systemd(newest.html) - phpMan

SYSTEMD(1)                          systemd                         SYSTEMD(1)
NAME
       systemd, init - systemd system and service manager
SYNOPSIS
       /usr/lib/systemd/systemd [OPTIONS...]
       init [OPTIONS...] {COMMAND}
DESCRIPTION
       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.
       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 telinit(8) 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.conf(5)
       for more information.
OPTIONS
       The following options are understood:
       --test
           Determine startup sequence, dump it and exit. This is an option
           useful for debugging only.
       --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 to dbus.
       --unit=
           Set default unit to activate on startup. If not specified, defaults
           to default.target.
       --system, --user
           For --system, tell systemd to run a system instance, even if the
           process ID is not 1, i.e. systemd is not run as init process.
           --user does the opposite, running a user instance even if the
           process ID is 1. Normally, it should not be necessary to pass these
           options, as systemd automatically detects the mode it is started
           in. These options are hence of little use except for debugging.
           Note that it is not supported booting and maintaining a full system
           with systemd running in --system mode, but PID not 1. In practice,
           passing --system explicitly is only useful in conjunction with
           --test.
       --dump-core
           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.
       --crash-vt=VT
           Switch 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.
       --crash-shell
           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.
       --crash-reboot
           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.
       --confirm-spawn
           Ask for confirmation when spawning processes. This switch has no
           effect when run as user instance.
       --show-status=
           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 ShowStatus=, see systemd-system.conf(5).
       --log-target=
           Set log target. Argument must be one of console, journal, kmsg,
           journal-or-kmsg, null.
       --log-level=
           Set log level. As argument this accepts a numerical log level or
           the well-known syslog(3) symbolic names (lowercase): emerg, alert,
           crit, err, warning, notice, info, debug.
       --log-color=
           Highlight important log messages. Argument is a boolean value. If
           the argument is omitted, it defaults to true.
       --log-location=
           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 true.
       --default-standard-output=, --default-standard-error=
           Sets the default output or error output for all services and
           sockets, respectively. That is, controls the default for
           StandardOutput= and StandardError= (see systemd.exec(5) for
           details). Takes one of inherit, null, tty, journal,
           journal+console, syslog, syslog+console, kmsg, kmsg+console. If the
           argument is omitted --default-standard-output= defaults to journal
           and --default-standard-error= to inherit.
       --machine-id=
           Override the machine-id set on the hard drive, useful for network
           booting or for containers. May not be set to all zeros.
       --service-watchdogs=
           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.
       -h, --help
           Print a short help text and exit.
       --version
           Print a short version string and exit.
CONCEPTS
       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, 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:
        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.
       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[1] 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-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 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.
       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[2].
       Note that some but not all interfaces provided by systemd are covered
       by the Interface Stability Promise[3].
       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).
       Systems which invoke systemd in a container or initrd environment
       should implement the Container Interface[4] or initrd Interface[5]
       specifications, respectively.
DIRECTORIES
       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[6] 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).
       SysV init scripts directory
           The 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 directory
           The 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.
SIGNALS
       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-irreversible.
       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-irreversible. 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 2s 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-irreversible.
       SIGRTMIN+4
           Powers off the machine, starts the poweroff.target unit. This is
           mostly equivalent to systemctl start poweroff.target
           --job-mode=replace-irreversible.
       SIGRTMIN+5
           Reboots the machine, starts the reboot.target unit. This is mostly
           equivalent to systemctl start reboot.target
           --job-mode=replace-irreversible.
       SIGRTMIN+6
           Reboots the machine via kexec, starts the kexec.target unit. This
           is mostly equivalent to systemctl start kexec.target
           --job-mode=replace-irreversible.
       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+20
           Enables display of status messages on the console, as controlled
           via systemd.show_status=1 on the kernel command line.
       SIGRTMIN+21
           Disables display of status messages on the console, as controlled
           via systemd.show_status=0 on the kernel command line.
       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".
       SIGRTMIN+24
           Immediately exits the manager (only available for --user
           instances).
       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.
       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.
ENVIRONMENT
       $SYSTEMD_LOG_LEVEL
           systemd reads the log level from this environment variable. This
           can be overridden with --log-level=.
       $SYSTEMD_LOG_TARGET
           systemd reads the log target from this environment variable. This
           can be overridden with --log-target=.
       $SYSTEMD_LOG_COLOR
           Controls whether systemd highlights important log messages. This
           can be overridden with --log-color=.
       $SYSTEMD_LOG_LOCATION
           Controls whether systemd prints the code location along with log
           messages. This can be overridden with --log-location=.
       $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[6] to find its configuration.
       $SYSTEMD_UNIT_PATH
           Controls where systemd looks for unit files.
       $SYSTEMD_SYSVINIT_PATH
           Controls where systemd looks for SysV init scripts.
       $SYSTEMD_SYSVRCND_PATH
           Controls where systemd looks for SysV init script runlevel link
           farms.
       $SYSTEMD_COLORS
           The 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_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.
       $SYSTEMD_PAGERSECURE
           Takes a boolean argument. When true, the "secure" mode of the pager
           is enabled; if false, disabled. If $SYSTEMD_PAGERSECURE is not set
           at all, 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). In secure mode, LESSSECURE=1 will be set
           when invoking the pager, and the pager shall disable commands that
           open or create new files or start new subprocesses. When
           $SYSTEMD_PAGERSECURE is not set at all, pagers which are not known
           to implement secure mode will not be used. (Currently only less(1)
           implements secure mode.)
           Note: when commands are invoked with elevated privileges, for
           example under sudo(8) or pkexec(1), care must be taken to ensure
           that unintended interactive features are not enabled. "Secure" mode
           for the pager may be enabled automatically as describe above.
           Setting SYSTEMD_PAGERSECURE=0 or not removing it from the inherited
           environment allows the user to invoke arbitrary commands. Note that
           if the $SYSTEMD_PAGER or $PAGER variables are to be honoured,
           $SYSTEMD_PAGERSECURE must be set too. It might be reasonable to
           completly disable the pager using --no-pager instead.
       $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 systemd for supervised processes for status and start-up
           completion notification. See sd_notify(3) for more information.
KERNEL COMMAND LINE
       When run as system instance systemd parses a number of kernel command
       line arguments[7]:
       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 initial RAM disk
           (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.
       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 (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_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, 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_reboot
           Takes 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_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.
       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.
       systemd.show_status
           Takes 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 false until a unit fails or 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 auto. If specified
           overrides the system manager configuration file option ShowStatus=,
           see systemd-system.conf(5). However, the process command line
           option --show-status= takes precedence over both this kernel
           command line option and the configuration file option.
       systemd.log_target=, systemd.log_level=, systemd.log_location=,
       systemd.log_color
           Controls 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 --default-standard-output= and
           --default-standard-error= 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_hierarchy
           When specified without an argument or with a true argument, enables
           the usage of unified cgroup hierarchy[8] (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 --with-default-hierarchy=
           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_controller
           Takes 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[9],
           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 --with-default-hierarchy=
           option). If the kernel does not support unified cgroup hierarchy,
           the legacy hierarchy will be used even if this option is specified.
       quiet
           Turn off status output at boot, much like systemd.show_status=false
           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.
       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.
       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.
       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.
       2, 3, 4, 5
           Boot 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.conf(5) and
           locale(7).
       For other kernel command line parameters understood by components of
       the core OS, please refer to kernel-command-line(7).
SOCKETS AND FIFOS
       /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.
       /dev/initctl
           Limited 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[10], systemd-system.conf(5), locale.conf(5),
       systemctl(1), journalctl(1), systemd-notify(1), daemon(7), sd-
       daemon(3), systemd.unit(5), systemd.special(5), pkg-config(1), kernel-
       command-line(7), bootup(7), systemd.directives(7)
NOTES
        1. cgroups.txt
           https://www.kernel.org/doc/Documentation/cgroup-v1/cgroups.txt
        2. Original Design Document
           http://0pointer.de/blog/projects/systemd.html
        3. Interface Stability Promise
           https://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise
        4. Container Interface
           https://www.freedesktop.org/wiki/Software/systemd/ContainerInterface
        5. initrd Interface
           https://www.freedesktop.org/wiki/Software/systemd/InitrdInterface
        6. XDG Base Directory specification
           http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html
        7. If 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.
        8. unified cgroup hierarchy
           https://www.kernel.org/doc/Documentation/cgroup-v2.txt
        9. legacy cgroup hierarchy
           https://www.kernel.org/doc/Documentation/cgroup-v1/
       10. systemd Homepage
           https://www.freedesktop.org/wiki/Software/systemd/
systemd 239                                                         SYSTEMD(1)