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's 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
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.
Added in version 198.
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".
Added in version 232.
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=.
Added in version 243.
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.
Added in version 212.
RESOURCE MANAGEMENT¶
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.
Added in version 198.
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).
Added in version 198.
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).
Added in version 243.
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).
Added in version 243.
DefaultCPUAccounting=, DefaultMemoryAccounting=,
DefaultTasksAccounting=, DefaultIOAccounting=,
DefaultIPAccounting=
Configure the default resource accounting settings, as
configured per-unit by
CPUAccounting=,
MemoryAccounting=,
TasksAccounting=,
IOAccounting= and
IPAccounting=. See
systemd.resource-control(5) for details on the per-unit settings.
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=
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.
Added in version 228.
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 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=
Configure the default policy for reacting to processes
being killed by the Linux Out-Of-Memory (OOM) killer or
systemd-oomd.
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.
Added in version 243.
DefaultOOMScoreAdjust=
Configures the default OOM score adjustments of processes
run by the service manager. This defaults to unset (meaning the forked off
processes inherit the service manager's OOM score adjustment value), except if
the service manager is run for an unprivileged user, in which case this
defaults to the service manager's OOM adjustment value plus 100 (this makes
service processes slightly more likely to be killed under memory pressure than
the manager itself). This may be used to pick a global default for the
per-unit
OOMScoreAdjust= setting. See
systemd.exec(5) for
details. Note that this setting has no effect on the OOM score adjustment
value of the service manager process itself, it retains the original value set
during its invocation.
Added in version 250.
DefaultMemoryPressureWatch=,
DefaultMemoryPressureThresholdSec=
Configures the default settings for the per-unit
MemoryPressureWatch= and
MemoryPressureThresholdSec= settings.
See
systemd.resource-control(5) for details. Defaults to
"auto" and "200ms", respectively. This also sets the
memory pressure monitoring threshold for the service manager itself.
Added in version 254.
HARDWARE WATCHDOG¶
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"),
or the special strings "off" or "default". If set to
"off" (alternatively: "0") the watchdog logic is disabled:
no watchdog device is opened, configured, or pinged. If set to the special
string "default" the watchdog is opened and pinged in regular
intervals, but the timeout is not changed from the default. If set to any
other time value the watchdog timeout is configured to the specified value (or
a value close to it, depending on hardware capabilities).
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=
Configure the hardware watchdog device pre-timeout value.
Takes a timeout value in seconds (or in other time units similar to
RuntimeWatchdogSec=). A watchdog pre-timeout is a notification
generated by the watchdog before the watchdog reset might occur in the event
the watchdog has not been serviced. This notification is handled by the kernel
and can be configured to take an action (i.e. generate a kernel panic) using
RuntimeWatchdogPreGovernor=. Not all watchdog hardware or drivers
support generating a pre-timeout and depending on the state of the system, the
kernel may be unable to take the configured action before the watchdog reboot.
The watchdog will be configured to generate the pre-timeout event at the
amount of time specified by
RuntimeWatchdogPreSec= before the runtime
watchdog timeout (set by
RuntimeWatchdogSec=). For example, if the we
have
RuntimeWatchdogSec=30 and
RuntimeWatchdogPreSec=10, then
the pre-timeout event will occur if the watchdog has not pinged for 20s (10s
before the watchdog would fire). By default,
RuntimeWatchdogPreSec=
defaults to 0 (off). The value set for
RuntimeWatchdogPreSec= must be
smaller than the timeout value for
RuntimeWatchdogSec=. This setting
has no effect if a hardware watchdog is not available or the hardware watchdog
does not support a pre-timeout and will be ignored by the kernel if the
setting is greater than the actual watchdog timeout.
Added in version 251.
RuntimeWatchdogPreGovernor=
Configure the action taken by the hardware watchdog
device when the pre-timeout expires. The default action for the pre-timeout
event depends on the kernel configuration, but it is usually to log a kernel
message. For a list of valid actions available for a given watchdog device,
check the content of the
/sys/class/watchdog/watchdog
X/pretimeout_available_governors file.
Typically, available governor types are
noop and
panic.
Availability, names and functionality might vary depending on the specific
device driver in use. If the pretimeout_available_governors sysfs file is
empty, the governor might be built as a kernel module and might need to be
manually loaded (e.g.
pretimeout_noop.ko), or the watchdog device might
not support pre-timeouts.
Added in version 251.
WatchdogDevice=
Configure the hardware watchdog device that the runtime
and shutdown watchdog timers will open and use. Defaults to /dev/watchdog0.
This setting has no effect if a hardware watchdog is not available.
Added in version 236.
SECURITY¶
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.
Added in version 198.
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[2].
Added in version 239.
ProtectSystem=
Takes a boolean argument or the string "auto".
If set to true this will remount /usr/ read-only. If set to "auto"
(the default) and running in an initrd equivalent to true, otherwise false.
This implements a restricted subset of the per-unit setting of the same name,
see
systemd.exec(5) for details: currently, the "full" or
"strict" values are not supported.
Added in version 256.
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.
Added in version 209.
DefaultSmackProcessLabel=
Takes a
SMACK64 security label as the argument.
The process executed by a unit will be started under this label if
SmackProcessLabel= is not set in the unit. See
systemd.exec(5)
for the details.
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=
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).
For non-service units,
DefaultTimeoutStartSec= sets the default
TimeoutSec= value.
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=
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 90 s in the system manager and 90 s in the
user manager.
Added in version 252.
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.
Added in version 209.
ReloadLimitIntervalSec=, ReloadLimitBurst=
Rate limiting for daemon-reload and (since v256)
daemon-reexec requests. The setting applies to both operations, but the rate
limits are tracked separately. Defaults to unset, and any number of operations
can be requested at any time.
ReloadLimitIntervalSec= takes a value in
seconds to configure the rate limit window, and
ReloadLimitBurst= takes
a positive integer to configure the maximum allowed number of operations
within the configured time window.
Added in version 253.
ENVIRONMENT¶
ManagerEnvironment=
Takes the same arguments as
DefaultEnvironment=,
see above. Sets environment variables for the manager process itself. These
variables are inherited by processes spawned by user managers, but not 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. As with
DefaultEnvironment=, this environment
block is internal, and changes are not reflected in the manager's
/proc/PID/environ.
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=
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".
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
Option
DefaultBlockIOAccounting= was deprecated.
Please switch to the unified cgroup hierarchy.
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