SYSTEMD-SYSTEM.CONF(5) systemd-system.conf SYSTEMD-SYSTEM.CONF(5)
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
/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, 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(5) for a general description of the syntax.
CONFIGURATION DIRECTORIES AND PRECEDENCE
The default configuration is defined during compilation, so a
configuration file is only needed when it is necessary to deviate from
those defaults. By default, the configuration file in /etc/systemd/
contains commented out entries showing the defaults as a guide to the
administrator. This file can be edited to create local overrides.
When packages need to customize the configuration, they can install
configuration snippets in /usr/lib/systemd/*.conf.d/ or
/usr/local/lib/systemd/*.conf.d/. The main configuration file is read
before any of the configuration directories, and has the lowest
precedence; entries in a file in any configuration directory override
entries in the single 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 with the
lexicographically latest name takes precedence. For options which
accept a list of values, entries are collected as they occur in files
sorted lexicographically.
Files in /etc/ are reserved for the local administrator, who may use
this logic to override the configuration files installed by vendor
packages. 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:
LogLevel=, LogTarget=, LogColor=, LogLocation=, 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=
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.
Example:
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.
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.
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, see systemd.exec(5), for
details, and they accept the same parameter syntax. Note that these
resource limits are only defaults for units, they are not applied
to the service manager process (i.e. PID 1) itself.
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.
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
systemd 245 SYSTEMD-SYSTEM.CONF(5)