Provided by: systemd_249.11-0ubuntu3_amd64 bug

NAME

       systemd-system.conf, system.conf.d, systemd-user.conf, user.conf.d - System and session
       service manager configuration files

SYNOPSIS

       /etc/systemd/system.conf, /etc/systemd/system.conf.d/*.conf,
       /run/systemd/system.conf.d/*.conf, /lib/systemd/system.conf.d/*.conf

       ~/.config/systemd/user.conf, /etc/systemd/user.conf, /etc/systemd/user.conf.d/*.conf,
       /run/systemd/user.conf.d/*.conf, /usr/lib/systemd/user.conf.d/*.conf

DESCRIPTION

       When run as a system instance, systemd interprets the configuration file system.conf and
       the files in system.conf.d directories; when run as a user instance, it interprets the
       configuration file user.conf (either in the home directory of the user, or if not found,
       under /etc/systemd/) and the files in user.conf.d directories. These configuration files
       contain a few settings controlling basic manager operations.

       See systemd.syntax(7) for a general description of the syntax.

CONFIGURATION DIRECTORIES AND PRECEDENCE

       The default configuration is set during compilation, so configuration is only needed when
       it is necessary to deviate from those defaults. Initially, the main configuration file in
       /etc/systemd/ contains commented out entries showing the defaults as a guide to the
       administrator. Local overrides can be created by editing this file or by creating
       drop-ins, as described below. Using drop-ins for local configuration is recommended over
       modifications to the main configuration file.

       In addition to the "main" configuration file, drop-in configuration snippets are read from
       /usr/lib/systemd/*.conf.d/, /usr/local/lib/systemd/*.conf.d/, and /etc/systemd/*.conf.d/.
       Those drop-ins have higher precedence and override the main configuration file. Files in
       the *.conf.d/ configuration subdirectories are sorted by their filename in lexicographic
       order, regardless of in which of the subdirectories they reside. When multiple files
       specify the same option, for options which accept just a single value, the entry in the
       file sorted last takes precedence, and for options which accept a list of values, entries
       are collected as they occur in the sorted files.

       When packages need to customize the configuration, they can install drop-ins under /usr/.
       Files in /etc/ are reserved for the local administrator, who may use this logic to
       override the configuration files installed by vendor packages. Drop-ins have to be used to
       override package drop-ins, since the main configuration file has lower precedence. It is
       recommended to prefix all filenames in those subdirectories with a two-digit number and a
       dash, to simplify the ordering of the files.

       To disable a configuration file supplied by the vendor, the recommended way is to place a
       symlink to /dev/null in the configuration directory in /etc/, with the same filename as
       the vendor configuration file.

OPTIONS

       All options are configured in the [Manager] section:

       LogColor=, LogLevel=, LogLocation=, LogTarget=, LogTime=, DumpCore=yes, CrashChangeVT=no,
       CrashShell=no, CrashReboot=no, ShowStatus=yes, DefaultStandardOutput=journal,
       DefaultStandardError=inherit
           Configures various parameters of basic manager operation. These options may be
           overridden by the respective process and kernel command line arguments. See systemd(1)
           for details.

       CtrlAltDelBurstAction=
           Defines what action will be performed if user presses Ctrl-Alt-Delete more than 7
           times in 2s. Can be set to "reboot-force", "poweroff-force", "reboot-immediate",
           "poweroff-immediate" or disabled with "none". Defaults to "reboot-force".

       CPUAffinity=
           Configures the CPU affinity for the service manager as well as the default CPU
           affinity for all forked off processes. Takes a list of CPU indices or ranges separated
           by either whitespace or commas. CPU ranges are specified by the lower and upper CPU
           indices separated by a dash. This option may be specified more than once, in which
           case the specified CPU affinity masks are merged. If the empty string is assigned, the
           mask is reset, all assignments prior to this will have no effect. Individual services
           may override the CPU affinity for their processes with the CPUAffinity= setting in
           unit files, see systemd.exec(5).

       NUMAPolicy=
           Configures the NUMA memory policy for the service manager and the default NUMA memory
           policy for all forked off processes. Individual services may override the default
           policy with the NUMAPolicy= setting in unit files, see systemd.exec(5).

       NUMAMask=
           Configures the NUMA node mask that will be associated with the selected NUMA policy.
           Note that default and local NUMA policies don't require explicit NUMA node mask and
           value of the option can be empty. Similarly to NUMAPolicy=, value can be overridden by
           individual services in unit files, see systemd.exec(5).

       RuntimeWatchdogSec=, RebootWatchdogSec=, KExecWatchdogSec=
           Configure the hardware watchdog at runtime and at reboot. Takes a timeout value in
           seconds (or in other time units if suffixed with "ms", "min", "h", "d", "w"). If
           RuntimeWatchdogSec= is set to a non-zero value, the watchdog hardware (/dev/watchdog
           or the path specified with WatchdogDevice= or the kernel option
           systemd.watchdog-device=) will be programmed to automatically reboot the system if it
           is not contacted within the specified timeout interval. The system manager will ensure
           to contact it at least once in half the specified timeout interval. This feature
           requires a hardware watchdog device to be present, as it is commonly the case in
           embedded and server systems. Not all hardware watchdogs allow configuration of all
           possible reboot timeout values, in which case the closest available timeout is picked.
           RebootWatchdogSec= may be used to configure the hardware watchdog when the system is
           asked to reboot. It works as a safety net to ensure that the reboot takes place even
           if a clean reboot attempt times out. Note that the RebootWatchdogSec= timeout applies
           only to the second phase of the reboot, i.e. after all regular services are already
           terminated, and after the system and service manager process (PID 1) got replaced by
           the systemd-shutdown binary, see system bootup(7) for details. During the first phase
           of the shutdown operation the system and service manager remains running and hence
           RuntimeWatchdogSec= is still honoured. In order to define a timeout on this first
           phase of system shutdown, configure JobTimeoutSec= and JobTimeoutAction= in the [Unit]
           section of the shutdown.target unit. By default RuntimeWatchdogSec= defaults to 0
           (off), and RebootWatchdogSec= to 10min.  KExecWatchdogSec= may be used to additionally
           enable the watchdog when kexec is being executed rather than when rebooting. Note that
           if the kernel does not reset the watchdog on kexec (depending on the specific hardware
           and/or driver), in this case the watchdog might not get disabled after kexec succeeds
           and thus the system might get rebooted, unless RuntimeWatchdogSec= is also enabled at
           the same time. For this reason it is recommended to enable KExecWatchdogSec= only if
           RuntimeWatchdogSec= is also enabled. These settings have no effect if a hardware
           watchdog is not available.

       WatchdogDevice=
           Configure the hardware watchdog device that the runtime and shutdown watchdog timers
           will open and use. Defaults to /dev/watchdog. This setting has no effect if a hardware
           watchdog is not available.

       CapabilityBoundingSet=
           Controls which capabilities to include in the capability bounding set for PID 1 and
           its children. See capabilities(7) for details. Takes a whitespace-separated list of
           capability names as read by cap_from_name(3). 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. The capability bounding set may
           also be individually configured for units using the CapabilityBoundingSet= directive
           for units, but note that capabilities dropped for PID 1 cannot be regained in
           individual units, they are lost for good.

       NoNewPrivileges=
           Takes a boolean argument. If true, ensures that PID 1 and all its children can never
           gain new privileges through execve(2) (e.g. via setuid or setgid bits, or filesystem
           capabilities). Defaults to false. General purpose distributions commonly rely on
           executables with setuid or setgid bits and will thus not function properly with this
           option enabled. Individual units cannot disable this option. Also see No New
           Privileges Flag[1].

       SystemCallArchitectures=
           Takes a space-separated list of architecture identifiers. Selects from which
           architectures system calls may be invoked on this system. This may be used as an
           effective way to disable invocation of non-native binaries system-wide, for example to
           prohibit execution of 32-bit x86 binaries on 64-bit x86-64 systems. This option
           operates system-wide, and acts similar to the SystemCallArchitectures= setting of unit
           files, see systemd.exec(5) for details. This setting defaults to the empty list, in
           which case no filtering of system calls based on architecture is applied. Known
           architecture identifiers are "x86", "x86-64", "x32", "arm" and the special identifier
           "native". The latter implicitly maps to the native architecture of the system (or more
           specifically, the architecture the system manager was compiled for). Set this setting
           to "native" to prohibit execution of any non-native binaries. When a binary executes a
           system call of an architecture that is not listed in this setting, it will be
           immediately terminated with the SIGSYS signal.

       TimerSlackNSec=
           Sets the timer slack in nanoseconds for PID 1, which is inherited by all executed
           processes, unless overridden individually, for example with the TimerSlackNSec=
           setting in service units (for details see systemd.exec(5)). The timer slack controls
           the accuracy of wake-ups triggered by system 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.

       StatusUnitFormat=
           Takes name, description or combined as the value. If name, the system manager will use
           unit names in status messages (e.g.  "systemd-journald.service"), instead of the
           longer and more informative descriptions set with Description= (e.g.  "Journal Logging
           Service"). If combined, the system manager will use both unit names and descriptions
           in status messages (e.g.  "systemd-journald.service - Journal Logging Service").

           See systemd.unit(5) for details about unit names and Description=.

       DefaultTimerAccuracySec=
           Sets the default accuracy of timer units. This controls the global default for the
           AccuracySec= setting of timer units, see systemd.timer(5) for details.  AccuracySec=
           set in individual units override the global default for the specific unit. Defaults to
           1min. Note that the accuracy of timer units is also affected by the configured timer
           slack for PID 1, see TimerSlackNSec= above.

       DefaultTimeoutStartSec=, DefaultTimeoutStopSec=, DefaultTimeoutAbortSec=,
       DefaultRestartSec=
           Configures the default timeouts for starting, stopping and aborting of units, as well
           as the default time to sleep between automatic restarts of units, as configured
           per-unit in TimeoutStartSec=, TimeoutStopSec=, TimeoutAbortSec= and RestartSec= (for
           services, see systemd.service(5) for details on the per-unit settings). Disabled by
           default, when service with Type=oneshot is used. For non-service units,
           DefaultTimeoutStartSec= sets the default TimeoutSec= value.  DefaultTimeoutStartSec=
           and DefaultTimeoutStopSec= default to 90s.  DefaultTimeoutAbortSec= is not set by
           default so that all units fall back to TimeoutStopSec=.  DefaultRestartSec= defaults
           to 100ms.

       DefaultStartLimitIntervalSec=, DefaultStartLimitBurst=
           Configure the default unit start rate limiting, as configured per-service by
           StartLimitIntervalSec= and StartLimitBurst=. See systemd.service(5) for details on the
           per-service settings.  DefaultStartLimitIntervalSec= defaults to 10s.
           DefaultStartLimitBurst= defaults to 5.

       DefaultEnvironment=
           Configures environment variables passed to all executed processes. Takes a
           space-separated list of variable assignments. See environ(7) for details about
           environment variables.

           Simple "%"-specifier expansion is supported, see below for a list of supported
           specifiers.

           Example:

               DefaultEnvironment="VAR1=word1 word2" VAR2=word3 "VAR3=word 5 6"

           Sets three variables "VAR1", "VAR2", "VAR3".

       ManagerEnvironment=
           Takes the same arguments as DefaultEnvironment=, see above. Sets environment variables
           just for the manager process itself. In contrast to user managers, these variables are
           not inherited by processes spawned by the system manager, use DefaultEnvironment= for
           that. Note that these variables are merged into the existing environment block. In
           particular, in case of the system manager, this includes variables set by the kernel
           based on the kernel command line.

           Setting environment variables for the manager process may be useful to modify its
           behaviour. See ENVIRONMENT[2] for a descriptions of some variables understood by
           systemd.

           Simple "%"-specifier expansion is supported, see below for a list of supported
           specifiers.

       DefaultCPUAccounting=, DefaultBlockIOAccounting=, DefaultMemoryAccounting=,
       DefaultTasksAccounting=, DefaultIOAccounting=, DefaultIPAccounting=
           Configure the default resource accounting settings, as configured per-unit by
           CPUAccounting=, BlockIOAccounting=, MemoryAccounting=, TasksAccounting=, IOAccounting=
           and IPAccounting=. See systemd.resource-control(5) for details on the per-unit
           settings.  DefaultTasksAccounting= defaults to yes, DefaultMemoryAccounting= to yes.
           DefaultCPUAccounting= defaults to yes if enabling CPU accounting doesn't require the
           CPU controller to be enabled (Linux 4.15+ using the unified hierarchy for resource
           control), otherwise it defaults to no. The other three settings default to no.

       DefaultTasksMax=
           Configure the default value for the per-unit TasksMax= setting. See systemd.resource-
           control(5) for details. This setting applies to all unit types that support resource
           control settings, with the exception of slice units. Defaults to 15% of the minimum of
           kernel.pid_max=, kernel.threads-max= and root cgroup pids.max. Kernel has a default
           value for kernel.pid_max= and an algorithm of counting in case of more than 32 cores.
           For example with the default kernel.pid_max=, DefaultTasksMax= defaults to 4915, but
           might be greater in other systems or smaller in OS containers.

       DefaultLimitCPU=, DefaultLimitFSIZE=, DefaultLimitDATA=, DefaultLimitSTACK=,
       DefaultLimitCORE=, DefaultLimitRSS=, DefaultLimitNOFILE=, DefaultLimitAS=,
       DefaultLimitNPROC=, DefaultLimitMEMLOCK=, DefaultLimitLOCKS=, DefaultLimitSIGPENDING=,
       DefaultLimitMSGQUEUE=, DefaultLimitNICE=, DefaultLimitRTPRIO=, DefaultLimitRTTIME=
           These settings control various default resource limits for processes executed by
           units. See setrlimit(2) for details. These settings may be overridden in individual
           units using the corresponding LimitXXX= directives and they accept the same parameter
           syntax, see systemd.exec(5) for details. Note that these resource limits are only
           defaults for units, they are not applied to the service manager process (i.e. PID 1)
           itself.

           Most of these settings are unset, which means the resource limits are inherited from
           the kernel or, if invoked in a container, from the container manager. However, the
           following have defaults:

           •   DefaultLimitNOFILE= defaults to "1024:524288".

           •   DefaultLimitCORE= does not have a default but it is worth mentioning that
               RLIMIT_CORE is set to "infinity" by PID 1 which is inherited by its children.

           •   Note that the service manager internally increases RLIMIT_MEMLOCK for itself,
               however the limit is reverted to the original value for child processes forked
               off.

       DefaultOOMPolicy=
           Configure the default policy for reacting to processes being killed by the Linux
           Out-Of-Memory (OOM) killer. This may be used to pick a global default for the per-unit
           OOMPolicy= setting. See systemd.service(5) for details. Note that this default is not
           used for services that have Delegate= turned on.

SPECIFIERS

       Specifiers may be used in the DefaultEnvironment= and ManagerEnvironment= settings. The
       following expansions are understood:

       Table 1. Specifiers available
       ┌──────────┬──────────────────────────┬──────────────────────────┐
       │SpecifierMeaningDetails                  │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%a"      │ Architecture             │ A short string           │
       │          │                          │ identifying the          │
       │          │                          │ architecture of the      │
       │          │                          │ local system. A string   │
       │          │                          │ such as x86, x86-64 or   │
       │          │                          │ arm64. See the           │
       │          │                          │ architectures defined    │
       │          │                          │ for                      │
       │          │                          │ ConditionArchitecture=   │
       │          │                          │ in systemd.unit(5) for a │
       │          │                          │ full list.               │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%A"      │ Operating system image   │ The operating system     │
       │          │ version                  │ image version identifier │
       │          │                          │ of the running system,   │
       │          │                          │ as read from the         │
       │          │                          │ IMAGE_VERSION= field of  │
       │          │                          │ /etc/os-release. If not  │
       │          │                          │ set, resolves to an      │
       │          │                          │ empty string. See os-    │
       │          │                          │ release(5) for more      │
       │          │                          │ information.             │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%b"      │ Boot ID                  │ The boot ID of the       │
       │          │                          │ running system,          │
       │          │                          │ formatted as string. See │
       │          │                          │ random(4) for more       │
       │          │                          │ information.             │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%B"      │ Operating system build   │ The operating system     │
       │          │ ID                       │ build identifier of the  │
       │          │                          │ running system, as read  │
       │          │                          │ from the BUILD_ID= field │
       │          │                          │ of /etc/os-release. If   │
       │          │                          │ not set, resolves to an  │
       │          │                          │ empty string. See os-    │
       │          │                          │ release(5) for more      │
       │          │                          │ information.             │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%H"      │ Host name                │ The hostname of the      │
       │          │                          │ running system.          │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%l"      │ Short host name          │ The hostname of the      │
       │          │                          │ running system,          │
       │          │                          │ truncated at the first   │
       │          │                          │ dot to remove any domain │
       │          │                          │ component.               │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%m"      │ Machine ID               │ The machine ID of the    │
       │          │                          │ running system,          │
       │          │                          │ formatted as string. See │
       │          │                          │ machine-id(5) for more   │
       │          │                          │ information.             │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%M"      │ Operating system image   │ The operating system     │
       │          │ identifier               │ image identifier of the  │
       │          │                          │ running system, as read  │
       │          │                          │ from the IMAGE_ID= field │
       │          │                          │ of /etc/os-release. If   │
       │          │                          │ not set, resolves to an  │
       │          │                          │ empty string. See os-    │
       │          │                          │ release(5) for more      │
       │          │                          │ information.             │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%o"      │ Operating system ID      │ The operating system     │
       │          │                          │ identifier of the        │
       │          │                          │ running system, as read  │
       │          │                          │ from the ID= field of    │
       │          │                          │ /etc/os-release. See os- │
       │          │                          │ release(5) for more      │
       │          │                          │ information.             │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%v"      │ Kernel release           │ Identical to uname -r    │
       │          │                          │ output.                  │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%w"      │ Operating system version │ The operating system     │
       │          │ ID                       │ version identifier of    │
       │          │                          │ the running system, as   │
       │          │                          │ read from the            │
       │          │                          │ VERSION_ID= field of     │
       │          │                          │ /etc/os-release. If not  │
       │          │                          │ set, resolves to an      │
       │          │                          │ empty string. See os-    │
       │          │                          │ release(5) for more      │
       │          │                          │ information.             │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%W"      │ Operating system variant │ The operating system     │
       │          │ ID                       │ variant identifier of    │
       │          │                          │ the running system, as   │
       │          │                          │ read from the            │
       │          │                          │ VARIANT_ID= field of     │
       │          │                          │ /etc/os-release. If not  │
       │          │                          │ set, resolves to an      │
       │          │                          │ empty string. See os-    │
       │          │                          │ release(5) for more      │
       │          │                          │ information.             │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%T"      │ Directory for temporary  │ This is either /tmp or   │
       │          │ files                    │ the path "$TMPDIR",      │
       │          │                          │ "$TEMP" or "$TMP" are    │
       │          │                          │ set to. (Note that the   │
       │          │                          │ directory may be         │
       │          │                          │ specified without a      │
       │          │                          │ trailing slash.)         │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%V"      │ Directory for larger and │ This is either /var/tmp  │
       │          │ persistent temporary     │ or the path "$TMPDIR",   │
       │          │ files                    │ "$TEMP" or "$TMP" are    │
       │          │                          │ set to. (Note that the   │
       │          │                          │ directory may be         │
       │          │                          │ specified without a      │
       │          │                          │ trailing slash.)         │
       ├──────────┼──────────────────────────┼──────────────────────────┤
       │"%%"      │ Single percent sign      │ Use "%%" in place of "%" │
       │          │                          │ to specify a single      │
       │          │                          │ percent sign.            │
       └──────────┴──────────────────────────┴──────────────────────────┘

SEE ALSO

       systemd(1), systemd.directives(7), systemd.exec(5), systemd.service(5), environ(7),
       capabilities(7)

NOTES

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

        2. ENVIRONMENT
           https://systemd.io/ENVIRONMENT