1SYSTEMD-SYSTEM.CONF(5) systemd-system.conf SYSTEMD-SYSTEM.CONF(5)
2
6 systemd-system.conf, system.conf.d, systemd-user.conf, user.conf.d -
7 System and session service manager configuration files
8
10 /etc/systemd/system.conf, /etc/systemd/system.conf.d/*.conf,
11 /run/systemd/system.conf.d/*.conf,
12 /usr/lib/systemd/system.conf.d/*.conf
13 ~/.config/systemd/user.conf, /etc/systemd/user.conf,
15 /etc/systemd/user.conf.d/*.conf, /run/systemd/user.conf.d/*.conf,
16 /usr/lib/systemd/user.conf.d/*.conf
17
19 When run as a system instance, systemd interprets the configuration
20 file system.conf and the files in system.conf.d directories; when run
21 as a user instance, it interprets the configuration file user.conf
22 (either in the home directory of the user, or if not found, under
23 /etc/systemd/) and the files in user.conf.d directories. These
24 configuration files contain a few settings controlling basic manager
25 operations.
26 See systemd.syntax(7) for a general description of the syntax.
28
30 The default configuration is set during compilation, so configuration
31 is only needed when it is necessary to deviate from those defaults.
32 Initially, the main configuration file in /etc/systemd/ contains
33 commented out entries showing the defaults as a guide to the
34 administrator. Local overrides can be created by editing this file or
35 by creating drop-ins, as described below. Using drop-ins for local
36 configuration is recommended over modifications to the main
37 configuration file.
38 In addition to the "main" configuration file, drop-in configuration
40 snippets are read from /usr/lib/systemd/*.conf.d/,
41 /usr/local/lib/systemd/*.conf.d/, and /etc/systemd/*.conf.d/. Those
42 drop-ins have higher precedence and override the main configuration
43 file. Files in the *.conf.d/ configuration subdirectories are sorted by
44 their filename in lexicographic order, regardless of in which of the
45 subdirectories they reside. When multiple files specify the same
46 option, for options which accept just a single value, the entry in the
47 file sorted last takes precedence, and for options which accept a list
48 of values, entries are collected as they occur in the sorted files.
49 When packages need to customize the configuration, they can install
51 drop-ins under /usr/. Files in /etc/ are reserved for the local
52 administrator, who may use this logic to override the configuration
53 files installed by vendor packages. Drop-ins have to be used to
54 override package drop-ins, since the main configuration file has lower
55 precedence. It is recommended to prefix all filenames in those
56 subdirectories with a two-digit number and a dash, to simplify the
57 ordering of the files.
58 To disable a configuration file supplied by the vendor, the recommended
60 way is to place a symlink to /dev/null in the configuration directory
61 in /etc/, with the same filename as the vendor configuration file.
62
64 All options are configured in the [Manager] section:
65 LogColor=, LogLevel=, LogLocation=, LogTarget=, LogTime=, DumpCore=yes,
67 CrashChangeVT=no, CrashShell=no, CrashReboot=no, ShowStatus=yes,
68 DefaultStandardOutput=journal, DefaultStandardError=inherit
69 Configures various parameters of basic manager operation. These
70 options may be overridden by the respective process and kernel
71 command line arguments. See systemd(1) for details.
72 CtrlAltDelBurstAction=
74 Defines what action will be performed if user presses
75 Ctrl-Alt-Delete more than 7 times in 2s. Can be set to
76 "reboot-force", "poweroff-force", "reboot-immediate",
77 "poweroff-immediate" or disabled with "none". Defaults to
78 "reboot-force".
79 CPUAffinity=
81 Configures the CPU affinity for the service manager as well as the
82 default CPU affinity for all forked off processes. Takes a list of
83 CPU indices or ranges separated by either whitespace or commas. CPU
84 ranges are specified by the lower and upper CPU indices separated
85 by a dash. This option may be specified more than once, in which
86 case the specified CPU affinity masks are merged. If the empty
87 string is assigned, the mask is reset, all assignments prior to
88 this will have no effect. Individual services may override the CPU
89 affinity for their processes with the CPUAffinity= setting in unit
90 files, see systemd.exec(5).
91 NUMAPolicy=
93 Configures the NUMA memory policy for the service manager and the
94 default NUMA memory policy for all forked off processes. Individual
95 services may override the default policy with the NUMAPolicy=
96 setting in unit files, see systemd.exec(5).
97 NUMAMask=
99 Configures the NUMA node mask that will be associated with the
100 selected NUMA policy. Note that default and local NUMA policies
101 don't require explicit NUMA node mask and value of the option can
102 be empty. Similarly to NUMAPolicy=, value can be overridden by
103 individual services in unit files, see systemd.exec(5).
104 RuntimeWatchdogSec=, RebootWatchdogSec=, KExecWatchdogSec=
106 Configure the hardware watchdog at runtime and at reboot. Takes a
107 timeout value in seconds (or in other time units if suffixed with
108 "ms", "min", "h", "d", "w"), or the special strings "off" or
109 "default". If set to "off" (alternatively: "0") the watchdog logic
110 is disabled: no watchdog device is opened, configured, or pinged.
111 If set to the special string "default" the watchdog is opened and
112 pinged in regular intervals, but the timeout is not changed from
113 the default. If set to any other time value the watchdog timeout is
114 configured to the specified value (or a value close to it,
115 depending on hardware capabilities).
116 If RuntimeWatchdogSec= is set to a non-zero value, the watchdog
118 hardware (/dev/watchdog0 or the path specified with WatchdogDevice=
119 or the kernel option systemd.watchdog-device=) will be programmed
120 to automatically reboot the system if it is not contacted within
121 the specified timeout interval. The system manager will ensure to
122 contact it at least once in half the specified timeout interval.
123 This feature requires a hardware watchdog device to be present, as
124 it is commonly the case in embedded and server systems. Not all
125 hardware watchdogs allow configuration of all possible reboot
126 timeout values, in which case the closest available timeout is
127 picked.
128 RebootWatchdogSec= may be used to configure the hardware watchdog
130 when the system is asked to reboot. It works as a safety net to
131 ensure that the reboot takes place even if a clean reboot attempt
132 times out. Note that the RebootWatchdogSec= timeout applies only to
133 the second phase of the reboot, i.e. after all regular services are
134 already terminated, and after the system and service manager
135 process (PID 1) got replaced by the systemd-shutdown binary, see
136 system bootup(7) for details. During the first phase of the
137 shutdown operation the system and service manager remains running
138 and hence RuntimeWatchdogSec= is still honoured. In order to define
139 a timeout on this first phase of system shutdown, configure
140 JobTimeoutSec= and JobTimeoutAction= in the [Unit] section of the
141 shutdown.target unit. By default RuntimeWatchdogSec= defaults to 0
142 (off), and RebootWatchdogSec= to 10min.
143 KExecWatchdogSec= may be used to additionally enable the watchdog
145 when kexec is being executed rather than when rebooting. Note that
146 if the kernel does not reset the watchdog on kexec (depending on
147 the specific hardware and/or driver), in this case the watchdog
148 might not get disabled after kexec succeeds and thus the system
149 might get rebooted, unless RuntimeWatchdogSec= is also enabled at
150 the same time. For this reason it is recommended to enable
151 KExecWatchdogSec= only if RuntimeWatchdogSec= is also enabled.
152 These settings have no effect if a hardware watchdog is not
154 available.
155 WatchdogDevice=
157 Configure the hardware watchdog device that the runtime and
158 shutdown watchdog timers will open and use. Defaults to
159 /dev/watchdog0. This setting has no effect if a hardware watchdog
160 is not available.
161 CapabilityBoundingSet=
163 Controls which capabilities to include in the capability bounding
164 set for PID 1 and its children. See capabilities(7) for details.
165 Takes a whitespace-separated list of capability names as read by
166 cap_from_name(3). Capabilities listed will be included in the
167 bounding set, all others are removed. If the list of capabilities
168 is prefixed with ~, all but the listed capabilities will be
169 included, the effect of the assignment inverted. Note that this
170 option also affects the respective capabilities in the effective,
171 permitted and inheritable capability sets. The capability bounding
172 set may also be individually configured for units using the
173 CapabilityBoundingSet= directive for units, but note that
174 capabilities dropped for PID 1 cannot be regained in individual
175 units, they are lost for good.
176 NoNewPrivileges=
178 Takes a boolean argument. If true, ensures that PID 1 and all its
179 children can never gain new privileges through execve(2) (e.g. via
180 setuid or setgid bits, or filesystem capabilities). Defaults to
181 false. General purpose distributions commonly rely on executables
182 with setuid or setgid bits and will thus not function properly with
183 this option enabled. Individual units cannot disable this option.
184 Also see No New Privileges Flag[1].
185 SystemCallArchitectures=
187 Takes a space-separated list of architecture identifiers. Selects
188 from which architectures system calls may be invoked on this
189 system. This may be used as an effective way to disable invocation
190 of non-native binaries system-wide, for example to prohibit
191 execution of 32-bit x86 binaries on 64-bit x86-64 systems. This
192 option operates system-wide, and acts similar to the
193 SystemCallArchitectures= setting of unit files, see systemd.exec(5)
194 for details. This setting defaults to the empty list, in which case
195 no filtering of system calls based on architecture is applied.
196 Known architecture identifiers are "x86", "x86-64", "x32", "arm"
197 and the special identifier "native". The latter implicitly maps to
198 the native architecture of the system (or more specifically, the
199 architecture the system manager was compiled for). Set this setting
200 to "native" to prohibit execution of any non-native binaries. When
201 a binary executes a system call of an architecture that is not
202 listed in this setting, it will be immediately terminated with the
203 SIGSYS signal.
204 TimerSlackNSec=
206 Sets the timer slack in nanoseconds for PID 1, which is inherited
207 by all executed processes, unless overridden individually, for
208 example with the TimerSlackNSec= setting in service units (for
209 details see systemd.exec(5)). The timer slack controls the accuracy
210 of wake-ups triggered by system timers. See prctl(2) for more
211 information. Note that in contrast to most other time span
212 definitions this parameter takes an integer value in nano-seconds
213 if no unit is specified. The usual time units are understood too.
214 StatusUnitFormat=
216 Takes name, description or combined as the value. If name, the
217 system manager will use unit names in status messages (e.g.
218 "systemd-journald.service"), instead of the longer and more
219 informative descriptions set with Description= (e.g. "Journal
220 Logging Service"). If combined, the system manager will use both
221 unit names and descriptions in status messages (e.g.
222 "systemd-journald.service - Journal Logging Service").
223 See systemd.unit(5) for details about unit names and Description=.
225 DefaultTimerAccuracySec=
227 Sets the default accuracy of timer units. This controls the global
228 default for the AccuracySec= setting of timer units, see
229 systemd.timer(5) for details. AccuracySec= set in individual units
230 override the global default for the specific unit. Defaults to
231 1min. Note that the accuracy of timer units is also affected by the
232 configured timer slack for PID 1, see TimerSlackNSec= above.
233 DefaultTimeoutStartSec=, DefaultTimeoutStopSec=,
235 DefaultTimeoutAbortSec=, DefaultRestartSec=
236 Configures the default timeouts for starting, stopping and aborting
237 of units, as well as the default time to sleep between automatic
238 restarts of units, as configured per-unit in TimeoutStartSec=,
239 TimeoutStopSec=, TimeoutAbortSec= and RestartSec= (for services,
240 see systemd.service(5) for details on the per-unit settings).
241 Disabled by default, when service with Type=oneshot is used. For
242 non-service units, DefaultTimeoutStartSec= sets the default
243 TimeoutSec= value. DefaultTimeoutStartSec= and
244 DefaultTimeoutStopSec= default to 90s. DefaultTimeoutAbortSec= is
245 not set by default so that all units fall back to TimeoutStopSec=.
246 DefaultRestartSec= defaults to 100ms.
247 DefaultStartLimitIntervalSec=, DefaultStartLimitBurst=
249 Configure the default unit start rate limiting, as configured
250 per-service by StartLimitIntervalSec= and StartLimitBurst=. See
251 systemd.service(5) for details on the per-service settings.
252 DefaultStartLimitIntervalSec= defaults to 10s.
253 DefaultStartLimitBurst= defaults to 5.
254 DefaultEnvironment=
256 Configures environment variables passed to all executed processes.
257 Takes a space-separated list of variable assignments. See
258 environ(7) for details about environment variables.
259 Simple "%"-specifier expansion is supported, see below for a list
261 of supported specifiers.
262 Example:
264 DefaultEnvironment="VAR1=word1 word2" VAR2=word3 "VAR3=word 5 6"
266 Sets three variables "VAR1", "VAR2", "VAR3".
268 ManagerEnvironment=
270 Takes the same arguments as DefaultEnvironment=, see above. Sets
271 environment variables just for the manager process itself. In
272 contrast to user managers, these variables are not inherited by
273 processes spawned by the system manager, use DefaultEnvironment=
274 for that. Note that these variables are merged into the existing
275 environment block. In particular, in case of the system manager,
276 this includes variables set by the kernel based on the kernel
277 command line.
278 Setting environment variables for the manager process may be useful
280 to modify its behaviour. See ENVIRONMENT[2] for a descriptions of
281 some variables understood by systemd.
282 Simple "%"-specifier expansion is supported, see below for a list
284 of supported specifiers.
285 DefaultCPUAccounting=, DefaultBlockIOAccounting=,
287 DefaultMemoryAccounting=, DefaultTasksAccounting=,
288 DefaultIOAccounting=, DefaultIPAccounting=
289 Configure the default resource accounting settings, as configured
290 per-unit by CPUAccounting=, BlockIOAccounting=, MemoryAccounting=,
291 TasksAccounting=, IOAccounting= and IPAccounting=. See
292 systemd.resource-control(5) for details on the per-unit settings.
293 DefaultTasksAccounting= defaults to yes, DefaultMemoryAccounting=
294 to yes. DefaultCPUAccounting= defaults to yes if enabling CPU
295 accounting doesn't require the CPU controller to be enabled (Linux
296 4.15+ using the unified hierarchy for resource control), otherwise
297 it defaults to no. The other three settings default to no.
298 DefaultTasksMax=
300 Configure the default value for the per-unit TasksMax= setting. See
301 systemd.resource-control(5) for details. This setting applies to
302 all unit types that support resource control settings, with the
303 exception of slice units. Defaults to 15% of the minimum of
304 kernel.pid_max=, kernel.threads-max= and root cgroup pids.max.
305 Kernel has a default value for kernel.pid_max= and an algorithm of
306 counting in case of more than 32 cores. For example with the
307 default kernel.pid_max=, DefaultTasksMax= defaults to 4915, but
308 might be greater in other systems or smaller in OS containers.
309 DefaultLimitCPU=, DefaultLimitFSIZE=, DefaultLimitDATA=,
311 DefaultLimitSTACK=, DefaultLimitCORE=, DefaultLimitRSS=,
312 DefaultLimitNOFILE=, DefaultLimitAS=, DefaultLimitNPROC=,
313 DefaultLimitMEMLOCK=, DefaultLimitLOCKS=, DefaultLimitSIGPENDING=,
314 DefaultLimitMSGQUEUE=, DefaultLimitNICE=, DefaultLimitRTPRIO=,
315 DefaultLimitRTTIME=
316 These settings control various default resource limits for
317 processes executed by units. See setrlimit(2) for details. These
318 settings may be overridden in individual units using the
319 corresponding LimitXXX= directives and they accept the same
320 parameter syntax, see systemd.exec(5) for details. Note that these
321 resource limits are only defaults for units, they are not applied
322 to the service manager process (i.e. PID 1) itself.
323 Most of these settings are unset, which means the resource limits
325 are inherited from the kernel or, if invoked in a container, from
326 the container manager. However, the following have defaults:
327 • DefaultLimitNOFILE= defaults to "1024:524288".
329 • DefaultLimitCORE= does not have a default but it is worth
331 mentioning that RLIMIT_CORE is set to "infinity" by PID 1 which
332 is inherited by its children.
333 • Note that the service manager internally increases
335 RLIMIT_MEMLOCK for itself, however the limit is reverted to the
336 original value for child processes forked off.
337 DefaultOOMPolicy=
339 Configure the default policy for reacting to processes being killed
340 by the Linux Out-Of-Memory (OOM) killer. This may be used to pick a
341 global default for the per-unit OOMPolicy= setting. See
342 systemd.service(5) for details. Note that this default is not used
343 for services that have Delegate= turned on.
344 DefaultOOMScoreAdjust=
346 Configures the default OOM score adjustments of processes run by
347 the service manager. This defaults to unset (meaning the forked off
348 processes inherit the service manager's OOM score adjustment
349 value), except if the service manager is run for an unprivileged
350 user, in which case this defaults to the service manager's OOM
351 adjustment value plus 100 (this makes service processes slightly
352 more likely to be killed under memory pressure than the manager
353 itself). This may be used to pick a global default for the per-unit
354 OOMScoreAdjust= setting. See systemd.exec(5) for details. Note that
355 this setting has no effect on the OOM score adjustment value of the
356 service manager process itself, it retains the original value set
357 during its invocation.
358
360 Specifiers may be used in the DefaultEnvironment= and
361 ManagerEnvironment= settings. The following expansions are understood:
362 Table 1. Specifiers available
364 ┌──────────┬─────────────────────┬────────────────────────┐
365 │Specifier │ Meaning │ Details │
366 ├──────────┼─────────────────────┼────────────────────────┤
367 │"%a" │ Architecture │ A short string │
368 │ │ │ identifying the │
369 │ │ │ architecture of the │
370 │ │ │ local system. A │
371 │ │ │ string such as x86, │
372 │ │ │ x86-64 or arm64. │
373 │ │ │ See the │
374 │ │ │ architectures │
375 │ │ │ defined for │
376 │ │ │ ConditionArchitecture= │
377 │ │ │ in systemd.unit(5) │
378 │ │ │ for a full list. │
379 ├──────────┼─────────────────────┼────────────────────────┤
380 │"%A" │ Operating system │ The operating system │
381 │ │ image version │ image version │
382 │ │ │ identifier of the │
383 │ │ │ running system, as │
384 │ │ │ read from the │
385 │ │ │ IMAGE_VERSION= field │
386 │ │ │ of /etc/os-release. If │
387 │ │ │ not set, resolves to │
388 │ │ │ an empty string. See │
389 │ │ │ os-release(5) for more │
390 │ │ │ information. │
391 ├──────────┼─────────────────────┼────────────────────────┤
392 │"%b" │ Boot ID │ The boot ID of the │
393 │ │ │ running system, │
394 │ │ │ formatted as string. │
395 │ │ │ See random(4) for more │
396 │ │ │ information. │
397 ├──────────┼─────────────────────┼────────────────────────┤
398 │"%B" │ Operating system │ The operating system │
399 │ │ build ID │ build identifier of │
400 │ │ │ the running system, as │
401 │ │ │ read from the │
402 │ │ │ BUILD_ID= field of │
403 │ │ │ /etc/os-release. If │
404 │ │ │ not set, resolves to │
405 │ │ │ an empty string. See │
406 │ │ │ os-release(5) for more │
407 │ │ │ information. │
408 ├──────────┼─────────────────────┼────────────────────────┤
409 │"%H" │ Host name │ The hostname of the │
410 │ │ │ running system. │
411 ├──────────┼─────────────────────┼────────────────────────┤
412 │"%l" │ Short host name │ The hostname of the │
413 │ │ │ running system, │
414 │ │ │ truncated at the first │
415 │ │ │ dot to remove any │
416 │ │ │ domain component. │
417 ├──────────┼─────────────────────┼────────────────────────┤
418 │"%m" │ Machine ID │ The machine ID of the │
419 │ │ │ running system, │
420 │ │ │ formatted as string. │
421 │ │ │ See machine-id(5) for │
422 │ │ │ more information. │
423 ├──────────┼─────────────────────┼────────────────────────┤
424 │"%M" │ Operating system │ The operating system │
425 │ │ image identifier │ image identifier of │
426 │ │ │ the running system, as │
427 │ │ │ read from the │
428 │ │ │ IMAGE_ID= field of │
429 │ │ │ /etc/os-release. If │
430 │ │ │ not set, resolves to │
431 │ │ │ an empty string. See │
432 │ │ │ os-release(5) for more │
433 │ │ │ information. │
434 ├──────────┼─────────────────────┼────────────────────────┤
435 │"%o" │ Operating system ID │ The operating system │
436 │ │ │ identifier of the │
437 │ │ │ running system, as │
438 │ │ │ read from the ID= │
439 │ │ │ field of │
440 │ │ │ /etc/os-release. See │
441 │ │ │ os-release(5) for more │
442 │ │ │ information. │
443 ├──────────┼─────────────────────┼────────────────────────┤
444 │"%v" │ Kernel release │ Identical to uname -r │
445 │ │ │ output. │
446 ├──────────┼─────────────────────┼────────────────────────┤
447 │"%w" │ Operating system │ The operating system │
448 │ │ version ID │ version identifier of │
449 │ │ │ the running system, as │
450 │ │ │ read from the │
451 │ │ │ VERSION_ID= field of │
452 │ │ │ /etc/os-release. If │
453 │ │ │ not set, resolves to │
454 │ │ │ an empty string. See │
455 │ │ │ os-release(5) for more │
456 │ │ │ information. │
457 ├──────────┼─────────────────────┼────────────────────────┤
458 │"%W" │ Operating system │ The operating system │
459 │ │ variant ID │ variant identifier of │
460 │ │ │ the running system, as │
461 │ │ │ read from the │
462 │ │ │ VARIANT_ID= field of │
463 │ │ │ /etc/os-release. If │
464 │ │ │ not set, resolves to │
465 │ │ │ an empty string. See │
466 │ │ │ os-release(5) for more │
467 │ │ │ information. │
468 ├──────────┼─────────────────────┼────────────────────────┤
469 │"%T" │ Directory for │ This is either /tmp or │
470 │ │ temporary files │ the path "$TMPDIR", │
471 │ │ │ "$TEMP" or "$TMP" are │
472 │ │ │ set to. (Note that the │
473 │ │ │ directory may be │
474 │ │ │ specified without a │
475 │ │ │ trailing slash.) │
476 ├──────────┼─────────────────────┼────────────────────────┤
477 │"%V" │ Directory for │ This is either │
478 │ │ larger and │ /var/tmp or the path │
479 │ │ persistent │ "$TMPDIR", "$TEMP" or │
480 │ │ temporary files │ "$TMP" are set to. │
481 │ │ │ (Note that the │
482 │ │ │ directory may be │
483 │ │ │ specified without a │
484 │ │ │ trailing slash.) │
485 ├──────────┼─────────────────────┼────────────────────────┤
486 │"%%" │ Single percent sign │ Use "%%" in place of │
487 │ │ │ "%" to specify a │
488 │ │ │ single percent sign. │
489 └──────────┴─────────────────────┴────────────────────────┘
490
492 systemd(1), systemd.directives(7), systemd.exec(5), systemd.service(5),
493 environ(7), capabilities(7)
494
496 1. No New Privileges Flag
497 https://www.kernel.org/doc/html/latest/userspace-api/no_new_privs.html
498 2. ENVIRONMENT
500 https://systemd.io/ENVIRONMENT
501systemd 250 SYSTEMD-SYSTEM.CONF(5)