systemctl Man page

Resume Wikipedia de Systemd

systemd est un système d’initialisation et un daemon qui a été spécifiquement conçu pour le noyau Linux comme alternative à System V. Il a pour but d’offrir un meilleur cadre pour la gestion des dépendances entre services, de permettre le chargement en parallèle des services au démarrage, et de réduire les appels aux scripts shell. Le projet a été lancé par Lennart Poettering en 2010 et publié sous licence GNU LGPL version 2.1. Le nom de ce programme vient de « system daemon » : le daemon du système.
Ce projet a suscité de vives controverses chez les développeurs de GNU/Linux.
En 2015, la plupart des distributions GNU/Linux ont adopté ce système d’initialisation.

SYSTEMCTL(1) systemctl SYSTEMCTL(1)

NAME

systemctl – Control the systemd system and service manager

SYNOPSIS

systemctl [OPTIONS…] COMMAND [NAME…]

DESCRIPTION

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

OPTIONS

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, show all loaded units, regardless of their
state, including inactive units. When showing unit/job/manager
properties, show all properties regardless whether they are set or
not.

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

-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.

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

-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.

–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 honoured.

–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.

–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.

–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 /bin/mount and /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 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, 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.

–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 an alternate root path when looking for unit files.

–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. 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
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
The following commands are understood:

Unit Commands
list-units [PATTERN…] List known units (subject to limitations specified with -t). If one
or more PATTERNs are specified, only units matching one of them are
shown.

This is the default command.

list-sockets [PATTERN…] List socket units 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.

See also the options –show-types, –all, and –state=.

list-timers [PATTERN…] List timer units ordered by the time they elapse next. If one or
more PATTERNs are specified, only units matching one of them are
shown.

See also the options –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
currently loaded units. Units which are not active and are not in a
failed state usually are not loaded, 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…
Restart one or more units specified on the command line. If the
units are not running yet, they will be started.

try-restart PATTERN…
Restart 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.

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 is
shown, and if a job ID is specified, properties of the job is
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.

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.

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 installed unit files and their enablement state (as reported
by is-enabled). If one or more PATTERNs are specified, only units
whose filename (just the last component of the path) matches one of
them are shown.

enable NAME…
Enable one or more unit files or unit file instances, as specified
on the command line. This will create a number of symlinks as
encoded in the “[Install]” sections of the unit files. After the
symlinks have been created, the systemd configuration is reloaded
(in a way that is equivalent to daemon-reload) 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, either –now should be used together with this
command, or an additional start command must be invoked for the
unit. Also note that, in case of instance enablement, symlinks
named the same as instances are created in the install location,
however they all point to the same template unit file.

This command will print the actions executed. This output may be
suppressed by passing –quiet.

Note that this operation creates only the suggested symlinks for
the units. 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 in the
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 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 results in an error.

disable NAME…
Disables one or more units. This removes all symlinks to the
specified unit files from the unit configuration directory, and
hence undoes the changes made by enable. Note however that this
removes all symlinks to the unit files (i.e. including manual
additions), not just those actually created by enable. This call
implicitly reloads the systemd daemon configuration after
completing the disabling of the units. Note that this command does
not implicitly stop the units that are being disabled. If this is
desired, either –now should be used together with this command, or
an additional stop command should be executed afterwards.

This command will print the actions 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 unit files, as specified on the command line.
This is a combination of disable and enable and is useful to reset
the symlinks a unit is enabled with to the defaults configured in
the “[Install]” section of the unit file.

preset NAME…
Reset 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.

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.

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]” │ │
│ │ section. │ │
├──────────────────┼─────────────────────────┼───────────┤
│”indirect” │ The unit file itself is │ 0 │
│ │ not enabled, but it has │ │
│ │ a non-empty Also= │ │
│ │ setting in the │ │
│ │ “[Install]” section, │ │
│ │ listing other unit │ │
│ │ files that might be │ │
│ │ enabled. │ │
├──────────────────┼─────────────────────────┼───────────┤
│”disabled” │ Unit file is not │ > 0 │
│ │ enabled, but contains │ │
│ │ an “[Install]” section │ │
│ │ with installation │ │
│ │ instructions. │ │
├──────────────────┼─────────────────────────┼───────────┤
│”bad” │ Unit file is invalid or │ > 0 │
│ │ 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 unit files, as specified on the command line. This
will link these units 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 can be used to ensure that the units are
also stopped.

unmask NAME…
Unmask one or more unit files, as specified on the command line.
This will undo the effect of mask.

link FILENAME…
Link a unit file that is not in the unit file search paths into the
unit file search path. This requires an absolute path to a unit
file. The effect of this can be undone with disable. The effect of
this command is that a unit file is available for start and other
commands although it is not installed directly in the unit search
path.

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 –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.

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. The environment block
will be dumped in straight-forward form suitable for sourcing into
a shell script. This environment block will be passed to all
processes the manager spawns.

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.

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.

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.

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. 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 or equal to the empty string, 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.

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 currently loaded units; 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 currently loaded
units, 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 loaded 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

or

# systemctl link /path/to/foo.service

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

ENVIRONMENT
$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, nano, vim, vi.

$SYSTEMD_PAGER
Pager to use when –no-pager is not given; overrides $PAGER.
Setting this to an empty string or the value “cat” is equivalent to
passing –no-pager.

$SYSTEMD_LESS
Override the default options passed to less (“FRSXMK”).

SEE ALSO

systemd, journalctl, loginctl, machinectl(1), systemd.unit(5),
systemd.resource-control(5), systemd.special(7), wall,
systemd.preset(5), systemd.generator(7), glob(7)

NOTES
1. Preset
http://freedesktop.org/wiki/Software/systemd/Preset

systemd 229 SYSTEMCTL(1)