systemdsystemdsystemd1systemdinitsystemd system and service manager/usr/lib/systemd/systemdOPTIONSinitOPTIONSCOMMANDDescriptionsystemd 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.For compatibility with SysV, if systemd is called as
init and a PID that is not 1, it will execute
telinit and pass all command line arguments
unmodified. That means init and
telinit are mostly equivalent when invoked from
normal login sessions. See
telinit8
for more information.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.conf5
for more information.OptionsThe following options are understood: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 to request
the initial transaction of the system service manager (this is also the implied default), combine
with to request the initial transaction of the per-user service manager
instead.Dump understood unit configuration items. This
outputs a terse but complete list of configuration items
understood in unit definition files.Dump exposed bus properties. This outputs a terse but complete list of properties
exposed on D-Bus.Set default unit to activate on startup. If
not specified, defaults to
default.target.When used in conjunction with , 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 , as during regular
(i.e. non-) 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 mode but with a PID other than 1.Enable core dumping on crash. This switch has
no effect when running as user instance. This setting may also
be enabled during boot on the kernel command line via the
systemd.dump_core= option, see
below.VTSwitch to a specific virtual console (VT) on
crash. Takes a positive integer in the range 1–63, or a
boolean argument. If an integer is passed, selects which VT to
switch to. If yes, the VT kernel messages
are written to is selected. If no, no VT
switch is attempted. This switch has no effect when running as
user instance. This setting may also be enabled during boot,
on the kernel command line via the
systemd.crash_vt= option, see
below.Run a shell on crash. This switch has no
effect when running as user instance. This setting may also be
enabled during boot, on the kernel command line via the
systemd.crash_shell= option, see
below.Automatically reboot the system on crash. This
switch has no effect when running as user instance. This
setting may also be enabled during boot, on the kernel command
line via the systemd.crash_reboot= option,
see below.Ask for confirmation when spawning processes.
This switch has no effect when run as user
instance.Takes a boolean argument or the special value auto. If on, terse unit
status information is shown on the console during boot-up and shutdown. If off, no such status information is
shown. If set to auto behavior is similar to off, except that it is automatically switched
to on, as soon as the first unit failure or significant boot delay is encountered. This switch has no effect
when invoked as user instance. If specified, overrides both the kernel command line setting
systemd.show_status= (see below) and the configuration file option
, see
systemd-system.conf5.Set log target. Argument must be one of
,
,
,
,
.Set log level. As
argument this accepts a numerical log
level or the well-known syslog3
symbolic names (lowercase):
,
,
,
,
,
,
,
.Highlight important log messages. Argument is
a boolean value. If the argument is omitted, it defaults to
.Include code location in log messages. This is
mostly relevant for debugging purposes. Argument is a boolean
value. If the argument is omitted it defaults to
.Sets the default output or error output for
all services and sockets, respectively. That is, controls the
default for and
(see
systemd.exec5
for details). Takes one of
,
,
,
,
,
,
. If the
argument is omitted
defaults to
and
to
.Override the machine-id set on the hard drive,
useful for network booting or for containers. May not be set
to all zeros.Globally enable/disable all service watchdog timeouts and emergency
actions. This setting may also be specified during boot, on the kernel
command line via the systemd.service_watchdogs=
option, see below. Defaults to enabled.Conceptssystemd 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.unit5,
however some are created automatically from other configuration,
dynamically from system state or programmatically at runtime.
Units may be "active" (meaning started, bound, plugged in, …,
depending on the unit type, see below), or "inactive" (meaning
stopped, unbound, unplugged, …), as well as in the process of
being activated or deactivated, i.e. between the two states (these
states are called "activating", "deactivating"). A special
"failed" state is available as well, which is very similar to
"inactive" and is entered when the service failed in some way
(process returned error code on exit, or crashed, an operation
timed out, or after too many restarts). If this state is entered,
the cause will be logged, for later reference. Note that the
various unit types may have a number of additional substates,
which are mapped to the five generalized unit states described
here.The following unit types are available:Service units, which start and control daemons
and the processes they consist of. For details, see
systemd.service5.Socket units, which encapsulate local IPC or
network sockets in the system, useful for socket-based
activation. For details about socket units, see
systemd.socket5,
for details on socket-based activation and other forms of
activation, see
daemon7.Target units are useful to group units, or
provide well-known synchronization points during boot-up, see
systemd.target5.Device units expose kernel devices in systemd
and may be used to implement device-based activation. For
details, see
systemd.device5.Mount units control mount points in the file
system, for details see
systemd.mount5.Automount units provide automount capabilities,
for on-demand mounting of file systems as well as parallelized
boot-up. See
systemd.automount5.Timer units are useful for triggering activation
of other units based on timers. You may find details in
systemd.timer5.Swap units are very similar to mount units and
encapsulate memory swap partitions or files of the operating
system. They are described in
systemd.swap5.Path units may be used to activate other
services when file system objects change or are modified. See
systemd.path5.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.slice5.Scope units are similar to service units, but
manage foreign processes instead of starting them as well. See
systemd.scope5.Units are named as their configuration files. Some units
have special semantics. A detailed list is available in
systemd.special7.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.special7
for details about these target units.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:It is in an active, activating, deactivating or failed state (i.e. in any unit state except for inactive)It has a job queued for itIt is a dependency of some sort of at least one other unit that is loaded into memoryIt 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)It has been pinned into memory programmatically by a D-Bus callsystemd 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 cgroups.txt
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/systemd/), or in tools such as
systemd-cgls1
or
ps1
(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 the SysV init system to a large
degree: SysV init scripts are supported and simply read as an
alternative (though limited) configuration file format. The SysV
/dev/initctl interface is provided, and
compatibility implementations of the various SysV client tools are
available. In addition to that, various established Unix
functionality such as /etc/fstab or the
utmp database are supported.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
our example, start jobs for any of those inactive units getting queued as
well.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 or /proc.For more information about the concepts and
ideas behind systemd, please refer to the
Original Design Document.Note that some but not all interfaces provided
by systemd are covered by the
Interface
Stability Promise.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.generator7.Systems which invoke systemd in a container or initrd
environment should implement the
Container Interface or
initrd Interface
specifications, respectively.DirectoriesSystem unit directoriesThe 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
systemctl1
tool. Full list of directories is provided in
systemd.unit5.
User unit directoriesSimilar rules apply for the user unit
directories. However, here the
XDG
Base Directory specification 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
systemctl1
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.unit5.
SysV init scripts directoryThe location of the SysV init script directory
varies between distributions. If systemd cannot find a native
unit file for a requested service, it will look for a SysV
init script of the same name (with the
.service suffix
removed).SysV runlevel link farm directoryThe location of the SysV runlevel link farm
directory varies between distributions. systemd will take the
link farm into account when figuring out whether a service
shall be enabled. Note that a service unit with a native unit
configuration file cannot be started by activating it in the
SysV runlevel link farm.SignalsSIGTERMUpon 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.SIGINTUpon 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
CtrlAltDel on the
console will trigger this signal. Hence, if a reboot is hanging, pressing
CtrlAltDel 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.SIGWINCHWhen 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.SIGPWRWhen this signal is received the systemd
manager will start the sigpwr.target
unit. This is mostly equivalent to systemctl start
sigpwr.target.SIGUSR1When this signal is received the systemd
manager will try to reconnect to the D-Bus
bus.SIGUSR2When 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.SIGHUPReloads the complete daemon configuration.
This is mostly equivalent to systemctl
daemon-reload.SIGRTMIN+0Enters default mode, starts the
default.target unit. This is mostly
equivalent to systemctl isolate
default.target.SIGRTMIN+1Enters rescue mode, starts the
rescue.target unit. This is mostly
equivalent to systemctl isolate
rescue.target.SIGRTMIN+2Enters emergency mode, starts the
emergency.service unit. This is mostly
equivalent to systemctl isolate
emergency.service.SIGRTMIN+3Halts the machine, starts the
halt.target unit. This is mostly
equivalent to systemctl start halt.target
--job-mode=replace-irreversibly.SIGRTMIN+4Powers off the machine, starts the
poweroff.target unit. This is mostly
equivalent to systemctl start poweroff.target
--job-mode=replace-irreversibly.SIGRTMIN+5Reboots the machine, starts the
reboot.target unit. This is mostly
equivalent to systemctl start reboot.target
--job-mode=replace-irreversibly.SIGRTMIN+6Reboots the machine via kexec, starts the
kexec.target unit. This is mostly
equivalent to systemctl start kexec.target
--job-mode=replace-irreversibly.SIGRTMIN+13Immediately halts the machine.SIGRTMIN+14Immediately powers off the machine.SIGRTMIN+15Immediately reboots the machine.SIGRTMIN+16Immediately reboots the machine with kexec.SIGRTMIN+20Enables display of status messages on the
console, as controlled via
systemd.show_status=1 on the kernel command
line.SIGRTMIN+21Disables display of
status messages on the console, as
controlled via
systemd.show_status=0
on the kernel command
line.SIGRTMIN+22Sets the service manager's log level to debug, in a fashion equivalent to
systemd.log_level=debug on the kernel command line.SIGRTMIN+23Restores 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 in the configuration file, or the built-in default of
info.SIGRTMIN+24Immediately exits the manager (only available
for --user instances).SIGRTMIN+26Restores 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 in the configuration file, or the built-in
default.SIGRTMIN+27SIGRTMIN+28Sets 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.Environment$SYSTEMD_LOG_LEVELsystemd reads the log level from this
environment variable. This can be overridden with
.$SYSTEMD_LOG_TARGETsystemd reads the log target from this
environment variable. This can be overridden with
.$SYSTEMD_LOG_COLORControls whether systemd highlights important
log messages. This can be overridden with
.$SYSTEMD_LOG_LOCATIONControls whether systemd prints the code
location along with log messages. This can be overridden with
.$XDG_CONFIG_HOME$XDG_CONFIG_DIRS$XDG_DATA_HOME$XDG_DATA_DIRSThe systemd user manager uses these variables
in accordance to the XDG
Base Directory specification to find its
configuration.$SYSTEMD_UNIT_PATHControls where systemd looks for unit
files.$SYSTEMD_SYSVINIT_PATHControls where systemd looks for SysV init
scripts.$SYSTEMD_SYSVRCND_PATHControls where systemd looks for SysV init
script runlevel link farms.$SYSTEMD_COLORSThe value must be a boolean. Controls whether colorized output should be
generated. This can be specified to override the decision that systemd
makes based on $TERM and what the console is connected to.$SYSTEMD_URLIFYThe 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_FDNAMESSet by systemd for supervised processes during
socket-based activation. See
sd_listen_fds3
for more information.$NOTIFY_SOCKETSet by systemd for supervised processes for
status and start-up completion notification. See
sd_notify3
for more information.For further environment variables understood by systemd and its various components, see Known Environment Variables.Kernel Command LineWhen run as system instance systemd parses a number of
kernel command line argumentsIf run inside a Linux
container these arguments may be passed as command line arguments
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.: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.special7
for details about these units. The option prefixed with
rd. is honored only in the initial RAM disk
(initrd), while the one that is not prefixed only in the main
system.systemd.dump_coreTakes 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.systemd.crash_chvtTakes 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 (VT) when it
crashes. Defaults to disabled, meaning that no such switch is attempted. If
set to enabled, the VT the kernel messages are written to is selected.
systemd.crash_shellTakes 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, after a 10s delay. Otherwise, no shell is spawned. Defaults
to disabled, for security reasons, as the shell is not protected by password
authentication.systemd.crash_rebootTakes a boolean argument or enables the option if specified
without an argument. If enabled, the system manager (PID 1) will reboot the
machine automatically when it crashes, after a 10s delay. Otherwise, the
system will hang indefinitely. Defaults to disabled, in order to avoid a
reboot loop. If combined with systemd.crash_shell, the
system is rebooted after the shell exits.systemd.confirm_spawnTakes 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 . 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.
systemd.service_watchdogs=Takes a boolean argument. If disabled, all service runtime
watchdogs () and emergency actions (e.g.
or ) are
ignored by the system manager (PID 1); see
systemd.service5.
Defaults to enabled, i.e. watchdogs and failure actions are processed
normally. The hardware watchdog is not affected by this
option.systemd.show_statusTakes a boolean argument or the constant
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.
auto behaves like until a unit
fails or there is a significant delay in boot. Defaults to enabled, unless
is passed as kernel command line option, in which case
it defaults to auto. If specified overrides the system
manager configuration file option , see
systemd-system.conf5.
However, the process command line option
takes precedence over both this kernel command line option and the
configuration file option.systemd.status_unit_format=Takes either or as the value. If
, the system manager will use unit names in status messages. If specified,
overrides the system manager configuration file option , see
systemd-system.conf5.
systemd.log_target=systemd.log_level=systemd.log_location=systemd.log_colorControls log output, with the same effect as the
$SYSTEMD_LOG_TARGET,
$SYSTEMD_LOG_LEVEL,
$SYSTEMD_LOG_LOCATION,
$SYSTEMD_LOG_COLOR environment variables described above.
systemd.log_color 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, with the same effect as the
and
command line
arguments described above, respectively.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.systemd.unified_cgroup_hierarchyWhen specified without an argument or with a true argument,
enables the usage of
unified cgroup hierarchy
(a.k.a. cgroups-v2). When specified with a false argument, fall back to
hybrid or full legacy cgroup hierarchy.If this option is not specified, the default behaviour is determined
during compilation (the meson
option). If the kernel does not support unified cgroup hierarchy, the legacy
hierarchy will be used even if this option is specified.systemd.legacy_systemd_cgroup_controllerTakes effect if the full unified cgroup hierarchy is not used
(see previous option). When specified without an argument or with a true
argument, disables the use of "hybrid" cgroup hierarchy (i.e. a cgroups-v2
tree used for systemd, and
legacy
cgroup hierarchy, a.k.a. cgroups-v1, for other controllers), and
forces a full "legacy" mode. When specified with a false argument, enables
the use of "hybrid" hierarchy.If this option is not specified, the default behaviour is determined
during compilation (the meson
option). If the kernel does not support unified cgroup hierarchy, the legacy
hierarchy will be used even if this option is specified.quietTurn 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.
debugTurn 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.emergencyrd.emergency-bBoot 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.rescuerd.rescuesinglesS1Boot 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.2345Boot into the specified legacy SysV runlevel.
These are equivalent to
systemd.unit=runlevel2.target,
systemd.unit=runlevel3.target,
systemd.unit=runlevel4.target, and
systemd.unit=runlevel5.target,
respectively, and provided for compatibility reasons and to be
easier to type.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.conf5
and
locale7.
For other kernel command line parameters understood by
components of the core OS, please refer to
kernel-command-line7.Sockets and FIFOs/run/systemd/notifyDaemon status notification socket. This is an
AF_UNIX datagram socket and is used to
implement the daemon notification logic as implemented by
sd_notify3./run/systemd/privateUsed internally as communication channel
between
systemctl1
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./dev/initctlLimited compatibility support for the SysV
client interface, as implemented by the
systemd-initctl.service unit. This is a
named pipe in the file system. This interface is obsolete and
should not be used in new applications.See Also
The systemd Homepage,
systemd-system.conf5,
locale.conf5,
systemctl1,
journalctl1,
systemd-notify1,
daemon7,
sd-daemon3,
systemd.unit5,
systemd.special5,
pkg-config1,
kernel-command-line7,
bootup7,
systemd.directives7