systemd.exec(5) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | IMPLICIT DEPENDENCIES | PATHS | USER/GROUP IDENTITY | CAPABILITIES | SECURITY | MANDATORY ACCESS CONTROL | PROCESS PROPERTIES | SCHEDULING | SANDBOXING | SYSTEM CALL FILTERING | ENVIRONMENT | LOGGING AND STANDARD INPUT/OUTPUT | CREDENTIALS | SYSTEM V COMPATIBILITY | ENVIRONMENT VARIABLES IN SPAWNED PROCESSES | PROCESS EXIT CODES | SEE ALSO | NOTES | COLOPHON

SYSTEMD.EXEC(5)               systemd.exec               SYSTEMD.EXEC(5)

NAME         top

       systemd.exec - Execution environment configuration

SYNOPSIS         top

       service.service, socket.socket, mount.mount, swap.swap

DESCRIPTION         top

       Unit configuration files for services, sockets, mount points, and
       swap devices share a subset of configuration options which define
       the execution environment of spawned processes.

       This man page lists the configuration options shared by these
       four unit types. See systemd.unit(5) for the common options of
       all unit configuration files, and systemd.service(5),
       systemd.socket(5), systemd.swap(5), and systemd.mount(5) for more
       information on the specific unit configuration files. The
       execution specific configuration options are configured in the
       [Service], [Socket], [Mount], or [Swap] sections, depending on
       the unit type.

       In addition, options which control resources through Linux
       Control Groups (cgroups) are listed in
       systemd.resource-control(5). Those options complement options
       listed here.

IMPLICIT DEPENDENCIES         top

       A few execution parameters result in additional, automatic
       dependencies to be added:

       •   Units with WorkingDirectory=, RootDirectory=, RootImage=,
           RuntimeDirectory=, StateDirectory=, CacheDirectory=,
           LogsDirectory= or ConfigurationDirectory= set automatically
           gain dependencies of type Requires= and After= on all mount
           units required to access the specified paths. This is
           equivalent to having them listed explicitly in
           RequiresMountsFor=.

       •   Similarly, units with PrivateTmp= enabled automatically get
           mount unit dependencies for all mounts required to access
           /tmp/ and /var/tmp/. They will also gain an automatic After=
           dependency on systemd-tmpfiles-setup.service(8).

       •   Units whose standard output or error output is connected to
           journal or kmsg (or their combinations with console output,
           see below) automatically acquire dependencies of type After=
           on systemd-journald.socket.

       •   Units using LogNamespace= will automatically gain ordering
           and requirement dependencies on the two socket units
           associated with systemd-journald@.service instances.

PATHS         top

       The following settings may be used to change a service's view of
       the filesystem. Please note that the paths must be absolute and
       must not contain a ".."  path component.

       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).

       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.

           If RootDirectory=/RootImage= are used together with
           NotifyAccess= the notification socket is automatically
           mounted from the host into the root environment, to ensure
           the notification interface can work correctly.

           Note that services using RootDirectory=/RootImage= will not
           be able to log via the syslog or journal protocols to the
           host logging infrastructure, unless the relevant sockets are
           mounted from the host, specifically:

           Example 1. Mounting logging sockets into root environment

               BindReadOnlyPaths=/dev/log /run/systemd/journal/socket /run/systemd/journal/stdout

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       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[1].

           When DevicePolicy= is set to "closed" or "strict", or set to
           "auto" and DeviceAllow= is set, then this setting adds
           /dev/loop-control with rw mode, "block-loop" and
           "block-blkext" with rwm mode to DeviceAllow=. See
           systemd.resource-control(5) for the details about
           DevicePolicy= or DeviceAllow=. Also, see PrivateDevices=
           below, as it may change the setting of DevicePolicy=.

           Units making use of RootImage= automatically gain an After=
           dependency on systemd-udevd.service.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       RootImageOptions=
           Takes a comma-separated list of mount options that will be
           used on disk images specified by RootImage=. Optionally a
           partition name can be prefixed, followed by colon, in case
           the image has multiple partitions, otherwise partition name
           "root" is implied. Options for multiple partitions can be
           specified in a single line with space separators. Assigning
           an empty string removes previous assignments. Duplicated
           options are ignored. For a list of valid mount options,
           please refer to mount(8).

           Valid partition names follow the Discoverable Partitions
           Specification[1]: root, usr, home, srv, esp, xbootldr, tmp,
           var.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       RootHash=
           Takes a data integrity (dm-verity) root hash specified in
           hexadecimal, or the path to a file containing a root hash in
           ASCII hexadecimal format. This option enables data integrity
           checks using dm-verity, if the used image contains the
           appropriate integrity data (see above) or if RootVerity= is
           used. The specified hash must match the root hash of
           integrity data, and is usually at least 256 bits (and hence
           64 formatted hexadecimal characters) long (in case of SHA256
           for example). If this option is not specified, but the image
           file carries the "user.verity.roothash" extended file
           attribute (see xattr(7)), then the root hash is read from it,
           also as formatted hexadecimal characters. If the extended
           file attribute is not found (or is not supported by the
           underlying file system), but a file with the .roothash suffix
           is found next to the image file, bearing otherwise the same
           name (except if the image has the .raw suffix, in which case
           the root hash file must not have it in its name), the root
           hash is read from it and automatically used, also as
           formatted hexadecimal characters.

           If the disk image contains a separate /usr/ partition it may
           also be Verity protected, in which case the root hash may
           configured via an extended attribute "user.verity.usrhash" or
           a .usrhash file adjacent to the disk image. There's currently
           no option to configure the root hash for the /usr/ file
           system via the unit file directly.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       RootHashSignature=
           Takes a PKCS7 signature of the RootHash= option as a path to
           a DER-encoded signature file, or as an ASCII base64 string
           encoding of a DER-encoded signature prefixed by "base64:".
           The dm-verity volume will only be opened if the signature of
           the root hash is valid and signed by a public key present in
           the kernel keyring. If this option is not specified, but a
           file with the .roothash.p7s suffix is found next to the image
           file, bearing otherwise the same name (except if the image
           has the .raw suffix, in which case the signature file must
           not have it in its name), the signature is read from it and
           automatically used.

           If the disk image contains a separate /usr/ partition it may
           also be Verity protected, in which case the signature for the
           root hash may configured via a .usrhash.p7s file adjacent to
           the disk image. There's currently no option to configure the
           root hash signature for the /usr/ via the unit file directly.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       RootVerity=
           Takes the path to a data integrity (dm-verity) file. This
           option enables data integrity checks using dm-verity, if
           RootImage= is used and a root-hash is passed and if the used
           image itself does not contains the integrity data. The
           integrity data must be matched by the root hash. If this
           option is not specified, but a file with the .verity suffix
           is found next to the image file, bearing otherwise the same
           name (except if the image has the .raw suffix, in which case
           the verity data file must not have it in its name), the
           verity data is read from it and automatically used.

           This option is supported only for disk images that contain a
           single file system, without an enveloping partition table.
           Images that contain a GPT partition table should instead
           include both root file system and matching Verity data in the
           same image, implementing the Discoverable Partitions
           Specification[1].

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       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/, /dev/ and /run/ (as an empty "tmpfs") 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 four 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 four 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=.

           In order to allow propagating mounts at runtime in a safe
           manner, /run/systemd/propagate on the host will be used to
           set up new mounts, and /run/host/incoming/ in the private
           namespace will be used as an intermediate step to store them
           before being moved to the final mount point.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       ProtectProc=
           Takes one of "noaccess", "invisible", "ptraceable" or
           "default" (which it defaults to). When set, this controls the
           "hidepid=" mount option of the "procfs" instance for the unit
           that controls which directories with process metainformation
           (/proc/PID) are visible and accessible: when set to
           "noaccess" the ability to access most of other users' process
           metadata in /proc/ is taken away for processes of the
           service. When set to "invisible" processes owned by other
           users are hidden from /proc/. If "ptraceable" all processes
           that cannot be ptrace()'ed by a process are hidden to it. If
           "default" no restrictions on /proc/ access or visibility are
           made. For further details see The /proc Filesystem[2]. It is
           generally recommended to run most system services with this
           option set to "invisible". This option is implemented via
           file system namespacing, and thus cannot be used with
           services that shall be able to install mount points in the
           host file system hierarchy. Note that the root user is
           unaffected by this option, so to be effective it has to be
           used together with User= or DynamicUser=yes, and also without
           the "CAP_SYS_PTRACE" capability, which also allows a process
           to bypass this feature. It cannot be used for services that
           need to access metainformation about other users' processes.
           This option implies MountAPIVFS=.

           If the kernel doesn't support per-mount point hidepid= mount
           options this setting remains without effect, and the unit's
           processes will be able to access and see other process as if
           the option was not used.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       ProcSubset=
           Takes one of "all" (the default) and "pid". If "pid", all
           files and directories not directly associated with process
           management and introspection are made invisible in the /proc/
           file system configured for the unit's processes. This
           controls the "subset=" mount option of the "procfs" instance
           for the unit. For further details see The /proc
           Filesystem[2]. Note that Linux exposes various kernel APIs
           via /proc/, which are made unavailable with this setting.
           Since these APIs are used frequently this option is useful
           only in a few, specific cases, and is not suitable for most
           non-trivial programs.

           Much like ProtectProc= above, this is implemented via file
           system mount namespacing, and hence the same restrictions
           apply: it is only available to system services, it disables
           mount propagation to the host mount table, and it implies
           MountAPIVFS=. Also, like ProtectProc= this setting is
           gracefully disabled if the used kernel does not support the
           "subset=" mount option of "procfs".

       BindPaths=, BindReadOnlyPaths=
           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. Each
           bind mount definition may be prefixed with "-", in which case
           it will be ignored when its source path does not exist.

           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.

           Note that the destination directory must exist or systemd
           must be able to create it. Thus, it is not possible to use
           those options for mount points nested underneath paths
           specified in InaccessiblePaths=, or under /home/ and other
           protected directories if ProtectHome=yes is specified.
           TemporaryFileSystem= with ":ro" or ProtectHome=tmpfs should
           be used instead.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       MountImages=
           This setting is similar to RootImage= in that it mounts a
           file system hierarchy from a block device node or loopback
           file, but the destination directory can be specified as well
           as mount options. This option expects a whitespace separated
           list of mount definitions. Each definition consists of a
           colon-separated tuple of source path and destination
           definitions, optionally followed by another colon and a list
           of mount options.

           Mount options may be defined as a single comma-separated list
           of options, in which case they will be implicitly applied to
           the root partition on the image, or a series of
           colon-separated tuples of partition name and mount options.
           Valid partition names and mount options are the same as for
           RootImageOptions= setting described above.

           Each mount definition may be prefixed with "-", in which case
           it will be ignored when its source path does not exist. The
           source argument is a path to a block device node or regular
           file. If source or destination contain a ":", it needs to be
           escaped as "\:". The device node or file system image file
           needs to follow the same rules as specified for RootImage=.
           Any mounts created with this option are specific to the unit,
           and are not visible in the host's mount table.

           These settings may be used more than once, each usage appends
           to the unit's list of mount paths. If the empty string is
           assigned, the entire list of mount paths defined prior to
           this is reset.

           Note that the destination directory must exist or systemd
           must be able to create it. Thus, it is not possible to use
           those options for mount points nested underneath paths
           specified in InaccessiblePaths=, or under /home/ and other
           protected directories if ProtectHome=yes is specified.

           When DevicePolicy= is set to "closed" or "strict", or set to
           "auto" and DeviceAllow= is set, then this setting adds
           /dev/loop-control with rw mode, "block-loop" and
           "block-blkext" with rwm mode to DeviceAllow=. See
           systemd.resource-control(5) for the details about
           DevicePolicy= or DeviceAllow=. Also, see PrivateDevices=
           below, as it may change the setting of DevicePolicy=.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       ExtensionImages=
           This setting is similar to MountImages= in that it mounts a
           file system hierarchy from a block device node or loopback
           file, but instead of providing a destination path, an overlay
           will be set up. This option expects a whitespace separated
           list of mount definitions. Each definition consists of a
           source path, optionally followed by a colon and a list of
           mount options.

           A read-only OverlayFS will be set up on top of /usr/ and
           /opt/ hierarchies. The order in which the images are listed
           will determine the order in which the overlay is laid down:
           images specified first to last will result in overlayfs
           layers bottom to top.

           Mount options may be defined as a single comma-separated list
           of options, in which case they will be implicitly applied to
           the root partition on the image, or a series of
           colon-separated tuples of partition name and mount options.
           Valid partition names and mount options are the same as for
           RootImageOptions= setting described above.

           Each mount definition may be prefixed with "-", in which case
           it will be ignored when its source path does not exist. The
           source argument is a path to a block device node or regular
           file. If the source path contains a ":", it needs to be
           escaped as "\:". The device node or file system image file
           needs to follow the same rules as specified for RootImage=.
           Any mounts created with this option are specific to the unit,
           and are not visible in the host's mount table.

           These settings may be used more than once, each usage appends
           to the unit's list of image paths. If the empty string is
           assigned, the entire list of mount paths defined prior to
           this is reset.

           Each image must carry a
           /usr/lib/extension-release.d/extension-release.IMAGE file,
           with the appropriate metadata which matches
           RootImage=/RootDirectory= or the host. See: os-release(5).

           When DevicePolicy= is set to "closed" or "strict", or set to
           "auto" and DeviceAllow= is set, then this setting adds
           /dev/loop-control with rw mode, "block-loop" and
           "block-blkext" with rwm mode to DeviceAllow=. See
           systemd.resource-control(5) for the details about
           DevicePolicy= or DeviceAllow=. Also, see PrivateDevices=
           below, as it may change the setting of DevicePolicy=.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

USER/GROUP IDENTITY         top

       These options are only available for system services and are not
       supported for services running in per-user instances of the
       service manager.

       User=, Group=
           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 this enforces only weak restrictions on the
           user/group name syntax, but will generate warnings in many
           cases where user/group names do not adhere to the following
           rules: the specified name should 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 and "_" (i.e. digits
           and "-" are not permitted as first character). The user/group
           name must have at least one character, and at most 31. These
           restrictions are made in order to avoid ambiguities and to
           ensure user/group names and unit files remain portable among
           Linux systems. For further details on the names accepted and
           the names warned about see User/Group Name Syntax[3].

           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. If the user does not exist by then
           program invocation will fail.

           If the User= setting is used the supplementary group list is
           initialized from the specified user's default group list, as
           defined in the system's user and group database. Additional
           groups may be configured through the SupplementaryGroups=
           setting (see below).

       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. Note that if User= is
           specified and the static group with the name exists, then it
           is required that the static user with the name already
           exists. Similarly, if Group= is specified and the static user
           with the name exists, then it is required that the static
           group with the name already exists. 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=
           and PrivateTmp= are implied (and cannot be turned off). 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. Furthermore
           NoNewPrivileges= and RestrictSUIDSGID= are implicitly enabled
           (and cannot be disabled), to ensure that processes invoked
           cannot take benefit or create SUID/SGID files or directories.
           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 allow-listed 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. Use StateDirectory=,
           CacheDirectory= and LogsDirectory= in order to assign a set
           of writable directories for specific purposes to the service
           in a way that they are protected from vulnerabilities due to
           UID reuse (see below). If this option is enabled, care should
           be taken that the unit's processes do not get access to
           directories outside of these explicitly configured and
           managed ones. Specifically, do not use BindPaths= and be
           careful with AF_UNIX file descriptor passing for directory
           file descriptors, as this would permit processes to create
           files or directories owned by the dynamic user/group that are
           not subject to the lifecycle and access guarantees of the
           service. Defaults to off.

       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 "+".

       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.

           Note that when this option is used for a unit it is very
           likely (depending on PAM configuration) that the main unit
           process will be migrated to its own session scope unit when
           it is activated. This process will hence be associated with
           two units: the unit it was originally started from (and for
           which PAMName= was configured), and the session scope unit.
           Any child processes of that process will however be
           associated with the session scope unit only. This has
           implications when used in combination with NotifyAccess=all,
           as these child processes will not be able to affect changes
           in the original unit through notification messages. These
           messages will be considered belonging to the session scope
           unit and not the original unit. It is hence not recommended
           to use PAMName= in combination with NotifyAccess=all.

CAPABILITIES         top

       These options are only available for system services and are not
       supported for services running in per-user instances of the
       service manager.

       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 by OR, or by AND
           if the lines are prefixed with "~" (see below). 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 "+".

           Use systemd-analyze(1)'s capability command to retrieve a
           list of capabilities defined on the local system.

           Example: if a unit has the following,

               CapabilityBoundingSet=CAP_A CAP_B
               CapabilityBoundingSet=CAP_B CAP_C

           then CAP_A, CAP_B, and CAP_C are set. If the second line is
           prefixed with "~", e.g.,

               CapabilityBoundingSet=CAP_A CAP_B
               CapabilityBoundingSet=~CAP_B CAP_C

           then, only CAP_A is set.

       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 (see the above examples in
           CapabilityBoundingSet=). 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 keep-caps is
           automatically added to SecureBits= to retain the capabilities
           over the user change.  AmbientCapabilities= does not affect
           commands prefixed with "+".

SECURITY         top

       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 override this and ignore the value of this
           setting. This is the case when DynamicUser=,
           LockPersonality=, MemoryDenyWriteExecute=, PrivateDevices=,
           ProtectClock=, ProtectHostname=, ProtectKernelLogs=,
           ProtectKernelModules=, ProtectKernelTunables=,
           RestrictAddressFamilies=, RestrictNamespaces=,
           RestrictRealtime=, RestrictSUIDSGID=,
           SystemCallArchitectures=, SystemCallFilter=, or
           SystemCallLog= are specified. Note that even if this setting
           is overridden by them, systemctl show shows the original
           value of this setting. In case the service will be run in a
           new mount namespace anyway and SELinux is disabled, all file
           systems are mounted with MS_NOSUID flag. Also see No New
           Privileges Flag[4].

       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.

MANDATORY ACCESS CONTROL         top

       These options are only available for system services and are not
       supported for services running in per-user instances of the
       service manager.

       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.

       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. If
           prefixed by "-", all errors will be ignored. This setting has
           no effect if AppArmor is not enabled. This setting does not
           affect commands prefixed with "+".

       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 "+".

PROCESS PROPERTIES         top

       LimitCPU=, LimitFSIZE=, LimitDATA=, LimitSTACK=, LimitCORE=,
       LimitRSS=, LimitNOFILE=, LimitAS=, LimitNPROC=, LimitMEMLOCK=,
       LimitLOCKS=, LimitSIGPENDING=, LimitMSGQUEUE=, LimitNICE=,
       LimitRTPRIO=, LimitRTTIME=
           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,
           MemoryMax= is a more powerful (and working) replacement for
           LimitRSS=.

           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 below).

           For system units these resource limits may be chosen freely.
           When these settings are configured in a user service (i.e. a
           service run by the per-user instance of the service manager)
           they cannot be used to raise the limits above those set for
           the user manager itself when it was first invoked, as the
           user's service manager generally lacks the privileges to do
           so. In user context these configuration options are hence
           only useful to lower the limits passed in or to raise the
           soft limit to the maximum of the hard limit as configured for
           the user. To raise the user's limits further, the available
           configuration mechanisms differ between operating systems,
           but typically require privileges. In most cases it is
           possible to configure higher per-user resource limits via PAM
           or by setting limits on the system service encapsulating the
           user's service manager, i.e. the user's instance of
           user@.service. After making such changes, make sure to
           restart the user's service manager.

           Table 1. Resource limit directives, their equivalent ulimit
           shell commands and the unit used
           ┌─────────────────┬───────────────────┬───────────────────┐
           │Directive        ulimit equivalent │ Unit              │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitCPU=        │ ulimit -t         │ Seconds           │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitFSIZE=      │ ulimit -f         │ Bytes             │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitDATA=       │ ulimit -d         │ Bytes             │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitSTACK=      │ ulimit -s         │ Bytes             │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitCORE=       │ ulimit -c         │ Bytes             │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitRSS=        │ ulimit -m         │ Bytes             │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitNOFILE=     │ ulimit -n         │ Number of File    │
           │                 │                   │ Descriptors       │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitAS=         │ ulimit -v         │ Bytes             │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitNPROC=      │ ulimit -u         │ Number of         │
           │                 │                   │ Processes         │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitMEMLOCK=    │ ulimit -l         │ Bytes             │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitLOCKS=      │ ulimit -x         │ Number of Locks   │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitSIGPENDING= │ ulimit -i         │ Number of Queued  │
           │                 │                   │ Signals           │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitMSGQUEUE=   │ ulimit -q         │ Bytes             │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitNICE=       │ ulimit -e         │ Nice Level        │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitRTPRIO=     │ ulimit -r         │ Realtime Priority │
           ├─────────────────┼───────────────────┼───────────────────┤
           │LimitRTTIME=     │ No equivalent     │ Microseconds      │
           └─────────────────┴───────────────────┴───────────────────┘

       UMask=
           Controls the file mode creation mask. Takes an access mode in
           octal notation. See umask(2) for details. Defaults to 0022
           for system units. For user units the default value is
           inherited from the per-user service manager (whose default is
           in turn inherited from the system service manager, and thus
           typically also is 0022 — unless overridden by a PAM module).
           In order to change the per-user mask for all user services,
           consider setting the UMask= setting of the user's
           user@.service system service instance. The per-user umask may
           also be set via the umask field of a user's JSON User
           Record[5] (for users managed by systemd-homed.service(8) this
           field may be controlled via homectl --umask=). It may also be
           set via a PAM module, such as pam_umask(8).

       CoredumpFilter=
           Controls which types of memory mappings will be saved if the
           process dumps core (using the /proc/pid/coredump_filter
           file). Takes a whitespace-separated combination of mapping
           type names or numbers (with the default base 16). Mapping
           type names are private-anonymous, shared-anonymous,
           private-file-backed, shared-file-backed, elf-headers,
           private-huge, shared-huge, private-dax, shared-dax, and the
           special values all (all types) and default (the kernel
           default of "private-anonymous shared-anonymous elf-headers
           private-huge"). See core(5) for the meaning of the mapping
           types. When specified multiple times, all specified masks are
           ORed. When not set, or if the empty value is assigned, the
           inherited value is not changed.

           Example 2. Add DAX pages to the dump filter

               CoredumpFilter=default private-dax shared-dax

       KeyringMode=
           Controls how the kernel session keyring is set up for the
           service (see session-keyring(7) for details on the session
           keyring). Takes one of inherit, private, shared. If set to
           inherit no special keyring setup is done, and the kernel's
           default behaviour is applied. If private is used a new
           session keyring is allocated when a service process is
           invoked, and it is not linked up with any user keyring. This
           is the recommended setting for system services, as this
           ensures that multiple services running under the same system
           user ID (in particular the root user) do not share their key
           material among each other. If shared is used a new session
           keyring is allocated as for private, but the user keyring of
           the user configured with User= is linked into it, so that
           keys assigned to the user may be requested by the unit's
           processes. In this modes multiple units running processes
           under the same user ID may share key material. Unless inherit
           is selected the unique invocation ID for the unit (see below)
           is added as a protected key by the name "invocation_id" to
           the newly created session keyring. Defaults to private for
           services of the system service manager and to inherit for
           non-service units and for services of the user service
           manager.

       OOMScoreAdjust=
           Sets the adjustment value for the Linux kernel's
           Out-Of-Memory (OOM) killer score for executed processes.
           Takes an integer between -1000 (to disable OOM killing of
           processes of this unit) and 1000 (to make killing of
           processes of this unit under memory pressure very likely).
           See proc.txt[6] for details. If not specified defaults to the
           OOM score adjustment level of the service manager itself,
           which is normally at 0.

           Use the OOMPolicy= setting of service units to configure how
           the service manager shall react to the kernel OOM killer
           terminating a process of the service. See systemd.service(5)
           for details.

       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.

       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.

       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.

SCHEDULING         top

       Nice=
           Sets the default nice level (scheduling priority) for
           executed processes. Takes an integer between -20 (highest
           priority) and 19 (lowest priority). In case of resource
           contention, smaller values mean more resources will be made
           available to the unit's processes, larger values mean less
           resources will be made available. See setpriority(2) for
           details.

       CPUSchedulingPolicy=
           Sets the CPU scheduling policy for executed processes. Takes
           one of other, batch, idle, fifo or rr. See
           sched_setscheduler(2) for details.

       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. In case of CPU resource
           contention, smaller values mean less CPU time is made
           available to the service, larger values mean more. See
           sched_setscheduler(2) for details.

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

       CPUAffinity=
           Controls the CPU affinity of the executed processes. Takes a
           list of CPU indices or ranges separated by either whitespace
           or commas. Alternatively, takes a special "numa" value in
           which case systemd automatically derives allowed CPU range
           based on the value of NUMAMask= option. 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.

       NUMAPolicy=
           Controls the NUMA memory policy of the executed processes.
           Takes a policy type, one of: default, preferred, bind,
           interleave and local. A list of NUMA nodes that should be
           associated with the policy must be specified in NUMAMask=.
           For more details on each policy please see, set_mempolicy(2).
           For overall overview of NUMA support in Linux see, numa(7).

       NUMAMask=
           Controls the NUMA node list which will be applied alongside
           with selected NUMA policy. Takes a list of NUMA nodes and has
           the same syntax as a list of CPUs for CPUAffinity= option or
           special "all" value which will include all available NUMA
           nodes in the mask. Note that the list of NUMA nodes is not
           required for default and local policies and for preferred
           policy we expect a single NUMA node.

       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. If the empty string is
           assigned to this option, all prior assignments to both
           IOSchedulingClass= and IOSchedulingPriority= have no effect.
           See ioprio_set(2) for details.

       IOSchedulingPriority=
           Sets the I/O scheduling priority for executed processes.
           Takes an integer between 0 (highest priority) and 7 (lowest
           priority). In case of I/O contention, smaller values mean
           more I/O bandwidth is made available to the unit's processes,
           larger values mean less bandwidth. The available priorities
           depend on the selected I/O scheduling class (see above). If
           the empty string is assigned to this option, all prior
           assignments to both IOSchedulingClass= and
           IOSchedulingPriority= have no effect. See ioprio_set(2) for
           details.

SANDBOXING         top

       The following sandboxing options are an effective way to limit
       the exposure of the system towards the unit's processes. It is
       recommended to turn on as many of these options for each unit as
       is possible without negatively affecting the process' ability to
       operate. Note that many of these sandboxing features are
       gracefully turned off on systems where the underlying security
       mechanism is not available. For example, ProtectSystem= has no
       effect if the kernel is built without file system namespacing or
       if the service manager runs in a container manager that makes
       file system namespacing unavailable to its payload. Similar,
       RestrictRealtime= has no effect on systems that lack support for
       SECCOMP system call filtering, or in containers where support for
       this is turned off.

       Also note that some sandboxing functionality is generally not
       available in user services (i.e. services run by the per-user
       service manager). Specifically, the various settings requiring
       file system namespacing support (such as ProtectSystem=) are not
       available, as the underlying kernel functionality is only
       accessible to privileged processes. However, most namespacing
       settings, that will not work on their own in user services, will
       work when used in conjunction with PrivateUsers=true.

       ProtectSystem=
           Takes a boolean argument or the special values "full" or
           "strict". If true, mounts the /usr/ and the boot loader
           directories (/boot and /efi) 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.
           This setting cannot ensure protection in all cases. In
           general it has the same limitations as ReadOnlyPaths=, see
           below. Defaults to off.

       ProtectHome=
           Takes a boolean argument or the special values "read-only" or
           "tmpfs". 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. If set to "tmpfs",
           temporary file systems are mounted on the three directories
           in read-only mode. The value "tmpfs" is useful to hide home
           directories not relevant to the processes invoked by the
           unit, while still allowing necessary directories to be made
           visible when listed in BindPaths= or BindReadOnlyPaths=.

           Setting this to "yes" is mostly equivalent to set the three
           directories in InaccessiblePaths=. Similarly, "read-only" is
           mostly equivalent to ReadOnlyPaths=, and "tmpfs" is mostly
           equivalent to TemporaryFileSystem= with ":ro".

           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. This setting
           cannot ensure protection in all cases. In general it has the
           same limitations as ReadOnlyPaths=, see below.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       RuntimeDirectory=, StateDirectory=, CacheDirectory=,
       LogsDirectory=, ConfigurationDirectory=
           These options take a whitespace-separated list of directory
           names. The specified directory names must be relative, and
           may not include "..". If set, when the unit is started, one
           or more directories by the specified names will be created
           (including their parents) below the locations defined in the
           following table. Also, the corresponding environment variable
           will be defined with the full paths of the directories. If
           multiple directories are set, then in the environment
           variable the paths are concatenated with colon (":").

           Table 2. Automatic directory creation and environment
           variables
           ┌────────────────────────┬────────────────┬───────────────────────┬──────────────────────────┐
           │Directory               Below path for Below path for        Environment              │
           │                        │ system units   user units            variable set             │
           ├────────────────────────┼────────────────┼───────────────────────┼──────────────────────────┤
           │RuntimeDirectory=       │ /run/          │ $XDG_RUNTIME_DIR$RUNTIME_DIRECTORY       │
           ├────────────────────────┼────────────────┼───────────────────────┼──────────────────────────┤
           │StateDirectory=         │ /var/lib/      │ $XDG_CONFIG_HOME$STATE_DIRECTORY         │
           ├────────────────────────┼────────────────┼───────────────────────┼──────────────────────────┤
           │CacheDirectory=         │ /var/cache/    │ $XDG_CACHE_HOME$CACHE_DIRECTORY         │
           ├────────────────────────┼────────────────┼───────────────────────┼──────────────────────────┤
           │LogsDirectory=          │ /var/log/      │ $XDG_CONFIG_HOME/log/ │ $LOGS_DIRECTORY          │
           ├────────────────────────┼────────────────┼───────────────────────┼──────────────────────────┤
           │ConfigurationDirectory= │ /etc/          │ $XDG_CONFIG_HOME$CONFIGURATION_DIRECTORY │
           └────────────────────────┴────────────────┴───────────────────────┴──────────────────────────┘
           In case of RuntimeDirectory= the innermost subdirectories are
           removed when the unit is stopped. It is possible to preserve
           the specified directories in this case if
           RuntimeDirectoryPreserve= is configured to restart or yes
           (see below). The directories specified with StateDirectory=,
           CacheDirectory=, LogsDirectory=, ConfigurationDirectory= are
           not removed when the unit is stopped.

           Except in case of ConfigurationDirectory=, the innermost
           specified directories will be owned by the user and group
           specified in User= and Group=. If the specified directories
           already exist and their owning user or group do not match the
           configured ones, all files and directories below the
           specified directories as well as the directories themselves
           will have their file ownership recursively changed to match
           what is configured. As an optimization, if the specified
           directories are already owned by the right user and group,
           files and directories below of them are left as-is, even if
           they do not match what is requested. The innermost specified
           directories will have their access mode adjusted to the what
           is specified in RuntimeDirectoryMode=, StateDirectoryMode=,
           CacheDirectoryMode=, LogsDirectoryMode= and
           ConfigurationDirectoryMode=.

           These options imply BindPaths= for the specified paths. When
           combined with RootDirectory= or RootImage= these paths always
           reside on the host and are mounted from there into the unit's
           file system namespace.

           If DynamicUser= is used, the logic for CacheDirectory=,
           LogsDirectory= and StateDirectory= is slightly altered: the
           directories are created below /var/cache/private,
           /var/log/private and /var/lib/private, respectively, which
           are host directories made inaccessible to unprivileged users,
           which ensures that access to these directories cannot be
           gained through dynamic user ID recycling. Symbolic links are
           created to hide this difference in behaviour. Both from
           perspective of the host and from inside the unit, the
           relevant directories hence always appear directly below
           /var/cache, /var/log and /var/lib.

           Use RuntimeDirectory= to manage one or more runtime
           directories for the unit and bind their lifetime to the
           daemon runtime. 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).

           The directories defined by these options are always created
           under the standard paths used by systemd (/var/, /run/,
           /etc/, ...). If the service needs directories in a different
           location, a different mechanism has to be used to create
           them.

           tmpfiles.d(5) provides functionality that overlaps with these
           options. Using these options is recommended, because the
           lifetime of the directories is tied directly to the lifetime
           of the unit, and it is not necessary to ensure that the
           tmpfiles.d configuration is executed before the unit is
           started.

           To remove any of the directories created by these settings,
           use the systemctl clean ...  command on the relevant units,
           see systemctl(1) for details.

           Example: if a system service unit has the following,

               RuntimeDirectory=foo/bar baz

           the service manager creates /run/foo (if it does not exist),
           /run/foo/bar, and /run/baz. The directories /run/foo/bar and
           /run/baz except /run/foo are owned by the user and group
           specified in User= and Group=, and removed when the service
           is stopped.

           Example: if a system service unit has the following,

               RuntimeDirectory=foo/bar
               StateDirectory=aaa/bbb ccc

           then the environment variable "RUNTIME_DIRECTORY" is set with
           "/run/foo/bar", and "STATE_DIRECTORY" is set with
           "/var/lib/aaa/bbb:/var/lib/ccc".

       RuntimeDirectoryMode=, StateDirectoryMode=, CacheDirectoryMode=,
       LogsDirectoryMode=, ConfigurationDirectoryMode=
           Specifies the access mode of the directories specified in
           RuntimeDirectory=, StateDirectory=, CacheDirectory=,
           LogsDirectory=, or ConfigurationDirectory=, respectively, as
           an octal number. Defaults to 0755. See "Permissions" in
           path_resolution(7) for a discussion of the meaning of
           permission bits.

       RuntimeDirectoryPreserve=
           Takes a boolean argument or restart. If set to no (the
           default), the directories specified in RuntimeDirectory= are
           always removed when the service stops. If set to restart the
           directories are preserved when the service is both
           automatically and manually restarted. Here, the automatic
           restart means the operation specified in Restart=, and manual
           restart means the one triggered by systemctl restart
           foo.service. If set to yes, then the directories are not
           removed when the service is stopped. Note that since the
           runtime directory /run/ is a mount point of "tmpfs", then for
           system services the directories specified in
           RuntimeDirectory= are removed when the system is rebooted.

       TimeoutCleanSec=
           Configures a timeout on the clean-up operation requested
           through systemctl clean ..., see systemctl(1) for details.
           Takes the usual time values and defaults to infinity, i.e. by
           default no timeout is applied. If a timeout is configured the
           clean operation will be aborted forcibly when the timeout is
           reached, potentially leaving resources on disk.

       ReadWritePaths=, ReadOnlyPaths=, InaccessiblePaths=, ExecPaths=,
       NoExecPaths=
           Sets up a new file system namespace for executed processes.
           These options may be used to limit access a process has to
           the file system. 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
           allow-list 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. This may be more
           restrictive than desired, because it is not possible to nest
           ReadWritePaths=, ReadOnlyPaths=, BindPaths=, or
           BindReadOnlyPaths= inside it. For a more flexible option, see
           TemporaryFileSystem=.

           Content in paths listed in NoExecPaths= are not executable
           even if the usual file access controls would permit this.
           Nest ExecPaths= inside of NoExecPaths= in order to provide
           executable content within non-executable directories.

           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=, InaccessiblePaths=,
           ExecPaths= and NoExecPaths= 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 these settings will disconnect propagation of
           mounts from the unit's processes to the host. This means that
           this setting may not be used for services which shall be able
           to install mount points in the main mount namespace. For
           ReadWritePaths= and ReadOnlyPaths= propagation in the other
           direction is not affected, i.e. mounts created on the host
           generally appear in the unit processes' namespace, and mounts
           removed on the host also disappear there too. In particular,
           note that mount propagation from host to unit will result in
           unmodified mounts to be created in the unit's namespace, i.e.
           writable mounts appearing on the host will be writable in the
           unit's namespace too, even when propagated below a path
           marked with ReadOnlyPaths=! Restricting access with these
           options hence does not extend to submounts of a directory
           that are created later on. This means the lock-down offered
           by that setting is not complete, and does not offer full
           protection.

           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.

           Simple allow-list example using these directives:

               [Service]
               ReadOnlyPaths=/
               ReadWritePaths=/var /run
               InaccessiblePaths=-/lost+found
               NoExecPaths=/
               ExecPaths=/usr/sbin/my_daemon /usr/lib /usr/lib64

           These options are only available for system services and are
           not supported for services running in per-user instances of
           the service manager.

       TemporaryFileSystem=
           Takes a space-separated list of mount points for temporary
           file systems (tmpfs). If set, a new file system namespace is
           set up for executed processes, and a temporary file system is
           mounted on each mount point. This option may be specified
           more than once, in which case temporary file systems are
           mounted on all listed mount points. If the empty string is
           assigned to this option, the list is reset, and all prior
           assignments have no effect. Each mount point may optionally
           be suffixed with a colon (":") and mount options such as
           "size=10%" or "ro". By default, each temporary file system is
           mounted with "nodev,strictatime,mode=0755". These can be
           disabled by explicitly specifying the corresponding mount
           options, e.g., "dev" or "nostrictatime".

           This is useful to hide files or directories not relevant to
           the processes invoked by the unit, while necessary files or
           directories can be still accessed by combining with
           BindPaths= or BindReadOnlyPaths=:

           Example: if a unit has the following,

               TemporaryFileSystem=/var:ro
               BindReadOnlyPaths=/var/lib/systemd

           then the invoked processes by the unit cannot see any files
           or directories under /var/ except for /var/lib/systemd or its
           contents.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       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 are 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 true,
           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.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       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. 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.

           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.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       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, including AF_NETLINK and AF_UNIX. Effectively,
           for AF_NETLINK this means that device configuration events
           received from systemd-udevd.service(8) are not delivered to
           the unit's processes. And for AF_UNIX this has the effect
           that AF_UNIX sockets in the abstract socket namespace of the
           host will become unavailable to the unit's 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.

           When this option is used on a socket unit any sockets bound
           on behalf of this unit will be bound within a private network
           namespace. This may be combined with JoinsNamespaceOf= to
           listen on sockets inside of network namespaces of other
           services.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       NetworkNamespacePath=
           Takes an absolute file system path refererring to a Linux
           network namespace pseudo-file (i.e. a file like
           /proc/$PID/ns/net or a bind mount or symlink to one). When
           set the invoked processes are added to the network namespace
           referenced by that path. The path has to point to a valid
           namespace file at the moment the processes are forked off. If
           this option is used PrivateNetwork= has no effect. If this
           option is used together with JoinsNamespaceOf= then it only
           has an effect if this unit is started before any of the
           listed units that have PrivateNetwork= or
           NetworkNamespacePath= configured, as otherwise the network
           namespace of those units is reused.

           When this option is used on a socket unit any sockets bound
           on behalf of this unit will be bound within the specified
           network namespace.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       PrivateIPC=
           Takes a boolean argument. If true, sets up a new IPC
           namespace for the executed processes. Each IPC namespace has
           its own set of System V IPC identifiers and its own POSIX
           message queue file system. This is useful to avoid name clash
           of IPC identifiers. Defaults to false. It is possible to run
           two or more units within the same private IPC namespace by
           using the JoinsNamespaceOf= directive, see systemd.unit(5)
           for details.

           Note that IPC namespacing does not have an effect on AF_UNIX
           sockets, which are the most common form of IPC used on Linux.
           Instead, AF_UNIX sockets in the file system are subject to
           mount namespacing, and those in the abstract namespace are
           subject to network namespacing. IPC namespacing only has an
           effect on SysV IPC (which is mostly legacy) as well as POSIX
           message queues (for which AF_UNIX/SOCK_SEQPACKET sockets are
           typically a better replacement). IPC namespacing also has no
           effect on POSIX shared memory (which is subject to mount
           namespacing) either. See ipc_namespaces(7) for the details.

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

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       IPCNamespacePath=
           Takes an absolute file system path refererring to a Linux IPC
           namespace pseudo-file (i.e. a file like /proc/$PID/ns/ipc or
           a bind mount or symlink to one). When set the invoked
           processes are added to the network namespace referenced by
           that path. The path has to point to a valid namespace file at
           the moment the processes are forked off. If this option is
           used PrivateIPC= has no effect. If this option is used
           together with JoinsNamespaceOf= then it only has an effect if
           this unit is started before any of the listed units that have
           PrivateIPC= or IPCNamespacePath= configured, as otherwise the
           network namespace of those units is reused.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       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.

           When this setting is set up by a per-user instance of the
           service manager, the mapping of the "root" user and group to
           itself is omitted (unless the user manager is root).
           Additionally, in the per-user instance manager case, the user
           namespace will be set up before most other namespaces. This
           means that combining PrivateUsers=true with other namespaces
           will enable use of features not normally supported by the
           per-user instances of the service manager.

           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.

       ProtectHostname=
           Takes a boolean argument. When set, sets up a new UTS
           namespace for the executed processes. In addition, changing
           hostname or domainname is prevented. Defaults to off.

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

           Note that when this option is enabled for a service hostname
           changes no longer propagate from the system into the service,
           it is hence not suitable for services that need to take
           notice of system hostname changes dynamically.

           If this setting is on, but the unit doesn't have the
           CAP_SYS_ADMIN capability (e.g. services for which User= is
           set), NoNewPrivileges=yes is implied.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       ProtectClock=
           Takes a boolean argument. If set, writes to the hardware
           clock or system clock will be denied. It is recommended to
           turn this on for most services that do not need modify the
           clock. Defaults to off. Enabling this option removes
           CAP_SYS_TIME and CAP_WAKE_ALARM from the capability bounding
           set for this unit, installs a system call filter to block
           calls that can set the clock, and DeviceAllow=char-rtc r is
           implied. This ensures /dev/rtc0, /dev/rtc1, etc. are made
           read-only to the service. See systemd.resource-control(5) for
           the details about DeviceAllow=. If this setting is on, but
           the unit doesn't have the CAP_SYS_ADMIN capability (e.g.
           services for which User= is set), NoNewPrivileges=yes is
           implied.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       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 this setting is
           on, but the unit doesn't have 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.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       ProtectKernelModules=
           Takes a boolean argument. If true, explicit module loading
           will be denied. This allows module load and unload operations
           to be turned off 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. Defaults 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 this
           setting is on, but the unit doesn't have the CAP_SYS_ADMIN
           capability (e.g. services for which User= is set),
           NoNewPrivileges=yes is implied.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       ProtectKernelLogs=
           Takes a boolean argument. If true, access to the kernel log
           ring buffer will be denied. It is recommended to turn this on
           for most services that do not need to read from or write to
           the kernel log ring buffer. Enabling this option removes
           CAP_SYSLOG from the capability bounding set for this unit,
           and installs a system call filter to block the syslog(2)
           system call (not to be confused with the libc API syslog(3)
           for userspace logging). The kernel exposes its log buffer to
           userspace via /dev/kmsg and /proc/kmsg. If enabled, these are
           made inaccessible to all the processes in the unit. If this
           setting is on, but the unit doesn't have the CAP_SYS_ADMIN
           capability (e.g. services for which User= is set),
           NoNewPrivileges=yes is implied.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       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.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       RestrictAddressFamilies=
           Restricts the set of socket address families accessible to
           the processes of this unit. Takes "none", or a
           space-separated list of address family names to allow-list,
           such as AF_UNIX, AF_INET or AF_INET6. When "none" is
           specified, then all address families will be denied. When
           prefixed with "~" the listed address families will be applied
           as deny list, otherwise as allow list. 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, ppc64, 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=),
           NoNewPrivileges=yes is implied. By default, no restrictions
           apply, all address families are accessible to processes. If
           assigned the empty string, any previous address family
           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 allow list as it is frequently used for local
           communication, including for syslog(2) logging.

       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 (allow-listing). By prepending the list with a
           single tilde character ("~") the effect may be inverted: only
           the listed namespace types will be made inaccessible, all
           unlisted ones are permitted (deny-listing). If the empty
           string is assigned, the default namespace restrictions are
           applied, which is equivalent to false. This option may appear
           more than once, in which case the namespace types are merged
           by OR, or by AND if the lines are prefixed with "~" (see
           examples below). 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.

           Example: if a unit has the following,

               RestrictNamespaces=cgroup ipc
               RestrictNamespaces=cgroup net

           then cgroup, ipc, and net are set. If the second line is
           prefixed with "~", e.g.,

               RestrictNamespaces=cgroup ipc
               RestrictNamespaces=~cgroup net

           then, only ipc is set.

       LockPersonality=
           Takes a boolean argument. If set, locks down the
           personality(2) system call so that the kernel execution
           domain may not be changed from the default or the personality
           selected with Personality= directive. This may be useful to
           improve security, because odd personality emulations may be
           poorly tested and source of vulnerabilities. If running in
           user mode, or in system mode, but without the CAP_SYS_ADMIN
           capability (e.g. setting User=), NoNewPrivileges=yes is
           implied.

       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) or pkey_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. However, the
           protection can be circumvented, if the service can write to a
           filesystem, which is not mounted with noexec (such as
           /dev/shm), or it can use memfd_create(). This can be
           prevented by making such file systems inaccessible to the
           service (e.g.  InaccessiblePaths=/dev/shm) and installing
           further system call filters (SystemCallFilter=~memfd_create).
           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.

       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.

       RestrictSUIDSGID=
           Takes a boolean argument. If set, any attempts to set the
           set-user-ID (SUID) or set-group-ID (SGID) bits on files or
           directories will be denied (for details on these bits see
           inode(7)). If running in user mode, or in system mode, but
           without the CAP_SYS_ADMIN capability (e.g. setting User=),
           NoNewPrivileges=yes is implied. As the SUID/SGID bits are
           mechanisms to elevate privileges, and allows users to acquire
           the identity of other users, it is recommended to restrict
           creation of SUID/SGID files to the few programs that actually
           require them. Note that this restricts marking of any type of
           file system object with these bits, including both regular
           files and directories (where the SGID is a different meaning
           than for files, see documentation). This option is implied if
           DynamicUser= is enabled. Defaults to off.

       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.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       PrivateMounts=
           Takes a boolean parameter. If set, the processes of this unit
           will be run in their own private file system (mount)
           namespace with all mount propagation from the processes
           towards the host's main file system namespace turned off.
           This means any file system mount points established or
           removed by the unit's processes will be private to them and
           not be visible to the host. However, file system mount points
           established or removed on the host will be propagated to the
           unit's processes. See mount_namespaces(7) for details on file
           system namespaces. Defaults to off.

           When turned on, this executes three operations for each
           invoked process: a new CLONE_NEWNS namespace is created,
           after which all existing mounts are remounted to MS_SLAVE to
           disable propagation from the unit's processes to the host
           (but leaving propagation in the opposite direction in
           effect). Finally, the mounts are remounted again to the
           propagation mode configured with MountFlags=, see below.

           File system namespaces are set up individually for each
           process forked off by the service manager. Mounts established
           in the namespace of the process created by ExecStartPre= will
           hence be cleaned up automatically as soon as that process
           exits and will not be available to subsequent processes
           forked off for ExecStart= (and similar applies to the various
           other commands configured for units). Similarly,
           JoinsNamespaceOf= does not permit sharing kernel mount
           namespaces between units, it only enables sharing of the
           /tmp/ and /var/tmp/ directories.

           Other file system namespace unit settings — PrivateMounts=,
           PrivateTmp=, PrivateDevices=, ProtectSystem=, ProtectHome=,
           ReadOnlyPaths=, InaccessiblePaths=, ReadWritePaths=, ... —
           also enable file system namespacing in a fashion equivalent
           to this option. Hence it is primarily useful to explicitly
           request this behaviour if none of the other settings are
           used.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       MountFlags=
           Takes a mount propagation setting: shared, slave or private,
           which controls whether file system mount points in the file
           system namespaces set up for this unit's processes will
           receive or propagate mounts and unmounts from other file
           system namespaces. See mount(2) for details on mount
           propagation, and the three propagation flags in particular.

           This setting only controls the final propagation setting in
           effect on all mount points of the file system namespace
           created for each process of this unit. Other file system
           namespacing unit settings (see the discussion in
           PrivateMounts= above) will implicitly disable mount and
           unmount propagation from the unit's processes towards the
           host by changing the propagation setting of all mount points
           in the unit's file system namespace to slave first. Setting
           this option to shared does not reestablish propagation in
           that case.

           If not set – but file system namespaces are enabled through
           another file system namespace unit setting – shared mount
           propagation is used, but — as mentioned — as slave is applied
           first, propagation from the unit's processes to the host is
           still turned off.

           It is not recommended to use private mount propagation for
           units, as this means temporary mounts (such as removable
           media) of the host will stay mounted and thus indefinitely
           busy in forked off processes, as unmount propagation events
           won't be received by the file system namespace of the unit.

           Usually, it is best to leave this setting unmodified, and use
           higher level file system namespacing options instead, in
           particular PrivateMounts=, see above.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

SYSTEM CALL FILTERING         top

       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 (allow-listing).
           (See SystemCallErrorNumber= below for changing the default
           action). If the first character of the list is "~", the
           effect is inverted: only the listed system calls will result
           in immediate process termination (deny-listing). Deny-listed
           system calls and system call groups may optionally be
           suffixed with a colon (":") and "errno" error number (between
           0 and 4095) or errno name such as EPERM, EACCES or EUCLEAN
           (see errno(3) for a full list). This value will be returned
           when a deny-listed system call is triggered, instead of
           terminating the processes immediately. Special setting "kill"
           can be used to explicitly specify killing. This value takes
           precedence over the one given in SystemCallErrorNumber=, see
           below. If running in user mode, or in system mode, but
           without the CAP_SYS_ADMIN capability (e.g. setting User=),
           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
           allow-listed 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. allow-listing
           and deny-listing), 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 an
           allow list rule for read() and write(), and right after it
           add a deny list rule for 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.

           Table 3. Currently predefined system call sets
           ┌────────────────┬──────────────────────────┐
           │Set             Description              │
           ├────────────────┼──────────────────────────┤
           │@aio            │ Asynchronous I/O (‐      │
           │                │ io_setup(2),             │
           │                │ io_submit(2), and        │
           │                │ related calls)           │
           ├────────────────┼──────────────────────────┤
           │@basic-io       │ System calls for basic   │
           │                │ I/O: reading, writing,   │
           │                │ seeking, file descriptor │
           │                │ duplication and closing  │
           │                │ (read(2), write(2), and  │
           │                │ related calls)           │
           ├────────────────┼──────────────────────────┤
           │@chown          │ Changing file ownership  │
           │                │ (chown(2), fchownat(2),  │
           │                │ and related calls)       │
           ├────────────────┼──────────────────────────┤
           │@clock          │ System calls for         │
           │                │ changing the system      │
           │                │ clock (adjtimex(2),      │
           │                │ settimeofday(2), and     │
           │                │ related calls)           │
           ├────────────────┼──────────────────────────┤
           │@cpu-emulation  │ System calls for CPU     │
           │                │ emulation functionality  │
           │                │ (vm86(2) and related     │
           │                │ calls)                   │
           ├────────────────┼──────────────────────────┤
           │@debug          │ Debugging, performance   │
           │                │ monitoring and tracing   │
           │                │ functionality (‐         │
           │                │ ptrace(2),               │
           │                │ perf_event_open(2) and   │
           │                │ related calls)           │
           ├────────────────┼──────────────────────────┤
           │@file-system    │ File 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-event       │ Event loop system calls  │
           │                │ (poll(2), select(2),     │
           │                │ epoll(7), eventfd(2) and │
           │                │ related calls)           │
           ├────────────────┼──────────────────────────┤
           │@ipc            │ Pipes, SysV IPC, POSIX   │
           │                │ Message Queues and other │
           │                │ IPC (mq_overview(7),     │
           │                │ svipc(7))                │
           ├────────────────┼──────────────────────────┤
           │@keyring        │ Kernel keyring access (‐ │
           │                │ keyctl(2) and related    │
           │                │ calls)                   │
           ├────────────────┼──────────────────────────┤
           │@memlock        │ Locking of memory in RAM │
           │                │ (mlock(2), mlockall(2)   │
           │                │ and related calls)       │
           ├────────────────┼──────────────────────────┤
           │@module         │ Loading and unloading of │
           │                │ kernel modules (‐        │
           │                │ init_module(2),          │
           │                │ delete_module(2) and     │
           │                │ related calls)           │
           ├────────────────┼──────────────────────────┤
           │@mount          │ Mounting and unmounting  │
           │                │ of file systems (‐       │
           │                │ mount(2), chroot(2), and │
           │                │ related calls)           │
           ├────────────────┼──────────────────────────┤
           │@network-io     │ Socket I/O (including    │
           │                │ local AF_UNIX):          │
           │                │ socket(7), unix(7)       │
           ├────────────────┼──────────────────────────┤
           │@obsolete       │ Unusual, obsolete or     │
           │                │ unimplemented (‐         │
           │                │ create_module(2),        │
           │                │ gtty(2), ...)            │
           ├────────────────┼──────────────────────────┤
           │@privileged     │ All system calls which   │
           │                │ need super-user          │
           │                │ capabilities (‐          │
           │                │ capabilities(7))         │
           ├────────────────┼──────────────────────────┤
           │@process        │ Process control,         │
           │                │ execution, namespacing   │
           │                │ operations (clone(2),    │
           │                │ kill(2), namespaces(7),  │
           │                │ ...)                     │
           ├────────────────┼──────────────────────────┤
           │@raw-io         │ Raw I/O port access (‐   │
           │                │ ioperm(2), iopl(2),      │
           │                │ pciconfig_read(), ...)   │
           ├────────────────┼──────────────────────────┤
           │@reboot         │ System calls for         │
           │                │ rebooting and reboot     │
           │                │ preparation (reboot(2),  │
           │                │ kexec(), ...)            │
           ├────────────────┼──────────────────────────┤
           │@resources      │ System calls for         │
           │                │ changing resource        │
           │                │ limits, memory and       │
           │                │ scheduling parameters (‐ │
           │                │ setrlimit(2),            │
           │                │ setpriority(2), ...)     │
           ├────────────────┼──────────────────────────┤
           │@setuid         │ System calls for         │
           │                │ changing user ID and     │
           │                │ group ID credentials, (‐ │
           │                │ setuid(2), setgid(2),    │
           │                │ setresuid(2), ...)       │
           ├────────────────┼──────────────────────────┤
           │@signal         │ System calls for         │
           │                │ manipulating and         │
           │                │ handling process signals │
           │                │ (signal(2),              │
           │                │ sigprocmask(2), ...)     │
           ├────────────────┼──────────────────────────┤
           │@swap           │ System calls for         │
           │                │ enabling/disabling swap  │
           │                │ devices (swapon(2),      │
           │                │ swapoff(2))              │
           ├────────────────┼──────────────────────────┤
           │@sync           │ Synchronizing files and  │
           │                │ memory to disk (‐        │
           │                │ fsync(2), msync(2), and  │
           │                │ related calls)           │
           ├────────────────┼──────────────────────────┤
           │@system-service │ A reasonable set of      │
           │                │ system calls used by     │
           │                │ common system services,  │
           │                │ excluding any special    │
           │                │ purpose calls. This is   │
           │                │ the recommended starting │
           │                │ point for allow-listing  │
           │                │ system calls for system  │
           │                │ services, as it contains │
           │                │ what is typically needed │
           │                │ by system services, but  │
           │                │ excludes overly specific │
           │                │ interfaces. For example, │
           │                │ the following APIs are   │
           │                │ excluded: "@clock",      │
           │                │ "@mount", "@swap",       │
           │                │ "@reboot".               │
           ├────────────────┼──────────────────────────┤
           │@timer          │ System calls for         │
           │                │ scheduling operations by │
           │                │ time (alarm(2),          │
           │                │ timer_create(2), ...)    │
           ├────────────────┼──────────────────────────┤
           │@known          │ All system calls defined │
           │                │ by the kernel. This list │
           │                │ is defined statically in │
           │                │ systemd based on a       │
           │                │ kernel version that was  │
           │                │ available when this      │
           │                │ systemd version was      │
           │                │ released. It will become │
           │                │ progressively more       │
           │                │ out-of-date as the       │
           │                │ kernel is updated.       │
           └────────────────┴──────────────────────────┘
           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.

           Generally, allow-listing system calls (rather than
           deny-listing) is the safer mode of operation. It is
           recommended to enforce system call allow lists for all
           long-running system services. Specifically, the following
           lines are a relatively safe basic choice for the majority of
           system services:

               [Service]
               SystemCallFilter=@system-service
               SystemCallErrorNumber=EPERM

           Note that various kernel system calls are defined
           redundantly: there are multiple system calls for executing
           the same operation. For example, the pidfd_send_signal()
           system call may be used to execute operations similar to what
           can be done with the older kill() system call, hence blocking
           the latter without the former only provides weak protection.
           Since new system calls are added regularly to the kernel as
           development progresses, keeping system call deny lists
           comprehensive requires constant work. It is thus recommended
           to use allow-listing instead, which offers the benefit that
           new system calls are by default implicitly blocked until the
           allow list is updated.

           Also note that a number of system calls are required to be
           accessible for the dynamic linker to work. The dynamic linker
           is required for running most regular programs (specifically:
           all dynamic ELF binaries, which is how most distributions
           build packaged programs). This means that blocking these
           system calls (which include open(), openat() or mmap()) will
           make most programs typically shipped with generic
           distributions unusable.

           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=,
           ProtectKernelLogs=, ProtectClock=, ReadOnlyPaths=,
           InaccessiblePaths= and ReadWritePaths=.

       SystemCallErrorNumber=
           Takes an "errno" error number (between 1 and 4095) or errno
           name such as EPERM, EACCES or EUCLEAN, to return when the
           system call filter configured with SystemCallFilter= is
           triggered, instead of terminating the process immediately.
           See errno(3) for a full list of error codes. When this
           setting is not used, or when the empty string or the special
           setting "kill" is assigned, the process will be terminated
           immediately when the filter is triggered.

       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. The special
           identifier native implicitly maps to the native architecture
           of the system (or more precisely: 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=), NoNewPrivileges=yes is implied. By
           default, this option is set to the empty list, i.e. no
           filtering is applied.

           If this setting is used, processes of this unit will only be
           permitted to call native system calls, and system calls of
           the specified architectures. For the purposes of this option,
           the x32 architecture is treated as including x86-64 system
           calls. However, this setting still fulfills its purpose, as
           explained below, on x32.

           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
           SystemCallArchitectures=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.

       SystemCallLog=
           Takes a space-separated list of system call names. If this
           setting is used, all system calls executed by the unit
           processes for the listed ones will be logged. If the first
           character of the list is "~", the effect is inverted: all
           system calls except the listed system calls will be logged.
           If running in user mode, or in system mode, but without the
           CAP_SYS_ADMIN capability (e.g. setting User=),
           NoNewPrivileges=yes is implied. This feature makes use of the
           Secure Computing Mode 2 interfaces of the kernel ('seccomp
           filtering') and is useful for auditing or setting up a
           minimal sandboxing environment. 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 "+".

ENVIRONMENT         top

       Environment=
           Sets environment variables for executed processes. Each line
           is unquoted using the rules described in "Quoting" section in
           systemd.syntax(7) and becomes a list of variable assignments.
           If you need to assign a value containing spaces or the equals
           sign to a variable, put quotes around the whole assignment.
           Variable expansion is not performed inside the strings and
           the "$" character has no special meaning. Specifier expansion
           is performed, see the "Specifiers" section in
           systemd.unit(5).

           This option may be specified more than once, in which case
           all listed variables will be set. If the same variable is
           listed 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.

           The names of the variables can contain ASCII letters, digits,
           and the underscore character. Variable names cannot be empty
           or start with a digit. In variable values, most characters
           are allowed, but non-printable characters are currently
           rejected.

           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.

           Note that environment variables are not suitable for passing
           secrets (such as passwords, key material, ...) to service
           processes. Environment variables set for a unit are exposed
           to unprivileged clients via D-Bus IPC, and generally not
           understood as being data that requires protection. Moreover,
           environment variables are propagated down the process tree,
           including across security boundaries (such as setuid/setgid
           executables), and hence might leak to processes that should
           not have access to the secret data. Use LoadCredential=,
           LoadCredentialEncrypted= or SetCredentialEncrypted= (see
           below) to pass data to unit processes securely.

       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 (").

           C escapes[7] are supported, but not most control
           characters[8].  "\t" and "\n" can be used to insert tabs and
           newlines within EnvironmentFile=.

           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. The files are read from the
           file system of the service manager, before any file system
           changes like bind mounts take place).

           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.

       PassEnvironment=
           Pass environment variables set for the system service 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 passed. If the
           empty string is assigned to this option, the list of
           environment variables to pass is reset, all prior assignments
           have no effect. Variables specified that are not set for the
           system manager will not be passed and will be silently
           ignored. Note that this option is only relevant for the
           system service manager, as system services by default do not
           automatically inherit any environment variables set for the
           service manager itself. However, in case of the user service
           manager all environment variables are passed to the executed
           processes anyway, hence this option is without effect for the
           user service manager.

           Variables set for invoked processes due to this setting are
           subject to being overridden by those configured with
           Environment= or EnvironmentFile=.

           C escapes[7] are supported, but not most control
           characters[8].  "\t" and "\n" can be used to insert tabs and
           newlines within 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.

       UnsetEnvironment=
           Explicitly unset environment variable assignments that would
           normally be passed from the service manager to invoked
           processes of this unit. Takes a space-separated list of
           variable names or variable assignments. This option may be
           specified more than once, in which case all listed
           variables/assignments will be unset. If the empty string is
           assigned to this option, the list of environment
           variables/assignments to unset is reset. If a variable
           assignment is specified (that is: a variable name, followed
           by "=", followed by its value), then any environment variable
           matching this precise assignment is removed. If a variable
           name is specified (that is a variable name without any
           following "=" or value), then any assignment matching the
           variable name, regardless of its value is removed. Note that
           the effect of UnsetEnvironment= is applied as final step when
           the environment list passed to executed processes is
           compiled. That means it may undo assignments from any
           configuration source, including assignments made through
           Environment= or EnvironmentFile=, inherited from the system
           manager's global set of environment variables, inherited via
           PassEnvironment=, set by the service manager itself (such as
           $NOTIFY_SOCKET and such), or set by a PAM module (in case
           PAMName= is used).

           See "Environment Variables in Spawned Processes" below for a
           description of how those settings combine to form the
           inherited environment. See environ(7) for general information
           about environment variables.

LOGGING AND STANDARD INPUT/OUTPUT         top

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

           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 data option may be used to configure arbitrary textual or
           binary data to pass via standard input to the executed
           process. The data to pass is configured via
           StandardInputText=/StandardInputData= (see below). Note that
           the actual file descriptor type passed (memory file, regular
           file, UNIX pipe, ...) might depend on the kernel and
           available privileges. In any case, the file descriptor is
           read-only, and when read returns the specified data followed
           by EOF.

           The file:path option may be used to connect a specific file
           system object to standard input. An absolute path following
           the ":" character is expected, which may refer to a regular
           file, a FIFO or special file. If an AF_UNIX socket in the
           file system is specified, a stream socket is connected to it.
           The latter is useful for connecting standard input of
           processes to arbitrary system services.

           The socket option is valid in socket-activated services only,
           and requires the relevant socket unit file (see
           systemd.socket(5) for details) to have Accept=yes set, or to
           specify 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)
           socket activation daemon.

           The fd:name option connects standard input to a specific,
           named file descriptor provided by a socket unit. The name may
           be specified as part of this option, following a ":"
           character (e.g.  "fd:foobar"). If no name is specified, the
           name "stdin" is implied (i.e.  "fd" is equivalent to
           "fd:stdin"). At least one socket unit defining the specified
           name must be provided via the Sockets= option, and the 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 file descriptors and their
           ordering.

           This setting defaults to null, unless
           StandardInputText=/StandardInputData= are set, in which case
           it defaults to data.

       StandardOutput=
           Controls where file descriptor 1 (stdout) of the executed
           processes is connected to. Takes one of inherit, null, tty,
           journal, kmsg, journal+console, kmsg+console, file:path,
           append:path, truncate:path, socket or fd:name.

           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 kmsg (see below) is implicitly stored in the
           journal as well, the specific option listed below is hence a
           superset of this one. (Also note that any external,
           additional syslog daemons receive their log data from the
           journal, too, hence this is the option to use when logging
           shall be processed with such a daemon.)

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

           The file:path option may be used to connect a specific file
           system object to standard output. The semantics are similar
           to the same option of StandardInput=, see above. If path
           refers to a regular file on the filesystem, it is opened
           (created if it doesn't exist yet) for writing at the
           beginning of the file, but without truncating it. If standard
           input and output are directed to the same file path, it is
           opened only once, for reading as well as writing and
           duplicated. This is particularly useful when the specified
           path refers to an AF_UNIX socket in the file system, as in
           that case only a single stream connection is created for both
           input and output.

           append:path is similar to file:path above, but it opens the
           file in append mode.

           truncate:path is similar to file:path above, but it truncates
           the file when opening it. For units with multiple command
           lines, e.g.  Type=oneshot services with multiple ExecStart=,
           or services with ExecCondition=, ExecStartPre= or
           ExecStartPost=, the output file is reopened and therefore
           re-truncated for each command line. If the output file is
           truncated while another process still has the file open, e.g.
           by an ExecReload= running concurrently with an ExecStart=,
           and the other process continues writing to the file without
           adjusting its offset, then the space between the file
           pointers of the two processes may be filled with NUL bytes,
           producing a sparse file. Thus, truncate:path is typically
           only useful for units where only one process runs at a time,
           such as services with a single ExecStart= and no
           ExecStartPost=, ExecReload=, ExecStop= or similar.

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

           The fd:name option connects standard output to a specific,
           named file descriptor provided by a socket unit. A name may
           be specified as part of this option, following a ":"
           character (e.g.  "fd:foobar"). If no name is specified, the
           name "stdout" is implied (i.e.  "fd" is equivalent to
           "fd:stdout"). At least one socket unit defining the specified
           name must be provided via the Sockets= option, and the 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 their ordering.

           If the standard output (or error output, see below) of a unit
           is connected to the journal or the kernel log buffer, the
           unit will implicitly gain a dependency of type After= on
           systemd-journald.socket (also see the "Implicit Dependencies"
           section above). Also note that in this case stdout (or
           stderr, see below) will be an AF_UNIX stream socket, and not
           a pipe or FIFO that can be re-opened. This means when
           executing shell scripts the construct echo "hello" >
           /dev/stderr for writing text to stderr will not work. To
           mitigate this use the construct echo "hello" >&2 instead,
           which is mostly equivalent and avoids this pitfall.

           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).

       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:name will
           use a default file descriptor name of "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).

       StandardInputText=, StandardInputData=
           Configures arbitrary textual or binary data to pass via file
           descriptor 0 (STDIN) to the executed processes. These
           settings have no effect unless StandardInput= is set to data
           (which is the default if StandardInput= is not set otherwise,
           but StandardInputText=/StandardInputData= is). Use this
           option to embed process input data directly in the unit file.

           StandardInputText= accepts arbitrary textual data. C-style
           escapes for special characters as well as the usual
           "%"-specifiers are resolved. Each time this setting is used
           the specified text is appended to the per-unit data buffer,
           followed by a newline character (thus every use appends a new
           line to the end of the buffer). Note that leading and
           trailing whitespace of lines configured with this option is
           removed. If an empty line is specified the buffer is cleared
           (hence, in order to insert an empty line, add an additional
           "\n" to the end or beginning of a line).

           StandardInputData= accepts arbitrary binary data, encoded in
           Base64[9]. No escape sequences or specifiers are resolved.
           Any whitespace in the encoded version is ignored during
           decoding.

           Note that StandardInputText= and StandardInputData= operate
           on the same data buffer, and may be mixed in order to
           configure both binary and textual data for the same input
           stream. The textual or binary data is joined strictly in the
           order the settings appear in the unit file. Assigning an
           empty string to either will reset the data buffer.

           Please keep in mind that in order to maintain readability
           long unit file settings may be split into multiple lines, by
           suffixing each line (except for the last) with a "\"
           character (see systemd.unit(5) for details). This is
           particularly useful for large data configured with these two
           options. Example:

               ...
               StandardInput=data
               StandardInputData=SWNrIHNpdHplIGRhIHVuJyBlc3NlIEtsb3BzLAp1ZmYgZWVtYWwga2xvcHAncy4KSWNrIGtpZWtl \
                                 LCBzdGF1bmUsIHd1bmRyZSBtaXIsCnVmZiBlZW1hbCBqZWh0IHNlIHVmZiBkaWUgVMO8ci4KTmFu \
                                 dSwgZGVuayBpY2ssIGljayBkZW5rIG5hbnUhCkpldHogaXNzZSB1ZmYsIGVyc2NodCB3YXIgc2Ug \
                                 enUhCkljayBqZWhlIHJhdXMgdW5kIGJsaWNrZSDigJQKdW5kIHdlciBzdGVodCBkcmF1w59lbj8g \
                                 SWNrZSEK
               ...

       LogLevelMax=
           Configures filtering by log level of log messages generated
           by this unit. Takes a syslog log level, one of emerg (lowest
           log level, only highest priority messages), alert, crit, err,
           warning, notice, info, debug (highest log level, also lowest
           priority messages). See syslog(3) for details. By default no
           filtering is applied (i.e. the default maximum log level is
           debug). Use this option to configure the logging system to
           drop log messages of a specific service above the specified
           level. For example, set LogLevelMax=info in order to turn off
           debug logging of a particularly chatty unit. Note that the
           configured level is applied to any log messages written by
           any of the processes belonging to this unit, as well as any
           log messages written by the system manager process (PID 1) in
           reference to this unit, sent via any supported logging
           protocol. The filtering is applied early in the logging
           pipeline, before any kind of further processing is done.
           Moreover, messages which pass through this filter
           successfully might still be dropped by filters applied at a
           later stage in the logging subsystem. For example,
           MaxLevelStore= configured in journald.conf(5) might prohibit
           messages of higher log levels to be stored on disk, even
           though the per-unit LogLevelMax= permitted it to be
           processed.

       LogExtraFields=
           Configures additional log metadata fields to include in all
           log records generated by processes associated with this unit.
           This setting takes one or more journal field assignments in
           the format "FIELD=VALUE" separated by whitespace. See
           systemd.journal-fields(7) for details on the journal field
           concept. Even though the underlying journal implementation
           permits binary field values, this setting accepts only valid
           UTF-8 values. To include space characters in a journal field
           value, enclose the assignment in double quotes (").  The
           usual specifiers are expanded in all assignments (see below).
           Note that this setting is not only useful for attaching
           additional metadata to log records of a unit, but given that
           all fields and values are indexed may also be used to
           implement cross-unit log record matching. Assign an empty
           string to reset the list.

       LogRateLimitIntervalSec=, LogRateLimitBurst=
           Configures the rate limiting that is applied to messages
           generated by this unit. If, in the time interval defined by
           LogRateLimitIntervalSec=, more messages than specified in
           LogRateLimitBurst= are logged by a service, all further
           messages within the interval are dropped until the interval
           is over. A message about the number of dropped messages is
           generated. The time specification for
           LogRateLimitIntervalSec= may be specified in the following
           units: "s", "min", "h", "ms", "us" (see systemd.time(7) for
           details). The default settings are set by
           RateLimitIntervalSec= and RateLimitBurst= configured in
           journald.conf(5).

       LogNamespace=
           Run the unit's processes in the specified journal namespace.
           Expects a short user-defined string identifying the
           namespace. If not used the processes of the service are run
           in the default journal namespace, i.e. their log stream is
           collected and processed by systemd-journald.service. If this
           option is used any log data generated by processes of this
           unit (regardless if via the syslog(), journal native logging
           or stdout/stderr logging) is collected and processed by an
           instance of the systemd-journald@.service template unit,
           which manages the specified namespace. The log data is stored
           in a data store independent from the default log namespace's
           data store. See systemd-journald.service(8) for details about
           journal namespaces.

           Internally, journal namespaces are implemented through Linux
           mount namespacing and over-mounting the directory that
           contains the relevant AF_UNIX sockets used for logging in the
           unit's mount namespace. Since mount namespaces are used this
           setting disconnects propagation of mounts from the unit's
           processes to the host, similar to how ReadOnlyPaths= and
           similar settings (see above) work. Journal namespaces may
           hence not be used for services that need to establish mount
           points on the host.

           When this option is used the unit will automatically gain
           ordering and requirement dependencies on the two socket units
           associated with the systemd-journald@.service instance so
           that they are automatically established prior to the unit
           starting up. Note that when this option is used log output of
           this service does not appear in the regular journalctl(1)
           output, unless the --namespace= option is used.

           This option is only available for system services and is not
           supported for services running in per-user instances of the
           service manager.

       SyslogIdentifier=
           Sets the process name ("syslog tag") 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 journal or kmsg (or to the same
           settings in combination with +console) and only applies to
           log messages written to stdout or stderr.

       SyslogFacility=
           Sets the syslog facility identifier to use when logging. 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 journal or kmsg (or to the same settings in
           combination with +console), and only applies to log messages
           written to stdout or stderr. Defaults to daemon.

       SyslogLevel=
           The default syslog log level to use when logging to the
           logging system 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 journal or kmsg (or to the same
           settings in combination with +console), and only applies to
           log messages written to stdout or stderr. Note that
           individual lines output by executed processes may 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.

       SyslogLevelPrefix=
           Takes a boolean argument. If true and StandardOutput= or
           StandardError= are set to journal or kmsg (or to the same
           settings in combination with +console), log lines written by
           the executed process that are prefixed with a log level will
           be processed 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. This only
           applies to log messages written to stdout or stderr. For
           details about this prefixing see sd-daemon(3). Defaults to
           true.

       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.

       TTYReset=
           Reset the terminal device specified with TTYPath= before and
           after execution. Defaults to "no".

       TTYVHangup=
           Disconnect all clients which have opened the terminal device
           specified with TTYPath= before and after execution. Defaults
           to "no".

       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".

CREDENTIALS         top

       LoadCredential=ID[:PATH], LoadCredentialEncrypted=ID[:PATH]
           Pass a credential to the unit. Credentials are limited-size
           binary or textual objects that may be passed to unit
           processes. They are primarily used for passing cryptographic
           keys (both public and private) or certificates, user account
           information or identity information from host to services.
           The data is accessible from the unit's processes via the file
           system, at a read-only location that (if possible and
           permitted) is backed by non-swappable memory. The data is
           only accessible to the user associated with the unit, via the
           User=/DynamicUser= settings (as well as the superuser). When
           available, the location of credentials is exported as the
           $CREDENTIALS_DIRECTORY environment variable to the unit's
           processes.

           The LoadCredential= setting takes a textual ID to use as name
           for a credential plus a file system path, separated by a
           colon. The ID must be a short ASCII string suitable as
           filename in the filesystem, and may be chosen freely by the
           user. If the specified path is absolute it is opened as
           regular file and the credential data is read from it. If the
           absolute path refers to an AF_UNIX stream socket in the file
           system a connection is made to it (only once at unit
           start-up) and the credential data read from the connection,
           providing an easy IPC integration point for dynamically
           providing credentials from other services. If the specified
           path is not absolute and itself qualifies as valid credential
           identifier it is understood to refer to a credential that the
           service manager itself received via the
           $CREDENTIALS_DIRECTORY environment variable, which may be
           used to propagate credentials from an invoking environment
           (e.g. a container manager that invoked the service manager)
           into a service. The contents of the file/socket may be
           arbitrary binary or textual data, including newline
           characters and NUL bytes. If the file system path is omitted
           it is chosen identical to the credential name, i.e. this is a
           terse way do declare credentials to inherit from the service
           manager into a service. This option may be used multiple
           times, each time defining an additional credential to pass to
           the unit.

           The LoadCredentialEncrypted= setting is identical to
           LoadCredential=, except that the credential data is decrypted
           before being passed on to the executed processes.
           Specifically, the referenced path should refer to a file or
           socket with an encrypted credential, as implemented by
           systemd-creds(1). This credential is loaded, decrypted and
           then passed to the application in decrypted plaintext form,
           in the same way a regular credential specified via
           LoadCredential= would be. A credential configured this way
           may encrypted with a secret key derived from the system's
           TPM2 security chip, or with a secret key stored in
           /var/lib/systemd/credentials.secret, or with both. Using
           encrypted credentials improves security as credentials are
           not stored in plaintext and only decrypted into plaintext the
           moment a service requiring them is started. Moreover,
           credentials may be bound to the local hardware and
           installations, so that they cannot easily be analyzed
           offline.

           The credential files/IPC sockets must be accessible to the
           service manager, but don't have to be directly accessible to
           the unit's processes: the credential data is read and copied
           into separate, read-only copies for the unit that are
           accessible to appropriately privileged processes. This is
           particularly useful in combination with DynamicUser= as this
           way privileged data can be made available to processes
           running under a dynamic UID (i.e. not a previously known one)
           without having to open up access to all users.

           In order to reference the path a credential may be read from
           within a ExecStart= command line use
           "${CREDENTIALS_DIRECTORY}/mycred", e.g.  "ExecStart=cat
           ${CREDENTIALS_DIRECTORY}/mycred".

           Currently, an accumulated credential size limit of 1 MB per
           unit is enforced.

           If referencing an AF_UNIX stream socket to connect to, the
           connection will originate from an abstract namespace socket,
           that includes information about the unit and the credential
           ID in its socket name. Use getpeername(2) to query this
           information. The returned socket name is formatted as NUL
           RANDOM "/unit/" UNIT "/" ID, i.e. a NUL byte (as required for
           abstract namespace socket names), followed by a random string
           (consisting of alphadecimal characters), followed by the
           literal string "/unit/", followed by the requesting unit
           name, followed by the literal character "/", followed by the
           textual credential ID requested. Example:
           "\0adf9d86b6eda275e/unit/foobar.service/credx" in case the
           credential "credx" is requested for a unit "foobar.service".
           This functionality is useful for using a single listening
           socket to serve credentials to multiple consumers.

       SetCredential=ID:VALUE, SetCredentialEncrypted=ID:VALUE
           The SetCredential= setting is similar to LoadCredential= but
           accepts a literal value to use as data for the credential,
           instead of a file system path to read the data from. Do not
           use this option for data that is supposed to be secret, as it
           is accessible to unprivileged processes via IPC. It's only
           safe to use this for user IDs, public key material and
           similar non-sensitive data. For everything else use
           LoadCredential=. In order to embed binary data into the
           credential data use C-style escaping (i.e.  "\n" to embed a
           newline, or "\x00" to embed a NUL byte).

           The SetCredentialEncrypted= setting is identical to
           SetCredential= but expects an encrypted credential in literal
           form as value. This allows embedding confidential credentials
           securely directly in unit files. Use systemd-creds(1)' -p
           switch to generate suitable SetCredentialEncrypted= lines
           directly from plaintext credentials. For further details see
           LoadCredentialEncrypted= above.

           If a credential of the same ID is listed in both
           LoadCredential= and SetCredential=, the latter will act as
           default if the former cannot be retrieved. In this case not
           being able to retrieve the credential from the path specified
           in LoadCredential= is not considered fatal.

SYSTEM V COMPATIBILITY         top

       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.

       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".

ENVIRONMENT VARIABLES IN SPAWNED PROCESSES         top

       Processes started by the service manager are executed with an
       environment variable block assembled from multiple sources.
       Processes started by the system service manager generally do not
       inherit environment variables set for the service manager itself
       (but this may be altered via PassEnvironment=), but processes
       started by the user service manager instances generally do
       inherit all environment variables set for the service manager
       itself.

       For each invoked process the list of environment variables set is
       compiled from the following sources:

       •   Variables globally configured for the service manager, using
           the DefaultEnvironment= setting in systemd-system.conf(5),
           the kernel command line option systemd.setenv= understood by
           systemd(1), or via systemctl(1) set-environment verb.

       •   Variables defined by the service manager itself (see the list
           below).

       •   Variables set in the service manager's own environment
           variable block (subject to PassEnvironment= for the system
           service manager).

       •   Variables set via Environment= in the unit file.

       •   Variables read from files specified via EnvironmentFile= in
           the unit file.

       •   Variables set by any PAM modules in case PAMName= is in
           effect, cf. pam_env(8).

       If the same environment variable is set by multiple of these
       sources, the later source — according to the order of the list
       above — wins. Note that as the final step all variables listed in
       UnsetEnvironment= are removed from the compiled environment
       variable list, immediately before it is passed to the executed
       process.

       The general philosophy is to expose a small curated list of
       environment variables to processes. Services started by the
       system manager (PID 1) will be started, without additional
       service-specific configuration, with just a few environment
       variables. The user manager inherits environment variables as any
       other system service, but in addition may receive additional
       environment variables from PAM, and, typically, additional
       imported variables when the user starts a graphical session. It
       is recommended to keep the environment blocks in both the system
       and user managers managers lean. Importing all variables
       inherited by the graphical session or by one of the user shells
       is strongly discouraged.

       Hint: systemd-run -P env and systemd-run --user -P env print the
       effective system and user service environment blocks.

   Environment Variables Set or Propagated by the Service Manager
       The following environment variables are propagated by the service
       manager or generated internally for each invoked process:

       $PATH
           Colon-separated list of directories to use when launching
           executables.  systemd uses a fixed value of
           "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin" in the
           system manager. When compiled for systems with "unmerged
           /usr/" (/bin is not a symlink to /usr/bin), ":/sbin:/bin" is
           appended. In case of the user manager, a different path may
           be configured by the distribution. It is recommended to not
           rely on the order of entries, and have only one program with
           a given name in $PATH.

       $LANG
           Locale. Can be set in locale.conf(5) or on the kernel command
           line (see systemd(1) and kernel-command-line(7)).

       $USER, $LOGNAME, $HOME, $SHELL
           User name (twice), home directory, and the login shell. The
           variables are set for the units that have User= set, which
           includes user systemd instances. See passwd(5).

       $INVOCATION_ID
           Contains a randomized, unique 128bit ID identifying each
           runtime cycle of the unit, formatted as 32 character
           hexadecimal string. A new ID is assigned each time the unit
           changes from an inactive state into an activating or active
           state, and may be used to identify this specific runtime
           cycle, in particular in data stored offline, such as the
           journal. The same ID is passed to all processes run as part
           of the unit.

       $XDG_RUNTIME_DIR
           The directory to use for runtime objects (such as IPC
           objects) and volatile state. Set for all services run by the
           user systemd instance, as well as any system services that
           use PAMName= with a PAM stack that includes pam_systemd. See
           below and pam_systemd(8) for more information.

       $RUNTIME_DIRECTORY, $STATE_DIRECTORY, $CACHE_DIRECTORY,
       $LOGS_DIRECTORY, $CONFIGURATION_DIRECTORY
           Absolute paths to the directories defined with
           RuntimeDirectory=, StateDirectory=, CacheDirectory=,
           LogsDirectory=, and ConfigurationDirectory= when those
           settings are used.

       $CREDENTIALS_DIRECTORY
           An absolute path to the per-unit directory with credentials
           configured via LoadCredential=/SetCredential=. The directory
           is marked read-only and is placed in unswappable memory (if
           supported and permitted), and is only accessible to the UID
           associated with the unit via User= or DynamicUser= (and the
           superuser).

       $MAINPID
           The PID of the unit's main process if it is known. This is
           only set for control processes as invoked by ExecReload= and
           similar.

       $MANAGERPID
           The PID of the user systemd instance, set for processes
           spawned by it.

       $LISTEN_FDS, $LISTEN_PID, $LISTEN_FDNAMES
           Information about file descriptors passed to a service for
           socket activation. See sd_listen_fds(3).

       $NOTIFY_SOCKET
           The socket sd_notify() talks to. See sd_notify(3).

       $WATCHDOG_PID, $WATCHDOG_USEC
           Information about watchdog keep-alive notifications. See
           sd_watchdog_enabled(3).

       $SYSTEMD_EXEC_PID
           The PID of the unit process (e.g. process invoked by
           ExecStart=). The child process can use this information to
           determine whether the process is directly invoked by the
           service manager or indirectly as a child of another process
           by comparing this value with the current PID (as similar to
           the scheme used in sd_listen_fds(3) with $LISTEN_PID and
           $LISTEN_FDS).

       $TERM
           Terminal type, set only for units connected to a terminal
           (StandardInput=tty, StandardOutput=tty, or
           StandardError=tty). See termcap(5).

       $LOG_NAMESPACE
           Contains the name of the selected logging namespace when the
           LogNamespace= service setting is used.

       $JOURNAL_STREAM
           If the standard output or standard error output of the
           executed processes are connected to the journal (for example,
           by setting StandardError=journal) $JOURNAL_STREAM contains
           the device and inode numbers of the connection file
           descriptor, formatted in decimal, separated by a colon (":").
           This permits invoked processes to safely detect whether their
           standard output or standard error output are connected to the
           journal. The device and inode numbers of the file descriptors
           should be compared with the values set in the environment
           variable to determine whether the process output is still
           connected to the journal. Note that it is generally not
           sufficient to only check whether $JOURNAL_STREAM is set at
           all as services might invoke external processes replacing
           their standard output or standard error output, without
           unsetting the environment variable.

           If both standard output and standard error of the executed
           processes are connected to the journal via a stream socket,
           this environment variable will contain information about the
           standard error stream, as that's usually the preferred
           destination for log data. (Note that typically the same
           stream is used for both standard output and standard error,
           hence very likely the environment variable contains device
           and inode information matching both stream file descriptors.)

           This environment variable is primarily useful to allow
           services to optionally upgrade their used log protocol to the
           native journal protocol (using sd_journal_print(3) and other
           functions) if their standard output or standard error output
           is connected to the journal anyway, thus enabling delivery of
           structured metadata along with logged messages.

       $SERVICE_RESULT
           Only defined for the service unit type, this environment
           variable is passed to all ExecStop= and ExecStopPost=
           processes, and encodes the service "result". Currently, the
           following values are defined:

           Table 4. Defined $SERVICE_RESULT values
           ┌──────────────────┬──────────────────────────┐
           │Value             Meaning                  │
           ├──────────────────┼──────────────────────────┤
           │"success"         │ The service ran          │
           │                  │ successfully and exited  │
           │                  │ cleanly.                 │
           ├──────────────────┼──────────────────────────┤
           │"protocol"        │ A protocol violation     │
           │                  │ occurred: the service    │
           │                  │ did not take the steps   │
           │                  │ required by its unit     │
           │                  │ configuration            │
           │                  │ (specifically what is    │
           │                  │ configured in its Type=  │
           │                  │ setting).                │
           ├──────────────────┼──────────────────────────┤
           │"timeout"         │ One of the steps timed   │
           │                  │ out.                     │
           ├──────────────────┼──────────────────────────┤
           │"exit-code"       │ Service process exited   │
           │                  │ with a non-zero exit     │
           │                  │ code; see $EXIT_CODE     │
           │                  │ below for the actual     │
           │                  │ exit code returned.      │
           ├──────────────────┼──────────────────────────┤
           │"signal"          │ A service process was    │
           │                  │ terminated abnormally by │
           │                  │ a signal, without        │
           │                  │ dumping core. See        │
           │                  │ $EXIT_CODE below for the │
           │                  │ actual signal causing    │
           │                  │ the termination.         │
           ├──────────────────┼──────────────────────────┤
           │"core-dump"       │ A service process        │
           │                  │ terminated abnormally    │
           │                  │ with a signal and dumped │
           │                  │ core. See $EXIT_CODE     │
           │                  │ below for the signal     │
           │                  │ causing the termination. │
           ├──────────────────┼──────────────────────────┤
           │"watchdog"        │ Watchdog keep-alive ping │
           │                  │ was enabled for the      │
           │                  │ service, but the         │
           │                  │ deadline was missed.     │
           ├──────────────────┼──────────────────────────┤
           │"start-limit-hit" │ A start limit was        │
           │                  │ defined for the unit and │
           │                  │ it was hit, causing the  │
           │                  │ unit to fail to start.   │
           │                  │ See systemd.unit(5)'s    │
           │                  │ StartLimitIntervalSec=   │
           │                  │ and StartLimitBurst= for │
           │                  │ details.                 │
           ├──────────────────┼──────────────────────────┤
           │"resources"       │ A catch-all condition in │
           │                  │ case a system operation  │
           │                  │ failed.                  │
           └──────────────────┴──────────────────────────┘
           This environment variable is useful to monitor failure or
           successful termination of a service. Even though this
           variable is available in both ExecStop= and ExecStopPost=, it
           is usually a better choice to place monitoring tools in the
           latter, as the former is only invoked for services that
           managed to start up correctly, and the latter covers both
           services that failed during their start-up and those which
           failed during their runtime.

       $EXIT_CODE, $EXIT_STATUS
           Only defined for the service unit type, these environment
           variables are passed to all ExecStop=, ExecStopPost=
           processes and contain exit status/code information of the
           main process of the service. For the precise definition of
           the exit code and status, see wait(2).  $EXIT_CODE is one of
           "exited", "killed", "dumped".  $EXIT_STATUS contains the
           numeric exit code formatted as string if $EXIT_CODE is
           "exited", and the signal name in all other cases. Note that
           these environment variables are only set if the service
           manager succeeded to start and identify the main process of
           the service.

           Table 5. Summary of possible service result variable values
           ┌──────────────────┬──────────────────┬──────────────────┐
           │$SERVICE_RESULT$EXIT_CODE$EXIT_STATUS     │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"success"         │ "killed"         │ "HUP", "INT",    │
           │                  │                  │ "TERM", "PIPE"   │
           │                  ├──────────────────┼──────────────────┤
           │                  │ "exited"         │ "0"              │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"protocol"        │ not set          │ not set          │
           │                  ├──────────────────┼──────────────────┤
           │                  │ "exited"         │ "0"              │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"timeout"         │ "killed"         │ "TERM", "KILL"   │
           │                  ├──────────────────┼──────────────────┤
           │                  │ "exited"         │ "0", "1", "2",   │
           │                  │                  │ "3", ..., "255"  │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"exit-code"       │ "exited"         │ "1", "2", "3",   │
           │                  │                  │ ..., "255"       │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"signal"          │ "killed"         │ "HUP", "INT",    │
           │                  │                  │ "KILL", ...      │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"core-dump"       │ "dumped"         │ "ABRT", "SEGV",  │
           │                  │                  │ "QUIT", ...      │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"watchdog"        │ "dumped"         │ "ABRT"           │
           │                  ├──────────────────┼──────────────────┤
           │                  │ "killed"         │ "TERM", "KILL"   │
           │                  ├──────────────────┼──────────────────┤
           │                  │ "exited"         │ "0", "1", "2",   │
           │                  │                  │ "3", ..., "255"  │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"exec-condition"  │ "exited"         │ "1", "2", "3",   │
           │                  │                  │ "4", ..., "254"  │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"oom-kill"        │ "killed"         │ "TERM", "KILL"   │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"start-limit-hit" │ not set          │ not set          │
           ├──────────────────┼──────────────────┼──────────────────┤
           │"resources"       │ any of the above │ any of the above │
           ├──────────────────┴──────────────────┴──────────────────┤
           │Note: the process may be also terminated by a signal    │
           │not sent by systemd. In particular the process may      │
           │send an arbitrary signal to itself in a handler for     │
           │any of the non-maskable signals. Nevertheless, in the   │
           │"timeout" and "watchdog" rows above only the signals    │
           │that systemd sends have been included. Moreover, using  │
           │SuccessExitStatus= additional exit statuses may be      │
           │declared to indicate clean termination, which is not    │
           │reflected by this table.                                │
           └────────────────────────────────────────────────────────┘

       $PIDFILE
           The path to the configured PID file, in case the process is
           forked off on behalf of a service that uses the PIDFile=
           setting, see systemd.service(5) for details. Service code may
           use this environment variable to automatically generate a PID
           file at the location configured in the unit file. This field
           is set to an absolute path in the file system.

       For system services, when PAMName= is enabled and pam_systemd is
       part of the selected PAM stack, additional environment variables
       defined by systemd may be set for services. Specifically, these
       are $XDG_SEAT, $XDG_VTNR, see pam_systemd(8) for details.

PROCESS EXIT CODES         top

       When invoking a unit process the service manager possibly fails
       to apply the execution parameters configured with the settings
       above. In that case the already created service process will exit
       with a non-zero exit code before the configured command line is
       executed. (Or in other words, the child process possibly exits
       with these error codes, after having been created by the fork(2)
       system call, but before the matching execve(2) system call is
       called.) Specifically, exit codes defined by the C library, by
       the LSB specification and by the systemd service manager itself
       are used.

       The following basic service exit codes are defined by the C
       library.

       Table 6. Basic C library exit codes
       ┌──────────┬───────────────┬────────────────────┐
       │Exit Code Symbolic Name Description        │
       ├──────────┼───────────────┼────────────────────┤
       │0         │ EXIT_SUCCESS  │ Generic success    │
       │          │               │ code.              │
       ├──────────┼───────────────┼────────────────────┤
       │1         │ EXIT_FAILURE  │ Generic failure or │
       │          │               │ unspecified error. │
       └──────────┴───────────────┴────────────────────┘

       The following service exit codes are defined by the LSB
       specification[10].

       Table 7. LSB service exit codes
       ┌──────────┬──────────────────────┬────────────────────┐
       │Exit Code Symbolic Name        Description        │
       ├──────────┼──────────────────────┼────────────────────┤
       │2         │ EXIT_INVALIDARGUMENT │ Invalid or excess  │
       │          │                      │ arguments.         │
       ├──────────┼──────────────────────┼────────────────────┤
       │3         │ EXIT_NOTIMPLEMENTED  │ Unimplemented      │
       │          │                      │ feature.           │
       ├──────────┼──────────────────────┼────────────────────┤
       │4         │ EXIT_NOPERMISSION    │ The user has       │
       │          │                      │ insufficient       │
       │          │                      │ privileges.        │
       ├──────────┼──────────────────────┼────────────────────┤
       │5         │ EXIT_NOTINSTALLED    │ The program is not │
       │          │                      │ installed.         │
       ├──────────┼──────────────────────┼────────────────────┤
       │6         │ EXIT_NOTCONFIGURED   │ The program is not │
       │          │                      │ configured.        │
       ├──────────┼──────────────────────┼────────────────────┤
       │7         │ EXIT_NOTRUNNING      │ The program is not │
       │          │                      │ running.           │
       └──────────┴──────────────────────┴────────────────────┘

       The LSB specification suggests that error codes 200 and above are
       reserved for implementations. Some of them are used by the
       service manager to indicate problems during process invocation:

       Table 8. systemd-specific exit codes
       ┌──────────┬──────────────────────────────┬─────────────────────────────────────────────┐
       │Exit Code Symbolic Name                Description                                 │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │200       │ EXIT_CHDIR                   │ Changing to the                             │
       │          │                              │ requested working                           │
       │          │                              │ directory failed.                           │
       │          │                              │ See                                         │
       │          │                              │ WorkingDirectory=                           │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │201       │ EXIT_NICE                    │ Failed to set up                            │
       │          │                              │ process scheduling                          │
       │          │                              │ priority (nice                              │
       │          │                              │ level). See Nice=                           │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │202       │ EXIT_FDS                     │ Failed to close                             │
       │          │                              │ unwanted file                               │
       │          │                              │ descriptors, or to                          │
       │          │                              │ adjust passed file                          │
       │          │                              │ descriptors.                                │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │203       │ EXIT_EXEC                    │ The actual process                          │
       │          │                              │ execution failed                            │
       │          │                              │ (specifically, the                          │
       │          │                              │ execve(2) system                            │
       │          │                              │ call). Most likely                          │
       │          │                              │ this is caused by                           │
       │          │                              │ a missing or                                │
       │          │                              │ non-accessible                              │
       │          │                              │ executable file.                            │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │204       │ EXIT_MEMORY                  │ Failed to perform                           │
       │          │                              │ an action due to                            │
       │          │                              │ memory shortage.                            │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │205       │ EXIT_LIMITS                  │ Failed to adjust                            │
       │          │                              │ resource limits.                            │
       │          │                              │ See LimitCPU= and                           │
       │          │                              │ related settings                            │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │206       │ EXIT_OOM_ADJUST              │ Failed to adjust                            │
       │          │                              │ the OOM setting.                            │
       │          │                              │ See                                         │
       │          │                              │ OOMScoreAdjust=                             │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │207       │ EXIT_SIGNAL_MASK             │ Failed to set                               │
       │          │                              │ process signal                              │
       │          │                              │ mask.                                       │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │208       │ EXIT_STDIN                   │ Failed to set up                            │
       │          │                              │ standard input.                             │
       │          │                              │ See StandardInput=                          │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │209       │ EXIT_STDOUT                  │ Failed to set up                            │
       │          │                              │ standard output.                            │
       │          │                              │ See                                         │
       │          │                              │ StandardOutput=                             │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │210       │ EXIT_CHROOT                  │ Failed to change                            │
       │          │                              │ root directory (‐                           │
       │          │                              │ chroot(2)). See                             │
       │          │                              │ RootDirectory=/RootImage=                   │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │211       │ EXIT_IOPRIO                  │ Failed to set up IO                         │
       │          │                              │ scheduling priority. See                    │
       │          │                              │ IOSchedulingClass=/IOSchedulingPriority=    │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │212       │ EXIT_TIMERSLACK              │ Failed to set up timer slack. See           │
       │          │                              │ TimerSlackNSec= above.                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │213       │ EXIT_SECUREBITS              │ Failed to set process secure bits. See      │
       │          │                              │ SecureBits= above.                          │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │214       │ EXIT_SETSCHEDULER            │ Failed to set up CPU scheduling. See        │
       │          │                              │ CPUSchedulingPolicy=/CPUSchedulingPriority= │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │215       │ EXIT_CPUAFFINITY             │ Failed to set up CPU affinity. See          │
       │          │                              │ CPUAffinity= above.                         │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │216       │ EXIT_GROUP                   │ Failed to determine or change group         │
       │          │                              │ credentials. See                            │
       │          │                              │ Group=/SupplementaryGroups= above.          │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │217       │ EXIT_USER                    │ Failed to determine or change user          │
       │          │                              │ credentials, or to set up user namespacing. │
       │          │                              │ See User=/PrivateUsers= above.              │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │218       │ EXIT_CAPABILITIES            │ Failed to drop capabilities, or apply       │
       │          │                              │ ambient capabilities. See                   │
       │          │                              │ CapabilityBoundingSet=/AmbientCapabilities= │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │219       │ EXIT_CGROUP                  │ Setting up the service control group        │
       │          │                              │ failed.                                     │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │220       │ EXIT_SETSID                  │ Failed to create new process session.       │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │221       │ EXIT_CONFIRM                 │ Execution has been cancelled by the user.   │
       │          │                              │ See the systemd.confirm_spawn= kernel       │
       │          │                              │ command line setting on                     │
       │          │                              │ kernel-command-line(7) for details.         │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │222       │ EXIT_STDERR                  │ Failed to set up standard error output. See │
       │          │                              │ StandardError= above.                       │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │224       │ EXIT_PAM                     │ Failed to set up PAM session. See PAMName=  │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │225       │ EXIT_NETWORK                 │ Failed to set up network namespacing. See   │
       │          │                              │ PrivateNetwork= above.                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │226       │ EXIT_NAMESPACE               │ Failed to set up mount, UTS, or IPC         │
       │          │                              │ namespacing. See ReadOnlyPaths=,            │
       │          │                              │ ProtectHostname=, PrivateIPC=, and related  │
       │          │                              │ settings above.                             │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │227       │ EXIT_NO_NEW_PRIVILEGES       │ Failed to disable new privileges. See       │
       │          │                              │ NoNewPrivileges=yes above.                  │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │228       │ EXIT_SECCOMP                 │ Failed to apply system call filters. See    │
       │          │                              │ SystemCallFilter= and related settings      │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │229       │ EXIT_SELINUX_CONTEXT         │ Determining or changing SELinux context     │
       │          │                              │ failed. See SELinuxContext= above.          │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │230       │ EXIT_PERSONALITY             │ Failed to set up an execution domain        │
       │          │                              │ (personality). See Personality= above.      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │231       │ EXIT_APPARMOR_PROFILE        │ Failed to prepare changing AppArmor         │
       │          │                              │ profile. See AppArmorProfile= above.        │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │232       │ EXIT_ADDRESS_FAMILIES        │ Failed to restrict address families. See    │
       │          │                              │ RestrictAddressFamilies= above.             │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │233       │ EXIT_RUNTIME_DIRECTORY       │ Setting up runtime directory failed. See    │
       │          │                              │ RuntimeDirectory= and related settings      │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │235       │ EXIT_CHOWN                   │ Failed to adjust socket ownership. Used for │
       │          │                              │ socket units only.                          │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │236       │ EXIT_SMACK_PROCESS_LABEL     │ Failed to set SMACK label. See              │
       │          │                              │ SmackProcessLabel= above.                   │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │237       │ EXIT_KEYRING                 │ Failed to set up kernel keyring.            │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │238       │ EXIT_STATE_DIRECTORY         │ Failed to set up unit's state directory.    │
       │          │                              │ See StateDirectory= above.                  │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │239       │ EXIT_CACHE_DIRECTORY         │ Failed to set up unit's cache directory.    │
       │          │                              │ See CacheDirectory= above.                  │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │240       │ EXIT_LOGS_DIRECTORY          │ Failed to set up unit's logging directory.  │
       │          │                              │ See LogsDirectory= above.                   │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │241       │ EXIT_CONFIGURATION_DIRECTORY │ Failed to set up unit's configuration       │
       │          │                              │ directory. See ConfigurationDirectory=      │
       │          │                              │ above.                                      │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │242       │ EXIT_NUMA_POLICY             │ Failed to set up unit's NUMA memory policy. │
       │          │                              │ See NUMAPolicy= and NUMAMask= above.        │
       ├──────────┼──────────────────────────────┼─────────────────────────────────────────────┤
       │243       │ EXIT_CREDENTIALS             │ Failed to set up unit's credentials. See    │
       │          │                              │ LoadCredential= and SetCredential= above.   │
       └──────────┴──────────────────────────────┴─────────────────────────────────────────────┘

       Finally, the BSD operating systems define a set of exit codes,
       typically defined on Linux systems too:

       Table 9. BSD exit codes
       ┌──────────┬────────────────┬────────────────────┐
       │Exit Code Symbolic Name  Description        │
       ├──────────┼────────────────┼────────────────────┤
       │64        │ EX_USAGE       │ Command line usage │
       │          │                │ error              │
       ├──────────┼────────────────┼────────────────────┤
       │65        │ EX_DATAERR     │ Data format error  │
       ├──────────┼────────────────┼────────────────────┤
       │66        │ EX_NOINPUT     │ Cannot open input  │
       ├──────────┼────────────────┼────────────────────┤
       │67        │ EX_NOUSER      │ Addressee unknown  │
       ├──────────┼────────────────┼────────────────────┤
       │68        │ EX_NOHOST      │ Host name unknown  │
       ├──────────┼────────────────┼────────────────────┤
       │69        │ EX_UNAVAILABLE │ Service            │
       │          │                │ unavailable        │
       ├──────────┼────────────────┼────────────────────┤
       │70        │ EX_SOFTWARE    │ internal software  │
       │          │                │ error              │
       ├──────────┼────────────────┼────────────────────┤
       │71        │ EX_OSERR       │ System error       │
       │          │                │ (e.g., can't fork) │
       ├──────────┼────────────────┼────────────────────┤
       │72        │ EX_OSFILE      │ Critical OS file   │
       │          │                │ missing            │
       ├──────────┼────────────────┼────────────────────┤
       │73        │ EX_CANTCREAT   │ Can't create       │
       │          │                │ (user) output file │
       ├──────────┼────────────────┼────────────────────┤
       │74        │ EX_IOERR       │ Input/output error │
       ├──────────┼────────────────┼────────────────────┤
       │75        │ EX_TEMPFAIL    │ Temporary failure; │
       │          │                │ user is invited to │
       │          │                │ retry              │
       ├──────────┼────────────────┼────────────────────┤
       │76        │ EX_PROTOCOL    │ Remote error in    │
       │          │                │ protocol           │
       ├──────────┼────────────────┼────────────────────┤
       │77        │ EX_NOPERM      │ Permission denied  │
       ├──────────┼────────────────┼────────────────────┤
       │78        │ EX_CONFIG      │ Configuration      │
       │          │                │ error              │
       └──────────┴────────────────┴────────────────────┘

SEE ALSO         top

       systemd(1), systemctl(1), systemd-analyze(1), journalctl(1),
       systemd-system.conf(5), systemd.unit(5), systemd.service(5),
       systemd.socket(5), systemd.swap(5), systemd.mount(5),
       systemd.kill(5), systemd.resource-control(5), systemd.time(7),
       systemd.directives(7), tmpfiles.d(5), exec(3), fork(2)

NOTES         top

        1. Discoverable Partitions Specification
           https://systemd.io/DISCOVERABLE_PARTITIONS

        2. The /proc Filesystem
           https://www.kernel.org/doc/html/latest/filesystems/proc.html#mount-options

        3. User/Group Name Syntax
           https://systemd.io/USER_NAMES

        4. No New Privileges Flag
           https://www.kernel.org/doc/html/latest/userspace-api/no_new_privs.html

        5. JSON User Record
           https://systemd.io/USER_RECORD

        6. proc.txt
           https://www.kernel.org/doc/Documentation/filesystems/proc.txt

        7. C escapes
           https://en.wikipedia.org/wiki/Escape_sequences_in_C#Table_of_escape_sequences

        8. most control characters
           https://en.wikipedia.org/wiki/Control_character#In_ASCII

        9. Base64
           https://tools.ietf.org/html/rfc2045#section-6.8

       10. LSB specification
           https://refspecs.linuxbase.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/iniscrptact.html

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have
       a bug report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-08-27.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 249                                              SYSTEMD.EXEC(5)

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