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"). If RuntimeWatchdogSec= is set to a
109 non-zero value, the watchdog hardware (/dev/watchdog or the path
110 specified with WatchdogDevice= or the kernel option
111 systemd.watchdog-device=) will be programmed to automatically
112 reboot the system if it is not contacted within the specified
113 timeout interval. The system manager will ensure to contact it at
114 least once in half the specified timeout interval. This feature
115 requires a hardware watchdog device to be present, as it is
116 commonly the case in embedded and server systems. Not all hardware
117 watchdogs allow configuration of all possible reboot timeout
118 values, in which case the closest available timeout is picked.
119 RebootWatchdogSec= may be used to configure the hardware watchdog
120 when the system is asked to reboot. It works as a safety net to
121 ensure that the reboot takes place even if a clean reboot attempt
122 times out. Note that the RebootWatchdogSec= timeout applies only to
123 the second phase of the reboot, i.e. after all regular services are
124 already terminated, and after the system and service manager
125 process (PID 1) got replaced by the systemd-shutdown binary, see
126 system bootup(7) for details. During the first phase of the
127 shutdown operation the system and service manager remains running
128 and hence RuntimeWatchdogSec= is still honoured. In order to define
129 a timeout on this first phase of system shutdown, configure
130 JobTimeoutSec= and JobTimeoutAction= in the [Unit] section of the
131 shutdown.target unit. By default RuntimeWatchdogSec= defaults to 0
132 (off), and RebootWatchdogSec= to 10min. KExecWatchdogSec= may be
133 used to additionally enable the watchdog when kexec is being
134 executed rather than when rebooting. Note that if the kernel does
135 not reset the watchdog on kexec (depending on the specific hardware
136 and/or driver), in this case the watchdog might not get disabled
137 after kexec succeeds and thus the system might get rebooted, unless
138 RuntimeWatchdogSec= is also enabled at the same time. For this
139 reason it is recommended to enable KExecWatchdogSec= only if
140 RuntimeWatchdogSec= is also enabled. These settings have no effect
141 if a hardware watchdog is not available.
142 WatchdogDevice=
144 Configure the hardware watchdog device that the runtime and
145 shutdown watchdog timers will open and use. Defaults to
146 /dev/watchdog. This setting has no effect if a hardware watchdog is
147 not available.
148 CapabilityBoundingSet=
150 Controls which capabilities to include in the capability bounding
151 set for PID 1 and its children. See capabilities(7) for details.
152 Takes a whitespace-separated list of capability names as read by
153 cap_from_name(3). Capabilities listed will be included in the
154 bounding set, all others are removed. If the list of capabilities
155 is prefixed with ~, all but the listed capabilities will be
156 included, the effect of the assignment inverted. Note that this
157 option also affects the respective capabilities in the effective,
158 permitted and inheritable capability sets. The capability bounding
159 set may also be individually configured for units using the
160 CapabilityBoundingSet= directive for units, but note that
161 capabilities dropped for PID 1 cannot be regained in individual
162 units, they are lost for good.
163 NoNewPrivileges=
165 Takes a boolean argument. If true, ensures that PID 1 and all its
166 children can never gain new privileges through execve(2) (e.g. via
167 setuid or setgid bits, or filesystem capabilities). Defaults to
168 false. General purpose distributions commonly rely on executables
169 with setuid or setgid bits and will thus not function properly with
170 this option enabled. Individual units cannot disable this option.
171 Also see No New Privileges Flag[1].
172 SystemCallArchitectures=
174 Takes a space-separated list of architecture identifiers. Selects
175 from which architectures system calls may be invoked on this
176 system. This may be used as an effective way to disable invocation
177 of non-native binaries system-wide, for example to prohibit
178 execution of 32-bit x86 binaries on 64-bit x86-64 systems. This
179 option operates system-wide, and acts similar to the
180 SystemCallArchitectures= setting of unit files, see systemd.exec(5)
181 for details. This setting defaults to the empty list, in which case
182 no filtering of system calls based on architecture is applied.
183 Known architecture identifiers are "x86", "x86-64", "x32", "arm"
184 and the special identifier "native". The latter implicitly maps to
185 the native architecture of the system (or more specifically, the
186 architecture the system manager was compiled for). Set this setting
187 to "native" to prohibit execution of any non-native binaries. When
188 a binary executes a system call of an architecture that is not
189 listed in this setting, it will be immediately terminated with the
190 SIGSYS signal.
191 TimerSlackNSec=
193 Sets the timer slack in nanoseconds for PID 1, which is inherited
194 by all executed processes, unless overridden individually, for
195 example with the TimerSlackNSec= setting in service units (for
196 details see systemd.exec(5)). The timer slack controls the accuracy
197 of wake-ups triggered by system timers. See prctl(2) for more
198 information. Note that in contrast to most other time span
199 definitions this parameter takes an integer value in nano-seconds
200 if no unit is specified. The usual time units are understood too.
201 StatusUnitFormat=
203 Takes name, description or combined as the value. If name, the
204 system manager will use unit names in status messages (e.g.
205 "systemd-journald.service"), instead of the longer and more
206 informative descriptions set with Description= (e.g. "Journal
207 Logging Service"). If combined, the system manager will use both
208 unit names and descriptions in status messages (e.g.
209 "systemd-journald.service - Journal Logging Service").
210 See systemd.unit(5) for details about unit names and Description=.
212 DefaultTimerAccuracySec=
214 Sets the default accuracy of timer units. This controls the global
215 default for the AccuracySec= setting of timer units, see
216 systemd.timer(5) for details. AccuracySec= set in individual units
217 override the global default for the specific unit. Defaults to
218 1min. Note that the accuracy of timer units is also affected by the
219 configured timer slack for PID 1, see TimerSlackNSec= above.
220 DefaultTimeoutStartSec=, DefaultTimeoutStopSec=,
222 DefaultTimeoutAbortSec=, DefaultRestartSec=
223 Configures the default timeouts for starting, stopping and aborting
224 of units, as well as the default time to sleep between automatic
225 restarts of units, as configured per-unit in TimeoutStartSec=,
226 TimeoutStopSec=, TimeoutAbortSec= and RestartSec= (for services,
227 see systemd.service(5) for details on the per-unit settings).
228 Disabled by default, when service with Type=oneshot is used. For
229 non-service units, DefaultTimeoutStartSec= sets the default
230 TimeoutSec= value. DefaultTimeoutStartSec= and
231 DefaultTimeoutStopSec= default to 90s. DefaultTimeoutAbortSec= is
232 not set by default so that all units fall back to TimeoutStopSec=.
233 DefaultRestartSec= defaults to 100ms.
234 DefaultStartLimitIntervalSec=, DefaultStartLimitBurst=
236 Configure the default unit start rate limiting, as configured
237 per-service by StartLimitIntervalSec= and StartLimitBurst=. See
238 systemd.service(5) for details on the per-service settings.
239 DefaultStartLimitIntervalSec= defaults to 10s.
240 DefaultStartLimitBurst= defaults to 5.
241 DefaultEnvironment=
243 Configures environment variables passed to all executed processes.
244 Takes a space-separated list of variable assignments. See
245 environ(7) for details about environment variables.
246 Simple "%"-specifier expansion is supported, see below for a list
248 of supported specifiers.
249 Example:
251 DefaultEnvironment="VAR1=word1 word2" VAR2=word3 "VAR3=word 5 6"
253 Sets three variables "VAR1", "VAR2", "VAR3".
255 ManagerEnvironment=
257 Takes the same arguments as DefaultEnvironment=, see above. Sets
258 environment variables just for the manager process itself. In
259 contrast to user managers, these variables are not inherited by
260 processes spawned by the system manager, use DefaultEnvironment=
261 for that. Note that these variables are merged into the existing
262 environment block. In particular, in case of the system manager,
263 this includes variables set by the kernel based on the kernel
264 command line.
265 Setting environment variables for the manager process may be useful
267 to modify its behaviour. See ENVIRONMENT[2] for a descriptions of
268 some variables understood by systemd.
269 Simple "%"-specifier expansion is supported, see below for a list
271 of supported specifiers.
272 DefaultCPUAccounting=, DefaultBlockIOAccounting=,
274 DefaultMemoryAccounting=, DefaultTasksAccounting=,
275 DefaultIOAccounting=, DefaultIPAccounting=
276 Configure the default resource accounting settings, as configured
277 per-unit by CPUAccounting=, BlockIOAccounting=, MemoryAccounting=,
278 TasksAccounting=, IOAccounting= and IPAccounting=. See
279 systemd.resource-control(5) for details on the per-unit settings.
280 DefaultTasksAccounting= defaults to yes, DefaultMemoryAccounting=
281 to yes. DefaultCPUAccounting= defaults to yes if enabling CPU
282 accounting doesn't require the CPU controller to be enabled (Linux
283 4.15+ using the unified hierarchy for resource control), otherwise
284 it defaults to no. The other three settings default to no.
285 DefaultTasksMax=
287 Configure the default value for the per-unit TasksMax= setting. See
288 systemd.resource-control(5) for details. This setting applies to
289 all unit types that support resource control settings, with the
290 exception of slice units. Defaults to 15% of the minimum of
291 kernel.pid_max=, kernel.threads-max= and root cgroup pids.max.
292 Kernel has a default value for kernel.pid_max= and an algorithm of
293 counting in case of more than 32 cores. For example with the
294 default kernel.pid_max=, DefaultTasksMax= defaults to 4915, but
295 might be greater in other systems or smaller in OS containers.
296 DefaultLimitCPU=, DefaultLimitFSIZE=, DefaultLimitDATA=,
298 DefaultLimitSTACK=, DefaultLimitCORE=, DefaultLimitRSS=,
299 DefaultLimitNOFILE=, DefaultLimitAS=, DefaultLimitNPROC=,
300 DefaultLimitMEMLOCK=, DefaultLimitLOCKS=, DefaultLimitSIGPENDING=,
301 DefaultLimitMSGQUEUE=, DefaultLimitNICE=, DefaultLimitRTPRIO=,
302 DefaultLimitRTTIME=
303 These settings control various default resource limits for
304 processes executed by units. See setrlimit(2) for details. These
305 settings may be overridden in individual units using the
306 corresponding LimitXXX= directives and they accept the same
307 parameter syntax, see systemd.exec(5) for details. Note that these
308 resource limits are only defaults for units, they are not applied
309 to the service manager process (i.e. PID 1) itself.
310 Most of these settings are unset, which means the resource limits
312 are inherited from the kernel or, if invoked in a container, from
313 the container manager. However, the following have defaults:
314 • DefaultLimitNOFILE= defaults to "1024:524288".
316 • DefaultLimitCORE= does not have a default but it is worth
318 mentioning that RLIMIT_CORE is set to "infinity" by PID 1 which
319 is inherited by its children.
320 • Note that the service manager internally increases
322 RLIMIT_MEMLOCK for itself, however the limit is reverted to the
323 original value for child processes forked off.
324 DefaultOOMPolicy=
326 Configure the default policy for reacting to processes being killed
327 by the Linux Out-Of-Memory (OOM) killer. This may be used to pick a
328 global default for the per-unit OOMPolicy= setting. See
329 systemd.service(5) for details. Note that this default is not used
330 for services that have Delegate= turned on.
331
333 Specifiers may be used in the DefaultEnvironment= and
334 ManagerEnvironment= settings. The following expansions are understood:
335 Table 1. Specifiers available
337 ┌──────────┬─────────────────────┬────────────────────────┐
338 │Specifier │ Meaning │ Details │
339 ├──────────┼─────────────────────┼────────────────────────┤
340 │"%a" │ Architecture │ A short string │
341 │ │ │ identifying the │
342 │ │ │ architecture of the │
343 │ │ │ local system. A │
344 │ │ │ string such as x86, │
345 │ │ │ x86-64 or arm64. │
346 │ │ │ See the │
347 │ │ │ architectures │
348 │ │ │ defined for │
349 │ │ │ ConditionArchitecture= │
350 │ │ │ in systemd.unit(5) │
351 │ │ │ for a full list. │
352 ├──────────┼─────────────────────┼────────────────────────┤
353 │"%A" │ Operating system │ The operating system │
354 │ │ image version │ image version │
355 │ │ │ identifier of the │
356 │ │ │ running system, as │
357 │ │ │ read from the │
358 │ │ │ IMAGE_VERSION= field │
359 │ │ │ of /etc/os-release. If │
360 │ │ │ not set, resolves to │
361 │ │ │ an empty string. See │
362 │ │ │ os-release(5) for more │
363 │ │ │ information. │
364 ├──────────┼─────────────────────┼────────────────────────┤
365 │"%b" │ Boot ID │ The boot ID of the │
366 │ │ │ running system, │
367 │ │ │ formatted as string. │
368 │ │ │ See random(4) for more │
369 │ │ │ information. │
370 ├──────────┼─────────────────────┼────────────────────────┤
371 │"%B" │ Operating system │ The operating system │
372 │ │ build ID │ build identifier of │
373 │ │ │ the running system, as │
374 │ │ │ read from the │
375 │ │ │ BUILD_ID= field of │
376 │ │ │ /etc/os-release. If │
377 │ │ │ not set, resolves to │
378 │ │ │ an empty string. See │
379 │ │ │ os-release(5) for more │
380 │ │ │ information. │
381 ├──────────┼─────────────────────┼────────────────────────┤
382 │"%H" │ Host name │ The hostname of the │
383 │ │ │ running system. │
384 ├──────────┼─────────────────────┼────────────────────────┤
385 │"%l" │ Short host name │ The hostname of the │
386 │ │ │ running system, │
387 │ │ │ truncated at the first │
388 │ │ │ dot to remove any │
389 │ │ │ domain component. │
390 ├──────────┼─────────────────────┼────────────────────────┤
391 │"%m" │ Machine ID │ The machine ID of the │
392 │ │ │ running system, │
393 │ │ │ formatted as string. │
394 │ │ │ See machine-id(5) for │
395 │ │ │ more information. │
396 ├──────────┼─────────────────────┼────────────────────────┤
397 │"%M" │ Operating system │ The operating system │
398 │ │ image identifier │ image identifier of │
399 │ │ │ the running system, as │
400 │ │ │ read from the │
401 │ │ │ IMAGE_ID= field of │
402 │ │ │ /etc/os-release. If │
403 │ │ │ not set, resolves to │
404 │ │ │ an empty string. See │
405 │ │ │ os-release(5) for more │
406 │ │ │ information. │
407 ├──────────┼─────────────────────┼────────────────────────┤
408 │"%o" │ Operating system ID │ The operating system │
409 │ │ │ identifier of the │
410 │ │ │ running system, as │
411 │ │ │ read from the ID= │
412 │ │ │ field of │
413 │ │ │ /etc/os-release. See │
414 │ │ │ os-release(5) for more │
415 │ │ │ information. │
416 ├──────────┼─────────────────────┼────────────────────────┤
417 │"%v" │ Kernel release │ Identical to uname -r │
418 │ │ │ output. │
419 ├──────────┼─────────────────────┼────────────────────────┤
420 │"%w" │ Operating system │ The operating system │
421 │ │ version ID │ version identifier of │
422 │ │ │ the running system, as │
423 │ │ │ read from the │
424 │ │ │ VERSION_ID= field of │
425 │ │ │ /etc/os-release. If │
426 │ │ │ not set, resolves to │
427 │ │ │ an empty string. See │
428 │ │ │ os-release(5) for more │
429 │ │ │ information. │
430 ├──────────┼─────────────────────┼────────────────────────┤
431 │"%W" │ Operating system │ The operating system │
432 │ │ variant ID │ variant identifier of │
433 │ │ │ the running system, as │
434 │ │ │ read from the │
435 │ │ │ VARIANT_ID= field of │
436 │ │ │ /etc/os-release. If │
437 │ │ │ not set, resolves to │
438 │ │ │ an empty string. See │
439 │ │ │ os-release(5) for more │
440 │ │ │ information. │
441 ├──────────┼─────────────────────┼────────────────────────┤
442 │"%T" │ Directory for │ This is either /tmp or │
443 │ │ temporary files │ the path "$TMPDIR", │
444 │ │ │ "$TEMP" or "$TMP" are │
445 │ │ │ set to. (Note that the │
446 │ │ │ directory may be │
447 │ │ │ specified without a │
448 │ │ │ trailing slash.) │
449 ├──────────┼─────────────────────┼────────────────────────┤
450 │"%V" │ Directory for │ This is either │
451 │ │ larger and │ /var/tmp or the path │
452 │ │ persistent │ "$TMPDIR", "$TEMP" or │
453 │ │ temporary files │ "$TMP" are set to. │
454 │ │ │ (Note that the │
455 │ │ │ directory may be │
456 │ │ │ specified without a │
457 │ │ │ trailing slash.) │
458 ├──────────┼─────────────────────┼────────────────────────┤
459 │"%%" │ Single percent sign │ Use "%%" in place of │
460 │ │ │ "%" to specify a │
461 │ │ │ single percent sign. │
462 └──────────┴─────────────────────┴────────────────────────┘
463
465 systemd(1), systemd.directives(7), systemd.exec(5), systemd.service(5),
466 environ(7), capabilities(7)
467
469 1. No New Privileges Flag
470 https://www.kernel.org/doc/html/latest/userspace-api/no_new_privs.html
471 2. ENVIRONMENT
473 https://systemd.io/ENVIRONMENT
474systemd 249 SYSTEMD-SYSTEM.CONF(5)