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

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

          /etc/systemd/user.conf, /etc/systemd/user.conf.d/*.conf,

          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,
          systemd interprets the configuration file user.conf 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

          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

          In addition to the "main" configuration file, drop-in
          configuration snippets are read from
          /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

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          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.

          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.

              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".

              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).

              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

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              files, see systemd.exec(5).

              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 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

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              KExecWatchdogSec= only if RuntimeWatchdogSec= is also
              enabled. These settings have no effect if a hardware
              watchdog is not available.

              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.

              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.

              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 m[blue]No New
              Privileges Flagm[][1].

              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

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              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.

              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.

              Takes either name or description as the value. If name,
              the system manager will use unit names in status
              messages, instead of the longer and more informative
              descriptions set with Description=, see systemd.unit(5).

              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=

          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.

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          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.

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


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

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

          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.

              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=,

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          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.

              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.

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

           1. No New Privileges Flag

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