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NAME | SYNOPSIS | DESCRIPTION | UNITS | DIRECTORIES | SIGNALS | ENVIRONMENT | KERNEL COMMAND LINE | SYSTEM CREDENTIALS | READINESS PROTOCOL | OPTIONS | SYSTEM CLOCK EPOCH | FILES | HISTORY | SEE ALSO | NOTES | COLOPHON |
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SYSTEMD(1) systemd SYSTEMD(1)
systemd, init - systemd system and service manager
/usr/lib/systemd/systemd [OPTIONS...]
init [OPTIONS...]
systemd is a system and service manager for Linux operating
systems. When run as first process on boot (as PID 1), it acts as
init system that brings up and maintains userspace services.
Separate instances are started for logged-in users to start their
services.
systemd is usually not invoked directly by the user, but is
installed as the /sbin/init symlink and started during early boot.
The user manager instances are started automatically through the
user@.service(5) service.
When run as a system instance, systemd interprets the
configuration file system.conf and the files in system.conf.d
directories; when run as a user instance, systemd interprets the
configuration file user.conf and the files in user.conf.d
directories. See systemd-system.conf(5) for more information.
systemd contains native implementations of various tasks that need
to be executed as part of the boot process. For example, it sets
the hostname or configures the loopback network device. It also
sets up and mounts various API file systems, such as /sys/,
/proc/, and /dev/.
systemd will also reset the system clock during early boot if it
appears to be set incorrectly. See "System clock epoch" section
below.
Note that some but not all interfaces provided by systemd are
covered by the Interface Portability and Stability Promise[1].
The D-Bus API of systemd is described in
org.freedesktop.systemd1(5) and org.freedesktop.LogControl1(5).
Systems which invoke systemd in a container or initrd environment
should implement the Container Interface[2] or initrd Interface[3]
specifications, respectively.
systemd provides a dependency system between various entities
called "units" of 11 different types. Units encapsulate various
objects that are relevant for system boot-up and maintenance. The
majority of units are configured in unit configuration files,
whose syntax and basic set of options is described in
systemd.unit(5), however some are created automatically from other
configuration files, dynamically from system state or
programmatically at runtime. Units may be in a number of states,
described in the following table. Note that the various unit types
may have a number of additional substates, which are mapped to the
generalized unit states described here.
Table 1. Unit ACTIVE states
┌──────────────┬──────────────────────────┐
│ State │ Description │
├──────────────┼──────────────────────────┤
│ active │ Started, bound, plugged │
│ │ in, ..., depending on │
│ │ the unit type. │
├──────────────┼──────────────────────────┤
│ inactive │ Stopped, unbound, │
│ │ unplugged, ..., │
│ │ depending on the unit │
│ │ type. │
├──────────────┼──────────────────────────┤
│ failed │ Similar to inactive, but │
│ │ the unit failed in some │
│ │ way (process returned │
│ │ error code on exit, │
│ │ crashed, an operation │
│ │ timed out, or after too │
│ │ many restarts). │
├──────────────┼──────────────────────────┤
│ activating │ Changing from inactive │
│ │ to active. │
├──────────────┼──────────────────────────┤
│ deactivating │ Changing from active to │
│ │ inactive. │
├──────────────┼──────────────────────────┤
│ maintenance │ Unit is inactive and a │
│ │ maintenance operation is │
│ │ in progress. │
├──────────────┼──────────────────────────┤
│ reloading │ Unit is active and it is │
│ │ reloading its │
│ │ configuration. │
├──────────────┼──────────────────────────┤
│ refreshing │ Unit is active and a new │
│ │ mount is being activated │
│ │ in its namespace. │
└──────────────┴──────────────────────────┘
The following unit types are available:
1. Service units, which start and control daemons and the
processes they consist of. For details, see
systemd.service(5).
2. Socket units, which encapsulate local IPC or network sockets
in the system, useful for socket-based activation. For details
about socket units, see systemd.socket(5), for details on
socket-based activation and other forms of activation, see
daemon(7).
3. Target units are useful to group units, or provide well-known
synchronization points during boot-up, see systemd.target(5).
4. Device units expose kernel devices in systemd and may be used
to implement device-based activation. For details, see
systemd.device(5).
5. Mount units control mount points in the file system, for
details see systemd.mount(5).
6. Automount units provide automount capabilities, for on-demand
mounting of file systems as well as parallelized boot-up. See
systemd.automount(5).
7. Timer units are useful for triggering activation of other
units based on timers. You may find details in
systemd.timer(5).
8. Swap units are very similar to mount units and encapsulate
memory swap partitions or files of the operating system. They
are described in systemd.swap(5).
9. Path units may be used to activate other services when file
system objects change or are modified. See systemd.path(5).
10. Slice units may be used to group units which manage system
processes (such as service and scope units) in a hierarchical
tree for resource management purposes. See systemd.slice(5).
11. Scope units are similar to service units, but manage foreign
processes instead of starting them as well. See
systemd.scope(5).
Units are named as their configuration files. Some units have
special semantics. A detailed list is available in
systemd.special(7).
systemd knows various kinds of dependencies, including positive
and negative requirement dependencies (i.e. Requires= and
Conflicts=) as well as ordering dependencies (After= and Before=).
NB: ordering and requirement dependencies are orthogonal. If only
a requirement dependency exists between two units (e.g.
foo.service requires bar.service), but no ordering dependency
(e.g. foo.service after bar.service) and both are requested to
start, they will be started in parallel. It is a common pattern
that both requirement and ordering dependencies are placed between
two units. Also note that the majority of dependencies are
implicitly created and maintained by systemd. In most cases, it
should be unnecessary to declare additional dependencies manually,
however it is possible to do this.
Application programs and units (via dependencies) may request
state changes of units. In systemd, these requests are
encapsulated as 'jobs' and maintained in a job queue. Jobs may
succeed or can fail, their execution is ordered based on the
ordering dependencies of the units they have been scheduled for.
On boot systemd activates the target unit default.target whose job
is to activate on-boot services and other on-boot units by pulling
them in via dependencies. Usually, the unit name is just an alias
(symlink) for either graphical.target (for fully-featured boots
into the UI) or multi-user.target (for limited console-only boots
for use in embedded or server environments, or similar; a subset
of graphical.target). However, it is at the discretion of the
administrator to configure it as an alias to any other target
unit. See systemd.special(7) for details about these target units.
On first boot, systemd will enable or disable units according to
preset policy. See systemd.preset(5) and "First Boot Semantics" in
machine-id(5).
systemd only keeps a minimal set of units loaded into memory.
Specifically, the only units that are kept loaded into memory are
those for which at least one of the following conditions is true:
1. It is in an active, activating, deactivating or failed state
(i.e. in any unit state except for "inactive")
2. It has a job queued for it
3. It is a dependency of at least one other unit that is loaded
into memory
4. It has some form of resource still allocated (e.g. a service
unit that is inactive but for which a process is still
lingering that ignored the request to be terminated)
5. It has been pinned into memory programmatically by a D-Bus
call
systemd will automatically and implicitly load units from disk —
if they are not loaded yet — as soon as operations are requested
for them. Thus, in many respects, the fact whether a unit is
loaded or not is invisible to clients. Use systemctl list-units
--all to comprehensively list all units currently loaded. Any unit
for which none of the conditions above applies is promptly
unloaded. Note that when a unit is unloaded from memory its
accounting data is flushed out too. However, this data is
generally not lost, as a journal log record is generated declaring
the consumed resources whenever a unit shuts down.
Processes systemd spawns are placed in individual Linux control
groups named after the unit which they belong to in the private
systemd hierarchy. (see Control Groups v2[4] for more information
about control groups, or short "cgroups"). systemd uses this to
effectively keep track of processes. Control group information is
maintained in the kernel, and is accessible via the file system
hierarchy (beneath /sys/fs/cgroup/), or in tools such as
systemd-cgls(1) or ps(1) (ps xawf -eo pid,user,cgroup,args is
particularly useful to list all processes and the systemd units
they belong to.).
systemd is compatible with various established Unix functionality
such as /etc/fstab or the utmp database.
systemd has a minimal transaction system: if a unit is requested
to start up or shut down it will add it and all its dependencies
to a temporary transaction. Then, it will verify if the
transaction is consistent (i.e. whether the ordering of all units
is cycle-free). If it is not, systemd will try to fix it up, and
removes non-essential jobs from the transaction that might remove
the loop. Also, systemd tries to suppress non-essential jobs in
the transaction that would stop a running service. Finally it is
checked whether the jobs of the transaction contradict jobs that
have already been queued, and optionally the transaction is
aborted then. If all worked out and the transaction is consistent
and minimized in its impact it is merged with all already
outstanding jobs and added to the run queue. Effectively this
means that before executing a requested operation, systemd will
verify that it makes sense, fixing it if possible, and only
failing if it really cannot work.
Note that transactions are generated independently of a unit's
state at runtime, hence, for example, if a start job is requested
on an already started unit, it will still generate a transaction
and wake up any inactive dependencies (and cause propagation of
other jobs as per the defined relationships). This is because the
enqueued job is at the time of execution compared to the target
unit's state and is marked successful and complete when both
satisfy. However, this job also pulls in other dependencies due to
the defined relationships and thus leads to, in our example, start
jobs for any of those inactive units getting queued as well.
Units may be generated dynamically at boot and system manager
reload time, for example based on other configuration files or
parameters passed on the kernel command line. For details, see
systemd.generator(7).
System unit directories
The systemd system manager reads unit configuration from
various directories. Packages that want to install unit files
shall place them in the directory returned by pkg-config
systemd --variable=systemdsystemunitdir. Other directories
checked are /usr/local/lib/systemd/system and
/usr/lib/systemd/system. User configuration always takes
precedence. pkg-config systemd
--variable=systemdsystemconfdir returns the path of the system
configuration directory. Packages should alter the content of
these directories only with the enable and disable commands of
the systemctl(1) tool. Full list of directories is provided in
systemd.unit(5).
User unit directories
Similar rules apply for the user unit directories. However,
here the XDG Base Directory specification[5] is followed to
find units. Applications should place their unit files in the
directory returned by pkg-config systemd
--variable=systemduserunitdir. Global configuration is done in
the directory reported by pkg-config systemd
--variable=systemduserconfdir. The enable and disable commands
of the systemctl(1) tool can handle both global (i.e. for all
users) and private (for one user) enabling/disabling of units.
Full list of directories is provided in systemd.unit(5).
The service listens to various UNIX process signals that can be
used to request various actions asynchronously. The signal
handling is enabled very early during boot, before any further
processes are invoked. However, a supervising container manager or
similar that intends to request these operations via this
mechanism must take into consideration that this functionality is
not available during the earliest initialization phase. An
sd_notify() notification message carrying the
X_SYSTEMD_SIGNALS_LEVEL=2 field is emitted once the signal
handlers are enabled, see below. This may be used to schedule
submission of these signals correctly.
SIGTERM
Upon receiving this signal the systemd system manager
serializes its state, reexecutes itself and deserializes the
saved state again. This is mostly equivalent to systemctl
daemon-reexec.
systemd user managers will start the exit.target unit when
this signal is received. This is mostly equivalent to
systemctl --user start exit.target
--job-mode=replace-irreversibly.
SIGINT
Upon receiving this signal the systemd system manager will
start the ctrl-alt-del.target unit. This is mostly equivalent
to systemctl start ctrl-alt-del.target
--job-mode=replace-irreversibly. If this signal is received
more than 7 times per 2s, an immediate reboot is triggered.
Note that pressing Ctrl+Alt+Del on the console will trigger
this signal. Hence, if a reboot is hanging, pressing
Ctrl+Alt+Del more than 7 times in 2 seconds is a relatively
safe way to trigger an immediate reboot.
systemd user managers treat this signal the same way as
SIGTERM.
SIGWINCH
When this signal is received the systemd system manager will
start the kbrequest.target unit. This is mostly equivalent to
systemctl start kbrequest.target.
This signal is ignored by systemd user managers.
SIGPWR
When this signal is received the systemd manager will start
the sigpwr.target unit. This is mostly equivalent to systemctl
start sigpwr.target.
SIGUSR1
When this signal is received the systemd manager will try to
reconnect to the D-Bus bus.
SIGUSR2
When this signal is received the systemd manager will log its
complete state in human-readable form. The data logged is the
same as printed by systemd-analyze dump.
SIGHUP
Reloads the complete daemon configuration. This is mostly
equivalent to systemctl daemon-reload.
SIGRTMIN+0
Enters default mode, starts the default.target unit. This is
mostly equivalent to systemctl isolate default.target.
SIGRTMIN+1
Enters rescue mode, starts the rescue.target unit. This is
mostly equivalent to systemctl isolate rescue.target.
SIGRTMIN+2
Enters emergency mode, starts the emergency.service unit. This
is mostly equivalent to systemctl isolate emergency.service.
SIGRTMIN+3
Halts the machine, starts the halt.target unit. This is mostly
equivalent to systemctl start halt.target
--job-mode=replace-irreversibly.
SIGRTMIN+4
Powers off the machine, starts the poweroff.target unit. This
is mostly equivalent to systemctl start poweroff.target
--job-mode=replace-irreversibly.
SIGRTMIN+5
Reboots the machine, starts the reboot.target unit. This is
mostly equivalent to systemctl start reboot.target
--job-mode=replace-irreversibly.
SIGRTMIN+6
Reboots the machine via kexec, starts the kexec.target unit.
This is mostly equivalent to systemctl start kexec.target
--job-mode=replace-irreversibly.
SIGRTMIN+7
Reboots userspace, starts the soft-reboot.target unit. This is
mostly equivalent to systemctl start soft-reboot.target
--job-mode=replace-irreversibly.
Added in version 254.
SIGRTMIN+13
Immediately halts the machine.
SIGRTMIN+14
Immediately powers off the machine.
SIGRTMIN+15
Immediately reboots the machine.
SIGRTMIN+16
Immediately reboots the machine with kexec.
SIGRTMIN+17
Immediately reboots the userspace.
Added in version 254.
SIGRTMIN+20
Enables display of status messages on the console, as
controlled via systemd.show_status=1 on the kernel command
line.
You may want to use SetShowStatus() instead of SIGRTMIN+20 in
order to prevent race conditions. See
org.freedesktop.systemd1(5).
SIGRTMIN+21
Disables display of status messages on the console, as
controlled via systemd.show_status=0 on the kernel command
line.
You may want to use SetShowStatus() instead of SIGRTMIN+21 in
order to prevent race conditions. See
org.freedesktop.systemd1(5).
SIGRTMIN+22
Sets the service manager's log level to "debug", in a fashion
equivalent to systemd.log_level=debug on the kernel command
line.
SIGRTMIN+23
Restores the log level to its configured value. The configured
value is derived from – in order of priority – the value
specified with systemd.log-level= on the kernel command line,
or the value specified with LogLevel= in the configuration
file, or the built-in default of "info".
Added in version 239.
SIGRTMIN+24
Immediately exits the manager (only available for --user
instances).
Added in version 195.
SIGRTMIN+25
Upon receiving this signal the systemd manager will reexecute
itself. This is mostly equivalent to systemctl daemon-reexec
except that it will be done asynchronously.
The systemd system manager treats this signal the same way as
SIGTERM.
Added in version 250.
SIGRTMIN+26
Restores the log target to its configured value. The
configured value is derived from – in order of priority – the
value specified with systemd.log-target= on the kernel command
line, or the value specified with LogTarget= in the
configuration file, or the built-in default.
Added in version 239.
SIGRTMIN+27, SIGRTMIN+28
Sets the log target to "console" on SIGRTMIN+27 (or "kmsg" on
SIGRTMIN+28), in a fashion equivalent to
systemd.log_target=console (or systemd.log_target=kmsg on
SIGRTMIN+28) on the kernel command line.
Added in version 239.
The environment block for the system manager is initially set by
the kernel. (In particular, "key=value" assignments on the kernel
command line are turned into environment variables for PID 1). For
the user manager, the system manager sets the environment as
described in the "Environment Variables in Spawned Processes"
section of systemd.exec(5). The DefaultEnvironment= setting in the
system manager applies to all services including user@.service.
Additional entries may be configured (as for any other service)
through the Environment= and EnvironmentFile= settings for
user@.service (see systemd.exec(5)). Also, additional environment
variables may be set through the ManagerEnvironment= setting in
systemd-system.conf(5) and systemd-user.conf(5).
Some of the variables understood by systemd:
$SYSTEMD_LOG_LEVEL
The maximum log level of emitted messages (messages with a
higher log level, i.e. less important ones, will be
suppressed). Takes a comma-separated list of values. A value
may be either one of (in order of decreasing importance)
emerg, alert, crit, err, warning, notice, info, debug, or an
integer in the range 0...7. See syslog(3) for more
information. Each value may optionally be prefixed with one of
console, syslog, kmsg or journal followed by a colon to set
the maximum log level for that specific log target (e.g.
SYSTEMD_LOG_LEVEL=debug,console:info specifies to log at debug
level except when logging to the console which should be at
info level). Note that the global maximum log level takes
priority over any per target maximum log levels.
This can be overridden with --log-level=.
$SYSTEMD_LOG_COLOR
A boolean. If true, messages written to the tty will be
colored according to priority.
This can be overridden with --log-color=.
$SYSTEMD_LOG_TIME
A boolean. If true, console log messages will be prefixed with
a timestamp.
This can be overridden with --log-time=.
Added in version 246.
$SYSTEMD_LOG_LOCATION
A boolean. If true, messages will be prefixed with a filename
and line number in the source code where the message
originates.
This can be overridden with --log-location=.
$SYSTEMD_LOG_TID
A boolean. If true, messages will be prefixed with the current
numerical thread ID (TID).
Added in version 247.
$SYSTEMD_LOG_TARGET
The destination for log messages. One of console (log to the
attached tty), console-prefixed (log to the attached tty but
with prefixes encoding the log level and "facility", see
syslog(3), kmsg (log to the kernel circular log buffer),
journal (log to the journal), journal-or-kmsg (log to the
journal if available, and to kmsg otherwise), auto (determine
the appropriate log target automatically, the default), null
(disable log output).
This can be overridden with --log-target=.
$SYSTEMD_LOG_RATELIMIT_KMSG
Whether to ratelimit kmsg or not. Takes a boolean. Defaults to
"true". If disabled, systemd will not ratelimit messages
written to kmsg.
Added in version 254.
$XDG_CONFIG_HOME, $XDG_CONFIG_DIRS, $XDG_DATA_HOME, $XDG_DATA_DIRS
The systemd user manager uses these variables in accordance to
the XDG Base Directory specification[5] to find its
configuration.
$SYSTEMD_UNIT_PATH, $SYSTEMD_GENERATOR_PATH,
$SYSTEMD_ENVIRONMENT_GENERATOR_PATH
Controls where systemd looks for unit files and generators.
These variables may contain a list of paths, separated by
colons (":"). When set, if the list ends with an empty
component ("...:"), this list is prepended to the usual set of
paths. Otherwise, the specified list replaces the usual set of
paths.
$SYSTEMD_PAGER, $PAGER
Pager to use when --no-pager is not given. $SYSTEMD_PAGER is
used if set; otherwise $PAGER is used. If neither
$SYSTEMD_PAGER nor $PAGER are set, a set of well-known pager
implementations is tried in turn, including less(1) and
more(1), until one is found. If no pager implementation is
discovered, no pager is invoked. Setting those environment
variables to an empty string or the value "cat" is equivalent
to passing --no-pager.
Note: if $SYSTEMD_PAGERSECURE is not set, $SYSTEMD_PAGER and
$PAGER can only be used to disable the pager (with "cat" or
""), and are otherwise ignored.
$SYSTEMD_LESS
Override the options passed to less (by default "FRSXMK").
Users might want to change two options in particular:
K
This option instructs the pager to exit immediately when
Ctrl+C is pressed. To allow less to handle Ctrl+C itself
to switch back to the pager command prompt, unset this
option.
If the value of $SYSTEMD_LESS does not include "K", and
the pager that is invoked is less, Ctrl+C will be ignored
by the executable, and needs to be handled by the pager.
X
This option instructs the pager to not send termcap
initialization and deinitialization strings to the
terminal. It is set by default to allow command output to
remain visible in the terminal even after the pager exits.
Nevertheless, this prevents some pager functionality from
working, in particular paged output cannot be scrolled
with the mouse.
Note that setting the regular $LESS environment variable has
no effect for less invocations by systemd tools.
See less(1) for more discussion.
$SYSTEMD_LESSCHARSET
Override the charset passed to less (by default "utf-8", if
the invoking terminal is determined to be UTF-8 compatible).
Note that setting the regular $LESSCHARSET environment
variable has no effect for less invocations by systemd tools.
$SYSTEMD_PAGERSECURE
Common pager commands like less(1), in addition to "paging",
i.e. scrolling through the output, support opening of or
writing to other files and running arbitrary shell commands.
When commands are invoked with elevated privileges, for
example under sudo(8) or pkexec(1), the pager becomes a
security boundary. Care must be taken that only programs with
strictly limited functionality are used as pagers, and
unintended interactive features like opening or creation of
new files or starting of subprocesses are not allowed. "Secure
mode" for the pager may be enabled as described below, if the
pager supports that (most pagers are not written in a way that
takes this into consideration). It is recommended to either
explicitly enable "secure mode" or to completely disable the
pager using --no-pager or PAGER=cat when allowing untrusted
users to execute commands with elevated privileges.
This option takes a boolean argument. When set to true, the
"secure mode" of the pager is enabled. In "secure mode",
LESSSECURE=1 will be set when invoking the pager, which
instructs the pager to disable commands that open or create
new files or start new subprocesses. Currently only less(1) is
known to understand this variable and implement "secure mode".
When set to false, no limitation is placed on the pager.
Setting SYSTEMD_PAGERSECURE=0 or not removing it from the
inherited environment may allow the user to invoke arbitrary
commands.
When $SYSTEMD_PAGERSECURE is not set, systemd tools attempt to
automatically figure out if "secure mode" should be enabled
and whether the pager supports it. "Secure mode" is enabled if
the effective UID is not the same as the owner of the login
session, see geteuid(2) and sd_pid_get_owner_uid(3), or when
running under sudo(8) or similar tools ($SUDO_UID is set [6]).
In those cases, SYSTEMD_PAGERSECURE=1 will be set and pagers
which are not known to implement "secure mode" will not be
used at all. Note that this autodetection only covers the most
common mechanisms to elevate privileges and is intended as
convenience. It is recommended to explicitly set
$SYSTEMD_PAGERSECURE or disable the pager.
Note that if the $SYSTEMD_PAGER or $PAGER variables are to be
honoured, other than to disable the pager,
$SYSTEMD_PAGERSECURE must be set too.
$SYSTEMD_COLORS
Takes a boolean argument. When true, systemd and related
utilities will use colors in their output, otherwise the
output will be monochrome. Additionally, the variable can take
one of the following special values: "16", "256" to restrict
the use of colors to the base 16 or 256 ANSI colors,
respectively. This can be specified to override the automatic
decision based on $TERM and what the console is connected to.
$SYSTEMD_URLIFY
The value must be a boolean. Controls whether clickable links
should be generated in the output for terminal emulators
supporting this. This can be specified to override the
decision that systemd makes based on $TERM and other
conditions.
$LISTEN_PID, $LISTEN_FDS, $LISTEN_FDNAMES
Set by systemd for supervised processes during socket-based
activation. See sd_listen_fds(3) for more information.
$NOTIFY_SOCKET
Set by service manager for its services for status and
readiness notifications. Also consumed by service manager for
notifying supervising container managers or service managers
up the stack about its own progress. See sd_notify(3) and the
relevant section below for more information.
For further environment variables understood by systemd and its
various components, see Known Environment Variables[7].
When run as the system instance, systemd parses a number of
options listed below. They can be specified as kernel command line
arguments which are parsed from a number of sources depending on
the environment in which systemd is executed. If run inside a
Linux container, these options are parsed from the command line
arguments passed to systemd itself, next to any of the command
line options listed in the Options section above. If run outside
of Linux containers, these arguments are parsed from /proc/cmdline
instead.
The following variables are understood:
systemd.unit=, rd.systemd.unit=
Overrides the unit to activate on boot. Defaults to
default.target. This may be used to temporarily boot into a
different boot unit, for example rescue.target or
emergency.service. See systemd.special(7) for details about
these units. The option prefixed with "rd." is honored only
in the initrd, while the one that is not prefixed only in the
main system.
systemd.dump_core
Takes a boolean argument or enables the option if specified
without an argument. If enabled, the systemd manager (PID 1)
dumps core when it crashes. Otherwise, no core dump is
created. Defaults to enabled.
Added in version 233.
systemd.crash_chvt
Takes a positive integer, or a boolean argument. Can be also
specified without an argument, with the same effect as a
positive boolean. If a positive integer (in the range 1–63) is
specified, the system manager (PID 1) will activate the
specified virtual terminal when it crashes. Defaults to
disabled, meaning that no such switch is attempted. If set to
enabled, the virtual terminal the kernel messages are written
to is used instead.
Added in version 233.
systemd.crash_shell
Takes a boolean argument or enables the option if specified
without an argument. If enabled, the system manager (PID 1)
spawns a shell when it crashes. Otherwise, no shell is
spawned. Defaults to disabled, for security reasons, as the
shell is not protected by password authentication.
Added in version 233.
systemd.crash_action=
Takes one of "freeze", "reboot" or "poweroff". Defaults to
"freeze". If set to "freeze", the system will hang
indefinitely when the system manager (PID 1) crashes. If set
to "reboot", the system manager (PID 1) will reboot the
machine automatically when it crashes, after a 10s delay. If
set to "poweroff", the system manager (PID 1) will power off
the machine immediately when it crashes. If combined with
systemd.crash_shell, the configured crash action is executed
after the shell exits.
Added in version 256.
systemd.confirm_spawn
Takes a boolean argument or a path to the virtual console
where the confirmation messages should be emitted. Can be also
specified without an argument, with the same effect as a
positive boolean. If enabled, the system manager (PID 1) asks
for confirmation when spawning processes using /dev/console.
If a path or a console name (such as "ttyS0") is provided, the
virtual console pointed to by this path or described by the
give name will be used instead. Defaults to disabled.
Added in version 233.
systemd.service_watchdogs=
Takes a boolean argument. If disabled, all service runtime
watchdogs (WatchdogSec=) and emergency actions (e.g.
OnFailure= or StartLimitAction=) are ignored by the system
manager (PID 1); see systemd.service(5). Defaults to enabled,
i.e. watchdogs and failure actions are processed normally. The
hardware watchdog is not affected by this option.
Added in version 237.
systemd.show_status
Takes a boolean argument or the constants error and auto. Can
be also specified without an argument, with the same effect as
a positive boolean. If enabled, the systemd manager (PID 1)
shows terse service status updates on the console during
bootup. With error, only messages about failures are shown,
but boot is otherwise quiet. auto behaves like false until
there is a significant delay in boot. Defaults to enabled,
unless quiet is passed as kernel command line option, in which
case it defaults to error. If specified overrides the system
manager configuration file option ShowStatus=, see
systemd-system.conf(5).
Added in version 233.
systemd.status_unit_format=
Takes name, description or combined as the value. If name, the
system manager will use unit names in status messages. If
combined, the system manager will use unit names and
description in status messages. When specified, overrides the
system manager configuration file option StatusUnitFormat=,
see systemd-system.conf(5).
Added in version 243.
systemd.log_color, systemd.log_level=, systemd.log_location,
systemd.log_target=, systemd.log_time, systemd.log_tid,
systemd.log_ratelimit_kmsg
Controls log output, with the same effect as the
$SYSTEMD_LOG_COLOR, $SYSTEMD_LOG_LEVEL, $SYSTEMD_LOG_LOCATION,
$SYSTEMD_LOG_TARGET, $SYSTEMD_LOG_TIME, $SYSTEMD_LOG_TID and
$SYSTEMD_LOG_RATELIMIT_KMSG environment variables described
above. systemd.log_color, systemd.log_location,
systemd.log_time, systemd.log_tid and
systemd.log_ratelimit_kmsg can be specified without an
argument, with the same effect as a positive boolean.
systemd.default_standard_output=, systemd.default_standard_error=
Controls default standard output and error output for services
and sockets. That is, controls the default for StandardOutput=
and StandardError= (see systemd.exec(5) for details). Takes
one of inherit, null, tty, journal, journal+console, kmsg,
kmsg+console. If the argument is omitted
systemd.default-standard-output= defaults to journal and
systemd.default-standard-error= to inherit.
systemd.setenv=
Takes a string argument in the form VARIABLE=VALUE. May be
used to set default environment variables to add to forked
child processes. May be used more than once to set multiple
variables.
systemd.machine_id=
Takes a 32 character hex value to be used for setting the
machine-id. Intended mostly for network booting where the same
machine-id is desired for every boot.
Added in version 229.
systemd.set_credential=, systemd.set_credential_binary=
Sets a system credential, which can then be propagated to
system services using the ImportCredential= or LoadCredential=
setting, see systemd.exec(5) for details. Takes a pair of
credential name and value, separated by a colon. The
systemd.set_credential= parameter expects the credential value
in literal text form, the systemd.set_credential_binary=
parameter takes binary data encoded in Base64. Note that the
kernel command line is typically accessible by unprivileged
programs in /proc/cmdline. Thus, this mechanism is not
suitable for transferring sensitive data. Use it only for data
that is not sensitive (e.g. public keys/certificates, rather
than private keys), or in testing/debugging environments.
For further information see System and Service Credentials[8]
documentation.
Added in version 251.
systemd.import_credentials=
Takes a boolean argument. If false disables importing
credentials from the kernel command line, the DMI/SMBIOS OEM
string table, the qemu_fw_cfg subsystem or the EFI kernel
stub.
Added in version 251.
quiet
Turn off status output at boot, much like
systemd.show_status=no would. Note that this option is also
read by the kernel itself and disables kernel log output.
Passing this option hence turns off the usual output from both
the system manager and the kernel.
Added in version 186.
debug
Turn on debugging output. This is equivalent to
systemd.log_level=debug. Note that this option is also read by
the kernel itself and enables kernel debug output. Passing
this option hence turns on the debug output from both the
system manager and the kernel.
Added in version 205.
emergency, rd.emergency, -b
Boot into emergency mode. This is equivalent to
systemd.unit=emergency.target or
rd.systemd.unit=emergency.target, respectively, and provided
for compatibility reasons and to be easier to type.
Added in version 186.
rescue, rd.rescue, single, s, S, 1
Boot into rescue mode. This is equivalent to
systemd.unit=rescue.target or rd.systemd.unit=rescue.target,
respectively, and provided for compatibility reasons and to be
easier to type.
Added in version 186.
2, 3, 4, 5
Boot into the specified legacy SysV runlevel. 2, 3, and 4 are
equivalent to systemd.unit=multi-user.target; and 5 is
equivalent to systemd.unit=graphical.target, and provided for
compatibility reasons and to be easier to type.
Added in version 186.
locale.LANG=, locale.LANGUAGE=, locale.LC_CTYPE=,
locale.LC_NUMERIC=, locale.LC_TIME=, locale.LC_COLLATE=,
locale.LC_MONETARY=, locale.LC_MESSAGES=, locale.LC_PAPER=,
locale.LC_NAME=, locale.LC_ADDRESS=, locale.LC_TELEPHONE=,
locale.LC_MEASUREMENT=, locale.LC_IDENTIFICATION=
Set the system locale to use. This overrides the settings in
/etc/locale.conf. For more information, see locale.conf(5) and
locale(7).
Added in version 186.
For other kernel command line parameters understood by components
of the core OS, please refer to kernel-command-line(7).
During initialization the service manager will import credentials
from various sources into the system's set of credentials, which
can then be propagated into services and consumed by generators:
• When the service manager first initializes it will read system
credentials from SMBIOS Type 11 vendor strings
io.systemd.credential:name=value, and
io.systemd.credential.binary:name=value.
• At the same time it will import credentials from QEMU
"fw_cfg". (Note that the SMBIOS mechanism is generally
preferred, because it is faster and generic.)
• Credentials may be passed via the kernel command line, using
the systemd.set-credential= parameter, see above.
• Credentials may be passed from the UEFI environment via
systemd-stub(7).
• When the service manager is invoked during the initrd → host
transition it will import all files in
/run/credentials/@initrd/ as system credentials.
Invoke systemd-creds(1) as follows to see the list of credentials
passed into the system:
# systemd-creds --system list
For further information see System and Service Credentials[8]
documentation.
The service manager when run as PID 1 consumes the following
system credentials:
vmm.notify_socket
Contains a AF_VSOCK or AF_UNIX address where to send a READY=1
notification message when the service manager has completed
booting. See sd_notify(3) and the next section for more
information. Note that in case the hypervisor does not support
SOCK_DGRAM over AF_VSOCK, SOCK_SEQPACKET will be tried
instead. The credential payload for AF_VSOCK should be a
string in the form "vsock:CID:PORT". "vsock-stream",
"vsock-dgram" and "vsock-seqpacket" can be used instead of
"vsock" to force usage of the corresponding socket type.
This feature is useful for machine managers or other processes
on the host to receive a notification via VSOCK when a virtual
machine has finished booting.
Added in version 254.
system.machine_id
Takes a 128bit hexadecimal ID to initialize /etc/machine-id
from, if the file is not set up yet. See machine-id(5) for
details.
Added in version 254.
For a list of system credentials various other components of
systemd consume, see systemd.system-credentials(7).
The service manager implements a readiness notification protocol
both between the manager and its services (i.e. down the stack),
and between the manager and a potential supervisor further up the
stack (the latter could be a machine or container manager, or in
case of a per-user service manager the system service manager
instance). The basic protocol (and the suggested API for it) is
described in sd_notify(3).
The notification socket the service manager (including PID 1) uses
for reporting readiness to its own supervisor is set via the usual
$NOTIFY_SOCKET environment variable (see above). Since this is
directly settable only for container managers and for the per-user
instance of the service manager, an additional mechanism to
configure this is available, in particular intended for use in VM
environments: the vmm.notify_socket system credential (see above)
may be set to a suitable socket (typically an AF_VSOCK one) via
SMBIOS Type 11 vendor strings. For details see above.
The notification protocol from the service manager up the stack
towards a supervisor supports a number of extension fields that
allow a supervisor to learn about specific properties of the
system and track its boot progress. Specifically the following
fields are sent:
• An X_SYSTEMD_HOSTNAME=... message will be sent out once the
initial hostname for the system has been determined. Note that
during later runtime the hostname might be changed again
programmatically, and (currently) no further notifications are
sent out in that case.
Added in version 256.
• An X_SYSTEMD_MACHINE_ID=... message will be sent out once the
machine ID of the system has been determined. See
machine-id(5) for details.
Added in version 256.
• An X_SYSTEMD_SIGNALS_LEVEL=... message will be sent out once
the service manager installed the various UNIX process signal
handlers described above. The field's value is an unsigned
integer formatted as decimal string, and indicates the
supported UNIX process signal feature level of the service
manager. Currently, only a single feature level is defined:
• X_SYSTEMD_SIGNALS_LEVEL=2 covers the various UNIX process
signals documented above – which are a superset of those
supported by the historical SysV init system.
Signals sent to PID 1 before this message is sent might not be
handled correctly yet. A consumer of these messages should
parse the value as an unsigned integer that indicates the
level of support. For now only the mentioned level 2 is
defined, but later on additional levels might be defined with
higher integers, that will implement a superset of the
currently defined behaviour.
Added in version 256.
• X_SYSTEMD_UNIT_ACTIVE=... and X_SYSTEMD_UNIT_INACTIVE=...
messages will be sent out for each target unit as it becomes
active or stops being active. This is useful to track boot
progress and functionality. For example, once the
ssh-access.target unit is reported started SSH access is
typically available, see systemd.special(7) for details.
Added in version 256.
• An X_SYSTEMD_SHUTDOWN=... message will be sent out very
shortly before the system shuts down. The value is one of the
strings "reboot", "halt", "poweroff", "kexec" and indicates
which kind of shutdown is being executed.
Added in version 256.
• An X_SYSTEMD_REBOOT_PARAMETER=... message will also be sent
out very shortly before the system shuts down. Its value is
the reboot argument as configured with systemctl
--reboot-argument=....
Added in version 256.
Note that these extension fields are sent in addition to the
regular "READY=1" and "RELOADING=1" notifications.
systemd is only very rarely invoked directly, since it is started
early and is already running by the time users may interact with
it. Normally, tools like systemctl(1) are used to give commands to
the manager. Since systemd is usually not invoked directly, the
options listed below are mostly useful for debugging and special
purposes.
Introspection and debugging options
Those options are used for testing and introspection, and systemd
may be invoked with them at any time:
--dump-configuration-items
Dump understood unit configuration items. This outputs a terse
but complete list of configuration items understood in unit
definition files.
--dump-bus-properties
Dump exposed bus properties. This outputs a terse but complete
list of properties exposed on D-Bus.
Added in version 239.
--test
Determine the initial start-up transaction (i.e. the list of
jobs enqueued at start-up), dump it and exit — without
actually executing any of the determined jobs. This option is
useful for debugging only. Note that during regular service
manager start-up additional units not shown by this operation
may be started, because hardware, socket, bus or other kinds
of activation might add additional jobs as the transaction is
executed. Use --system to request the initial transaction of
the system service manager (this is also the implied default),
combine with --user to request the initial transaction of the
per-user service manager instead.
--system, --user
When used in conjunction with --test, selects whether to
calculate the initial transaction for the system instance or
for a per-user instance. These options have no effect when
invoked without --test, as during regular (i.e. non---test)
invocations the service manager will automatically detect
whether it shall operate in system or per-user mode, by
checking whether the PID it is run as is 1 or not. Note that
it is not supported booting and maintaining a system with the
service manager running in --system mode but with a PID other
than 1.
-h, --help
Print a short help text and exit.
--version
Print a short version string and exit.
Options that duplicate kernel command line settings
Those options correspond directly to options listed above in
"Kernel Command Line". Both forms may be used equivalently for the
system manager, but it is recommended to use the forms listed
above in this context, because they are properly namespaced. When
an option is specified both on the kernel command line and as a
normal command line argument, the latter has higher precedence.
When systemd is used as a user manager, the kernel command line is
ignored and only the options described below are understood.
Nevertheless, systemd is usually started in this mode through the
user@.service(5) service, which is shared between all users. It
may be more convenient to use configuration files to modify
settings (see systemd-user.conf(5)), or environment variables. See
the "Environment" section above for a discussion of how the
environment block is set.
--unit=
Set default unit to activate on startup. If not specified,
defaults to default.target. See systemd.unit= above.
--dump-core
Enable core dumping on crash. This switch has no effect when
running as user instance. Same as systemd.dump_core= above.
--crash-vt=VT
Switch to a specific virtual console (VT) on crash. This
switch has no effect when running as user instance. Same as
systemd.crash_chvt= above (but not the different spelling!).
Added in version 227.
--crash-shell
Run a shell on crash. This switch has no effect when running
as user instance. See systemd.crash_shell= above.
--crash-action=
Specify what to do when the system manager (PID 1) crashes.
This switch has no effect when systemd is running as user
instance. See systemd.crash_action= above.
Added in version 256.
--confirm-spawn
Ask for confirmation when spawning processes. This switch has
no effect when run as user instance. See systemd.confirm_spawn
above.
--show-status
Show terse unit status information on the console during
boot-up and shutdown. See systemd.show_status above.
Added in version 244.
--log-color
Highlight important log messages. See systemd.log_color above.
Added in version 244.
--log-level=
Set log level. See systemd.log_level above.
--log-location
Include code location in log messages. See
systemd.log_location above.
Added in version 244.
--log-target=
Set log target. See systemd.log_target above.
--log-time=
Prefix console messages with timestamp. See systemd.log_time
above.
Added in version 246.
--machine-id=
Override the machine-id set on the hard drive. See
systemd.machine_id= above.
Added in version 229.
--service-watchdogs
Globally enable/disable all service watchdog timeouts and
emergency actions. See systemd.service_watchdogs above.
Added in version 237.
--default-standard-output=, --default-standard-error=
Sets the default output or error output for all services and
sockets, respectively. See systemd.default_standard_output=
and systemd.default_standard_error= above.
When systemd is started or restarted, it may set the system clock
to the "epoch". This mechanism is used to ensure that the system
clock remains somewhat reasonably initialized and roughly
monotonic across reboots, in case no battery-backed local RTC is
available or it does not work correctly.
The epoch is the lowest date above which the system clock time is
assumed to be set correctly. When initializing, the local clock is
advanced to the epoch if it was set to a lower value. As a special
case, if the local clock is sufficiently far in the future (by
default 15 years, but this can be configured at build time), the
hardware clock is assumed to be broken, and the system clock is
rewound to the epoch.
The epoch is set to the highest of: the build time of systemd, the
modification time ("mtime") of /usr/lib/clock-epoch, and the
modification time of /var/lib/systemd/timesync/clock.
/run/systemd/notify
Daemon status notification socket. This is an AF_UNIX datagram
socket and is used to implement the daemon notification logic
as implemented by sd_notify(3).
/run/systemd/private
Used internally as communication channel between systemctl(1)
and the systemd process. This is an AF_UNIX stream socket.
This interface is private to systemd and should not be used in
external projects.
/usr/lib/clock-epoch
The modification time ("mtime") of this file is used for the
time epoch, see previous section.
Added in version 247.
/var/lib/systemd/timesync/clock
The modification time ("mtime") of this file is updated by
systemd-timesyncd.service(8). If present, the modification
time of file is used for the epoch, see previous section.
Added in version 257.
systemd 252
Kernel command-line arguments systemd.unified_cgroup_hierarchy
and systemd.legacy_systemd_cgroup_controller were deprecated.
Please switch to the unified cgroup hierarchy.
The systemd Homepage[9], systemd-system.conf(5), locale.conf(5),
systemctl(1), journalctl(1), systemd-notify(1), daemon(7),
sd-daemon(3), org.freedesktop.systemd1(5), systemd.unit(5),
systemd.special(7), pkg-config(1), kernel-command-line(7),
bootup(7), systemd.directives(7), org.freedesktop.systemd1(5)
For more information about the concepts and ideas behind systemd,
please refer to the Original Design Document[10].
1. Interface Portability and Stability Promise
https://systemd.io/PORTABILITY_AND_STABILITY/
2. Container Interface
https://systemd.io/CONTAINER_INTERFACE
3. initrd Interface
https://systemd.io/INITRD_INTERFACE/
4. Control Groups v2
https://docs.kernel.org/admin-guide/cgroup-v2.html
5. XDG Base Directory specification
https://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
6. It is recommended for other tools to set and check $SUDO_UID
as appropriate, treating it is a common interface.
7. Known Environment Variables
https://systemd.io/ENVIRONMENT
8. System and Service Credentials
https://systemd.io/CREDENTIALS
9. systemd Homepage
https://systemd.io/
10. Original Design Document
https://0pointer.de/blog/projects/systemd.html
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~rc2 SYSTEMD(1)
Pages that refer to this page: busctl(1), homectl(1), hostnamectl(1), importctl(1), journalctl(1), localectl(1), logger(1), loginctl(1), machinectl(1), oomctl(1), pcp-check(1), pcp-geolocate(1), pcp-reboot-init(1), pmfind_check(1), pmie(1), pmie_check(1), pmlogctl(1), pmlogger(1), pmlogger_check(1), pmlogger_daily(1), pmproxy(1), pmseries_import(1), portablectl(1), resolvectl(1), run0(1), systemctl(1), systemd-ac-power(1), systemd-analyze(1), systemd-ask-password(1), systemd-cat(1), systemd-cgls(1), systemd-cgtop(1), systemd-creds(1), systemd-cryptenroll(1), systemd-delta(1), systemd-detect-virt(1), systemd-dissect(1), systemd-escape(1), systemd-firstboot(1), systemd-id128(1), systemd-inhibit(1), systemd-machine-id-setup(1), systemd-measure(1), systemd-mount(1), systemd-notify(1), systemd-nspawn(1), systemd-path(1), systemd-run(1), systemd-socket-activate(1), systemd-ssh-issue(1), systemd-ssh-proxy(1), systemd-stdio-bridge(1), systemd-tty-ask-password-agent(1), systemd-vmspawn(1), 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sd_bus_set_connected_signal(3), sd_bus_set_description(3), sd_bus_set_exit_on_disconnect(3), sd_bus_set_fd(3), sd_bus_set_method_call_timeout(3), sd_bus_set_property(3), sd_bus_set_sender(3), sd_bus_set_server(3), sd_bus_set_watch_bind(3), sd_bus_slot_get_bus(3), sd_bus_slot_ref(3), sd_bus_slot_set_description(3), sd_bus_slot_set_destroy_callback(3), sd_bus_slot_set_floating(3), sd_bus_slot_set_userdata(3), sd_bus_start(3), sd_bus_track_add_name(3), sd_bus_track_new(3), sd_bus_wait(3), sd-daemon(3), sd-device(3), sd_device_get_syspath(3), sd-event(3), sd_event_add_child(3), sd_event_add_defer(3), sd_event_add_inotify(3), sd_event_add_io(3), sd_event_add_memory_pressure(3), sd_event_add_signal(3), sd_event_add_time(3), sd_event_exit(3), sd_event_new(3), sd_event_now(3), sd_event_run(3), sd_event_set_signal_exit(3), sd_event_set_watchdog(3), sd_event_source_set_destroy_callback(3), sd_event_wait(3), sd_get_seats(3), sd-hwdb(3), sd_hwdb_get(3), sd_hwdb_new(3), sd-id128(3), sd_id128_get_machine(3), sd_id128_randomize(3), sd_id128_to_string(3), sd_is_fifo(3), sd-journal(3), sd_journal_add_match(3), sd_journal_enumerate_fields(3), sd_journal_get_catalog(3), sd_journal_get_cursor(3), sd_journal_get_cutoff_realtime_usec(3), sd_journal_get_data(3), sd_journal_get_fd(3), sd_journal_get_realtime_usec(3), sd_journal_get_seqnum(3), sd_journal_get_usage(3), sd_journal_has_runtime_files(3), sd_journal_next(3), sd_journal_open(3), sd_journal_print(3), sd_journal_query_unique(3), sd_journal_seek_head(3), sd_journal_stream_fd(3), sd-json(3), sd_listen_fds(3), sd-login(3), sd_login_monitor_new(3), sd_machine_get_class(3), sd_notify(3), sd_path_lookup(3), sd_pidfd_get_inode_id(3), sd_pid_get_owner_uid(3), sd_seat_get_active(3), sd_session_is_active(3), sd_uid_get_state(3), sd-varlink(3), sd_varlink_push_fd(3), sd_varlink_send(3), sd_varlink_set_description(3), sd_watchdog_enabled(3), ttyslot(3), udev_device_get_syspath(3), udev_device_has_tag(3), udev_device_new_from_syspath(3), udev_enumerate_add_match_subsystem(3), udev_enumerate_new(3), udev_enumerate_scan_devices(3), udev_list_entry(3), udev_monitor_filter_update(3), udev_monitor_new_from_netlink(3), udev_monitor_receive_device(3), udev_new(3), binfmt.d(5), capsule@.service(5), core(5), crypttab(5), dnf4.conf(5), dnssec-trust-anchors.d(5), environment.d(5), homed.conf(5), hostname(5), integritytab(5), journald.conf(5), journal-remote.conf(5), journal-upload.conf(5), locale.conf(5), localtime(5), logind.conf(5), machine-id(5), machine-info(5), modules-load.d(5), networkd.conf(5), oomd.conf(5), org.freedesktop.home1(5), org.freedesktop.hostname1(5), org.freedesktop.import1(5), org.freedesktop.locale1(5), org.freedesktop.LogControl1(5), org.freedesktop.login1(5), org.freedesktop.machine1(5), org.freedesktop.network1(5), org.freedesktop.oom1(5), org.freedesktop.portable1(5), org.freedesktop.resolve1(5), org.freedesktop.systemd1(5), org.freedesktop.sysupdate1(5), org.freedesktop.timedate1(5), org.freedesktop.timesync1(5), os-release(5), pmlogger.control(5), proc(5), proc_sys_kernel(5), repart.d(5), resolved.conf(5), sysctl.d(5), systemd.automount(5), systemd.device(5), systemd.dns-delegate(5), systemd.dnssd(5), systemd.exec(5), systemd.kill(5), systemd.mount(5), systemd.netdev(5), systemd.network(5), systemd.nspawn(5), systemd.path(5), systemd.pcrlock(5), systemd.preset(5), systemd.resource-control(5), systemd.scope(5), systemd.service(5), systemd-sleep.conf(5), systemd.slice(5), systemd.socket(5), systemd.swap(5), systemd-system.conf(5), systemd.target(5), systemd.timer(5), systemd.unit(5), sysupdate.d(5), sysupdate.features(5), sysusers.d(5), timesyncd.conf(5), tmpfiles.d(5), user@.service(5), utmp(5), vconsole.conf(5), veritytab(5), yum.conf(5), boot(7), bootparam(7), bootup(7), cgroups(7), daemon(7), file-hierarchy(7), kernel-command-line(7), lvmthin(7), mount_namespaces(7), pid_namespaces(7), smbios-type-11(7), systemd.directives(7), systemd.environment-generator(7), systemd.generator(7), systemd.image-filter(7), systemd.image-policy(7), systemd.index(7), systemd.journal-fields(7), systemd.offline-updates(7), systemd.special(7), systemd.syntax(7), systemd.system-credentials(7), systemd.time(7), systemd.v(7), agetty(8), cryptsetup(8), ctrlaltdel(8), integritysetup(8), logrotate(8), nss-myhostname(8), nss-mymachines(8), nss-resolve(8), nss-systemd(8), pam_systemd(8), pam_systemd_home(8), poweroff(8), rpm-plugin-prioreset(8), rpm-plugin-systemd-inhibit(8), shutdown(8), systemd-ask-password-console.service(8), systemd-backlight@.service(8), systemd-battery-check.service(8), systemd-binfmt.service(8), systemd-bless-boot-generator(8), systemd-bless-boot.service(8), systemd-boot-check-no-failures.service(8), systemd-boot-clear-sysfail.service(8), systemd-boot-random-seed.service(8), systemd-bsod.service(8), systemd-cryptsetup(8), systemd-cryptsetup-generator(8), systemd-debug-generator(8), systemd-environment-d-generator(8), systemd-factory-reset(8), systemd-factory-reset-generator(8), systemd-fsck@.service(8), systemd-fstab-generator(8), systemd-getty-generator(8), systemd-gpt-auto-generator(8), systemd-hibernate-resume-generator(8), systemd-hibernate-resume.service(8), systemd-homed.service(8), systemd-hostnamed.service(8), systemd-hwdb(8), systemd-importd.service(8), systemd-import-generator(8), systemd-integritysetup-generator(8), systemd-integritysetup@.service(8), systemd-journald.service(8), systemd-journal-gatewayd.service(8), systemd-localed.service(8), systemd-logind.service(8), systemd-loop@.service(8), systemd-machined.service(8), systemd-machine-id-commit.service(8), systemd-makefs@.service(8), systemd-modules-load.service(8), systemd-mountfsd.service(8), systemd-networkd.service(8), systemd-networkd-wait-online.service(8), systemd-network-generator.service(8), systemd-nsresourced.service(8), systemd-oomd.service(8), systemd-pcrlock(8), systemd-pcrphase.service(8), systemd-portabled.service(8), systemd-poweroff.service(8), systemd-quotacheck@.service(8), systemd-random-seed.service(8), systemd-rc-local-generator(8), systemd-remount-fs.service(8), systemd-repart(8), systemd-resolved.service(8), systemd-rfkill.service(8), systemd-run-generator(8), systemd-socket-proxyd(8), systemd-soft-reboot.service(8), systemd-ssh-generator(8), systemd-storagetm.service(8), systemd-suspend.service(8), systemd-sysctl.service(8), systemd-sysext(8), systemd-system-update-generator(8), systemd-sysupdate(8), systemd-sysupdated.service(8), systemd-sysusers(8), systemd-sysv-generator(8), systemd-timedated.service(8), systemd-timesyncd.service(8), systemd-time-wait-sync.service(8), systemd-tmpfiles(8), systemd-tpm2-clear.service(8), systemd-tpm2-generator(8), systemd-tpm2-setup.service(8), systemd-update-done.service(8), systemd-update-utmp.service(8), systemd-userdbd.service(8), systemd-user-sessions.service(8), systemd-validatefs@.service(8), systemd-vconsole-setup.service(8), systemd-veritysetup-generator(8), systemd-veritysetup@.service(8), systemd-volatile-root.service(8), systemd-xdg-autostart-generator(8), uuidd(8), veritysetup(8)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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