systemctl 命令管理系统服务

以网络服务为例：

1、 查看已开启服务：systemctl list-units

2、 关闭已开启服务：systemctl stop ****.service

3、 开启：systemctl start ****.service

4、 重启：systemctl restart ****.service

如重启网络服务：systemctl restart network-manager.service

man 文件：

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(1) system and service manager.

Options

The following options are understood:

--help

,

-h

Prints a short help text and exits.

--version

Prints a short version string and exits.

--type=

,

-t

The argument should be a unit type name such as

service

and

socket

, or a unit load state such as

loaded

and

masked

.

If the argument is a unit type, when listing units, limit display to certain unit types. If not specified units of all types will be shown.

If the argument is a unit load state, when listing units, limit display to certain unit types. If not specified units of in all load states will be shown.

As a special case, if the argument is

help

, a list of allowed values will be printed and the program will exit.

--property=

,

-p

When showing unit/job/manager properties, limit display to certain properties as specified as argument. If not specified all set properties are shown. The argument should be a property name, such as

MainPID

. If specified more than once all properties with the specified names are shown.

--all

,

-a

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

--failed

When listing units, show only failed units. Do not confuse with

--fail

.

--full

Do not ellipsize unit names, cgroup members, and truncate unit descriptions in the output of
list-units and
list-jobs.

--fail

If the requested operation conflicts with a pending unfinished job, fail the command. If this is not specified the requested operation will replace the pending job, if necessary. Do not confuse with

--failed

.

--ignore-dependencies

When enqueuing a new job ignore all its dependencies and execute it 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.

-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 if privileged or not) and 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.

--quiet

,

-q

Suppress output to STDOUT in snapshot,
is-active, is-failed,
enable and disable.

--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 it is completed. By passing this argument it is only verified and enqueued.

--no-legend

Do not print a legend, i.e. the column headers and the footer with hints.

--no-pager

Do not pipe output into a pager.

--system

Talk to the systemd system manager. (Default)

--user

Talk to the systemd manager of the calling user.

--order

,

--require

When used in conjunction with the dot command (see below), selects which dependencies are shown in the dependency graph. If

--order

is passed only dependencies of type

After=

or

Before=

are shown. If

--require

is passed only dependencies of type

Requires=

,

RequiresOverridable=

,

Requisite=

,

RequisiteOverridable=

,

Wants=

and

Conflicts=

are shown. If neither is passed, shows dependencies of all these types.

--no-wall

Don't 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 kill. Must be one of

main

,

control

or

all

to select whether to kill only the main process of the unit, the control process or all processes of the unit. If omitted defaults to

all

.

--signal=

,

-s

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

.

--force

,

-f

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 umounting any file systems. Warning: specifying

--force

twice with any of these operations might result in data loss.

--root=

When used with enable/disable/is-enabled (and related commands), use alternative root path when looking for unit files.

--runtime

When used with enable/disable/is-enabled (and related commands), make changes only temporarily, so that they are dropped
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.

-H

,

--host

Execute operation remotely. Specify a hostname, or username and hostname separated by @, to connect to. This will use SSH to talk to the remote systemd instance.

-P

,

--privileged

Acquire privileges via PolicyKit before executing the operation.

--lines=

,

-n

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.

--output=

,

-o

When used with status controls the formatting of the journal entries that are shown. For the available choices see
journalctl(1). Defaults to

short

.

The following commands are understood:

list-units
List known units.

start [NAME...]
Start (activate) one or more units specified on the command line.

stop [NAME...]
Stop (deactivate) one or more units specified on the command line.

reload [NAME...]
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 or
load commands.

restart [NAME...]
Restart one or more units specified on the command line. If the units are not running yet they will be started.

try-restart [NAME...]
Restart one or more units specified on the command line if the units are running. Do nothing if units are not running. Note that for compatibility with Red Hat init scripts
condrestart is equivalent to this command.

reload-or-restart [NAME...]
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.

reload-or-try-restart [NAME...]
Reload one or more units if they support it. If not, restart them instead. Do nothing if the units are not running. Note that for compatibility with SysV init scripts
force-reload is equivalent to this command.

isolate [NAME]
Start the unit specified on the command line and its dependencies and stop all others.

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 works only on units where

AllowIsolate=

is enabled. See
systemd.unit(5) for details.

kill [NAME...]
Send a signal to one or more processes of the unit. Use

--kill-who=

to select which process to kill. Use

--kill-mode=

to select the kill mode and

--signal=

to select the signal to send.

is-active [NAME...]
Check whether any of the specified units are active (i.e. running). Returns an exit code 0 if at least one is active, non-zero otherwise. Unless

--quiet

is specified this will also print the current unit state to STDOUT.

is-failed [NAME...]
Check whether any of the specified units are failed. Returns an exit code 0 if at least one is failed, non-zero otherwise. Unless

--quiet

is specified this will also print the current unit state to STDOUT.

status [NAME...|PID...]
Show terse runtime status information about one or more units, followed by its most recent log data from the journal. This function is intended to generate human-readable output. If you are looking for computer-parsable output, use
show instead. If a PID is passed information about the unit the process of the PID belongs to is shown.

show [NAME...|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.

help [NAME...|PID...]
Show manual pages for one or more units, if available. If a PID is passed the manual pages for the unit the process of the PID belongs to is shown.

reset-failed [NAME...]
Reset the '

failed

' state of the specified units, or if no unit name is passed 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-unit-files
List installed unit files.

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 that any of the units enabled are also started at the same time. If this is desired a separate
start command must be invoked for the unit. Also note that in case of instance enablement, symlinks named same as instances are created in 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 his 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

or

--global

is specified this enables the unit for the system, for the calling user only or for all future logins of all users. Note that in the latter case no systemd daemon configuration is reloaded.

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
an additional stop command should be executed afterwards.

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

--quiet

.

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. To suppress this output use

--quiet

.

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. For more information on preset policy format see
systemd.preset(5). For more information on the concept of presets please consult the

Preset document.

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 manual activation. Use this option with care.

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

link [NAME...]
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 isn't installed directly in the unit search path.

load [NAME...]
Load one or more units specified on the command line. This will simply load their configuration from disk, but not start them. To start them you need to use the
start command which will implicitly load a unit that has not been loaded yet. Note that systemd garbage collects loaded units that are not active or referenced by an active unit. This means that units loaded this
way will usually not stay loaded for long. Also note that this command cannot be used to reload unit configuration. Use the
daemon-reload command for that. All in all, this command is of little use except for debugging.

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

list-jobs
List jobs that are in progress.

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.

dump
Dump server status. This will output a (usually very long) human readable manager status dump. Its format is subject to change without notice and should not be parsed by applications.

dot
Generate textual dependency graph description in dot format for further processing with the GraphViz
dot(1) tool. Use a command line like
systemctl dot | dot -Tsvg > systemd.svg to generate a graphical dependency tree. Unless

--order

or

--require

is passed the generated graph will show both ordering and requirement dependencies.

list-dependencies [NAME]
Shows required and wanted units of the specified unit. If no unit is specified

default.target

is implied. Target units are recursively expanded. When

--all

is passed all other units aare recursively expanded as well.

snapshot [NAME]
Create a snapshot. If a snapshot name is specified, the new snapshot will be named after it. If none is specified an automatic snapshot name is generated. In either case, the snapshot name used is printed to STDOUT, unless

--quiet

is specified.

A snapshot refers to a saved state of the systemd manager. It is implemented itself as a unit that is generated dynamically with this command and has dependencies on all units active at the time. At a later time the user may return to this state by using
the isolate command on the snapshot unit.

delete [NAME...]
Remove a snapshot previously created with snapshot.

daemon-reload
Reload systemd manager configuration. This will reload all unit files and recreate the entire dependency tree. While the daemon is reloaded, all sockets systemd listens on on behalf of user configuration will stay accessible.

This command should not be confused with the load or
reload commands.

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 reexecuted all sockets systemd listens on on behalf of user configuration will stay accessible.

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 [NAME=VALUE...]
Set one or more systemd manager environment variables, as specified on the command line.

unset-environment [NAME...]
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.

default
Enter default mode. This is mostly equivalent to start 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 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 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
Shut down and reboot the system. This is mostly equivalent to
start reboot.target 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.

kexec
Shut down and reboot the system via kexec. This is mostly equivalent to
start kexec.target 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
Ask the systemd manager to quit. This is only supported for user service managers (i.e. in conjunction with the

--user

option) and will fail otherwise.

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.

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. Takes two arguments: the directory to make 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 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.

Exit status

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

Environment

$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

.

See Also

systemd(1),
systemadm(1),
journalctl(1),
loginctl(1),
systemd.unit(5),
systemd.special(7),
wall(1),
systemd.preset(5)

以 httpd.service 为例：

任务	旧指令	新指令
使某服务自动启动	chkconfig --level 3 httpd on	systemctl enable httpd.service
使某服务不自动启动	chkconfig --level 3 httpd off	systemctl disable httpd.service
检查服务状态	service httpd status	systemctl status httpd.service （服务详细信息） systemctl is-active httpd.service （仅显示是否 Active)
显示所有已启动的服务	chkconfig --list	systemctl list-units --type=service
启动某服务	service httpd start	systemctl start httpd.service
停止某服务	service httpd stop	systemctl stop httpd.service
重启某服务	service httpd restart	systemctl restart httpd.service