systemd-system.conf(5) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | CONFIGURATION DIRECTORIES AND PRECEDENCE | OPTIONS | SPECIFIERS | SEE ALSO | NOTES | COLOPHON

SYSTEMD-SYSTEM.CONF(5)     systemd-system.conf    SYSTEMD-SYSTEM.CONF(5)

NAME         top

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

SYNOPSIS         top

       /etc/systemd/system.conf, /etc/systemd/system.conf.d/*.conf,
       /run/systemd/system.conf.d/*.conf,
       /usr/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         top

       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         top

       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         top

       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 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).

       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         top

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

       Table 1. Specifiers available
       ┌──────────┬──────────────────┬────────────────────────┐
       │Specifier Meaning          Details                │
       ├──────────┼──────────────────┼────────────────────────┤
       │"%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 │ The operating system   │
       │          │ image 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 │ The operating system   │
       │          │ build 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 │ The operating system   │
       │          │ image 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 │ The operating system   │
       │          │ ID               │ 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 │ The operating system   │
       │          │ version 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 │ The operating system   │
       │          │ variant 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    │ This is either /tmp or │
       │          │ temporary files  │ the path "$TMPDIR",    │
       │          │                  │ "$TEMP" or "$TMP" are  │
       │          │                  │ set to. (Note that the │
       │          │                  │ directory may be       │
       │          │                  │ specified without a    │
       │          │                  │ trailing slash.)       │
       ├──────────┼──────────────────┼────────────────────────┤
       │"%V"      │ Directory for    │ This is either         │
       │          │ larger and       │ /var/tmp or the path   │
       │          │ persistent       │ "$TMPDIR", "$TEMP" or  │
       │          │ temporary files  │ "$TMP" are set to.     │
       │          │                  │ (Note that the         │
       │          │                  │ directory may be       │
       │          │                  │ specified without a    │
       │          │                  │ trailing slash.)       │
       ├──────────┼──────────────────┼────────────────────────┤
       │"%%"      │ Single percent   │ Use "%%" in place of   │
       │          │ sign             │ "%" to specify a       │
       │          │                  │ single percent sign.   │
       └──────────┴──────────────────┴────────────────────────┘

SEE ALSO         top

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

NOTES         top

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

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

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 2021-06-20.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-06-19.)  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-SYSTEM.CONF(5)

Pages that refer to this page: systemctl(1)systemd(1)journald.conf(5)logind.conf(5)systemd.exec(5)systemd.mount(5)systemd.resource-control(5)systemd.service(5)systemd.socket(5)systemd.swap(5)systemd.timer(5)systemd.unit(5)kernel-command-line(7)systemd.directives(7)systemd.index(7)systemd.syntax(7)systemd-oomd.service(8)