systemd-system.conf(5)

—

Options · 3

1.	💣💥🧨💥💥💣 Please note that those configuration files must be available at all times. If /usr/local/ is a separate partition, it may not be available during early boot, and must not be used for configuration.
2.	No New Privileges Flag
3.	Known Environment Variables

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, /run/systemd/system.conf, /usr/lib/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, /run/systemd/user.conf, /usr/lib/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 (in order of priority, in the home directory of the user and under /etc/systemd/, /run/systemd/, and /usr/lib/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. The main configuration file is loaded from one of the listed directories in order of priority, only the first file found is used: /etc/systemd/, /run/systemd/, /usr/local/lib/systemd/ [1], /usr/lib/systemd/. The vendor version of the file contains commented out entries showing the defaults as a guide to the administrator. Local overrides can also be created by creating drop-ins, as described below. The main configuration file can also be edited for this purpose (or a copy in /etc/ if it is shipped under /usr/), however 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. This also defines a concept of drop-in priorities to allow OS vendors to ship drop-ins within a specific range lower than the range used by users. This should lower the risk of package drop-ins overriding accidentally drop-ins defined by users. It is recommended to use the range 10-40 for drop-ins in /usr/ and the range 60-90 for drop-ins in /etc/ and /run/, to make sure that local and transient drop-ins take priority over drop-ins shipped by the OS vendor.

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, CrashAction=freeze, ShowStatus=yes, DefaultStandardOutput=journal, DefaultStandardError=inherit

Added in version 198.

CtrlAltDelBurstAction=

Added in version 232.

StatusUnitFormat=

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

Added in version 243.

DefaultTimerAccuracySec=

Added in version 212.

RESOURCE MANAGEMENT

TimerSlackNSec=

Added in version 198.

CPUAffinity=

Added in version 198.

NUMAPolicy=

Added in version 243.

NUMAMask=

Added in version 243.

DefaultCPUAccounting=, DefaultMemoryAccounting=, DefaultTasksAccounting=, DefaultIOAccounting=, DefaultIPAccounting=

DefaultCPUAccounting= defaults to yes when running on kernel ≥4.15, and no on older versions. DefaultMemoryAccounting= defaults to yes. DefaultTasksAccounting= defaults to yes. The other settings default to no.

Added in version 211.

DefaultTasksMax=

Added in version 228.

DefaultLimitCPU=, DefaultLimitFSIZE=, DefaultLimitDATA=, DefaultLimitSTACK=, DefaultLimitCORE=, DefaultLimitRSS=, DefaultLimitNOFILE=, DefaultLimitAS=, DefaultLimitNPROC=, DefaultLimitMEMLOCK=, DefaultLimitLOCKS=, DefaultLimitSIGPENDING=, DefaultLimitMSGQUEUE=, DefaultLimitNICE=, DefaultLimitRTPRIO=, DefaultLimitRTTIME=

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:

Note that the service manager internally in PID 1 bumps RLIMIT_NOFILE and RLIMIT_MEMLOCK to higher values, however the limit is reverted to the mentioned defaults for all child processes forked off.

Added in version 198.

DefaultOOMPolicy=

Added in version 243.

DefaultOOMScoreAdjust=

Added in version 250.

DefaultMemoryPressureWatch=, DefaultMemoryPressureThresholdSec=

Added in version 254.

HARDWARE WATCHDOG

RuntimeWatchdogSec=, RebootWatchdogSec=, KExecWatchdogSec=

If RuntimeWatchdogSec= is set to a non-zero value, the watchdog hardware (/dev/watchdog0 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.

Added in version 198.

RuntimeWatchdogPreSec=

Added in version 251.

RuntimeWatchdogPreGovernor=

Added in version 251.

WatchdogDevice=

Added in version 236.

SECURITY

CapabilityBoundingSet=

Added in version 198.

NoNewPrivileges=

Added in version 239.

ProtectSystem=

Added in version 256.

SystemCallArchitectures=

Added in version 209.

DefaultSmackProcessLabel=

If the value is "/", only labels specified with SmackProcessLabel= are assigned and the compile-time default is ignored.

Added in version 252.

TIMEOUTS AND RATE LIMITS

DefaultTimeoutStartSec=, DefaultTimeoutStopSec=, DefaultTimeoutAbortSec=, DefaultRestartSec=

DefaultTimeoutStartSec= and DefaultTimeoutStopSec= default to 90 s in the system manager and 90 s in the user manager. DefaultTimeoutAbortSec= is not set by default so that all units fall back to TimeoutStopSec=. DefaultRestartSec= defaults to 100 ms.

Added in version 209.

DefaultDeviceTimeoutSec=

Added in version 252.

DefaultStartLimitIntervalSec=, DefaultStartLimitBurst=

Added in version 209.

ReloadLimitIntervalSec=, ReloadLimitBurst=

Added in version 253.

ENVIRONMENT

ManagerEnvironment=

Setting environment variables for the manager process may be useful to modify its behaviour. See Known Environment Variables[3] for a descriptions of some variables understood by systemd.

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

Added in version 248.

DefaultEnvironment=

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

Example:

bash

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

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

Added in version 205.

SPECIFIERS

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 image version	The operating system 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 ID	The operating system 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 identifier	The operating system 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 ID	The operating system 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 ID	The operating system 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 files	This is either /tmp or the path "$TMPDIR", "$TEMP" or "$TMP" are set to. (Note that the directory may be specified without a trailing slash.)
"%V"	Directory for larger and persistent temporary files	This is either /var/tmp or the path "$TMPDIR", "$TEMP" or "$TMP" are set to. (Note that the directory may be specified without a trailing slash.)
"%h"	User home directory	This is the home directory of the user running the service manager instance .
"%u"	Username	This is the username of the user running the service manager instance .
"%U"	User id	This is the user id of the user running the service manager instance .
"%g"	Primary group	This is the primary group of the user running the service manager instance .
"%G"	Primary group id	This is the primary group id of the user running the service manager instance .
"%s"	User shell	This is the shell of the user running the service manager instance .
"%%"	Single percent sign	Use "%%" in place of "%" to specify a single percent sign.

HISTORY

systemd 252

Added in version 252.

NOTES

1.: 💣💥🧨💥💥💣 Please note that those configuration files must be available at all times. If /usr/local/ is a separate partition, it may not be available during early boot, and must not be used for configuration.
2.: No New Privileges Flag

3.: Known Environment Variables