NAME

Config::Model::models::Systemd::Section::Service - Configuration class Systemd::Section::Service

DESCRIPTION

Configuration classes used by Config::Model

A unit configuration file whose name ends in .service encodes information about a process controlled and supervised by systemd.

This man page lists the configuration options specific to this unit type. See systemd.unit(5) for the common options of all unit configuration files. The common configuration items are configured in the generic [Unit] and [Install] sections. The service specific configuration options are configured in the [Service] section.

Additional options are listed in systemd.exec(5), which define the execution environment the commands are executed in, and in systemd.kill(5), which define the way the processes of the service are terminated, and in systemd.resource-control(5), which configure resource control settings for the processes of the service.

If a service is requested under a certain name but no unit configuration file is found, systemd looks for a SysV init script by the same name (with the .service suffix removed) and dynamically creates a service unit from that script. This is useful for compatibility with SysV. Note that this compatibility is quite comprehensive but not 100%. For details about the incompatibilities, see the Incompatibilities with SysV document. This configuration class was generated from systemd documentation. by parse-man.pl

Elements

CPUAccounting

Turn on CPU usage accounting for this unit. Takes a boolean argument. Note that turning on CPU accounting for one unit will also implicitly turn it on for all units contained in the same slice and for all its parent slices and the units contained therein. The system default for this setting may be controlled with DefaultCPUAccounting in systemd-system.conf(5). Optional. Type boolean.

CPUWeight

Assign the specified CPU time weight to the processes executed, if the unified control group hierarchy is used on the system. These options take an integer value and control the cpu.weight control group attribute. The allowed range is 1 to 10000. Defaults to 100. For details about this control group attribute, see cgroup-v2.txt and sched-design-CFS.txt. The available CPU time is split up among all units within one slice relative to their CPU time weight.

While StartupCPUWeight only applies to the startup phase of the system, CPUWeight applies to normal runtime of the system, and if the former is not set also to the startup phase. Using StartupCPUWeight allows prioritizing specific services at boot-up differently than during normal runtime.

Implies CPUAccounting=true.

These settings replace CPUShares and StartupCPUShares. Optional. Type integer.

upstream_default value :: 100

StartupCPUWeight

Implies CPUAccounting=true.

These settings replace CPUShares and StartupCPUShares. Optional. Type integer.

upstream_default value :: 100

CPUQuota

Assign the specified CPU time quota to the processes executed. Takes a percentage value, suffixed with "%". The percentage specifies how much CPU time the unit shall get at maximum, relative to the total CPU time available on one CPU. Use values > 100% for allotting CPU time on more than one CPU. This controls the cpu.max attribute on the unified control group hierarchy and cpu.cfs_quota_us on legacy. For details about these control group attributes, see cgroup-v2.txt and sched-design-CFS.txt.

Example: CPUQuota=20% ensures that the executed processes will never get more than 20% CPU time on one CPU.

Implies CPUAccounting=true. Optional. Type uniline.

MemoryAccounting

Turn on process and kernel memory accounting for this unit. Takes a boolean argument. Note that turning on memory accounting for one unit will also implicitly turn it on for all units contained in the same slice and for all its parent slices and the units contained therein. The system default for this setting may be controlled with DefaultMemoryAccounting in systemd-system.conf(5). Optional. Type boolean.

MemoryLow

Specify the best-effort memory usage protection of the executed processes in this unit. If the memory usages of this unit and all its ancestors are below their low boundaries, this unit's memory won't be reclaimed as long as memory can be reclaimed from unprotected units.

Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the specified memory size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. Alternatively, a percentage value may be specified, which is taken relative to the installed physical memory on the system. This controls the memory.low control group attribute. For details about this control group attribute, see cgroup-v2.txt.

Implies MemoryAccounting=true.

This setting is supported only if the unified control group hierarchy is used and disables MemoryLimit. Optional. Type uniline.

MemoryHigh

Specify the high limit on memory usage of the executed processes in this unit. Memory usage may go above the limit if unavoidable, but the processes are heavily slowed down and memory is taken away aggressively in such cases. This is the main mechanism to control memory usage of a unit.

Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the specified memory size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. Alternatively, a percentage value may be specified, which is taken relative to the installed physical memory on the system. If assigned the special value infinity, no memory limit is applied. This controls the memory.high control group attribute. For details about this control group attribute, see cgroup-v2.txt.

Implies MemoryAccounting=true.

This setting is supported only if the unified control group hierarchy is used and disables MemoryLimit. Optional. Type uniline.

MemoryMax

Specify the absolute limit on memory usage of the executed processes in this unit. If memory usage cannot be contained under the limit, out-of-memory killer is invoked inside the unit. It is recommended to use MemoryHigh as the main control mechanism and use MemoryMax as the last line of defense.

Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the specified memory size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. Alternatively, a percentage value may be specified, which is taken relative to the installed physical memory on the system. If assigned the special value infinity, no memory limit is applied. This controls the memory.max control group attribute. For details about this control group attribute, see cgroup-v2.txt.

Implies MemoryAccounting=true.

This setting replaces MemoryLimit. Optional. Type uniline.

MemorySwapMax

Specify the absolute limit on swap usage of the executed processes in this unit.

Takes a swap size in bytes. If the value is suffixed with K, M, G or T, the specified swap size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. If assigned the special value infinity, no swap limit is applied. This controls the memory.swap.max control group attribute. For details about this control group attribute, see cgroup-v2.txt.

Implies MemoryAccounting=true.

This setting is supported only if the unified control group hierarchy is used and disables MemoryLimit. Optional. Type uniline.

TasksAccounting

Turn on task accounting for this unit. Takes a boolean argument. If enabled, the system manager will keep track of the number of tasks in the unit. The number of tasks accounted this way includes both kernel threads and userspace processes, with each thread counting individually. Note that turning on tasks accounting for one unit will also implicitly turn it on for all units contained in the same slice and for all its parent slices and the units contained therein. The system default for this setting may be controlled with DefaultTasksAccounting in systemd-system.conf(5). Optional. Type boolean.

TasksMax

Specify the maximum number of tasks that may be created in the unit. This ensures that the number of tasks accounted for the unit (see above) stays below a specific limit. This either takes an absolute number of tasks or a percentage value that is taken relative to the configured maximum number of tasks on the system. If assigned the special value infinity, no tasks limit is applied. This controls the pids.max control group attribute. For details about this control group attribute, see pids.txt.

Implies TasksAccounting=true. The system default for this setting may be controlled with DefaultTasksMax in systemd-system.conf(5). Optional. Type uniline.

IOAccounting

Turn on Block I/O accounting for this unit, if the unified control group hierarchy is used on the system. Takes a boolean argument. Note that turning on block I/O accounting for one unit will also implicitly turn it on for all units contained in the same slice and all for its parent slices and the units contained therein. The system default for this setting may be controlled with DefaultIOAccounting in systemd-system.conf(5).

This setting replaces BlockIOAccounting and disables settings prefixed with BlockIO or StartupBlockIO. Optional. Type boolean.

IOWeight

Set the default overall block I/O weight for the executed processes, if the unified control group hierarchy is used on the system. Takes a single weight value (between 1 and 10000) to set the default block I/O weight. This controls the io.weight control group attribute, which defaults to 100. For details about this control group attribute, see cgroup-v2.txt. The available I/O bandwidth is split up among all units within one slice relative to their block I/O weight.

While StartupIOWeight only applies to the startup phase of the system, IOWeight applies to the later runtime of the system, and if the former is not set also to the startup phase. This allows prioritizing specific services at boot-up differently than during runtime.

Implies IOAccounting=true.

These settings replace BlockIOWeight and StartupBlockIOWeight and disable settings prefixed with BlockIO or StartupBlockIO. Optional. Type uniline.

StartupIOWeight

Implies IOAccounting=true.

These settings replace BlockIOWeight and StartupBlockIOWeight and disable settings prefixed with BlockIO or StartupBlockIO. Optional. Type uniline.

IODeviceWeight

Set the per-device overall block I/O weight for the executed processes, if the unified control group hierarchy is used on the system. Takes a space-separated pair of a file path and a weight value to specify the device specific weight value, between 1 and 10000. (Example: "/dev/sda 1000"). The file path may be specified as path to a block device node or as any other file, in which case the backing block device of the file system of the file is determined. This controls the io.weight control group attribute, which defaults to 100. Use this option multiple times to set weights for multiple devices. For details about this control group attribute, see cgroup-v2.txt.

Implies IOAccounting=true.

This setting replaces BlockIODeviceWeight and disables settings prefixed with BlockIO or StartupBlockIO. Optional. Type uniline.

IOReadBandwidthMax

Set the per-device overall block I/O bandwidth maximum limit for the executed processes, if the unified control group hierarchy is used on the system. This limit is not work-conserving and the executed processes are not allowed to use more even if the device has idle capacity. Takes a space-separated pair of a file path and a bandwidth value (in bytes per second) to specify the device specific bandwidth. The file path may be a path to a block device node, or as any other file in which case the backing block device of the file system of the file is used. If the bandwidth is suffixed with K, M, G, or T, the specified bandwidth is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes, respectively, to the base of 1000. (Example: "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 5M"). This controls the io.max control group attributes. Use this option multiple times to set bandwidth limits for multiple devices. For details about this control group attribute, see cgroup-v2.txt.

Implies IOAccounting=true.

These settings replace BlockIOReadBandwidth and BlockIOWriteBandwidth and disable settings prefixed with BlockIO or StartupBlockIO. Optional. Type uniline.

IOWriteBandwidthMax

Implies IOAccounting=true.

These settings replace BlockIOReadBandwidth and BlockIOWriteBandwidth and disable settings prefixed with BlockIO or StartupBlockIO. Optional. Type uniline.

IOReadIOPSMax

Set the per-device overall block I/O IOs-Per-Second maximum limit for the executed processes, if the unified control group hierarchy is used on the system. This limit is not work-conserving and the executed processes are not allowed to use more even if the device has idle capacity. Takes a space-separated pair of a file path and an IOPS value to specify the device specific IOPS. The file path may be a path to a block device node, or as any other file in which case the backing block device of the file system of the file is used. If the IOPS is suffixed with K, M, G, or T, the specified IOPS is parsed as KiloIOPS, MegaIOPS, GigaIOPS, or TeraIOPS, respectively, to the base of 1000. (Example: "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 1K"). This controls the io.max control group attributes. Use this option multiple times to set IOPS limits for multiple devices. For details about this control group attribute, see cgroup-v2.txt.

Implies IOAccounting=true.

These settings are supported only if the unified control group hierarchy is used and disable settings prefixed with BlockIO or StartupBlockIO. Optional. Type uniline.

IOWriteIOPSMax

Implies IOAccounting=true.

These settings are supported only if the unified control group hierarchy is used and disable settings prefixed with BlockIO or StartupBlockIO. Optional. Type uniline.

DeviceAllow

Control access to specific device nodes by the executed processes. Takes two space-separated strings: a device node specifier followed by a combination of r, w, m to control reading, writing, or creation of the specific device node(s) by the unit (mknod), respectively. This controls the devices.allow and devices.deny control group attributes. For details about these control group attributes, see devices.txt.

The device node specifier is either a path to a device node in the file system, starting with /dev/, or a string starting with either char- or block- followed by a device group name, as listed in /proc/devices. The latter is useful to whitelist all current and future devices belonging to a specific device group at once. The device group is matched according to file name globbing rules, you may hence use the * and ? wildcards. Examples: /dev/sda5 is a path to a device node, referring to an ATA or SCSI block device. char-pts and char-alsa are specifiers for all pseudo TTYs and all ALSA sound devices, respectively. char-cpu/* is a specifier matching all CPU related device groups. Optional. Type list of uniline.

DevicePolicy

Control the policy for allowing device access: Optional. Type enum. choice: 'auto', 'closed', 'strict'.

Slice

The name of the slice unit to place the unit in. Defaults to system.slice for all non-instantiated units of all unit types (except for slice units themselves see below). Instance units are by default placed in a subslice of system.slice that is named after the template name.

This option may be used to arrange systemd units in a hierarchy of slices each of which might have resource settings applied.

For units of type slice, the only accepted value for this setting is the parent slice. Since the name of a slice unit implies the parent slice, it is hence redundant to ever set this parameter directly for slice units.

Special care should be taken when relying on the default slice assignment in templated service units that have DefaultDependencies=no set, see systemd.service(5), section "Automatic Dependencies" for details. Optional. Type uniline.

Delegate

Turns on delegation of further resource control partitioning to processes of the unit. For unprivileged services (i.e. those using the User setting), this allows processes to create a subhierarchy beneath its control group path. For privileged services and scopes, this ensures the processes will have all control group controllers enabled. Optional. Type uniline.

CPUShares

Assign the specified CPU time share weight to the processes executed. These options take an integer value and control the cpu.shares control group attribute. The allowed range is 2 to 262144. Defaults to 1024. For details about this control group attribute, see sched-design-CFS.txt. The available CPU time is split up among all units within one slice relative to their CPU time share weight.

While StartupCPUShares only applies to the startup phase of the system, CPUShares applies to normal runtime of the system, and if the former is not set also to the startup phase. Using StartupCPUShares allows prioritizing specific services at boot-up differently than during normal runtime.

Implies CPUAccounting=true.

These settings are deprecated. Use CPUWeight and StartupCPUWeight instead. Optional. Type integer.

upstream_default value :: 1024

StartupCPUShares

Implies CPUAccounting=true.

These settings are deprecated. Use CPUWeight and StartupCPUWeight instead. Optional. Type integer.

upstream_default value :: 1024

MemoryLimit

Specify the limit on maximum memory usage of the executed processes. The limit specifies how much process and kernel memory can be used by tasks in this unit. Takes a memory size in bytes. If the value is suffixed with K, M, G or T, the specified memory size is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes (with the base 1024), respectively. Alternatively, a percentage value may be specified, which is taken relative to the installed physical memory on the system. If assigned the special value infinity, no memory limit is applied. This controls the memory.limit_in_bytes control group attribute. For details about this control group attribute, see memory.txt.

Implies MemoryAccounting=true.

This setting is deprecated. Use MemoryMax instead. Optional. Type uniline.

BlockIOAccounting

Turn on Block I/O accounting for this unit, if the legacy control group hierarchy is used on the system. Takes a boolean argument. Note that turning on block I/O accounting for one unit will also implicitly turn it on for all units contained in the same slice and all for its parent slices and the units contained therein. The system default for this setting may be controlled with DefaultBlockIOAccounting in systemd-system.conf(5).

This setting is deprecated. Use IOAccounting instead. Optional. Type boolean.

BlockIOWeight

Set the default overall block I/O weight for the executed processes, if the legacy control group hierarchy is used on the system. Takes a single weight value (between 10 and 1000) to set the default block I/O weight. This controls the blkio.weight control group attribute, which defaults to 500. For details about this control group attribute, see blkio-controller.txt. The available I/O bandwidth is split up among all units within one slice relative to their block I/O weight.

While StartupBlockIOWeight only applies to the startup phase of the system, BlockIOWeight applies to the later runtime of the system, and if the former is not set also to the startup phase. This allows prioritizing specific services at boot-up differently than during runtime.

Implies BlockIOAccounting=true.

These settings are deprecated. Use IOWeight and StartupIOWeight instead. Optional. Type uniline.

StartupBlockIOWeight

Implies BlockIOAccounting=true.

These settings are deprecated. Use IOWeight and StartupIOWeight instead. Optional. Type uniline.

BlockIODeviceWeight

Set the per-device overall block I/O weight for the executed processes, if the legacy control group hierarchy is used on the system. Takes a space-separated pair of a file path and a weight value to specify the device specific weight value, between 10 and 1000. (Example: "/dev/sda 500"). The file path may be specified as path to a block device node or as any other file, in which case the backing block device of the file system of the file is determined. This controls the blkio.weight_device control group attribute, which defaults to 1000. Use this option multiple times to set weights for multiple devices. For details about this control group attribute, see blkio-controller.txt.

Implies BlockIOAccounting=true.

This setting is deprecated. Use IODeviceWeight instead. Optional. Type uniline.

BlockIOReadBandwidth

Set the per-device overall block I/O bandwidth limit for the executed processes, if the legacy control group hierarchy is used on the system. Takes a space-separated pair of a file path and a bandwidth value (in bytes per second) to specify the device specific bandwidth. The file path may be a path to a block device node, or as any other file in which case the backing block device of the file system of the file is used. If the bandwidth is suffixed with K, M, G, or T, the specified bandwidth is parsed as Kilobytes, Megabytes, Gigabytes, or Terabytes, respectively, to the base of 1000. (Example: "/dev/disk/by-path/pci-0000:00:1f.2-scsi-0:0:0:0 5M"). This controls the blkio.throttle.read_bps_device and blkio.throttle.write_bps_device control group attributes. Use this option multiple times to set bandwidth limits for multiple devices. For details about these control group attributes, see blkio-controller.txt.

Implies BlockIOAccounting=true.

These settings are deprecated. Use IOReadBandwidthMax and IOWriteBandwidthMax instead. Optional. Type uniline.

BlockIOWriteBandwidth

Implies BlockIOAccounting=true.

These settings are deprecated. Use IOReadBandwidthMax and IOWriteBandwidthMax instead. Optional. Type uniline.

WorkingDirectory

Takes a directory path relative to the service's root directory specified by RootDirectory, or the special value ~. Sets the working directory for executed processes. If set to ~, the home directory of the user specified in User is used. If not set, defaults to the root directory when systemd is running as a system instance and the respective user's home directory if run as user. If the setting is prefixed with the - character, a missing working directory is not considered fatal. If RootDirectory/RootImage is not set, then WorkingDirectory is relative to the root of the system running the service manager. Note that setting this parameter might result in additional dependencies to be added to the unit (see above). Optional. Type uniline.

RootDirectory

Takes a directory path relative to the host's root directory (i.e. the root of the system running the service manager). Sets the root directory for executed processes, with the chroot(2) system call. If this is used, it must be ensured that the process binary and all its auxiliary files are available in the chroot() jail. Note that setting this parameter might result in additional dependencies to be added to the unit (see above).

The MountAPIVFS and PrivateUsers settings are particularly useful in conjunction with RootDirectory. For details, see below. Optional. Type uniline.

RootImage

Takes a path to a block device node or regular file as argument. This call is similar to RootDirectory however mounts a file system hierarchy from a block device node or loopback file instead of a directory. The device node or file system image file needs to contain a file system without a partition table, or a file system within an MBR/MS-DOS or GPT partition table with only a single Linux-compatible partition, or a set of file systems within a GPT partition table that follows the Discoverable Partitions Specification. Optional. Type uniline.

MountAPIVFS

Takes a boolean argument. If on, a private mount namespace for the unit's processes is created and the API file systems /proc, /sys, and /dev are mounted inside of it, unless they are already mounted. Note that this option has no effect unless used in conjunction with RootDirectory/RootImage as these three mounts are generally mounted in the host anyway, and unless the root directory is changed, the private mount namespace will be a 1:1 copy of the host's, and include these three mounts. Note that the /dev file system of the host is bind mounted if this option is used without PrivateDevices. To run the service with a private, minimal version of /dev/, combine this option with PrivateDevices. Optional. Type boolean.

User

Set the UNIX user or group that the processes are executed as, respectively. Takes a single user or group name, or a numeric ID as argument. For system services (services run by the system service manager, i.e. managed by PID 1) and for user services of the root user (services managed by root's instance of systemd --user), the default is root, but User may be used to specify a different user. For user services of any other user, switching user identity is not permitted, hence the only valid setting is the same user the user's service manager is running as. If no group is set, the default group of the user is used. This setting does not affect commands whose command line is prefixed with +.

Note that restrictions on the user/group name syntax are enforced: the specified name must consist only of the characters a-z, A-Z, 0-9, _ and -, except for the first character which must be one of a-z, A-Z or _ (i.e. numbers and - are not permitted as first character). The user/group name must have at least one character, and at most 31. These restrictions are enforced in order to avoid ambiguities and to ensure user/group names and unit files remain portable among Linux systems.

When used in conjunction with DynamicUser the user/group name specified is dynamically allocated at the time the service is started, and released at the time the service is stopped — unless it is already allocated statically (see below). If DynamicUser is not used the specified user and group must have been created statically in the user database no later than the moment the service is started, for example using the sysusers.d(5) facility, which is applied at boot or package install time. Optional. Type uniline.

Group

DynamicUser

Takes a boolean parameter. If set, a UNIX user and group pair is allocated dynamically when the unit is started, and released as soon as it is stopped. The user and group will not be added to /etc/passwd or /etc/group, but are managed transiently during runtime. The nss-systemd(8) glibc NSS module provides integration of these dynamic users/groups into the system's user and group databases. The user and group name to use may be configured via User and Group (see above). If these options are not used and dynamic user/group allocation is enabled for a unit, the name of the dynamic user/group is implicitly derived from the unit name. If the unit name without the type suffix qualifies as valid user name it is used directly, otherwise a name incorporating a hash of it is used. If a statically allocated user or group of the configured name already exists, it is used and no dynamic user/group is allocated. Dynamic users/groups are allocated from the UID/GID range 61184…65519. It is recommended to avoid this range for regular system or login users. At any point in time each UID/GID from this range is only assigned to zero or one dynamically allocated users/groups in use. However, UID/GIDs are recycled after a unit is terminated. Care should be taken that any processes running as part of a unit for which dynamic users/groups are enabled do not leave files or directories owned by these users/groups around, as a different unit might get the same UID/GID assigned later on, and thus gain access to these files or directories. If DynamicUser is enabled, RemoveIPC, PrivateTmp are implied. This ensures that the lifetime of IPC objects and temporary files created by the executed processes is bound to the runtime of the service, and hence the lifetime of the dynamic user/group. Since /tmp and /var/tmp are usually the only world-writable directories on a system this ensures that a unit making use of dynamic user/group allocation cannot leave files around after unit termination. Moreover ProtectSystem=strict and ProtectHome=read-only are implied, thus prohibiting the service to write to arbitrary file system locations. In order to allow the service to write to certain directories, they have to be whitelisted using ReadWritePaths, but care must be taken so that UID/GID recycling doesn't create security issues involving files created by the service. Use RuntimeDirectory (see below) in order to assign a writable runtime directory to a service, owned by the dynamic user/group and removed automatically when the unit is terminated. Defaults to off. Optional. Type boolean.

SupplementaryGroups

Sets the supplementary Unix groups the processes are executed as. This takes a space-separated list of group names or IDs. This option may be specified more than once, in which case all listed groups are set as supplementary groups. When the empty string is assigned, the list of supplementary groups is reset, and all assignments prior to this one will have no effect. In any way, this option does not override, but extends the list of supplementary groups configured in the system group database for the user. This does not affect commands prefixed with +. Optional. Type list of uniline.

RemoveIPC

Takes a boolean parameter. If set, all System V and POSIX IPC objects owned by the user and group the processes of this unit are run as are removed when the unit is stopped. This setting only has an effect if at least one of User, Group and DynamicUser are used. It has no effect on IPC objects owned by the root user. Specifically, this removes System V semaphores, as well as System V and POSIX shared memory segments and message queues. If multiple units use the same user or group the IPC objects are removed when the last of these units is stopped. This setting is implied if DynamicUser is set. Optional. Type boolean.

Nice

Sets the default nice level (scheduling priority) for executed processes. Takes an integer between -20 (highest priority) and 19 (lowest priority). See setpriority(2) for details. Optional. Type integer.

OOMScoreAdjust

Sets the adjustment level for the Out-Of-Memory killer for executed processes. Takes an integer between -1000 (to disable OOM killing for this process) and 1000 (to make killing of this process under memory pressure very likely). See proc.txt for details. Optional. Type integer.

IOSchedulingClass

Sets the I/O scheduling class for executed processes. Takes an integer between 0 and 3 or one of the strings none, realtime, best-effort or idle. See ioprio_set(2) for details. Optional. Type enum. choice: '0', '1', '2', '3', 'none', 'realtime', 'best-effort', 'idle'.

IOSchedulingPriority

Sets the I/O scheduling priority for executed processes. Takes an integer between 0 (highest priority) and 7 (lowest priority). The available priorities depend on the selected I/O scheduling class (see above). See ioprio_set(2) for details. Optional. Type integer.

CPUSchedulingPolicy

Sets the CPU scheduling policy for executed processes. Takes one of other, batch, idle, fifo or rr. See sched_setscheduler(2) for details. Optional. Type enum. choice: 'other', 'batch', 'idle', 'fifo', 'rr'.

CPUSchedulingPriority

Sets the CPU scheduling priority for executed processes. The available priority range depends on the selected CPU scheduling policy (see above). For real-time scheduling policies an integer between 1 (lowest priority) and 99 (highest priority) can be used. See sched_setscheduler(2) for details. Optional. Type uniline.

CPUSchedulingResetOnFork

Takes a boolean argument. If true, elevated CPU scheduling priorities and policies will be reset when the executed processes fork, and can hence not leak into child processes. See sched_setscheduler(2) for details. Defaults to false. Optional. Type boolean.

CPUAffinity

Controls the CPU affinity of the executed processes. Takes a list of CPU indices or ranges separated by either whitespace or commas. CPU ranges are specified by the lower and upper CPU indices separated by a dash. This option may be specified more than once, in which case the specified CPU affinity masks are merged. If the empty string is assigned, the mask is reset, all assignments prior to this will have no effect. See sched_setaffinity(2) for details. Optional. Type list of uniline.

UMask

Controls the file mode creation mask. Takes an access mode in octal notation. See umask(2) for details. Defaults to 0022. Optional. Type uniline.

Environment

Sets environment variables for executed processes. Takes a space-separated list of variable assignments. This option may be specified more than once, in which case all listed variables will be set. If the same variable is set twice, the later setting will override the earlier setting. If the empty string is assigned to this option, the list of environment variables is reset, all prior assignments have no effect. Variable expansion is not performed inside the strings, however, specifier expansion is possible. The $ character has no special meaning. If you need to assign a value containing spaces or the equals sign to a variable, use double quotes (") for the assignment.

Example:

Environment="VAR1=word1 word2" VAR2=word3 "VAR3=$word 5 6"

gives three variables VAR1, VAR2, VAR3 with the values word1 word2, word3, $word 5 6.

See environ(7) for details about environment variables. Optional. Type list of uniline.

EnvironmentFile

Similar to Environment but reads the environment variables from a text file. The text file should contain new-line-separated variable assignments. Empty lines, lines without an = separator, or lines starting with ; or # will be ignored, which may be used for commenting. A line ending with a backslash will be concatenated with the following one, allowing multiline variable definitions. The parser strips leading and trailing whitespace from the values of assignments, unless you use double quotes (").

The argument passed should be an absolute filename or wildcard expression, optionally prefixed with -, which indicates that if the file does not exist, it will not be read and no error or warning message is logged. This option may be specified more than once in which case all specified files are read. If the empty string is assigned to this option, the list of file to read is reset, all prior assignments have no effect.

The files listed with this directive will be read shortly before the process is executed (more specifically, after all processes from a previous unit state terminated. This means you can generate these files in one unit state, and read it with this option in the next).

Settings from these files override settings made with Environment. If the same variable is set twice from these files, the files will be read in the order they are specified and the later setting will override the earlier setting. Optional. Type list of uniline.

PassEnvironment

Pass environment variables from the systemd system manager to executed processes. Takes a space-separated list of variable names. This option may be specified more than once, in which case all listed variables will be set. If the empty string is assigned to this option, the list of environment variables is reset, all prior assignments have no effect. Variables that are not set in the system manager will not be passed and will be silently ignored.

Variables passed from this setting are overridden by those passed from Environment or EnvironmentFile.

Example:

PassEnvironment=VAR1 VAR2 VAR3

passes three variables VAR1, VAR2, VAR3 with the values set for those variables in PID1.

See environ(7) for details about environment variables. Optional. Type list of uniline.

StandardInput

Controls where file descriptor 0 (STDIN) of the executed processes is connected to. Takes one of null, tty, tty-force, tty-fail, socket or fd.

If null is selected, standard input will be connected to /dev/null, i.e. all read attempts by the process will result in immediate EOF.

If tty is selected, standard input is connected to a TTY (as configured by TTYPath, see below) and the executed process becomes the controlling process of the terminal. If the terminal is already being controlled by another process, the executed process waits until the current controlling process releases the terminal.

tty-force is similar to tty, but the executed process is forcefully and immediately made the controlling process of the terminal, potentially removing previous controlling processes from the terminal.

tty-fail is similar to tty but if the terminal already has a controlling process start-up of the executed process fails.

The socket option is only valid in socket-activated services, and only when the socket configuration file (see systemd.socket(5) for details) specifies a single socket only. If this option is set, standard input will be connected to the socket the service was activated from, which is primarily useful for compatibility with daemons designed for use with the traditional inetd(8) daemon.

The fd option connects the input stream to a single file descriptor provided by a socket unit. A custom named file descriptor can be specified as part of this option, after a : (e.g. fd:foobar). If no name is specified, stdin is assumed (i.e. fd is equivalent to fd:stdin). At least one socket unit defining such name must be explicitly provided via the Sockets option, and file descriptor name may differ from the name of its containing socket unit. If multiple matches are found, the first one will be used. See FileDescriptorName in systemd.socket(5) for more details about named descriptors and ordering.

This setting defaults to null. Optional. Type enum. choice: 'null', 'tty', 'tty-force', 'tty-fail', 'socket', 'fd'.

StandardOutput

Controls where file descriptor 1 (STDOUT) of the executed processes is connected to. Takes one of inherit, null, tty, journal, syslog, kmsg, journal+console, syslog+console, kmsg+console, socket or fd.

inherit duplicates the file descriptor of standard input for standard output.

null connects standard output to /dev/null, i.e. everything written to it will be lost.

tty connects standard output to a tty (as configured via TTYPath, see below). If the TTY is used for output only, the executed process will not become the controlling process of the terminal, and will not fail or wait for other processes to release the terminal.

journal connects standard output with the journal which is accessible via journalctl(1). Note that everything that is written to syslog or kmsg (see below) is implicitly stored in the journal as well, the specific two options listed below are hence supersets of this one.

syslog connects standard output to the syslog(3) system syslog service, in addition to the journal. Note that the journal daemon is usually configured to forward everything it receives to syslog anyway, in which case this option is no different from journal.

kmsg connects standard output with the kernel log buffer which is accessible via dmesg(1), in addition to the journal. The journal daemon might be configured to send all logs to kmsg anyway, in which case this option is no different from journal.

journal+console, syslog+console and kmsg+console work in a similar way as the three options above but copy the output to the system console as well.

socket connects standard output to a socket acquired via socket activation. The semantics are similar to the same option of StandardInput.

The fd option connects the output stream to a single file descriptor provided by a socket unit. A custom named file descriptor can be specified as part of this option, after a : (e.g. fd:foobar). If no name is specified, stdout is assumed (i.e. fd is equivalent to fd:stdout). At least one socket unit defining such name must be explicitly provided via the Sockets option, and file descriptor name may differ from the name of its containing socket unit. If multiple matches are found, the first one will be used. See FileDescriptorName in systemd.socket(5) for more details about named descriptors and ordering.

If the standard output (or error output, see below) of a unit is connected to the journal, syslog or the kernel log buffer, the unit will implicitly gain a dependency of type After on systemd-journald.socket (also see the automatic dependencies section above).

This setting defaults to the value set with DefaultStandardOutput in systemd-system.conf(5), which defaults to journal. Note that setting this parameter might result in additional dependencies to be added to the unit (see above). Optional. Type enum. choice: 'inherit', 'null', 'tty', 'journal', 'syslog', 'kmsg', 'journal+console', 'syslog+console', 'kmsg+console', 'socket', 'fd'.

StandardError

Controls where file descriptor 2 (STDERR) of the executed processes is connected to. The available options are identical to those of StandardOutput, with some exceptions: if set to inherit the file descriptor used for standard output is duplicated for standard error, while fd operates on the error stream and will look by default for a descriptor named stderr.

This setting defaults to the value set with DefaultStandardError in systemd-system.conf(5), which defaults to inherit. Note that setting this parameter might result in additional dependencies to be added to the unit (see above). Optional. Type uniline.

TTYPath

Sets the terminal device node to use if standard input, output, or error are connected to a TTY (see above). Defaults to /dev/console. Optional. Type uniline.

TTYReset

Reset the terminal device specified with TTYPath before and after execution. Defaults to no. Optional. Type uniline.

TTYVHangup

Disconnect all clients which have opened the terminal device specified with TTYPath before and after execution. Defaults to no. Optional. Type uniline.

TTYVTDisallocate

If the terminal device specified with TTYPath is a virtual console terminal, try to deallocate the TTY before and after execution. This ensures that the screen and scrollback buffer is cleared. Defaults to no. Optional. Type uniline.

SyslogIdentifier

Sets the process name to prefix log lines sent to the logging system or the kernel log buffer with. If not set, defaults to the process name of the executed process. This option is only useful when StandardOutput or StandardError are set to syslog, journal or kmsg (or to the same settings in combination with +console). Optional. Type uniline.

SyslogFacility

Sets the syslog facility to use when logging to syslog. One of kern, user, mail, daemon, auth, syslog, lpr, news, uucp, cron, authpriv, ftp, local0, local1, local2, local3, local4, local5, local6 or local7. See syslog(3) for details. This option is only useful when StandardOutput or StandardError are set to syslog. Defaults to daemon. Optional. Type uniline.

SyslogLevel

The default syslog level to use when logging to syslog or the kernel log buffer. One of emerg, alert, crit, err, warning, notice, info, debug. See syslog(3) for details. This option is only useful when StandardOutput or StandardError are set to syslog or kmsg. Note that individual lines output by the daemon might be prefixed with a different log level which can be used to override the default log level specified here. The interpretation of these prefixes may be disabled with SyslogLevelPrefix, see below. For details, see sd-daemon(3). Defaults to info. Optional. Type uniline.

SyslogLevelPrefix

Takes a boolean argument. If true and StandardOutput or StandardError are set to syslog, kmsg or journal, log lines written by the executed process that are prefixed with a log level will be passed on to syslog with this log level set but the prefix removed. If set to false, the interpretation of these prefixes is disabled and the logged lines are passed on as-is. For details about this prefixing see sd-daemon(3). Defaults to true. Optional. Type boolean.

TimerSlackNSec

Sets the timer slack in nanoseconds for the executed processes. The timer slack controls the accuracy of wake-ups triggered by timers. See prctl(2) for more information. Note that in contrast to most other time span definitions this parameter takes an integer value in nano-seconds if no unit is specified. The usual time units are understood too. Optional. Type uniline.

LimitCPU

Set soft and hard limits on various resources for executed processes. See setrlimit(2) for details on the resource limit concept. Resource limits may be specified in two formats: either as single value to set a specific soft and hard limit to the same value, or as colon-separated pair soft:hard to set both limits individually (e.g. LimitAS=4G:16G). Use the string infinity to configure no limit on a specific resource. The multiplicative suffixes K, M, G, T, P and E (to the base 1024) may be used for resource limits measured in bytes (e.g. LimitAS=16G). For the limits referring to time values, the usual time units ms, s, min, h and so on may be used (see systemd.time(7) for details). Note that if no time unit is specified for LimitCPU the default unit of seconds is implied, while for LimitRTTIME the default unit of microseconds is implied. Also, note that the effective granularity of the limits might influence their enforcement. For example, time limits specified for LimitCPU will be rounded up implicitly to multiples of 1s. For LimitNICE the value may be specified in two syntaxes: if prefixed with + or -, the value is understood as regular Linux nice value in the range -20..19. If not prefixed like this the value is understood as raw resource limit parameter in the range 0..40 (with 0 being equivalent to 1).

Note that most process resource limits configured with these options are per-process, and processes may fork in order to acquire a new set of resources that are accounted independently of the original process, and may thus escape limits set. Also note that LimitRSS is not implemented on Linux, and setting it has no effect. Often it is advisable to prefer the resource controls listed in systemd.resource-control(5) over these per-process limits, as they apply to services as a whole, may be altered dynamically at runtime, and are generally more expressive. For example, MemoryLimit is a more powerful (and working) replacement for LimitRSS.

For system units these resource limits may be chosen freely. For user units however (i.e. units run by a per-user instance of systemd(1)), these limits are bound by (possibly more restrictive) per-user limits enforced by the OS.

Resource limits not configured explicitly for a unit default to the value configured in the various DefaultLimitCPU, DefaultLimitFSIZE, … options available in systemd-system.conf(5), and – if not configured there – the kernel or per-user defaults, as defined by the OS (the latter only for user services, see above). Optional. Type uniline.

LimitFSIZE

LimitDATA

LimitSTACK

LimitCORE

LimitRSS

LimitNOFILE

LimitAS

LimitNPROC

LimitMEMLOCK

LimitLOCKS

LimitSIGPENDING

LimitMSGQUEUE

LimitNICE

LimitRTPRIO

LimitRTTIME

PAMName

Sets the PAM service name to set up a session as. If set, the executed process will be registered as a PAM session under the specified service name. This is only useful in conjunction with the User setting, and is otherwise ignored. If not set, no PAM session will be opened for the executed processes. See pam(8) for details.

Note that for each unit making use of this option a PAM session handler process will be maintained as part of the unit and stays around as long as the unit is active, to ensure that appropriate actions can be taken when the unit and hence the PAM session terminates. This process is named (sd-pam) and is an immediate child process of the unit's main process. Optional. Type uniline.

CapabilityBoundingSet

Controls which capabilities to include in the capability bounding set for the executed process. See capabilities(7) for details. Takes a whitespace-separated list of capability names, e.g. CAP_SYS_ADMIN, CAP_DAC_OVERRIDE, CAP_SYS_PTRACE. Capabilities listed will be included in the bounding set, all others are removed. If the list of capabilities is prefixed with ~, all but the listed capabilities will be included, the effect of the assignment inverted. Note that this option also affects the respective capabilities in the effective, permitted and inheritable capability sets. If this option is not used, the capability bounding set is not modified on process execution, hence no limits on the capabilities of the process are enforced. This option may appear more than once, in which case the bounding sets are merged. If the empty string is assigned to this option, the bounding set is reset to the empty capability set, and all prior settings have no effect. If set to ~ (without any further argument), the bounding set is reset to the full set of available capabilities, also undoing any previous settings. This does not affect commands prefixed with +. Optional. Type uniline.

AmbientCapabilities

Controls which capabilities to include in the ambient capability set for the executed process. Takes a whitespace-separated list of capability names, e.g. CAP_SYS_ADMIN, CAP_DAC_OVERRIDE, CAP_SYS_PTRACE. This option may appear more than once in which case the ambient capability sets are merged. If the list of capabilities is prefixed with ~, all but the listed capabilities will be included, the effect of the assignment inverted. If the empty string is assigned to this option, the ambient capability set is reset to the empty capability set, and all prior settings have no effect. If set to ~ (without any further argument), the ambient capability set is reset to the full set of available capabilities, also undoing any previous settings. Note that adding capabilities to ambient capability set adds them to the process's inherited capability set.

Ambient capability sets are useful if you want to execute a process as a
non-privileged user but still want to give it some capabilities.  Note that in this case option
C<keep-caps> is automatically added to C<SecureBits> to retain the
capabilities over the user change. C<AmbientCapabilities> does not affect commands prefixed
with C<+>. I< Optional. Type uniline.  >

SecureBits

Controls the secure bits set for the executed process. Takes a space-separated combination of options from the following list: keep-caps, keep-caps-locked, no-setuid-fixup, no-setuid-fixup-locked, noroot, and noroot-locked. This option may appear more than once, in which case the secure bits are ORed. If the empty string is assigned to this option, the bits are reset to 0. This does not affect commands prefixed with +. See capabilities(7) for details. Optional. Type uniline.

ReadWritePaths

Sets up a new file system namespace for executed processes. These options may be used to limit access a process might have to the file system hierarchy. Each setting takes a space-separated list of paths relative to the host's root directory (i.e. the system running the service manager). Note that if paths contain symlinks, they are resolved relative to the root directory set with RootDirectory/RootImage.

Paths listed in ReadWritePaths are accessible from within the namespace with the same access modes as from outside of it. Paths listed in ReadOnlyPaths are accessible for reading only, writing will be refused even if the usual file access controls would permit this. Nest ReadWritePaths inside of ReadOnlyPaths in order to provide writable subdirectories within read-only directories. Use ReadWritePaths in order to whitelist specific paths for write access if ProtectSystem=strict is used. Paths listed in InaccessiblePaths will be made inaccessible for processes inside the namespace (along with everything below them in the file system hierarchy).

Note that restricting access with these options does not extend to submounts of a directory that are created later on. Non-directory paths may be specified as well. These options may be specified more than once, in which case all paths listed will have limited access from within the namespace. If the empty string is assigned to this option, the specific list is reset, and all prior assignments have no effect.

Paths in ReadWritePaths, ReadOnlyPaths and InaccessiblePaths may be prefixed with -, in which case they will be ignored when they do not exist. If prefixed with + the paths are taken relative to the root directory of the unit, as configured with RootDirectory/RootImage, instead of relative to the root directory of the host (see above). When combining - and + on the same path make sure to specify - first, and + second.

Note that using this setting will disconnect propagation of mounts from the service to the host (propagation in the opposite direction continues to work). This means that this setting may not be used for services which shall be able to install mount points in the main mount namespace. Note that the effect of these settings may be undone by privileged processes. In order to set up an effective sandboxed environment for a unit it is thus recommended to combine these settings with either CapabilityBoundingSet=~CAP_SYS_ADMIN or SystemCallFilter=~@mount. Optional. Type list of uniline.

ReadOnlyPaths

InaccessiblePaths

BindPaths

Configures unit-specific bind mounts. A bind mount makes a particular file or directory available at an additional place in the unit's view of the file system. Any bind mounts created with this option are specific to the unit, and are not visible in the host's mount table. This option expects a whitespace separated list of bind mount definitions. Each definition consists of a colon-separated triple of source path, destination path and option string, where the latter two are optional. If only a source path is specified the source and destination is taken to be the same. The option string may be either rbind or norbind for configuring a recursive or non-recursive bind mount. If the destination path is omitted, the option string must be omitted too.

BindPaths creates regular writable bind mounts (unless the source file system mount is already marked read-only), while BindReadOnlyPaths creates read-only bind mounts. These settings may be used more than once, each usage appends to the unit's list of bind mounts. If the empty string is assigned to either of these two options the entire list of bind mounts defined prior to this is reset. Note that in this case both read-only and regular bind mounts are reset, regardless which of the two settings is used.

This option is particularly useful when RootDirectory/RootImage is used. In this case the source path refers to a path on the host file system, while the destination path refers to a path below the root directory of the unit. Optional. Type list of uniline.

BindReadOnlyPaths

PrivateTmp

Takes a boolean argument. If true, sets up a new file system namespace for the executed processes and mounts private /tmp and /var/tmp directories inside it that is not shared by processes outside of the namespace. This is useful to secure access to temporary files of the process, but makes sharing between processes via /tmp or /var/tmp impossible. If this is enabled, all temporary files created by a service in these directories will be removed after the service is stopped. Defaults to false. It is possible to run two or more units within the same private /tmp and /var/tmp namespace by using the JoinsNamespaceOf directive, see systemd.unit(5) for details. This setting is implied if DynamicUser is set. For this setting the same restrictions regarding mount propagation and privileges apply as for ReadOnlyPaths and related calls, see above. Enabling this setting has the side effect of adding Requires and After dependencies on all mount units necessary to access /tmp and /var/tmp. Moreover an implicitly After ordering on systemd-tmpfiles-setup.service(8) is added.

Note that the implementation of this setting might be impossible (for example if mount namespaces are not available), and the unit should be written in a way that does not solely rely on this setting for security. Optional. Type boolean.

PrivateDevices

Takes a boolean argument. If true, sets up a new /dev mount for the executed processes and only adds API pseudo devices such as /dev/null, /dev/zero or /dev/random (as well as the pseudo TTY subsystem) to it, but no physical devices such as /dev/sda, system memory /dev/mem, system ports /dev/port and others. This is useful to securely turn off physical device access by the executed process. Defaults to false. Enabling this option will install a system call filter to block low-level I/O system calls that are grouped in the @raw-io set, will also remove CAP_MKNOD and CAP_SYS_RAWIO from the capability bounding set for the unit (see above), and set DevicePolicy=closed (see systemd.resource-control(5) for details). Note that using this setting will disconnect propagation of mounts from the service to the host (propagation in the opposite direction continues to work). This means that this setting may not be used for services which shall be able to install mount points in the main mount namespace. The new /dev will be mounted read-only and 'noexec'. The latter may break old programs which try to set up executable memory by using mmap(2) of /dev/zero instead of using MAP_ANON. This setting is implied if DynamicUser is set. For this setting the same restrictions regarding mount propagation and privileges apply as for ReadOnlyPaths and related calls, see above. If turned on and if running in user mode, or in system mode, but without the CAP_SYS_ADMIN capability (e.g. setting User), NoNewPrivileges=yes is implied.

PrivateNetwork

Takes a boolean argument. If true, sets up a new network namespace for the executed processes and configures only the loopback network device lo inside it. No other network devices will be available to the executed process. This is useful to turn off network access by the executed process. Defaults to false. It is possible to run two or more units within the same private network namespace by using the JoinsNamespaceOf directive, see systemd.unit(5) for details. Note that this option will disconnect all socket families from the host, this includes AF_NETLINK and AF_UNIX. The latter has the effect that AF_UNIX sockets in the abstract socket namespace will become unavailable to the processes (however, those located in the file system will continue to be accessible).

Note that the implementation of this setting might be impossible (for example if network namespaces are not available), and the unit should be written in a way that does not solely rely on this setting for security. Optional. Type boolean.

PrivateUsers

Takes a boolean argument. If true, sets up a new user namespace for the executed processes and configures a minimal user and group mapping, that maps the root user and group as well as the unit's own user and group to themselves and everything else to the nobody user and group. This is useful to securely detach the user and group databases used by the unit from the rest of the system, and thus to create an effective sandbox environment. All files, directories, processes, IPC objects and other resources owned by users/groups not equaling root or the unit's own will stay visible from within the unit but appear owned by the nobody user and group. If this mode is enabled, all unit processes are run without privileges in the host user namespace (regardless if the unit's own user/group is root or not). Specifically this means that the process will have zero process capabilities on the host's user namespace, but full capabilities within the service's user namespace. Settings such as CapabilityBoundingSet will affect only the latter, and there's no way to acquire additional capabilities in the host's user namespace. Defaults to off.

This setting is particularly useful in conjunction with RootDirectory/RootImage, as the need to synchronize the user and group databases in the root directory and on the host is reduced, as the only users and groups who need to be matched are root, nobody and the unit's own user and group.

Note that the implementation of this setting might be impossible (for example if user namespaces are not available), and the unit should be written in a way that does not solely rely on this setting for security. Optional. Type boolean.

ProtectSystem

Takes a boolean argument or the special values full or strict. If true, mounts the /usr and /boot directories read-only for processes invoked by this unit. If set to full, the /etc directory is mounted read-only, too. If set to strict the entire file system hierarchy is mounted read-only, except for the API file system subtrees /dev, /proc and /sys (protect these directories using PrivateDevices, ProtectKernelTunables, ProtectControlGroups). This setting ensures that any modification of the vendor-supplied operating system (and optionally its configuration, and local mounts) is prohibited for the service. It is recommended to enable this setting for all long-running services, unless they are involved with system updates or need to modify the operating system in other ways. If this option is used, ReadWritePaths may be used to exclude specific directories from being made read-only. This setting is implied if DynamicUser is set. For this setting the same restrictions regarding mount propagation and privileges apply as for ReadOnlyPaths and related calls, see above. Defaults to off. Optional. Type enum. choice: 'no', 'yes', 'full', 'strict'.

ProtectHome

Takes a boolean argument or read-only. If true, the directories /home, /root and /run/user are made inaccessible and empty for processes invoked by this unit. If set to read-only, the three directories are made read-only instead. It is recommended to enable this setting for all long-running services (in particular network-facing ones), to ensure they cannot get access to private user data, unless the services actually require access to the user's private data. This setting is implied if DynamicUser is set. For this setting the same restrictions regarding mount propagation and privileges apply as for ReadOnlyPaths and related calls, see above. Optional. Type enum. choice: 'no', 'yes', 'read-only'.

ProtectKernelTunables

Takes a boolean argument. If true, kernel variables accessible through /proc/sys, /sys, /proc/sysrq-trigger, /proc/latency_stats, /proc/acpi, /proc/timer_stats, /proc/fs and /proc/irq will be made read-only to all processes of the unit. Usually, tunable kernel variables should be initialized only at boot-time, for example with the sysctl.d(5) mechanism. Few services need to write to these at runtime; it is hence recommended to turn this on for most services. For this setting the same restrictions regarding mount propagation and privileges apply as for ReadOnlyPaths and related calls, see above. Defaults to off. If turned on and if running in user mode, or in system mode, but without the CAP_SYS_ADMIN capability (e.g. services for which User is set), NoNewPrivileges=yes is implied. Note that this option does not prevent indirect changes to kernel tunables effected by IPC calls to other processes. However, InaccessiblePaths may be used to make relevant IPC file system objects inaccessible. If ProtectKernelTunables is set, MountAPIVFS=yes is implied. Optional. Type boolean.

ProtectKernelModules

Takes a boolean argument. If true, explicit module loading will be denied. This allows to turn off module load and unload operations on modular kernels. It is recommended to turn this on for most services that do not need special file systems or extra kernel modules to work. Default to off. Enabling this option removes CAP_SYS_MODULE from the capability bounding set for the unit, and installs a system call filter to block module system calls, also /usr/lib/modules is made inaccessible. For this setting the same restrictions regarding mount propagation and privileges apply as for ReadOnlyPaths and related calls, see above. Note that limited automatic module loading due to user configuration or kernel mapping tables might still happen as side effect of requested user operations, both privileged and unprivileged. To disable module auto-load feature please see sysctl.d(5)kernel.modules_disabled mechanism and /proc/sys/kernel/modules_disabled documentation. If turned on and if running in user mode, or in system mode, but without the CAP_SYS_ADMIN capability (e.g. setting User), NoNewPrivileges=yes is implied. Optional. Type boolean.

ProtectControlGroups

Takes a boolean argument. If true, the Linux Control Groups (cgroups(7)) hierarchies accessible through /sys/fs/cgroup will be made read-only to all processes of the unit. Except for container managers no services should require write access to the control groups hierarchies; it is hence recommended to turn this on for most services. For this setting the same restrictions regarding mount propagation and privileges apply as for ReadOnlyPaths and related calls, see above. Defaults to off. If ProtectControlGroups is set, MountAPIVFS=yes is implied. Optional. Type boolean.

MountFlags

Takes a mount propagation flag: shared, slave or private, which control whether mounts in the file system namespace set up for this unit's processes will receive or propagate mounts and unmounts. See mount(2) for details. Defaults to shared. Use shared to ensure that mounts and unmounts are propagated from systemd's namespace to the service's namespace and vice versa. Use slave to run processes so that none of their mounts and unmounts will propagate to the host. Use private to also ensure that no mounts and unmounts from the host will propagate into the unit processes' namespace. If this is set to slave or private, any mounts created by spawned processes will be unmounted after the completion of the current command line of ExecStartPre, ExecStartPost, ExecStart, and ExecStopPost. Note that slave means that file systems mounted on the host might stay mounted continuously in the unit's namespace, and thus keep the device busy. Note that the file system namespace related options (PrivateTmp, PrivateDevices, ProtectSystem, ProtectHome, ProtectKernelTunables, ProtectControlGroups, ReadOnlyPaths, InaccessiblePaths, ReadWritePaths) require that mount and unmount propagation from the unit's file system namespace is disabled, and hence downgrade shared to slave. Optional. Type uniline.

UtmpIdentifier

Takes a four character identifier string for an utmp(5) and wtmp entry for this service. This should only be set for services such as getty implementations (such as agetty(8)) where utmp/wtmp entries must be created and cleared before and after execution, or for services that shall be executed as if they were run by a getty process (see below). If the configured string is longer than four characters, it is truncated and the terminal four characters are used. This setting interprets %I style string replacements. This setting is unset by default, i.e. no utmp/wtmp entries are created or cleaned up for this service. Optional. Type uniline.

UtmpMode

Takes one of init, login or user. If UtmpIdentifier is set, controls which type of utmp(5)/wtmp entries for this service are generated. This setting has no effect unless UtmpIdentifier is set too. If init is set, only an INIT_PROCESS entry is generated and the invoked process must implement a getty-compatible utmp/wtmp logic. If login is set, first an INIT_PROCESS entry, followed by a LOGIN_PROCESS entry is generated. In this case, the invoked process must implement a login(1)-compatible utmp/wtmp logic. If user is set, first an INIT_PROCESS entry, then a LOGIN_PROCESS entry and finally a USER_PROCESS entry is generated. In this case, the invoked process may be any process that is suitable to be run as session leader. Defaults to init. Optional. Type enum. choice: 'init', 'login', 'user'.

SELinuxContext

Set the SELinux security context of the executed process. If set, this will override the automated domain transition. However, the policy still needs to authorize the transition. This directive is ignored if SELinux is disabled. If prefixed by -, all errors will be ignored. This does not affect commands prefixed with +. See setexeccon(3) for details. Optional. Type uniline.

AppArmorProfile

Takes a profile name as argument. The process executed by the unit will switch to this profile when started. Profiles must already be loaded in the kernel, or the unit will fail. This result in a non operation if AppArmor is not enabled. If prefixed by -, all errors will be ignored. This does not affect commands prefixed with +. Optional. Type uniline.

SmackProcessLabel

Takes a SMACK64 security label as argument. The process executed by the unit will be started under this label and SMACK will decide whether the process is allowed to run or not, based on it. The process will continue to run under the label specified here unless the executable has its own SMACK64EXEC label, in which case the process will transition to run under that label. When not specified, the label that systemd is running under is used. This directive is ignored if SMACK is disabled.

The value may be prefixed by -, in which case all errors will be ignored. An empty value may be specified to unset previous assignments. This does not affect commands prefixed with +. Optional. Type uniline.

IgnoreSIGPIPE

Takes a boolean argument. If true, causes SIGPIPE to be ignored in the executed process. Defaults to true because SIGPIPE generally is useful only in shell pipelines. Optional. Type boolean.

NoNewPrivileges

Takes a boolean argument. If true, ensures that the service process and all its children can never gain new privileges through execve() (e.g. via setuid or setgid bits, or filesystem capabilities). This is the simplest and most effective way to ensure that a process and its children can never elevate privileges again. Defaults to false, but certain settings force NoNewPrivileges=yes, ignoring the value of this setting. This is the case when SystemCallFilter, SystemCallArchitectures, RestrictAddressFamilies, RestrictNamespaces, PrivateDevices, ProtectKernelTunables, ProtectKernelModules, MemoryDenyWriteExecute, or RestrictRealtime are specified. Optional. Type boolean.

SystemCallFilter

Takes a space-separated list of system call names. If this setting is used, all system calls executed by the unit processes except for the listed ones will result in immediate process termination with the SIGSYS signal (whitelisting). If the first character of the list is ~, the effect is inverted: only the listed system calls will result in immediate process termination (blacklisting). If running in user mode, or in system mode, but without the CAP_SYS_ADMIN capability (e.g. setting User=nobody), NoNewPrivileges=yes is implied. This feature makes use of the Secure Computing Mode 2 interfaces of the kernel ('seccomp filtering') and is useful for enforcing a minimal sandboxing environment. Note that the execve, exit, exit_group, getrlimit, rt_sigreturn, sigreturn system calls and the system calls for querying time and sleeping are implicitly whitelisted and do not need to be listed explicitly. This option may be specified more than once, in which case the filter masks are merged. If the empty string is assigned, the filter is reset, all prior assignments will have no effect. This does not affect commands prefixed with +.

Note that on systems supporting multiple ABIs (such as x86/x86-64) it is recommended to turn off alternative ABIs for services, so that they cannot be used to circumvent the restrictions of this option. Specifically, it is recommended to combine this option with SystemCallArchitectures=native or similar.

Note that strict system call filters may impact execution and error handling code paths of the service invocation. Specifically, access to the execve system call is required for the execution of the service binary — if it is blocked service invocation will necessarily fail. Also, if execution of the service binary fails for some reason (for example: missing service executable), the error handling logic might require access to an additional set of system calls in order to process and log this failure correctly. It might be necessary to temporarily disable system call filters in order to simplify debugging of such failures.

If you specify both types of this option (i.e. whitelisting and blacklisting), the first encountered will take precedence and will dictate the default action (termination or approval of a system call). Then the next occurrences of this option will add or delete the listed system calls from the set of the filtered system calls, depending of its type and the default action. (For example, if you have started with a whitelisting of read and write, and right after it add a blacklisting of write, then write will be removed from the set.)

As the number of possible system calls is large, predefined sets of system calls are provided. A set starts with @ character, followed by name of the set. Currently predefined system call setsSetDescription@basic-ioSystem calls for basic I/O: reading, writing, seeking, file descriptor duplication and closing (read(2), write(2), and related calls)@clockSystem calls for changing the system clock (adjtimex(2), settimeofday(2), and related calls)@cpu-emulationSystem calls for CPU emulation functionality (vm86(2) and related calls)@debugDebugging, performance monitoring and tracing functionality (ptrace(2), perf_event_open(2) and related calls)@file-systemFile system operations: opening, creating files and directories for read and write, renaming and removing them, reading file properties, or creating hard and symbolic links.@io-eventEvent loop system calls (poll(2), select(2), epoll(7), eventfd(2) and related calls)@ipcPipes, SysV IPC, POSIX Message Queues and other IPC (mq_overview(7), svipc(7))@keyringKernel keyring access (keyctl(2) and related calls)@moduleLoading and unloading of kernel modules (init_module(2), delete_module(2) and related calls)@mountMounting and unmounting of file systems (mount(2), chroot(2), and related calls)@network-ioSocket I/O (including local AF_UNIX): socket(7), unix(7)@obsoleteUnusual, obsolete or unimplemented (create_module(2), gtty(2), …)@privilegedAll system calls which need super-user capabilities (capabilities(7))@processProcess control, execution, namespaceing operations (clone(2), kill(2), namespaces(7), …@raw-ioRaw I/O port access (ioperm(2), iopl(2), pciconfig_read(), …)@rebootSystem calls for rebooting and reboot preparation (reboot(2), kexec(), …)@resourcesSystem calls for changing resource limits, memory and scheduling parameters (setrlimit(2), setpriority(2), …)@swapSystem calls for enabling/disabling swap devices (swapon(2), swapoff(2)) Note, that as new system calls are added to the kernel, additional system calls might be added to the groups above. Contents of the sets may also change between systemd versions. In addition, the list of system calls depends on the kernel version and architecture for which systemd was compiled. Use systemd-analyze syscall-filter to list the actual list of system calls in each filter.

It is recommended to combine the file system namespacing related options with SystemCallFilter=~@mount, in order to prohibit the unit's processes to undo the mappings. Specifically these are the options PrivateTmp, PrivateDevices, ProtectSystem, ProtectHome, ProtectKernelTunables, ProtectControlGroups, ReadOnlyPaths, InaccessiblePaths and ReadWritePaths. Optional. Type list of uniline.

SystemCallErrorNumber

Takes an errno error number name to return when the system call filter configured with SystemCallFilter is triggered, instead of terminating the process immediately. Takes an error name such as EPERM, EACCES or EUCLEAN. When this setting is not used, or when the empty string is assigned, the process will be terminated immediately when the filter is triggered. Optional. Type uniline.

SystemCallArchitectures

Takes a space-separated list of architecture identifiers to include in the system call filter. The known architecture identifiers are the same as for ConditionArchitecture described in systemd.unit(5), as well as x32, mips64-n32, mips64-le-n32, and the special identifier native. Only system calls of the specified architectures will be permitted to processes of this unit. This is an effective way to disable compatibility with non-native architectures for processes, for example to prohibit execution of 32-bit x86 binaries on 64-bit x86-64 systems. The special native identifier implicitly maps to the native architecture of the system (or more strictly: to the architecture the system manager is compiled for). If running in user mode, or in system mode, but without the CAP_SYS_ADMIN capability (e.g. setting User=nobody), NoNewPrivileges=yes is implied. Note that setting this option to a non-empty list implies that native is included too. By default, this option is set to the empty list, i.e. no system call architecture filtering is applied.

Note that system call filtering is not equally effective on all architectures. For example, on x86 filtering of network socket-related calls is not possible, due to ABI limitations — a limitation that x86-64 does not have, however. On systems supporting multiple ABIs at the same time — such as x86/x86-64 — it is hence recommended to limit the set of permitted system call architectures so that secondary ABIs may not be used to circumvent the restrictions applied to the native ABI of the system. In particular, setting SystemCallFilter=native is a good choice for disabling non-native ABIs.

System call architectures may also be restricted system-wide via the SystemCallArchitectures option in the global configuration. See systemd-system.conf(5) for details. Optional. Type uniline.

RestrictAddressFamilies

Restricts the set of socket address families accessible to the processes of this unit. Takes a space-separated list of address family names to whitelist, such as AF_UNIX, AF_INET or AF_INET6. When prefixed with ~ the listed address families will be applied as blacklist, otherwise as whitelist. Note that this restricts access to the socket(2) system call only. Sockets passed into the process by other means (for example, by using socket activation with socket units, see systemd.socket(5)) are unaffected. Also, sockets created with socketpair() (which creates connected AF_UNIX sockets only) are unaffected. Note that this option has no effect on 32-bit x86, s390, s390x, mips, mips-le, ppc, ppc-le, pcc64, ppc64-le and is ignored (but works correctly on other ABIs, including x86-64). Note that on systems supporting multiple ABIs (such as x86/x86-64) it is recommended to turn off alternative ABIs for services, so that they cannot be used to circumvent the restrictions of this option. Specifically, it is recommended to combine this option with SystemCallArchitectures=native or similar. If running in user mode, or in system mode, but without the CAP_SYS_ADMIN capability (e.g. setting User=nobody), NoNewPrivileges=yes is implied. By default, no restrictions apply, all address families are accessible to processes. If assigned the empty string, any previous address familiy restriction changes are undone. This setting does not affect commands prefixed with +.

Use this option to limit exposure of processes to remote access, in particular via exotic and sensitive network protocols, such as AF_PACKET. Note that in most cases, the local AF_UNIX address family should be included in the configured whitelist as it is frequently used for local communication, including for syslog(2) logging. Optional. Type uniline.

RestrictNamespaces

Restricts access to Linux namespace functionality for the processes of this unit. For details about Linux namespaces, see namespaces(7). Either takes a boolean argument, or a space-separated list of namespace type identifiers. If false (the default), no restrictions on namespace creation and switching are made. If true, access to any kind of namespacing is prohibited. Otherwise, a space-separated list of namespace type identifiers must be specified, consisting of any combination of: cgroup, ipc, net, mnt, pid, user and uts. Any namespace type listed is made accessible to the unit's processes, access to namespace types not listed is prohibited (whitelisting). By prepending the list with a single tilda character (~) the effect may be inverted: only the listed namespace types will be made inaccessible, all unlisted ones are permitted (blacklisting). If the empty string is assigned, the default namespace restrictions are applied, which is equivalent to false. Internally, this setting limits access to the unshare(2), clone(2) and setns(2) system calls, taking the specified flags parameters into account. Note that — if this option is used — in addition to restricting creation and switching of the specified types of namespaces (or all of them, if true) access to the setns() system call with a zero flags parameter is prohibited. This setting is only supported on x86, x86-64, mips, mips-le, mips64, mips64-le, mips64-n32, mips64-le-n32, ppc64, ppc64-le, s390 and s390x, and enforces no restrictions on other architectures. If running in user mode, or in system mode, but without the CAP_SYS_ADMIN capability (e.g. setting User), NoNewPrivileges=yes is implied. Optional. Type uniline.

Personality

Controls which kernel architecture uname(2) shall report, when invoked by unit processes. Takes one of the architecture identifiers x86, x86-64, ppc, ppc-le, ppc64, ppc64-le, s390 or s390x. Which personality architectures are supported depends on the system architecture. Usually the 64bit versions of the various system architectures support their immediate 32bit personality architecture counterpart, but no others. For example, x86-64 systems support the x86-64 and x86 personalities but no others. The personality feature is useful when running 32-bit services on a 64-bit host system. If not specified, the personality is left unmodified and thus reflects the personality of the host system's kernel. Optional. Type enum. choice: 'x86', 'x86-64', 'ppc', 'ppc-le', 'ppc64', 'ppc64-le', 's390', 's390x'.

RuntimeDirectory

Takes a list of directory names. If set, one or more directories by the specified names will be created below /run (for system services) or below $XDG_RUNTIME_DIR (for user services) when the unit is started, and removed when the unit is stopped. The directories will have the access mode specified in RuntimeDirectoryMode, and will be owned by the user and group specified in User and Group. Use this to manage one or more runtime directories of the unit and bind their lifetime to the daemon runtime. The specified directory names must be relative, and may not include a /, i.e. must refer to simple directories to create or remove. This is particularly useful for unprivileged daemons that cannot create runtime directories in /run due to lack of privileges, and to make sure the runtime directory is cleaned up automatically after use. For runtime directories that require more complex or different configuration or lifetime guarantees, please consider using tmpfiles.d(5). Optional. Type uniline.

RuntimeDirectoryMode

Specifies the access mode of the directories specified in RuntimeDirectory as an octal number. Defaults to 0755. See "Permissions" in path_resolution(7) for a discussion of the meaning of permission bits. Optional. Type uniline.

MemoryDenyWriteExecute

Takes a boolean argument. If set, attempts to create memory mappings that are writable and executable at the same time, or to change existing memory mappings to become executable, or mapping shared memory segments as executable are prohibited. Specifically, a system call filter is added that rejects mmap(2) system calls with both PROT_EXEC and PROT_WRITE set, mprotect(2) system calls with PROT_EXEC set and shmat(2) system calls with SHM_EXEC set. Note that this option is incompatible with programs and libraries that generate program code dynamically at runtime, including JIT execution engines, executable stacks, and code "trampoline" feature of various C compilers. This option improves service security, as it makes harder for software exploits to change running code dynamically. Note that this feature is fully available on x86-64, and partially on x86. Specifically, the shmat() protection is not available on x86. Note that on systems supporting multiple ABIs (such as x86/x86-64) it is recommended to turn off alternative ABIs for services, so that they cannot be used to circumvent the restrictions of this option. Specifically, it is recommended to combine this option with SystemCallArchitectures=native or similar. If running in user mode, or in system mode, but without the CAP_SYS_ADMIN capability (e.g. setting User), NoNewPrivileges=yes is implied. Optional. Type boolean.

RestrictRealtime

Takes a boolean argument. If set, any attempts to enable realtime scheduling in a process of the unit are refused. This restricts access to realtime task scheduling policies such as SCHED_FIFO, SCHED_RR or SCHED_DEADLINE. See sched(7) for details about these scheduling policies. If running in user mode, or in system mode, but without the CAP_SYS_ADMIN capability (e.g. setting User), NoNewPrivileges=yes is implied. Realtime scheduling policies may be used to monopolize CPU time for longer periods of time, and may hence be used to lock up or otherwise trigger Denial-of-Service situations on the system. It is hence recommended to restrict access to realtime scheduling to the few programs that actually require them. Defaults to off. Optional. Type boolean.

KillMode

Specifies how processes of this unit shall be killed. One of control-group, process, mixed, none.

If set to control-group, all remaining processes in the control group of this unit will be killed on unit stop (for services: after the stop command is executed, as configured with ExecStop). If set to process, only the main process itself is killed. If set to mixed, the SIGTERM signal (see below) is sent to the main process while the subsequent SIGKILL signal (see below) is sent to all remaining processes of the unit's control group. If set to none, no process is killed. In this case, only the stop command will be executed on unit stop, but no process be killed otherwise. Processes remaining alive after stop are left in their control group and the control group continues to exist after stop unless it is empty.

Processes will first be terminated via SIGTERM (unless the signal to send is changed via KillSignal). Optionally, this is immediately followed by a SIGHUP (if enabled with SendSIGHUP). If then, after a delay (configured via the TimeoutStopSec option), processes still remain, the termination request is repeated with the SIGKILL signal (unless this is disabled via the SendSIGKILL option). See kill(2) for more information.

Defaults to control-group. Optional. Type uniline.

KillSignal

Specifies which signal to use when killing a service. This controls the signal that is sent as first step of shutting down a unit (see above), and is usually followed by SIGKILL (see above and below). For a list of valid signals, see signal(7). Defaults to SIGTERM.

Note that, right after sending the signal specified in this setting, systemd will always send SIGCONT, to ensure that even suspended tasks can be terminated cleanly. Optional. Type uniline.

SendSIGHUP

Specifies whether to send SIGHUP to remaining processes immediately after sending the signal configured with KillSignal. This is useful to indicate to shells and shell-like programs that their connection has been severed. Takes a boolean value. Defaults to "no". Optional. Type boolean.

SendSIGKILL

Specifies whether to send SIGKILL to remaining processes after a timeout, if the normal shutdown procedure left processes of the service around. Takes a boolean value. Defaults to "yes". Optional. Type boolean.

Type

Configures the process start-up type for this service unit. One of simple, forking, oneshot, dbus, notify or idle.

If set to simple (the default if neither Type nor BusName, but ExecStart are specified), it is expected that the process configured with ExecStart is the main process of the service. In this mode, if the process offers functionality to other processes on the system, its communication channels should be installed before the daemon is started up (e.g. sockets set up by systemd, via socket activation), as systemd will immediately proceed starting follow-up units.

If set to forking, it is expected that the process configured with ExecStart will call fork() as part of its start-up. The parent process is expected to exit when start-up is complete and all communication channels are set up. The child continues to run as the main daemon process. This is the behavior of traditional UNIX daemons. If this setting is used, it is recommended to also use the PIDFile option, so that systemd can identify the main process of the daemon. systemd will proceed with starting follow-up units as soon as the parent process exits.

Behavior of oneshot is similar to simple; however, it is expected that the process has to exit before systemd starts follow-up units. RemainAfterExit is particularly useful for this type of service. This is the implied default if neither Type nor ExecStart are specified.

Behavior of dbus is similar to simple; however, it is expected that the daemon acquires a name on the D-Bus bus, as configured by BusName. systemd will proceed with starting follow-up units after the D-Bus bus name has been acquired. Service units with this option configured implicitly gain dependencies on the dbus.socket unit. This type is the default if BusName is specified.

Behavior of notify is similar to simple; however, it is expected that the daemon sends a notification message via sd_notify(3) or an equivalent call when it has finished starting up. systemd will proceed with starting follow-up units after this notification message has been sent. If this option is used, NotifyAccess (see below) should be set to open access to the notification socket provided by systemd. If NotifyAccess is missing or set to none, it will be forcibly set to main. Note that currently Typenotify will not work if used in combination with PrivateNetworkyes.

Behavior of idle is very similar to simple; however, actual execution of the service binary is delayed until all active jobs are dispatched. This may be used to avoid interleaving of output of shell services with the status output on the console. Note that this type is useful only to improve console output, it is not useful as a general unit ordering tool, and the effect of this service type is subject to a 5s time-out, after which the service binary is invoked anyway. Optional. Type uniline.

RemainAfterExit

Takes a boolean value that specifies whether the service shall be considered active even when all its processes exited. Defaults to no. Optional. Type boolean.

GuessMainPID

Takes a boolean value that specifies whether systemd should try to guess the main PID of a service if it cannot be determined reliably. This option is ignored unless Type=forking is set and PIDFile is unset because for the other types or with an explicitly configured PID file, the main PID is always known. The guessing algorithm might come to incorrect conclusions if a daemon consists of more than one process. If the main PID cannot be determined, failure detection and automatic restarting of a service will not work reliably. Defaults to yes. Optional. Type boolean.

PIDFile

Takes an absolute file name pointing to the PID file of this daemon. Use of this option is recommended for services where Type is set to forking. systemd will read the PID of the main process of the daemon after start-up of the service. systemd will not write to the file configured here, although it will remove the file after the service has shut down if it still exists. Optional. Type uniline.

BusName

Takes a D-Bus bus name that this service is reachable as. This option is mandatory for services where Type is set to dbus. Optional. Type uniline.

ExecStart

Commands with their arguments that are executed when this service is started. The value is split into zero or more command lines according to the rules described below (see section "Command Lines" below).

Unless Type is oneshot, exactly one command must be given. When Type=oneshot is used, zero or more commands may be specified. Commands may be specified by providing multiple command lines in the same directive, or alternatively, this directive may be specified more than once with the same effect. If the empty string is assigned to this option, the list of commands to start is reset, prior assignments of this option will have no effect. If no ExecStart is specified, then the service must have RemainAfterExit=yes and at least one ExecStop line set. (Services lacking both ExecStart and ExecStop are not valid.)

For each of the specified commands, the first argument must be an absolute path to an executable. Optionally, if this file name is prefixed with @, the second token will be passed as argv[0] to the executed process, followed by the further arguments specified. If the absolute filename is prefixed with -, an exit code of the command normally considered a failure (i.e. non-zero exit status or abnormal exit due to signal) is ignored and considered success. If the absolute path is prefixed with + then it is executed with full privileges. @, -, and + may be used together and they can appear in any order.

If more than one command is specified, the commands are invoked sequentially in the order they appear in the unit file. If one of the commands fails (and is not prefixed with -), other lines are not executed, and the unit is considered failed.

Unless Type=forking is set, the process started via this command line will be considered the main process of the daemon. Optional. Type list of uniline.

ExecStartPre

Additional commands that are executed before or after the command in ExecStart, respectively. Syntax is the same as for ExecStart, except that multiple command lines are allowed and the commands are executed one after the other, serially.

If any of those commands (not prefixed with -) fail, the rest are not executed and the unit is considered failed.

ExecStart commands are only run after all ExecStartPre commands that were not prefixed with a - exit successfully.

ExecStartPost commands are only run after the commands specified in ExecStart have been invoked successfully, as determined by Type (i.e. the process has been started for Type=simple or Type=idle, the last ExecStart process exited successfully for Type=oneshot, the initial process exited successfully for Type=forking, READY=1 is sent for Type=notify, or the BusName has been taken for Type=dbus).

Note that ExecStartPre may not be used to start long-running processes. All processes forked off by processes invoked via ExecStartPre will be killed before the next service process is run.

Note that if any of the commands specified in ExecStartPre, ExecStart, or ExecStartPost fail (and are not prefixed with -, see above) or time out before the service is fully up, execution continues with commands specified in ExecStopPost, the commands in ExecStop are skipped. Optional. Type list of uniline.

ExecStartPost

If any of those commands (not prefixed with -) fail, the rest are not executed and the unit is considered failed.

ExecStart commands are only run after all ExecStartPre commands that were not prefixed with a - exit successfully.

Note that ExecStartPre may not be used to start long-running processes. All processes forked off by processes invoked via ExecStartPre will be killed before the next service process is run.

ExecReload

Commands to execute to trigger a configuration reload in the service. This argument takes multiple command lines, following the same scheme as described for ExecStart above. Use of this setting is optional. Specifier and environment variable substitution is supported here following the same scheme as for ExecStart.

One additional, special environment variable is set: if known, $MAINPID is set to the main process of the daemon, and may be used for command lines like the following:

Note however that reloading a daemon by sending a signal (as with the example line above) is usually not a good choice, because this is an asynchronous operation and hence not suitable to order reloads of multiple services against each other. It is strongly recommended to set ExecReload to a command that not only triggers a configuration reload of the daemon, but also synchronously waits for it to complete. Optional. Type list of uniline.

ExecStop

Commands to execute to stop the service started via ExecStart. This argument takes multiple command lines, following the same scheme as described for ExecStart above. Use of this setting is optional. After the commands configured in this option are run, it is implied that the service is stopped, and any processes remaining for it are terminated according to the KillMode setting (see systemd.kill(5)). If this option is not specified, the process is terminated by sending the signal specified in KillSignal when service stop is requested. Specifier and environment variable substitution is supported (including $MAINPID, see above).

Note that it is usually not sufficient to specify a command for this setting that only asks the service to terminate (for example, by queuing some form of termination signal for it), but does not wait for it to do so. Since the remaining processes of the services are killed according to KillMode and KillSignal as described above immediately after the command exited, this may not result in a clean stop. The specified command should hence be a synchronous operation, not an asynchronous one.

Note that the commands specified in ExecStop are only executed when the service started successfully first. They are not invoked if the service was never started at all, or in case its start-up failed, for example because any of the commands specified in ExecStart, ExecStartPre or ExecStartPost failed (and weren't prefixed with -, see above) or timed out. Use ExecStopPost to invoke commands when a service failed to start up correctly and is shut down again.

It is recommended to use this setting for commands that communicate with the service requesting clean termination. When the commands specified with this option are executed it should be assumed that the service is still fully up and is able to react correctly to all commands. For post-mortem clean-up steps use ExecStopPost instead. Optional. Type list of uniline.

ExecStopPost

Additional commands that are executed after the service is stopped. This includes cases where the commands configured in ExecStop were used, where the service does not have any ExecStop defined, or where the service exited unexpectedly. This argument takes multiple command lines, following the same scheme as described for ExecStart. Use of these settings is optional. Specifier and environment variable substitution is supported. Note that – unlike ExecStop – commands specified with this setting are invoked when a service failed to start up correctly and is shut down again.

It is recommended to use this setting for clean-up operations that shall be executed even when the service failed to start up correctly. Commands configured with this setting need to be able to operate even if the service failed starting up half-way and left incompletely initialized data around. As the service's processes have been terminated already when the commands specified with this setting are executed they should not attempt to communicate with them.

Note that all commands that are configured with this setting are invoked with the result code of the service, as well as the main process' exit code and status, set in the $SERVICE_RESULT, $EXIT_CODE and $EXIT_STATUS environment variables, see systemd.exec(5) for details. Optional. Type list of uniline.

RestartSec

Configures the time to sleep before restarting a service (as configured with Restart). Takes a unit-less value in seconds, or a time span value such as "5min 20s". Defaults to 100ms. Optional. Type uniline.

TimeoutStartSec

Configures the time to wait for start-up. If a daemon service does not signal start-up completion within the configured time, the service will be considered failed and will be shut down again. Takes a unit-less value in seconds, or a time span value such as "5min 20s". Pass infinity to disable the timeout logic. Defaults to DefaultTimeoutStartSec from the manager configuration file, except when Type=oneshot is used, in which case the timeout is disabled by default (see systemd-system.conf(5)). Optional. Type uniline.

TimeoutStopSec

Configures the time to wait for stop. If a service is asked to stop, but does not terminate in the specified time, it will be terminated forcibly via SIGTERM, and after another timeout of equal duration with SIGKILL (see KillMode in systemd.kill(5)). Takes a unit-less value in seconds, or a time span value such as "5min 20s". Pass infinity to disable the timeout logic. Defaults to DefaultTimeoutStopSec from the manager configuration file (see systemd-system.conf(5)). Optional. Type uniline.

TimeoutSec

A shorthand for configuring both TimeoutStartSec and TimeoutStopSec to the specified value. Optional. Type uniline.

RuntimeMaxSec

Configures a maximum time for the service to run. If this is used and the service has been active for longer than the specified time it is terminated and put into a failure state. Note that this setting does not have any effect on Type=oneshot services, as they terminate immediately after activation completed. Pass infinity (the default) to configure no runtime limit. Optional. Type uniline.

WatchdogSec

Configures the watchdog timeout for a service. The watchdog is activated when the start-up is completed. The service must call sd_notify(3) regularly with WATCHDOG=1 (i.e. the "keep-alive ping"). If the time between two such calls is larger than the configured time, then the service is placed in a failed state and it will be terminated with SIGABRT. By setting Restart to on-failure, on-watchdog, on-abnormal or always, the service will be automatically restarted. The time configured here will be passed to the executed service process in the WATCHDOG_USEC environment variable. This allows daemons to automatically enable the keep-alive pinging logic if watchdog support is enabled for the service. If this option is used, NotifyAccess (see below) should be set to open access to the notification socket provided by systemd. If NotifyAccess is not set, it will be implicitly set to main. Defaults to 0, which disables this feature. The service can check whether the service manager expects watchdog keep-alive notifications. See sd_watchdog_enabled(3) for details. sd_event_set_watchdog(3) may be used to enable automatic watchdog notification support. Optional. Type uniline.

Restart

Configures whether the service shall be restarted when the service process exits, is killed, or a timeout is reached. The service process may be the main service process, but it may also be one of the processes specified with ExecStartPre, ExecStartPost, ExecStop, ExecStopPost, or ExecReload. When the death of the process is a result of systemd operation (e.g. service stop or restart), the service will not be restarted. Timeouts include missing the watchdog "keep-alive ping" deadline and a service start, reload, and stop operation timeouts.

Takes one of no, on-success, on-failure, on-abnormal, on-watchdog, on-abort, or always. If set to no (the default), the service will not be restarted. If set to on-success, it will be restarted only when the service process exits cleanly. In this context, a clean exit means an exit code of 0, or one of the signals SIGHUP, SIGINT, SIGTERM or SIGPIPE, and additionally, exit statuses and signals specified in SuccessExitStatus. If set to on-failure, the service will be restarted when the process exits with a non-zero exit code, is terminated by a signal (including on core dump, but excluding the aforementioned four signals), when an operation (such as service reload) times out, and when the configured watchdog timeout is triggered. If set to on-abnormal, the service will be restarted when the process is terminated by a signal (including on core dump, excluding the aforementioned four signals), when an operation times out, or when the watchdog timeout is triggered. If set to on-abort, the service will be restarted only if the service process exits due to an uncaught signal not specified as a clean exit status. If set to on-watchdog, the service will be restarted only if the watchdog timeout for the service expires. If set to always, the service will be restarted regardless of whether it exited cleanly or not, got terminated abnormally by a signal, or hit a timeout.

As exceptions to the setting above, the service will not be restarted if the exit code or signal is specified in RestartPreventExitStatus (see below) or the service is stopped with systemctl stop or an equivalent operation. Also, the services will always be restarted if the exit code or signal is specified in RestartForceExitStatus (see below).

Note that service restart is subject to unit start rate limiting configured with StartLimitIntervalSec and StartLimitBurst, see systemd.unit(5) for details.

Setting this to on-failure is the recommended choice for long-running services, in order to increase reliability by attempting automatic recovery from errors. For services that shall be able to terminate on their own choice (and avoid immediate restarting), on-abnormal is an alternative choice. Optional. Type enum. choice: 'no', 'on-success', 'on-failure', 'on-abnormal', 'on-watchdog', 'on-abort', 'always'.

SuccessExitStatus

Takes a list of exit status definitions that, when returned by the main service process, will be considered successful termination, in addition to the normal successful exit code 0 and the signals SIGHUP, SIGINT, SIGTERM, and SIGPIPE. Exit status definitions can either be numeric exit codes or termination signal names, separated by spaces. For example:

SuccessExitStatus=1 2 8 SIGKILL

ensures that exit codes 1, 2, 8 and the termination signal SIGKILL are considered clean service terminations.

Note that if a process has a signal handler installed and exits by calling _exit(2) in response to a signal, the information about the signal is lost. Programs should instead perform cleanup and kill themselves with the same signal instead. See Proper handling of SIGINT/SIGQUIT — How to be a proper program.

This option may appear more than once, in which case the list of successful exit statuses is merged. If the empty string is assigned to this option, the list is reset, all prior assignments of this option will have no effect. Optional. Type uniline.

RestartPreventExitStatus

Takes a list of exit status definitions that, when returned by the main service process, will prevent automatic service restarts, regardless of the restart setting configured with Restart. Exit status definitions can either be numeric exit codes or termination signal names, and are separated by spaces. Defaults to the empty list, so that, by default, no exit status is excluded from the configured restart logic. For example:

RestartPreventExitStatus=1 6 SIGABRT

ensures that exit codes 1 and 6 and the termination signal SIGABRT will not result in automatic service restarting. This option may appear more than once, in which case the list of restart-preventing statuses is merged. If the empty string is assigned to this option, the list is reset and all prior assignments of this option will have no effect. Optional. Type uniline.

RestartForceExitStatus

Takes a list of exit status definitions that, when returned by the main service process, will force automatic service restarts, regardless of the restart setting configured with Restart. The argument format is similar to RestartPreventExitStatus. Optional. Type uniline.

PermissionsStartOnly

Takes a boolean argument. If true, the permission-related execution options, as configured with User and similar options (see systemd.exec(5) for more information), are only applied to the process started with ExecStart, and not to the various other ExecStartPre, ExecStartPost, ExecReload, ExecStop, and ExecStopPost commands. If false, the setting is applied to all configured commands the same way. Defaults to false. Optional. Type boolean.

RootDirectoryStartOnly

Takes a boolean argument. If true, the root directory, as configured with the RootDirectory option (see systemd.exec(5) for more information), is only applied to the process started with ExecStart, and not to the various other ExecStartPre, ExecStartPost, ExecReload, ExecStop, and ExecStopPost commands. If false, the setting is applied to all configured commands the same way. Defaults to false. Optional. Type boolean.

NonBlocking

Set the O_NONBLOCK flag for all file descriptors passed via socket-based activation. If true, all file descriptors >= 3 (i.e. all except stdin, stdout, stderr), excluding those passed in via the file descriptor storage logic (see FileDescriptorStoreMax for details), will have the O_NONBLOCK flag set and hence are in non-blocking mode. This option is only useful in conjunction with a socket unit, as described in systemd.socket(5) and has no effect on file descriptors which were previously saved in the file-descriptor store for example. Defaults to false. Optional. Type uniline.

NotifyAccess

Controls access to the service status notification socket, as accessible via the sd_notify(3) call. Takes one of none (the default), main, exec or all. If none, no daemon status updates are accepted from the service processes, all status update messages are ignored. If main, only service updates sent from the main process of the service are accepted. If exec, only service updates sent from any of the main or control processes originating from one of the Exec*= commands are accepted. If all, all services updates from all members of the service's control group are accepted. This option should be set to open access to the notification socket when using Type=notify or WatchdogSec (see above). If those options are used but NotifyAccess is not configured, it will be implicitly set to main.

Note that sd_notify() notifications may be attributed to units correctly only if either the sending process is still around at the time PID 1 processes the message, or if the sending process is explicitly runtime-tracked by the service manager. The latter is the case if the service manager originally forked off the process, i.e. on all processes that match main or exec. Conversely, if an auxiliary process of the unit sends an sd_notify() message and immediately exits, the service manager might not be able to properly attribute the message to the unit, and thus will ignore it, even if NotifyAccessall is set for it. Optional. Type enum. choice: 'none', 'main', 'exec', 'all'.

Sockets

Specifies the name of the socket units this service shall inherit socket file descriptors from when the service is started. Normally, it should not be necessary to use this setting, as all socket file descriptors whose unit shares the same name as the service (subject to the different unit name suffix of course) are passed to the spawned process.

Note that the same socket file descriptors may be passed to multiple processes simultaneously. Also note that a different service may be activated on incoming socket traffic than the one which is ultimately configured to inherit the socket file descriptors. Or, in other words: the Service setting of .socket units does not have to match the inverse of the Sockets setting of the .service it refers to.

This option may appear more than once, in which case the list of socket units is merged. If the empty string is assigned to this option, the list of sockets is reset, and all prior uses of this setting will have no effect. Optional. Type uniline.

FailureAction

Configure the action to take when the service enters a failed state. Takes the same values as the unit setting StartLimitAction and executes the same actions (see systemd.unit(5)). Defaults to none. Optional. Type uniline.

FileDescriptorStoreMax

Configure how many file descriptors may be stored in the service manager for the service using sd_pid_notify_with_fds(3)'s FDSTORE=1 messages. This is useful for implementing services that can restart after an explicit request or a crash without losing state. Any open sockets and other file descriptors which should not be closed during the restart may be stored this way. Application state can either be serialized to a file in /run, or better, stored in a memfd_create(2) memory file descriptor. Defaults to 0, i.e. no file descriptors may be stored in the service manager. All file descriptors passed to the service manager from a specific service are passed back to the service's main process on the next service restart. Any file descriptors passed to the service manager are automatically closed when POLLHUP or POLLERR is seen on them, or when the service is fully stopped and no job is queued or being executed for it. Optional. Type uniline.

USBFunctionDescriptors

Configure the location of a file containing USB FunctionFS descriptors, for implementation of USB gadget functions. This is used only in conjunction with a socket unit with ListenUSBFunction configured. The contents of this file are written to the ep0 file after it is opened. Optional. Type uniline.

USBFunctionStrings

Configure the location of a file containing USB FunctionFS strings. Behavior is similar to USBFunctionDescriptors above. Optional. Type uniline.

COPYRIGHT

2010-2016 Lennart Poettering and others
2016 Dominique Dumont

LICENSE

LGPLv2.1+

To install Config::Model::Systemd, copy and paste the appropriate command in to your terminal.

cpanm

cpanm Config::Model::Systemd

CPAN shell

perl -MCPAN -e shell
install Config::Model::Systemd

For more information on module installation, please visit the detailed CPAN module installation guide.

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