
+
+
+
+ See Also
+
+ systemd1,
+ systemctl1,
+ systemd.special7,
+ systemd.service5,
+ systemd.socket5,
+ systemd.device5,
+ systemd.mount5,
+ systemd.automount5,
+ systemd.swap5,
+ systemd.target5,
+ systemd.path5,
+ systemd.timer5,
+ systemd.snapshot5,
+ systemd.scope5,
+ systemd.slice5,
+ systemd.time7,
+ systemd-analyze1,
+ capabilities7,
+ systemd.directives7,
+ uname1
+
+