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systemctl manual --详细的介绍_do not send wall message before halt, power-off, r

作者：weixin_40725706 | 2024-02-27 18:56:25

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do not send wall message before halt, power-off, reboot

转自http://man7.org/linux/man-pages/man1/systemctl.1.html

let's take "systemctl status rsh.socket" as example

● rsh.socket - Remote Shell Facilities Activation Socket
   Loaded: loaded (/usr/lib/systemd/system/rsh.socket; disabled; vendor preset: disabled)
   Active: inactive (dead)
   Listen: [::]:514 (Stream)
Accepted: 0; Connected: 0

说明： Loaded行表示Unit是否被load到内存里了。后面的值可以有：loaded，error，“not-found" and "masked"

Active行表示service是否被activated. 通常的value为"active" or "inactive"。

SYSTEMCTL(1)                      systemctl                     SYSTEMCTL(1)

NAME top

       systemctl - Control the systemd system and service manager

SYNOPSIS top

       systemctl [OPTIONS...] COMMAND [NAME...]

DESCRIPTION top

       systemctl may be used to introspect and control the state of the
       "systemd" system and service manager. Please refer to systemd(1) for
       an introduction into the basic concepts and functionality this tool
       manages.

OPTIONS top

       The following options are understood:

       -t, --type=
           The argument should be a comma-separated list of unit types such
           as service and socket.

           If one of the arguments is a unit type, when listing units, limit
           display to certain unit types. Otherwise, units of all types will
           be shown.

           As a special case, if one of the arguments is help, a list of
           allowed values will be printed and the program will exit.

       --state=
           The argument should be a comma-separated list of unit LOAD, SUB,
           or ACTIVE states. When listing units, show only those in the
           specified states. Use --state=failed to show only failed units.

           As a special case, if one of the arguments is help, a list of
           allowed values will be printed and the program will exit.

       -p, --property=
           When showing unit/job/manager properties with the show command,
           limit display to properties specified in the argument. The
           argument should be a comma-separated list of property names, such
           as "MainPID". Unless specified, all known properties are shown.
           If specified more than once, all properties with the specified
           names are shown. Shell completion is implemented for property
           names.

           For the manager itself, systemctl show will show all available
           properties. Those properties are documented in
           systemd-system.conf(5).

           Properties for units vary by unit type, so showing any unit (even
           a non-existent one) is a way to list properties pertaining to
           this type. Similarly, showing any job will list properties
           pertaining to all jobs. Properties for units are documented in
           systemd.unit(5), and the pages for individual unit types
           systemd.service(5), systemd.socket(5), etc.

       -a, --all
           When listing units with list-units, also show inactive units and
           units which are following other units. When showing
           unit/job/manager properties, show all properties regardless
           whether they are set or not.

           To list all units installed in the file system, use the
           list-unit-files command instead.

           When listing units with list-dependencies, recursively show
           dependencies of all dependent units (by default only dependencies
           of target units are shown).

       -r, --recursive
           When listing units, also show units of local containers. Units of
           local containers will be prefixed with the container name,
           separated by a single colon character (":").

       --reverse
           Show reverse dependencies between units with list-dependencies,
           i.e. follow dependencies of type WantedBy=, RequiredBy=, PartOf=,
           BoundBy=, instead of Wants= and similar.

       --after
           With list-dependencies, show the units that are ordered before
           the specified unit. In other words, recursively list units
           following the After= dependency.

           Note that any After= dependency is automatically mirrored to
           create a Before= dependency. Temporal dependencies may be
           specified explicitly, but are also created implicitly for units
           which are WantedBy= targets (see systemd.target(5)), and as a
           result of other directives (for example RequiresMountsFor=). Both
           explicitly and implicitly introduced dependencies are shown with
           list-dependencies.

           When passed to the list-jobs command, for each printed job show
           which other jobs are waiting for it. May be combined with
           --before to show both the jobs waiting for each job as well as
           all jobs each job is waiting for.

       --before
           With list-dependencies, show the units that are ordered after the
           specified unit. In other words, recursively list units following
           the Before= dependency.

           When passed to the list-jobs command, for each printed job show
           which other jobs it is waiting for. May be combined with --after
           to show both the jobs waiting for each job as well as all jobs
           each job is waiting for.

       -l, --full
           Do not ellipsize unit names, process tree entries, journal
           output, or truncate unit descriptions in the output of status,
           list-units, list-jobs, and list-timers.

           Also, show installation targets in the output of is-enabled.

       --value
           When printing properties with show, only print the value, and
           skip the property name and "=".

       --show-types
           When showing sockets, show the type of the socket.

       --job-mode=
           When queuing a new job, this option controls how to deal with
           already queued jobs. It takes one of "fail", "replace",
           "replace-irreversibly", "isolate", "ignore-dependencies",
           "ignore-requirements" or "flush". Defaults to "replace", except
           when the isolate command is used which implies the "isolate" job
           mode.

           If "fail" is specified and a requested operation conflicts with a
           pending job (more specifically: causes an already pending start
           job to be reversed into a stop job or vice versa), cause the
           operation to fail.

           If "replace" (the default) is specified, any conflicting pending
           job will be replaced, as necessary.

           If "replace-irreversibly" is specified, operate like "replace",
           but also mark the new jobs as irreversible. This prevents future
           conflicting transactions from replacing these jobs (or even being
           enqueued while the irreversible jobs are still pending).
           Irreversible jobs can still be cancelled using the cancel
           command.

           "isolate" is only valid for start operations and causes all other
           units to be stopped when the specified unit is started. This mode
           is always used when the isolate command is used.

           "flush" will cause all queued jobs to be canceled when the new
           job is enqueued.

           If "ignore-dependencies" is specified, then all unit dependencies
           are ignored for this new job and the operation is executed
           immediately. If passed, no required units of the unit passed will
           be pulled in, and no ordering dependencies will be honored. This
           is mostly a debugging and rescue tool for the administrator and
           should not be used by applications.

           "ignore-requirements" is similar to "ignore-dependencies", but
           only causes the requirement dependencies to be ignored, the
           ordering dependencies will still be honored.

       --fail
           Shorthand for --job-mode=fail.

           When used with the kill command, if no units were killed, the
           operation results in an error.

       -i, --ignore-inhibitors
           When system shutdown or a sleep state is requested, ignore
           inhibitor locks. Applications can establish inhibitor locks to
           avoid that certain important operations (such as CD burning or
           suchlike) are interrupted by system shutdown or a sleep state.
           Any user may take these locks and privileged users may override
           these locks. If any locks are taken, shutdown and sleep state
           requests will normally fail (regardless of whether privileged or
           not) and a list of active locks is printed. However, if
           --ignore-inhibitors is specified, the locks are ignored and not
           printed, and the operation attempted anyway, possibly requiring
           additional privileges.

       -q, --quiet
           Suppress printing of the results of various commands and also the
           hints about truncated log lines. This does not suppress output of
           commands for which the printed output is the only result (like
           show). Errors are always printed.

       --no-block
           Do not synchronously wait for the requested operation to finish.
           If this is not specified, the job will be verified, enqueued and
           systemctl will wait until the unit's start-up is completed. By
           passing this argument, it is only verified and enqueued. This
           option may not be combined with --wait.

       --wait
           Synchronously wait for started units to terminate again. This
           option may not be combined with --no-block. Note that this will
           wait forever if any given unit never terminates (by itself or by
           getting stopped explicitly); particularly services which use
           "RemainAfterExit=yes".

       --user
           Talk to the service manager of the calling user, rather than the
           service manager of the system.

       --system
           Talk to the service manager of the system. This is the implied
           default.

       --failed
           List units in failed state. This is equivalent to --state=failed.

       --no-wall
           Do not send wall message before halt, power-off, reboot.

       --global
           When used with enable and disable, operate on the global user
           configuration directory, thus enabling or disabling a unit file
           globally for all future logins of all users.

       --no-reload
           When used with enable and disable, do not implicitly reload
           daemon configuration after executing the changes.

       --no-ask-password
           When used with start and related commands, disables asking for
           passwords. Background services may require input of a password or
           passphrase string, for example to unlock system hard disks or
           cryptographic certificates. Unless this option is specified and
           the command is invoked from a terminal, systemctl will query the
           user on the terminal for the necessary secrets. Use this option
           to switch this behavior off. In this case, the password must be
           supplied by some other means (for example graphical password
           agents) or the service might fail. This also disables querying
           the user for authentication for privileged operations.

       --kill-who=
           When used with kill, choose which processes to send a signal to.
           Must be one of main, control or all to select whether to kill
           only the main process, the control process or all processes of
           the unit. The main process of the unit is the one that defines
           the life-time of it. A control process of a unit is one that is
           invoked by the manager to induce state changes of it. For
           example, all processes started due to the ExecStartPre=,
           ExecStop= or ExecReload= settings of service units are control
           processes. Note that there is only one control process per unit
           at a time, as only one state change is executed at a time. For
           services of type Type=forking, the initial process started by the
           manager for ExecStart= is a control process, while the process
           ultimately forked off by that one is then considered the main
           process of the unit (if it can be determined). This is different
           for service units of other types, where the process forked off by
           the manager for ExecStart= is always the main process itself. A
           service unit consists of zero or one main process, zero or one
           control process plus any number of additional processes. Not all
           unit types manage processes of these types however. For example,
           for mount units, control processes are defined (which are the
           invocations of /usr/bin/mount and /usr/bin/umount), but no main
           process is defined. If omitted, defaults to all.

       -s, --signal=
           When used with kill, choose which signal to send to selected
           processes. Must be one of the well-known signal specifiers such
           as SIGTERM, SIGINT or SIGSTOP. If omitted, defaults to SIGTERM.

       -f, --force
           When used with enable, overwrite any existing conflicting
           symlinks.

           When used with edit, create all of the specified units which do
           not already exist.

           When used with halt, poweroff, reboot or kexec, execute the
           selected operation without shutting down all units. However, all
           processes will be killed forcibly and all file systems are
           unmounted or remounted read-only. This is hence a drastic but
           relatively safe option to request an immediate reboot. If --force
           is specified twice for these operations (with the exception of
           kexec), they will be executed immediately, without terminating
           any processes or unmounting any file systems. Warning: specifying
           --force twice with any of these operations might result in data
           loss. Note that when --force is specified twice the selected
           operation is executed by systemctl itself, and the system manager
           is not contacted. This means the command should succeed even when
           the system manager hangs or crashed.

       --message=
           When used with halt, poweroff, reboot or kexec, set a short
           message explaining the reason for the operation. The message will
           be logged together with the default shutdown message.

       --now
           When used with enable, the units will also be started. When used
           with disable or mask, the units will also be stopped. The start
           or stop operation is only carried out when the respective enable
           or disable operation has been successful.

       --root=
           When used with enable/disable/is-enabled (and related commands),
           use the specified root path when looking for unit files. If this
           option is present, systemctl will operate on the file system
           directly, instead of communicating with the systemd daemon to
           carry out changes.

       --runtime
           When used with enable, disable, edit, (and related commands),
           make changes only temporarily, so that they are lost on the next
           reboot. This will have the effect that changes are not made in
           subdirectories of /etc but in /run, with identical immediate
           effects, however, since the latter is lost on reboot, the changes
           are lost too.

           Similarly, when used with set-property, make changes only
           temporarily, so that they are lost on the next reboot.

       --preset-mode=
           Takes one of "full" (the default), "enable-only", "disable-only".
           When used with the preset or preset-all commands, controls
           whether units shall be disabled and enabled according to the
           preset rules, or only enabled, or only disabled.

       -n, --lines=
           When used with status, controls the number of journal lines to
           show, counting from the most recent ones. Takes a positive
           integer argument. Defaults to 10.

       -o, --output=
           When used with status, controls the formatting of the journal
           entries that are shown. For the available choices, see
           journalctl(1). Defaults to "short".

       --firmware-setup
           When used with the reboot command, indicate to the system's
           firmware to boot into setup mode. Note that this is currently
           only supported on some EFI systems and only if the system was
           booted in EFI mode.

       --plain
           When used with list-dependencies, list-units or list-machines,
           the output is printed as a list instead of a tree, and the bullet
           circles are omitted.

       -H, --host=
           Execute the operation remotely. Specify a hostname, or a username
           and hostname separated by "@", to connect to. The hostname may
           optionally be suffixed by a container name, separated by ":",
           which connects directly to a specific container on the specified
           host. This will use SSH to talk to the remote machine manager
           instance. Container names may be enumerated with machinectl -H
           HOST.

       -M, --machine=
           Execute operation on a local container. Specify a container name
           to connect to.

       --no-pager
           Do not pipe output into a pager.

       --no-legend
           Do not print the legend, i.e. column headers and the footer with
           hints.

       -h, --help
           Print a short help text and exit.

       --version
           Print a short version string and exit.

COMMANDS top

The following commands are understood:

Unit Commands
list-units [PATTERN...]
List units that systemd currently has in memory. This includes
units that are either referenced directly or through a
dependency, units that are pinned by applications
programmatically, or units that were active in the past and have
failed. By default only units which are active, have pending
jobs, or have failed are shown; this can be changed with option
--all. If one or more PATTERNs are specified, only units matching
one of them are shown. The units that are shown are additionally
filtered by --type= and --state= if those options are specified.

This is the default command.

list-sockets [PATTERN...]
List socket units currently in memory, ordered by listening
address. If one or more PATTERNs are specified, only socket units
matching one of them are shown. Produces output similar to

LISTEN UNIT ACTIVATES
/dev/initctl systemd-initctl.socket systemd-initctl.service
...
[::]:22 sshd.socket sshd.service
kobject-uevent 1 systemd-udevd-kernel.socket systemd-udevd.service

5 sockets listed.

Note: because the addresses might contains spaces, this output is
not suitable for programmatic consumption.

Also see --show-types, --all, and --state=.

list-timers [PATTERN...]
List timer units currently in memory, ordered by the time they
elapse next. If one or more PATTERNs are specified, only units
matching one of them are shown. Produces output similar to

NEXT LEFT LAST PASSED UNIT ACTIVATES
n/a n/a Thu 2017-02-23 13:40:29 EST 3 days ago ureadahead-stop.timer ureadahead-stop.service
Sun 2017-02-26 18:55:42 EST 1min 14s left Thu 2017-02-23 13:54:44 EST 3 days ago systemd-tmpfiles-clean.timer systemd-tmpfiles-clean.service
Sun 2017-02-26 20:37:16 EST 1h 42min left Sun 2017-02-26 11:56:36 EST 6h ago apt-daily.timer apt-daily.service
Sun 2017-02-26 20:57:49 EST 2h 3min left Sun 2017-02-26 11:56:36 EST 6h ago snapd.refresh.timer snapd.refresh.service

NEXT shows the next time the timer will run.

LEFT shows how long till the next time the timer runs.

LAST shows the last time the timer ran.

PASSED shows has long as passed since the timer laset ran.

UNIT shows the name of the timer

ACTIVATES shows the the name the service the timer activates when
it runs.

Also see --all and --state=.

start PATTERN...
Start (activate) one or more units specified on the command line.

Note that glob patterns operate on the set of primary names of
units currently in memory. Units which are not active and are not
in a failed state usually are not in memory, and will not be
matched by any pattern. In addition, in case of instantiated
units, systemd is often unaware of the instance name until the
instance has been started. Therefore, using glob patterns with
start has limited usefulness. Also, secondary alias names of
units are not considered.

stop PATTERN...
Stop (deactivate) one or more units specified on the command
line.

reload PATTERN...
Asks all units listed on the command line to reload their
configuration. Note that this will reload the service-specific
configuration, not the unit configuration file of systemd. If you
want systemd to reload the configuration file of a unit, use the
daemon-reload command. In other words: for the example case of
Apache, this will reload Apache's httpd.conf in the web server,
not the apache.service systemd unit file.

This command should not be confused with the daemon-reload
command.

restart PATTERN...
Stop and then start one or more units specified on the command
line. If the units are not running yet, they will be started.

try-restart PATTERN...
Stop and then start one or more units specified on the command
line if the units are running. This does nothing if units are not
running.

reload-or-restart PATTERN...
Reload one or more units if they support it. If not, restart them
instead. If the units are not running yet, they will be started.

try-reload-or-restart PATTERN...
Reload one or more units if they support it. If not, restart them
instead. This does nothing if the units are not running.

isolate NAME
Start the unit specified on the command line and its dependencies
and stop all others. If a unit name with no extension is given,
an extension of ".target" will be assumed.

This is similar to changing the runlevel in a traditional init
system. The isolate command will immediately stop processes that
are not enabled in the new unit, possibly including the graphical
environment or terminal you are currently using.

Note that this is allowed only on units where AllowIsolate= is
enabled. See systemd.unit(5) for details.

kill PATTERN...
Send a signal to one or more processes of the unit. Use
--kill-who= to select which process to kill. Use --signal= to
select the signal to send.

is-active PATTERN...
Check whether any of the specified units are active (i.e.
running). Returns an exit code 0 if at least one is active, or
non-zero otherwise. Unless --quiet is specified, this will also
print the current unit state to standard output.

is-failed PATTERN...
Check whether any of the specified units are in a "failed" state.
Returns an exit code 0 if at least one has failed, non-zero
otherwise. Unless --quiet is specified, this will also print the
current unit state to standard output.

status [PATTERN...|PID...]]
Show terse runtime status information about one or more units,
followed by most recent log data from the journal. If no units
are specified, show system status. If combined with --all, also
show the status of all units (subject to limitations specified
with -t). If a PID is passed, show information about the unit the
process belongs to.

This function is intended to generate human-readable output. If
you are looking for computer-parsable output, use show instead.
By default, this function only shows 10 lines of output and
ellipsizes lines to fit in the terminal window. This can be
changed with --lines and --full, see above. In addition,
journalctl --unit=NAME or journalctl --user-unit=NAME use a
similar filter for messages and might be more convenient.

Systemd implicitly loads units as necessary, so just running the
status will attempt to load a file. The command is thus not
useful for determining if something was already loaded or not.
The units may possibly also be quickly unloaded after the
operation is completed if there's no reason to keep it in memory
thereafter.

Example 1. Example output from systemctl status

$ systemctl status bluetooth
● bluetooth.service - Bluetooth service
Loaded: loaded (/usr/lib/systemd/system/bluetooth.service; enabled; vendor preset: enabled)
Active: active (running) since Wed 2017-01-04 13:54:04 EST; 1 weeks 0 days ago
Docs: man:bluetoothd(8)
Main PID: 930 (bluetoothd)
Status: "Running"
Tasks: 1
Memory: 648.0K
CPU: 435ms
CGroup: /system.slice/bluetooth.service
└─930 /usr/lib/bluetooth/bluetoothd

Jan 12 10:46:45 example.com bluetoothd[8900]: Not enough free handles to register service
Jan 12 10:46:45 example.com bluetoothd[8900]: Current Time Service could not be registered
Jan 12 10:46:45 example.com bluetoothd[8900]: gatt-time-server: Input/output error (5)

The dot ("●") uses color on supported terminals to summarize the
unit state at a glance. White indicates an "inactive" or
"deactivating" state. Red indicates a "failed" or "error" state
and green indicates an "active", "reloading" or "activating"
state.

The "Loaded:" line in the output will show "loaded" if the unit
has been loaded into memory. Other possible values for "Loaded:"
include: "error" if there was a problem loading it, "not-found",
and "masked". Along with showing the path to the unit file, this
line will also show the enablement state. Enabled commands start
at boot. See the full table of possible enablement states —
including the definition of "masked" — in the documentation for
the is-enabled command.

The "Active:" line shows active state. The value is usually
"active" or "inactive". Active could mean started, bound, plugged
in, etc depending on the unit type. The unit could also be in
process of changing states, reporting a state of "activating" or
"deactivating". A special "failed" state is entered when the
service failed in some way, such as a crash, exiting with an
error code or timing out. If the failed state is entered the
cause will be logged for later reference.

show [PATTERN...|JOB...]
Show properties of one or more units, jobs, or the manager
itself. If no argument is specified, properties of the manager
will be shown. If a unit name is specified, properties of the
unit are shown, and if a job ID is specified, properties of the
job are shown. By default, empty properties are suppressed. Use
--all to show those too. To select specific properties to show,
use --property=. This command is intended to be used whenever
computer-parsable output is required. Use status if you are
looking for formatted human-readable output.

Many properties shown by systemctl show map directly to
configuration settings of the system and service manager and its
unit files. Note that the properties shown by the command are
generally more low-level, normalized versions of the original
configuration settings and expose runtime state in addition to
configuration. For example, properties shown for service units
include the service's current main process identifier as
"MainPID" (which is runtime state), and time settings are always
exposed as properties ending in the "...USec" suffix even if a
matching configuration options end in "...Sec", because
microseconds is the normalized time unit used by the system and
service manager.

cat PATTERN...
Show backing files of one or more units. Prints the "fragment"
and "drop-ins" (source files) of units. Each file is preceded by
a comment which includes the file name. Note that this shows the
contents of the backing files on disk, which may not match the
system manager's understanding of these units if any unit files
were updated on disk and the daemon-reload command wasn't issued
since.

set-property NAME ASSIGNMENT...
Set the specified unit properties at runtime where this is
supported. This allows changing configuration parameter
properties such as resource control settings at runtime. Not all
properties may be changed at runtime, but many resource control
settings (primarily those in systemd.resource-control(5)) may.
The changes are applied instantly, and stored on disk for future
boots, unless --runtime is passed, in which case the settings
only apply until the next reboot. The syntax of the property
assignment follows closely the syntax of assignments in unit
files.

Example: systemctl set-property foobar.service CPUShares=777

If the specified unit appears to be inactive, the changes will be
only stored on disk as described previously hence they will be
effective when the unit will be started.

Note that this command allows changing multiple properties at the
same time, which is preferable over setting them individually.
Like unit file configuration settings, assigning the empty list
to list parameters will reset the list.

help PATTERN...|PID...
Show manual pages for one or more units, if available. If a PID
is given, the manual pages for the unit the process belongs to
are shown.

reset-failed [PATTERN...]
Reset the "failed" state of the specified units, or if no unit
name is passed, reset the state of all units. When a unit fails
in some way (i.e. process exiting with non-zero error code,
terminating abnormally or timing out), it will automatically
enter the "failed" state and its exit code and status is recorded
for introspection by the administrator until the service is
restarted or reset with this command.

list-dependencies [NAME]
Shows units required and wanted by the specified unit. This
recursively lists units following the Requires=, Requisite=,
ConsistsOf=, Wants=, BindsTo= dependencies. If no unit is
specified, default.target is implied.

By default, only target units are recursively expanded. When
--all is passed, all other units are recursively expanded as
well.

Options --reverse, --after, --before may be used to change what
types of dependencies are shown.

Unit File Commands
list-unit-files [PATTERN...]
List unit files installed on the system, in combination with
their enablement state (as reported by is-enabled). If one or
more PATTERNs are specified, only unit files whose name matches
one of them are shown (patterns matching unit file system paths
are not supported).

enable NAME..., enable PATH...
Enable one or more units or unit instances. This will create a
set of symlinks, as encoded in the "[Install]" sections of the
indicated unit files. After the symlinks have been created, the
system manager configuration is reloaded (in a way equivalent to
daemon-reload), in order to ensure the changes are taken into
account immediately. Note that this does not have the effect of
also starting any of the units being enabled. If this is desired,
combine this command with the --now switch, or invoke start with
appropriate arguments later. Note that in case of unit instance
enablement (i.e. enablement of units of the form
foo@bar.service), symlinks named the same as instances are
created in the unit configuration directory, however they point
to the single template unit file they are instantiated from.

This command expects either valid unit names (in which case
various unit file directories are automatically searched for unit
files with appropriate names), or absolute paths to unit files
(in which case these files are read directly). If a specified
unit file is located outside of the usual unit file directories,
an additional symlink is created, linking it into the unit
configuration path, thus ensuring it is found when requested by
commands such as start.

This command will print the file system operations executed. This
output may be suppressed by passing --quiet.

Note that this operation creates only the symlinks suggested in
the "[Install]" section of the unit files. While this command is
the recommended way to manipulate the unit configuration
directory, the administrator is free to make additional changes
manually by placing or removing symlinks below this directory.
This is particularly useful to create configurations that deviate
from the suggested default installation. In this case, the
administrator must make sure to invoke daemon-reload manually as
necessary, in order to ensure the changes are taken into account.

Enabling units should not be confused with starting (activating)
units, as done by the start command. Enabling and starting units
is orthogonal: units may be enabled without being started and
started without being enabled. Enabling simply hooks the unit
into various suggested places (for example, so that the unit is
automatically started on boot or when a particular kind of
hardware is plugged in). Starting actually spawns the daemon
process (in case of service units), or binds the socket (in case
of socket units), and so on.

Depending on whether --system, --user, --runtime, or --global is
specified, this enables the unit for the system, for the calling
user only, for only this boot of the system, or for all future
logins of all users, or only this boot. Note that in the last
case, no systemd daemon configuration is reloaded.

Using enable on masked units is not supported and results in an
error.

disable NAME...
Disables one or more units. This removes all symlinks to the unit
files backing the specified units from the unit configuration
directory, and hence undoes any changes made by enable or link.
Note that this removes all symlinks to matching unit files,
including manually created symlinks, and not just those actually
created by enable or link. Note that while disable undoes the
effect of enable, the two commands are otherwise not symmetric,
as disable may remove more symlinks than a prior enable
invocation of the same unit created.

This command expects valid unit names only, it does not accept
paths to unit files.

In addition to the units specified as arguments, all units are
disabled that are listed in the Also= setting contained in the
"[Install]" section of any of the unit files being operated on.

This command implicitly reloads the system manager configuration
after completing the operation. Note that this command does not
implicitly stop the units that are being disabled. If this is
desired, either combine this command with the --now switch, or
invoke the stop command with appropriate arguments later.

This command will print information about the file system
operations (symlink removals) executed. This output may be
suppressed by passing --quiet.

This command honors --system, --user, --runtime and --global in a
similar way as enable.

reenable NAME...
Reenable one or more units, as specified on the command line.
This is a combination of disable and enable and is useful to
reset the symlinks a unit file is enabled with to the defaults
configured in its "[Install]" section. This command expects a
unit name only, it does not accept paths to unit files.

preset NAME...
Reset the enable/disable status one or more unit files, as
specified on the command line, to the defaults configured in the
preset policy files. This has the same effect as disable or
enable, depending how the unit is listed in the preset files.

Use --preset-mode= to control whether units shall be enabled and
disabled, or only enabled, or only disabled.

If the unit carries no install information, it will be silently
ignored by this command. NAME must be the real unit name, any
alias names are ignored silently.

For more information on the preset policy format, see
systemd.preset(5). For more information on the concept of
presets, please consult the Preset[1] document.

preset-all
Resets all installed unit files to the defaults configured in the
preset policy file (see above).

Use --preset-mode= to control whether units shall be enabled and
disabled, or only enabled, or only disabled.

is-enabled NAME...
Checks whether any of the specified unit files are enabled (as
with enable). Returns an exit code of 0 if at least one is
enabled, non-zero otherwise. Prints the current enable status
(see table). To suppress this output, use --quiet. To show
installation targets, use --full.

Table 1. is-enabled output
┌──────────────────┬─────────────────────────┬───────────┐
│Name │ Description │ Exit Code │
├──────────────────┼─────────────────────────┼───────────┤
│"enabled" │ Enabled via │ │
├──────────────────┤ .wants/, .requires/ │ │
│"enabled-runtime" │ or alias symlinks │ │
│ │ (permanently in │ 0 │
│ │ /etc/systemd/system/, │ │
│ │ or transiently in │ │
│ │ /run/systemd/system/). │ │
├──────────────────┼─────────────────────────┼───────────┤
│"linked" │ Made available through │ │
├──────────────────┤ one or more symlinks │ │
│"linked-runtime" │ to the unit file │ │
│ │ (permanently in │ │
│ │ /etc/systemd/system/ │ │
│ │ or transiently in │ > 0 │
│ │ /run/systemd/system/), │ │
│ │ even though the unit │ │
│ │ file might reside │ │
│ │ outside of the unit │ │
│ │ file search path. │ │
├──────────────────┼─────────────────────────┼───────────┤
│"masked" │ Completely disabled, │ │
├──────────────────┤ so that any start │ │
│"masked-runtime" │ operation on it fails │ │
│ │ (permanently in │ > 0 │
│ │ /etc/systemd/system/ │ │
│ │ or transiently in │ │
│ │ /run/systemd/systemd/). │ │
├──────────────────┼─────────────────────────┼───────────┤
│"static" │ The unit file is not │ 0 │
│ │ enabled, and has no │ │
│ │ provisions for enabling │ │
│ │ in the "[Install]" unit │ │
│ │ file section. │ │
├──────────────────┼─────────────────────────┼───────────┤
│"indirect" │ The unit file itself is │ 0 │
│ │ not enabled, but it has │ │
│ │ a non-empty Also= │ │
│ │ setting in the │ │
│ │ "[Install]" unit file │ │
│ │ section, listing other │ │
│ │ unit files that might │ │
│ │ be enabled. │ │
├──────────────────┼─────────────────────────┼───────────┤
│"disabled" │ The unit file is not │ > 0 │
│ │ enabled, but contains │ │
│ │ an "[Install]" section │ │
│ │ with installation │ │
│ │ instructions. │ │
├──────────────────┼─────────────────────────┼───────────┤
│"generated" │ The unit file was │ 0 │
│ │ generated dynamically │ │
│ │ via a generator tool. │ │
│ │ See │ │
│ │ systemd.generator(7). │ │
│ │ Generated unit files │ │
│ │ may not be enabled, │ │
│ │ they are enabled │ │
│ │ implicitly by their │ │
│ │ generator. │ │
├──────────────────┼─────────────────────────┼───────────┤
│"transient" │ The unit file has been │ 0 │
│ │ created dynamically │ │
│ │ with the runtime API. │ │
│ │ Transient units may not │ │
│ │ be enabled. │ │
├──────────────────┼─────────────────────────┼───────────┤
│"bad" │ The unit file is │ > 0 │
│ │ invalid or another │ │
│ │ error occurred. Note │ │
│ │ that is-enabled will │ │
│ │ not actually return │ │
│ │ this state, but print │ │
│ │ an error message │ │
│ │ instead. However the │ │
│ │ unit file listing │ │
│ │ printed by │ │
│ │ list-unit-files might │ │
│ │ show it. │ │
└──────────────────┴─────────────────────────┴───────────┘

mask NAME...
Mask one or more units, as specified on the command line. This
will link these unit files to /dev/null, making it impossible to
start them. This is a stronger version of disable, since it
prohibits all kinds of activation of the unit, including
enablement and manual activation. Use this option with care. This
honors the --runtime option to only mask temporarily until the
next reboot of the system. The --now option may be used to ensure
that the units are also stopped. This command expects valid unit
names only, it does not accept unit file paths.

unmask NAME...
Unmask one or more unit files, as specified on the command line.
This will undo the effect of mask. This command expects valid
unit names only, it does not accept unit file paths.

link PATH...
Link a unit file that is not in the unit file search paths into
the unit file search path. This command expects an absolute path
to a unit file. The effect of this may be undone with disable.
The effect of this command is that a unit file is made available
for commands such as start, even though it is not installed
directly in the unit search path.

revert NAME...
Revert one or more unit files to their vendor versions. This
command removes drop-in configuration files that modify the
specified units, as well as any user-configured unit file that
overrides a matching vendor supplied unit file. Specifically, for
a unit "foo.service" the matching directories "foo.service.d/"
with all their contained files are removed, both below the
persistent and runtime configuration directories (i.e. below
/etc/systemd/system and /run/systemd/system); if the unit file
has a vendor-supplied version (i.e. a unit file located below
/usr) any matching persistent or runtime unit file that overrides
it is removed, too. Note that if a unit file has no
vendor-supplied version (i.e. is only defined below
/etc/systemd/system or /run/systemd/system, but not in a unit
file stored below /usr), then it is not removed. Also, if a unit
is masked, it is unmasked.

Effectively, this command may be used to undo all changes made
with systemctl edit, systemctl set-property and systemctl mask
and puts the original unit file with its settings back in effect.

add-wants TARGET NAME..., add-requires TARGET NAME...
Adds "Wants=" or "Requires=" dependencies, respectively, to the
specified TARGET for one or more units.

This command honors --system, --user, --runtime and --global in a
way similar to enable.

edit NAME...
Edit a drop-in snippet or a whole replacement file if --full is
specified, to extend or override the specified unit.

Depending on whether --system (the default), --user, or --global
is specified, this command creates a drop-in file for each unit
either for the system, for the calling user, or for all futures
logins of all users. Then, the editor (see the "Environment"
section below) is invoked on temporary files which will be
written to the real location if the editor exits successfully.

If --full is specified, this will copy the original units instead
of creating drop-in files.

If --force is specified and any units do not already exist, new
unit files will be opened for editing.

If --runtime is specified, the changes will be made temporarily
in /run and they will be lost on the next reboot.

If the temporary file is empty upon exit, the modification of the
related unit is canceled.

After the units have been edited, systemd configuration is
reloaded (in a way that is equivalent to daemon-reload).

Note that this command cannot be used to remotely edit units and
that you cannot temporarily edit units which are in /etc, since
they take precedence over /run.

get-default
Return the default target to boot into. This returns the target
unit name default.target is aliased (symlinked) to.

set-default NAME
Set the default target to boot into. This sets (symlinks) the
default.target alias to the given target unit.

Machine Commands
list-machines [PATTERN...]
List the host and all running local containers with their state.
If one or more PATTERNs are specified, only containers matching
one of them are shown.

Job Commands
list-jobs [PATTERN...]
List jobs that are in progress. If one or more PATTERNs are
specified, only jobs for units matching one of them are shown.

When combined with --after or --before the list is augmented with
information on which other job each job is waiting for, and which
other jobs are waiting for it, see above.

cancel JOB...
Cancel one or more jobs specified on the command line by their
numeric job IDs. If no job ID is specified, cancel all pending
jobs.

Environment Commands
show-environment
Dump the systemd manager environment block. This is the
environment block that is passed to all processes the manager
spawns. The environment block will be dumped in straight-forward
form suitable for sourcing into most shells. If no special
characters or whitespace is present in the variable values, no
escaping is performed, and the assignments have the form
"VARIABLE=value". If whitespace or characters which have special
meaning to the shell are present, dollar-single-quote escaping is
used, and assignments have the form "VARIABLE=$'value'". This
syntax is known to be supported by bash(1), zsh(1), ksh(1), and
busybox(1)'s ash(1), but not dash(1) or fish(1).

set-environment VARIABLE=VALUE...
Set one or more systemd manager environment variables, as
specified on the command line.

unset-environment VARIABLE...
Unset one or more systemd manager environment variables. If only
a variable name is specified, it will be removed regardless of
its value. If a variable and a value are specified, the variable
is only removed if it has the specified value.

import-environment [VARIABLE...]
Import all, one or more environment variables set on the client
into the systemd manager environment block. If no arguments are
passed, the entire environment block is imported. Otherwise, a
list of one or more environment variable names should be passed,
whose client-side values are then imported into the manager's
environment block.

Manager Lifecycle Commands
daemon-reload
Reload the systemd manager configuration. This will rerun all
generators (see systemd.generator(7)), reload all unit files, and
recreate the entire dependency tree. While the daemon is being
reloaded, all sockets systemd listens on behalf of user
configuration will stay accessible.

This command should not be confused with the reload command.

daemon-reexec
Reexecute the systemd manager. This will serialize the manager
state, reexecute the process and deserialize the state again.
This command is of little use except for debugging and package
upgrades. Sometimes, it might be helpful as a heavy-weight
daemon-reload. While the daemon is being reexecuted, all sockets
systemd listening on behalf of user configuration will stay
accessible.

System Commands
is-system-running
Checks whether the system is operational. This returns success
(exit code 0) when the system is fully up and running,
specifically not in startup, shutdown or maintenance mode, and
with no failed services. Failure is returned otherwise (exit code
non-zero). In addition, the current state is printed in a short
string to standard output, see the table below. Use --quiet to
suppress this output.

Table 2. is-system-running output
┌─────────────┬─────────────────────┬───────────┐
│Name │ Description │ Exit Code │
├─────────────┼─────────────────────┼───────────┤
│initializing │ Early bootup, │ > 0 │
│ │ before basic.target │ │
│ │ is reached or the │ │
│ │ maintenance state │ │
│ │ entered. │ │
├─────────────┼─────────────────────┼───────────┤
│starting │ Late bootup, before │ > 0 │
│ │ the job queue │ │
│ │ becomes idle for │ │
│ │ the first time, or │ │
│ │ one of the rescue │ │
│ │ targets are │ │
│ │ reached. │ │
├─────────────┼─────────────────────┼───────────┤
│running │ The system is fully │ 0 │
│ │ operational. │ │
├─────────────┼─────────────────────┼───────────┤
│degraded │ The system is │ > 0 │
│ │ operational but one │ │
│ │ or more units │ │
│ │ failed. │ │
├─────────────┼─────────────────────┼───────────┤
│maintenance │ The rescue or │ > 0 │
│ │ emergency target is │ │
│ │ active. │ │
├─────────────┼─────────────────────┼───────────┤
│stopping │ The manager is │ > 0 │
│ │ shutting down. │ │
├─────────────┼─────────────────────┼───────────┤
│offline │ The manager is not │ > 0 │
│ │ running. │ │
│ │ Specifically, this │ │
│ │ is the operational │ │
│ │ state if an │ │
│ │ incompatible │ │
│ │ program is running │ │
│ │ as system manager │ │
│ │ (PID 1). │ │
├─────────────┼─────────────────────┼───────────┤
│unknown │ The operational │ > 0 │
│ │ state could not be │ │
│ │ determined, due to │ │
│ │ lack of resources │ │
│ │ or another error │ │
│ │ cause. │ │
└─────────────┴─────────────────────┴───────────┘

default
Enter default mode. This is mostly equivalent to isolate
default.target.

rescue
Enter rescue mode. This is mostly equivalent to isolate
rescue.target, but also prints a wall message to all users.

emergency
Enter emergency mode. This is mostly equivalent to isolate
emergency.target, but also prints a wall message to all users.

halt
Shut down and halt the system. This is mostly equivalent to start
halt.target --job-mode=replace-irreversibly, but also prints a
wall message to all users. If combined with --force, shutdown of
all running services is skipped, however all processes are killed
and all file systems are unmounted or mounted read-only,
immediately followed by the system halt. If --force is specified
twice, the operation is immediately executed without terminating
any processes or unmounting any file systems. This may result in
data loss. Note that when --force is specified twice the halt
operation is executed by systemctl itself, and the system manager
is not contacted. This means the command should succeed even when
the system manager hangs or crashed.

poweroff
Shut down and power-off the system. This is mostly equivalent to
start poweroff.target --job-mode=replace-irreversibly, but also
prints a wall message to all users. If combined with --force,
shutdown of all running services is skipped, however all
processes are killed and all file systems are unmounted or
mounted read-only, immediately followed by the powering off. If
--force is specified twice, the operation is immediately executed
without terminating any processes or unmounting any file systems.
This may result in data loss. Note that when --force is specified
twice the power-off operation is executed by systemctl itself,
and the system manager is not contacted. This means the command
should succeed even when the system manager hangs or crashed.

reboot [arg]
Shut down and reboot the system. This is mostly equivalent to
start reboot.target --job-mode=replace-irreversibly, but also
prints a wall message to all users. If combined with --force,
shutdown of all running services is skipped, however all
processes are killed and all file systems are unmounted or
mounted read-only, immediately followed by the reboot. If --force
is specified twice, the operation is immediately executed without
terminating any processes or unmounting any file systems. This
may result in data loss. Note that when --force is specified
twice the reboot operation is executed by systemctl itself, and
the system manager is not contacted. This means the command
should succeed even when the system manager hangs or crashed.

If the optional argument arg is given, it will be passed as the
optional argument to the reboot(2) system call. The value is
architecture and firmware specific. As an example, "recovery"
might be used to trigger system recovery, and "fota" might be
used to trigger a “firmware over the air” update.

kexec
Shut down and reboot the system via kexec. This is mostly
equivalent to start kexec.target --job-mode=replace-irreversibly,
but also prints a wall message to all users. If combined with
--force, shutdown of all running services is skipped, however all
processes are killed and all file systems are unmounted or
mounted read-only, immediately followed by the reboot.

exit [EXIT_CODE]
Ask the systemd manager to quit. This is only supported for user
service managers (i.e. in conjunction with the --user option) or
in containers and is equivalent to poweroff otherwise.

The systemd manager can exit with a non-zero exit code if the
optional argument EXIT_CODE is given.

switch-root ROOT [INIT]
Switches to a different root directory and executes a new system
manager process below it. This is intended for usage in initial
RAM disks ("initrd"), and will transition from the initrd's
system manager process (a.k.a. "init" process) to the main system
manager process which is loaded from the actual host volume. This
call takes two arguments: the directory that is to become the new
root directory, and the path to the new system manager binary
below it to execute as PID 1. If the latter is omitted or the
empty string, a systemd binary will automatically be searched for
and used as init. If the system manager path is omitted, equal to
the empty string or identical to the path to the systemd binary,
the state of the initrd's system manager process is passed to the
main system manager, which allows later introspection of the
state of the services involved in the initrd boot phase.

suspend
Suspend the system. This will trigger activation of the special
suspend.target target.

hibernate
Hibernate the system. This will trigger activation of the special
hibernate.target target.

hybrid-sleep
Hibernate and suspend the system. This will trigger activation of
the special hybrid-sleep.target target.

Parameter Syntax
Unit commands listed above take either a single unit name (designated
as NAME), or multiple unit specifications (designated as PATTERN...).
In the first case, the unit name with or without a suffix must be
given. If the suffix is not specified (unit name is "abbreviated"),
systemctl will append a suitable suffix, ".service" by default, and a
type-specific suffix in case of commands which operate only on
specific unit types. For example,

# systemctl start sshd

and

# systemctl start sshd.service

are equivalent, as are

# systemctl isolate default

and

# systemctl isolate default.target

Note that (absolute) paths to device nodes are automatically
converted to device unit names, and other (absolute) paths to mount
unit names.

# systemctl status /dev/sda
# systemctl status /home

are equivalent to:

# systemctl status dev-sda.device
# systemctl status home.mount

In the second case, shell-style globs will be matched against the
primary names of all units currently in memory; literal unit names,
with or without a suffix, will be treated as in the first case. This
means that literal unit names always refer to exactly one unit, but
globs may match zero units and this is not considered an error.

Glob patterns use fnmatch(3), so normal shell-style globbing rules
are used, and "*", "?", "[]" may be used. See glob(7) for more
details. The patterns are matched against the primary names of units
currently in memory, and patterns which do not match anything are
silently skipped. For example:

# systemctl stop sshd@*.service

will stop all sshd@.service instances. Note that alias names of
units, and units that aren't in memory are not considered for glob
expansion.

For unit file commands, the specified NAME should be the name of the
unit file (possibly abbreviated, see above), or the absolute path to
the unit file:

# systemctl enable foo.service

# systemctl link /path/to/foo.service

EXIT STATUS top

       On success, 0 is returned, a non-zero failure code otherwise.

ENVIRONMENT top

       $SYSTEMD_EDITOR
           Editor to use when editing units; overrides $EDITOR and $VISUAL.
           If neither $SYSTEMD_EDITOR nor $EDITOR nor $VISUAL are present or
           if it is set to an empty string or if their execution failed,
           systemctl will try to execute well known editors in this order:
           editor(1), nano(1), vim(1), vi(1).

       $SYSTEMD_PAGER
           Pager to use when --no-pager is not given; overrides $PAGER. If
           neither $SYSTEMD_PAGER nor $PAGER are set, a set of well-known
           pager implementations are tried in turn, including less(1) and
           more(1), until one is found. If no pager implementation is
           discovered no pager is invoked. Setting this environment variable
           to an empty string or the value "cat" is equivalent to passing
           --no-pager.

       $SYSTEMD_LESS
           Override the options passed to less (by default "FRSXMK").

       $SYSTEMD_LESSCHARSET
           Override the charset passed to less (by default "utf-8", if the
           invoking terminal is determined to be UTF-8 compatible).

NOTES top

        1. Preset
           https://www.freedesktop.org/wiki/Software/systemd/Preset

COLOPHON top

       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 2019-03-06.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2019-03-06.)  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 234                                                     SYSTEMCTL(1)

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