systemd-system.conf
From: https://manpages.ubuntu.com/manpages/jammy/man5/systemd-system.conf.5.html
jammy (5) systemd-system.conf.5.gz
Provided by: systemd_249.11-0ubuntu3_amd64 bug
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
~/.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
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
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
default-standard-error
ctrl-alt-del-burst
cpu-affinity
NUMA Policy
NUMA Mask
Run Time Watchdog
Watch Dog Device
Capability Bonding
No New Privileges
System Call Architecture
Timer Slack NSec
Status Unit Format
Default Timeout Start
Default Environment
Manager Environment
Default CPU Accounting
Default Tasks Max
Default Limit
Default OOM Policy
Specifiers
See Also
notes
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 name, description or combined as the value. If name, the system manager
will use unit names in status messages (e.g. "systemd-journald.service"),
instead of the longer and more informative descriptions set with Description=
(e.g. "Journal Logging Service"). If combined, the system manager will use both
unit names and descriptions in status messages (e.g. "systemd-journald.service
- Journal Logging Service").
See systemd.unit(5) for details about unit names and Description=.
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.
Default Timeout
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.
DefaultStartLimitInterval
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=, D
efaultMemoryAccounting=,
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.
DefaultLimit
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".
- DefaultLimitMEMLOCK= defaults to 8M.
- 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
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 | The operating system
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.
│
├──────────┼───
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│"%b" │ Boot ID │ The boot ID of the
│
│ │ │ running system,
│
│ │ │ formatted as string.
See │
│ │ │ random(4) for more
│
│ │ │ information.
│
├──────────┼───
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│"%B" │ Operating system build │ The operating system
│
│ │ 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.
│
├──────────┼───
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│"%H" │ Host name │ The hostname of the
│
│ │ │ running system.
│
├──────────┼───
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│"%l" │ Short host name │ The hostname of the
│
│ │ │ running system,
│
│ │ │ truncated at the first
│
│ │ │ dot to remove any
domain │
│ │ │ component.
│
├──────────┼───
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│"%m" │ Machine ID │ The machine ID of the
│
│ │ │ running system,
│
│ │ │ formatted as string.
See │
│ │ │ machine-id(5) for more
│
│ │ │ information.
│
├──────────┼───
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│"%M" │ Operating system image │ The operating system
│
│ │ 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.
│
├──────────┼───
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│"%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.
│
├──────────┼───
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│"%v" │ Kernel release │ Identical to uname -r
│
│ │ │ output.
│
├──────────┼───
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│"%w" │ Operating system version │ The operating system
│
│ │ 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.
│
├──────────┼───
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│"%W" │ Operating system variant │ The operating system
│
│ │ 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.
│
├──────────┼───
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│"%T" │ Directory for temporary │ This is either /tmp or
│
│ │ files │ the path "$TMPDIR",
│
│ │ │ "$TEMP" or "$TMP" are
│
│ │ │ set to. (Note that the
│
│ │ │ directory may be
│
│ │ │ specified without a
│
│ │ │ trailing slash.)
│
├──────────┼───
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│"%V" │ Directory for larger and │ This is either
/var/tmp
│
│ │ persistent temporary │ or the path "$TMPDIR",
│
│ │ files │ "$TEMP" or "$TMP" are
│
│ │ │ set to. (Note that the
│
│ │ │ directory may be
│
│ │ │ specified without a
│
│ │ │ trailing slash.)
│
├──────────┼───
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│"%%" │ Single percent sign │ Use "%%" in place of
"%" │
│ │ │ to specify a single
│
│ │ │ percent sign.
│
└──────────┴───
─────────────────â
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SEE ALSO
- systemd(1), systemd.directives(7), systemd.exec(5), systemd.service(5),
environ(7),
capabilities(7)
NOTES
- No New Privileges Flag
https://www.kernel.org/doc/html/latest/userspace-api/no_new_privs.html
- ENVIRONMENT
https://systemd.io/ENVIRONMENT
|