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,
/usr/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/. Files in /etc/
are reserved for the local administrator, who may use this logic to
override the configuration files installed by vendor packages. 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 which of the subdirectories they
reside in. 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. 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).
JoinControllers=cpu,cpuacct net_cls,netprio
Configures controllers that shall be mounted in a single hierarchy.
By default, systemd will mount all controllers which are enabled in
the kernel in individual hierarchies, with the exception of those
listed in this setting. Takes a space-separated list of
comma-separated controller names, in order to allow multiple joined
hierarchies. Defaults to 'cpu,cpuacct'. Pass an empty string to
ensure that systemd mounts all controllers in separate hierarchies.
Note that this option is only applied once, at very early boot. If
you use an initial RAM disk (initrd) that uses systemd, it might
hence be necessary to rebuild the initrd if this option is changed,
and make sure the new configuration file is included in it.
Otherwise, the initrd might mount the controller hierarchies in a
different configuration than intended, and the main system cannot
remount them anymore.
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 overriden by
individual services in unit files, see systemd.exec(5).
RuntimeWatchdogSec=, ShutdownWatchdogSec=
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.
ShutdownWatchdogSec= 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 ShutdownWatchdogSec= 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 ShutdownWatchdogSec= to 10min. 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.
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=, DefaultRestartSec=
Configures the default timeouts for starting and stopping of units,
as well as the default time to sleep between automatic restarts of
units, as configured per-unit in TimeoutStartSec=, TimeoutStopSec=
and RestartSec= (for services, see systemd.service(5) for details
on the per-unit settings). For non-service units,
DefaultTimeoutStartSec= sets the default TimeoutSec= value.
DefaultTimeoutStartSec= and DefaultTimeoutStopSec= default to 90s.
DefaultRestartSec= defaults to 100ms.
DefaultDeviceTimeoutSec=
Configures the default timeout for waiting for devices. It can be
changed per device via the x-systemd.device-timeout= option in
/etc/fstab and /etc/crypttab (see systemd.mount(5), crypttab(5)).
Defaults to 90s.
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=, DefaultIPAccounting=
Configure the default resource accounting settings, as configured
per-unit by CPUAccounting=, BlockIOAccounting=, MemoryAccounting=,
TasksAccounting= and IPAccounting=. See systemd.resource-control(5)
for details on the per-unit settings. DefaultTasksAccounting=
defaults to on, DefaultMemoryAccounting= to yes, the other three
settings to off.
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 80%, which equals 26214 with
the kernel's defaults on the host, but might be 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 units.
See setrlimit(2) for details. The resource limit is possible to
specify in two formats, value to set soft and hard limits to the
same value, or soft:hard to set both limits individually (e.g.
DefaultLimitAS=4G:16G). Use the string infinity to configure no
limit on a specific resource. The multiplicative suffixes K
(=1024), M (=1024*1024) and so on for G, T, P and E may be used for
resource limits measured in bytes (e.g. DefaultLimitAS=16G). For
the limits referring to time values, the usual time units ms, s,
min, h and so on may be used (see systemd.time(7) for details).
Note that if no time unit is specified for DefaultLimitCPU= the
default unit of seconds is implied, while for DefaultLimitRTTIME=
the default unit of microseconds is implied. Also, note that the
effective granularity of the limits might influence their
enforcement. For example, time limits specified for
DefaultLimitCPU= will be rounded up implicitly to multiples of 1s.
These settings may be overridden in individual units using the
corresponding LimitXXX= directives. Note that these resource limits
are only defaults for units, they are not applied to PID 1 itself.
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 239 SYSTEMD-SYSTEM.CONF(5)
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