V2AS问路
systemctl 命令完全指南
阅读原文时间：2021年04月20日阅读：1

from：https://linux.cn/article-5926-1.html

先来个简单总结（后面才是from的链接的内容）：

启动一个服务：systemctl start postfix.service
关闭一个服务：systemctl stop postfix.service
重启一个服务：systemctl restart postfix.service
显示一个服务的状态：systemctl status postfix.service
在开机时启用一个服务：systemctl enable postfix.service
在开机时禁用一个服务：systemctl disable postfix.service
查看服务是否开机启动：systemctl is-enabled postfix.service;echo $?
查看已启动的服务列表：systemctl list-unit-files|grep enabled

说明：启用服务就是在当前“runlevel”的配置文件目录/etc/systemd/system/multi-user.target.wants/里，建立/usr/lib/systemd/system里面对应服务配置文件的软链接；禁用服务就是删除此软链接。

Systemctl是一个systemd工具，主要负责控制systemd系统和服务管理器。

Systemd是一个系统管理守护进程、工具和库的集合，用于取代System V初始进程。Systemd的功能是用于集中管理和配置类UNIX系统。

在Linux生态系统中，Systemd被部署到了大多数的标准Linux发行版中，只有为数不多的几个发行版尚未部署。Systemd通常是所有其它守护进程的父进程，但并非总是如此。

使用Systemctl管理Linux服务

本文旨在阐明在运行systemd的系统上“如何控制系统和服务”。

Systemd初体验和Systemctl基础

1. 首先检查你的系统中是否安装有systemd并确定当前安装的版本

  1. # systemctl --version

  2. systemd 215

  3. +PAM +AUDIT +SELINUX +IMA +SYSVINIT +LIBCRYPTSETUP +GCRYPT +ACL +XZ -SECCOMP -APPARMOR

上例中很清楚地表明，我们安装了215版本的systemd。

2. 检查systemd和systemctl的二进制文件和库文件的安装位置

  1. # whereis systemd

  2. systemd: /usr/lib/systemd /etc/systemd /usr/share/systemd /usr/share/man/man1/systemd.1.gz

  3. # whereis systemctl

  4. systemctl: /usr/bin/systemctl /usr/share/man/man1/systemctl.1.gz

3. 检查systemd是否运行

  1. # ps -eaf | grep [s]ystemd

  2. root 1 0 0 16:27 ? 00:00:00 /usr/lib/systemd/systemd --switched-root --system --deserialize 23

  3. root 444 1 0 16:27 ? 00:00:00 /usr/lib/systemd/systemd-journald

  4. root 469 1 0 16:27 ? 00:00:00 /usr/lib/systemd/systemd-udevd

  5. root 555 1 0 16:27 ? 00:00:00 /usr/lib/systemd/systemd-logind

  6. dbus 556 1 0 16:27 ? 00:00:00 /bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation

注意：systemd是作为父进程（PID=1）运行的。在上面带（-e）参数的ps命令输出中，选择所有进程，（-a）选择除会话前导外的所有进程，并使用（-f）参数输出完整格式列表（即 -eaf）。

也请注意上例中后随的方括号和例子中剩余部分。方括号表达式是grep的字符类表达式的一部分。

4. 分析systemd启动进程

  1. # systemd-analyze
  2. Startup finished in 487ms (kernel) + 2.776s (initrd) + 20.229s (userspace) = 23.493s

5. 分析启动时各个进程花费的时间

  1. # systemd-analyze blame

  2. 8.565s mariadb.service

  3. 7.991s webmin.service

  4. 6.095s postfix.service

  5. 4.311s httpd.service

  6. 3.926s firewalld.service

  7. 3.780s kdump.service

  8. 3.238s tuned.service

  9. 1.712s network.service

  10. 1.394s lvm2-monitor.service

  11. 1.126s systemd-logind.service

  12. ....

6. 分析启动时的关键链

  1. # systemd-analyze critical-chain

  2. The time after the unit is active or started is printed after the "@" character.

  3. The time the unit takes to start is printed after the "+" character.

  4. multi-user.target @20.222s

  5. └─mariadb.service @11.657s +8.565s

  6. └─network.target @11.168s

  7. └─network.service @9.456s +1.712s

  8. └─NetworkManager.service @8.858s +596ms

  9. └─firewalld.service @4.931s +3.926s

  10. └─basic.target @4.916s

  11. └─sockets.target @4.916s

  12. └─dbus.socket @4.916s

  13. └─sysinit.target @4.905s

  14. └─systemd-update-utmp.service @4.864s +39ms

  15. └─auditd.service @4.563s +301ms

  16. └─systemd-tmpfiles-setup.service @4.485s +69ms

  17. └─rhel-import-state.service @4.342s +142ms

  18. └─local-fs.target @4.324s

  19. └─boot.mount @4.286s +31ms

  20. └─systemd-fsck@dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d19608096

  21. └─dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d196080964.device @4

重要：Systemctl接受服务（.service），挂载点（.mount），套接口（.socket）和设备（.device）作为单元。

7. 列出所有可用单元

  1. # systemctl list-unit-files

  2. UNIT FILE STATE

  3. proc-sys-fs-binfmt_misc.automount static

  4. dev-hugepages.mount static

  5. dev-mqueue.mount static

  6. proc-sys-fs-binfmt_misc.mount static

  7. sys-fs-fuse-connections.mount static

  8. sys-kernel-config.mount static

  9. sys-kernel-debug.mount static

  10. tmp.mount disabled

  11. brandbot.path disabled

  12. .....

8. 列出所有运行中单元

  1. # systemctl list-units

  2. UNIT LOAD ACTIVE SUB DESCRIPTION

  3. proc-sys-fs-binfmt_misc.automount loaded active waiting Arbitrary Executable File Formats File Syste

  4. sys-devices-pc...0-1:0:0:0-block-sr0.device loaded active plugged VBOX_CD-ROM

  5. sys-devices-pc...:00:03.0-net-enp0s3.device loaded active plugged PRO/1000 MT Desktop Adapter

  6. sys-devices-pc...00:05.0-sound-card0.device loaded active plugged 82801AA AC'97 Audio Controller

  7. sys-devices-pc...:0:0-block-sda-sda1.device loaded active plugged VBOX_HARDDISK

  8. sys-devices-pc...:0:0-block-sda-sda2.device loaded active plugged LVM PV Qzyo3l-qYaL-uRUa-Cjuk-pljo-qKtX-VgBQ8

  9. sys-devices-pc...0-2:0:0:0-block-sda.device loaded active plugged VBOX_HARDDISK

  10. sys-devices-pl...erial8250-tty-ttyS0.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS0

  11. sys-devices-pl...erial8250-tty-ttyS1.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS1

  12. sys-devices-pl...erial8250-tty-ttyS2.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS2

  13. sys-devices-pl...erial8250-tty-ttyS3.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS3

  14. sys-devices-virtual-block-dm\x2d0.device loaded active plugged /sys/devices/virtual/block/dm-0

  15. sys-devices-virtual-block-dm\x2d1.device loaded active plugged /sys/devices/virtual/block/dm-1

  16. sys-module-configfs.device loaded active plugged /sys/module/configfs

  17. ...

9. 列出所有失败单元

  1. # systemctl --failed

  2. UNIT LOAD ACTIVE SUB DESCRIPTION

  3. kdump.service loaded failed failed Crash recovery kernel arming

  4. LOAD = Reflects whether the unit definition was properly loaded.

  5. ACTIVE = The high-level unit activation state, i.e. generalization of SUB.

  6. SUB = The low-level unit activation state, values depend on unit type.

  7. 1 loaded units listed. Pass --all to see loaded but inactive units, too.

  8. To show all installed unit files use 'systemctl list-unit-files'.

10. 检查某个单元（如 cron.service）是否启用

  1. # systemctl is-enabled crond.service

  2. enabled

11. 检查某个单元或服务是否运行

  1. # systemctl status firewalld.service

  2. firewalld.service - firewalld - dynamic firewall daemon

  3. Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled)

  4. Active: active (running) since Tue 2015-04-28 16:27:55 IST; 34min ago

  5. Main PID: 549 (firewalld)

  6. CGroup: /system.slice/firewalld.service

  7. └─549 /usr/bin/python -Es /usr/sbin/firewalld --nofork --nopid

  8. Apr 28 16:27:51 tecmint systemd[1]: Starting firewalld - dynamic firewall daemon...

  9. Apr 28 16:27:55 tecmint systemd[1]: Started firewalld - dynamic firewall daemon.

使用Systemctl控制并管理服务

12. 列出所有服务（包括启用的和禁用的）

  1. # systemctl list-unit-files --type=service

  2. UNIT FILE STATE

  3. arp-ethers.service disabled

  4. auditd.service enabled

  5. autovt@.service disabled

  6. blk-availability.service disabled

  7. brandbot.service static

  8. collectd.service disabled

  9. console-getty.service disabled

  10. console-shell.service disabled

  11. cpupower.service disabled

  12. crond.service enabled

  13. dbus-org.fedoraproject.FirewallD1.service enabled

  14. ....

13. Linux中如何启动、重启、停止、重载服务以及检查服务（如 httpd.service）状态

  1. # systemctl start httpd.service

  2. # systemctl restart httpd.service

  3. # systemctl stop httpd.service

  4. # systemctl reload httpd.service

  5. # systemctl status httpd.service

  6. httpd.service - The Apache HTTP Server

  7. Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)

  8. Active: active (running) since Tue 2015-04-28 17:21:30 IST; 6s ago

  9. Process: 2876 ExecStop=/bin/kill -WINCH ${MAINPID} (code=exited, status=0/SUCCESS)

  10. Main PID: 2881 (httpd)

  11. Status: "Processing requests..."

  12. CGroup: /system.slice/httpd.service

  13. ├─2881 /usr/sbin/httpd -DFOREGROUND

  14. ├─2884 /usr/sbin/httpd -DFOREGROUND

  15. ├─2885 /usr/sbin/httpd -DFOREGROUND

  16. ├─2886 /usr/sbin/httpd -DFOREGROUND

  17. ├─2887 /usr/sbin/httpd -DFOREGROUND

  18. └─2888 /usr/sbin/httpd -DFOREGROUND

  19. Apr 28 17:21:30 tecmint systemd[1]: Starting The Apache HTTP Server...

  20. Apr 28 17:21:30 tecmint httpd[2881]: AH00558: httpd: Could not reliably determine the server's fully q...ssage

  21. Apr 28 17:21:30 tecmint systemd[1]: Started The Apache HTTP Server.

  22. Hint: Some lines were ellipsized, use -l to show in full.

注意：当我们使用systemctl的start，restart，stop和reload命令时，我们不会从终端获取到任何输出内容，只有status命令可以打印输出。

14. 如何激活服务并在启动时启用或禁用服务（即系统启动时自动启动服务）

  1. # systemctl is-active httpd.service
  2. # systemctl enable httpd.service
  3. # systemctl disable httpd.service

15. 如何屏蔽（让它不能启动）或显示服务（如 httpd.service）

  1. # systemctl mask httpd.service

  2. ln -s '/dev/null' '/etc/systemd/system/httpd.service'

  3. # systemctl unmask httpd.service

  4. rm '/etc/systemd/system/httpd.service'

16. 使用systemctl命令杀死服务

  1. # systemctl kill httpd

  2. # systemctl status httpd

  3. httpd.service - The Apache HTTP Server

  4. Loaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)

  5. Active: failed (Result: exit-code) since Tue 2015-04-28 18:01:42 IST; 28min ago

  6. Main PID: 2881 (code=exited, status=0/SUCCESS)

  7. Status: "Total requests: 0; Current requests/sec: 0; Current traffic: 0 B/sec"

  8. Apr 28 17:37:29 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.

  9. Apr 28 17:37:29 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.

  10. Apr 28 17:37:39 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.

  11. Apr 28 17:37:39 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.

  12. Apr 28 17:37:49 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.

  13. Apr 28 17:37:49 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.

  14. Apr 28 17:37:59 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.

  15. Apr 28 17:37:59 tecmint systemd[1]: httpd.service: Got notification message from PID 2881, but recepti...bled.

  16. Apr 28 18:01:42 tecmint systemd[1]: httpd.service: control process exited, code=exited status=226

  17. Apr 28 18:01:42 tecmint systemd[1]: Unit httpd.service entered failed state.

  18. Hint: Some lines were ellipsized, use -l to show in full.

使用Systemctl控制并管理挂载点

17. 列出所有系统挂载点

  1. # systemctl list-unit-files --type=mount

  2. UNIT FILE STATE

  3. dev-hugepages.mount static

  4. dev-mqueue.mount static

  5. proc-sys-fs-binfmt_misc.mount static

  6. sys-fs-fuse-connections.mount static

  7. sys-kernel-config.mount static

  8. sys-kernel-debug.mount static

  9. tmp.mount disabled

18. 挂载、卸载、重新挂载、重载系统挂载点并检查系统中挂载点状态

  1. # systemctl start tmp.mount

  2. # systemctl stop tmp.mount

  3. # systemctl restart tmp.mount

  4. # systemctl reload tmp.mount

  5. # systemctl status tmp.mount

  6. tmp.mount - Temporary Directory

  7. Loaded: loaded (/usr/lib/systemd/system/tmp.mount; disabled)

  8. Active: active (mounted) since Tue 2015-04-28 17:46:06 IST; 2min 48s ago

  9. Where: /tmp

  10. What: tmpfs

  11. Docs: man:hier(7)

  12. http://www.freedesktop.org/wiki/Software/systemd/APIFileSystems

  13. Process: 3908 ExecMount=/bin/mount tmpfs /tmp -t tmpfs -o mode=1777,strictatime (code=exited, status=0/SUCCESS)

  14. Apr 28 17:46:06 tecmint systemd[1]: Mounting Temporary Directory...

  15. Apr 28 17:46:06 tecmint systemd[1]: tmp.mount: Directory /tmp to mount over is not empty, mounting anyway.

  16. Apr 28 17:46:06 tecmint systemd[1]: Mounted Temporary Directory.

19. 在启动时激活、启用或禁用挂载点（系统启动时自动挂载）

  1. # systemctl is-active tmp.mount
  2. # systemctl enable tmp.mount
  3. # systemctl disable tmp.mount

20. 在Linux中屏蔽（让它不能启用）或可见挂载点

  1. # systemctl mask tmp.mount

  2. ln -s '/dev/null' '/etc/systemd/system/tmp.mount'

  3. # systemctl unmask tmp.mount

  4. rm '/etc/systemd/system/tmp.mount'

使用Systemctl控制并管理套接口

21. 列出所有可用系统套接口

  1. # systemctl list-unit-files --type=socket

  2. UNIT FILE STATE

  3. dbus.socket static

  4. dm-event.socket enabled

  5. lvm2-lvmetad.socket enabled

  6. rsyncd.socket disabled

  7. sshd.socket disabled

  8. syslog.socket static

  9. systemd-initctl.socket static

  10. systemd-journald.socket static

  11. systemd-shutdownd.socket static

  12. systemd-udevd-control.socket static

  13. systemd-udevd-kernel.socket static

  14. 11 unit files listed.

22. 在Linux中启动、重启、停止、重载套接口并检查其状态

  1. # systemctl start cups.socket

  2. # systemctl restart cups.socket

  3. # systemctl stop cups.socket

  4. # systemctl reload cups.socket

  5. # systemctl status cups.socket

  6. cups.socket - CUPS Printing Service Sockets

  7. Loaded: loaded (/usr/lib/systemd/system/cups.socket; enabled)

  8. Active: active (listening) since Tue 2015-04-28 18:10:59 IST; 8s ago

  9. Listen: /var/run/cups/cups.sock (Stream)

  10. Apr 28 18:10:59 tecmint systemd[1]: Starting CUPS Printing Service Sockets.

  11. Apr 28 18:10:59 tecmint systemd[1]: Listening on CUPS Printing Service Sockets.

23. 在启动时激活套接口，并启用或禁用它（系统启动时自启动）

  1. # systemctl is-active cups.socket
  2. # systemctl enable cups.socket
  3. # systemctl disable cups.socket

24. 屏蔽（使它不能启动）或显示套接口

  1. # systemctl mask cups.socket

  2. ln -s '/dev/null' '/etc/systemd/system/cups.socket'

  3. # systemctl unmask cups.socket

  4. rm '/etc/systemd/system/cups.socket'

服务的CPU利用率（分配额）

25. 获取当前某个服务的CPU分配额（如httpd）

  1. # systemctl show -p CPUShares httpd.service

  2. CPUShares=1024

注意：各个服务的默认CPU分配份额=1024，你可以增加/减少某个进程的CPU分配份额。

26. 将某个服务（httpd.service）的CPU分配份额限制为2000 CPUShares/

  1. # systemctl set-property httpd.service CPUShares=2000

  2. # systemctl show -p CPUShares httpd.service

  3. CPUShares=2000

注意：当你为某个服务设置CPUShares，会自动创建一个以服务名命名的目录（如 httpd.service），里面包含了一个名为90-CPUShares.conf的文件，该文件含有CPUShare限制信息，你可以通过以下方式查看该文件：

  1. # vi /etc/systemd/system/httpd.service.d/90-CPUShares.conf

  2. [Service]

  3. CPUShares=2000

27. 检查某个服务的所有配置细节

  1. # systemctl show httpd

  2. Id=httpd.service

  3. Names=httpd.service

  4. Requires=basic.target

  5. Wants=system.slice

  6. WantedBy=multi-user.target

  7. Conflicts=shutdown.target

  8. Before=shutdown.target multi-user.target

  9. After=network.target remote-fs.target nss-lookup.target systemd-journald.socket basic.target system.slice

  10. Description=The Apache HTTP Server

  11. LoadState=loaded

  12. ActiveState=active

  13. SubState=running

  14. FragmentPath=/usr/lib/systemd/system/httpd.service

  15. ....

28. 分析某个服务（httpd）的关键链

  1. # systemd-analyze critical-chain httpd.service

  2. The time after the unit is active or started is printed after the "@" character.

  3. The time the unit takes to start is printed after the "+" character.

  4. httpd.service +142ms

  5. └─network.target @11.168s

  6. └─network.service @9.456s +1.712s

  7. └─NetworkManager.service @8.858s +596ms

  8. └─firewalld.service @4.931s +3.926s

  9. └─basic.target @4.916s

  10. └─sockets.target @4.916s

  11. └─dbus.socket @4.916s

  12. └─sysinit.target @4.905s

  13. └─systemd-update-utmp.service @4.864s +39ms

  14. └─auditd.service @4.563s +301ms

  15. └─systemd-tmpfiles-setup.service @4.485s +69ms

  16. └─rhel-import-state.service @4.342s +142ms

  17. └─local-fs.target @4.324s

  18. └─boot.mount @4.286s +31ms

  19. └─systemd-fsck@dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d196080964.service @4.092s +149ms

  20. └─dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d196080964.device @4.092s

29. 获取某个服务（httpd）的依赖性列表

  1. # systemctl list-dependencies httpd.service

  2. httpd.service

  3. ├─system.slice

  4. └─basic.target

  5. ├─firewalld.service

  6. ├─microcode.service

  7. ├─rhel-autorelabel-mark.service

  8. ├─rhel-autorelabel.service

  9. ├─rhel-configure.service

  10. ├─rhel-dmesg.service

  11. ├─rhel-loadmodules.service

  12. ├─paths.target

  13. ├─slices.target

  14. │ ├─-.slice

  15. │ └─system.slice

  16. ├─sockets.target

  17. │ ├─dbus.socket

  18. ....

30. 按等级列出控制组

  1. # systemd-cgls

  2. ├─1 /usr/lib/systemd/systemd --switched-root --system --deserialize 23

  3. ├─user.slice

  4. │ └─user-0.slice

  5. │ └─session-1.scope

  6. │ ├─2498 sshd: root@pts/0

  7. │ ├─2500 -bash

  8. │ ├─4521 systemd-cgls

  9. │ └─4522 systemd-cgls

  10. └─system.slice

  11. ├─httpd.service

  12. │ ├─4440 /usr/sbin/httpd -DFOREGROUND

  13. │ ├─4442 /usr/sbin/httpd -DFOREGROUND

  14. │ ├─4443 /usr/sbin/httpd -DFOREGROUND

  15. │ ├─4444 /usr/sbin/httpd -DFOREGROUND

  16. │ ├─4445 /usr/sbin/httpd -DFOREGROUND

  17. │ └─4446 /usr/sbin/httpd -DFOREGROUND

  18. ├─polkit.service

  19. │ └─721 /usr/lib/polkit-1/polkitd --no-debug

  20. ....

31. 按CPU、内存、输入和输出列出控制组

  1. # systemd-cgtop

  2. Path Tasks %CPU Memory Input/s Output/s

  3. / 83 1.0 437.8M - -

  4. /system.slice - 0.1 - - -

  5. /system.slice/mariadb.service 2 0.1 - - -

  6. /system.slice/tuned.service 1 0.0 - - -

  7. /system.slice/httpd.service 6 0.0 - - -

  8. /system.slice/NetworkManager.service 1 - - - -

  9. /system.slice/atop.service 1 - - - -

  10. /system.slice/atopacct.service 1 - - - -

  11. /system.slice/auditd.service 1 - - - -

  12. /system.slice/crond.service 1 - - - -

  13. /system.slice/dbus.service 1 - - - -

  14. /system.slice/firewalld.service 1 - - - -

  15. /system.slice/lvm2-lvmetad.service 1 - - - -

  16. /system.slice/polkit.service 1 - - - -

  17. /system.slice/postfix.service 3 - - - -

  18. /system.slice/rsyslog.service 1 - - - -

  19. /system.slice/system-getty.slice/getty@tty1.service 1 - - - -

  20. /system.slice/systemd-journald.service 1 - - - -

  21. /system.slice/systemd-logind.service 1 - - - -

  22. /system.slice/systemd-udevd.service 1 - - - -

  23. /system.slice/webmin.service 1 - - - -

  24. /user.slice/user-0.slice/session-1.scope 3 - - - -

控制系统运行等级

32. 启动系统救援模式

  1. # systemctl rescue

  2. Broadcast message from root@tecmint on pts/0 (Wed 2015-04-29 11:31:18 IST):

  3. The system is going down to rescue mode NOW!

33. 进入紧急模式

  1. # systemctl emergency

  2. Welcome to emergency mode! After logging in, type "journalctl -xb" to view

  3. system logs, "systemctl reboot" to reboot, "systemctl default" to try again

  4. to boot into default mode.

34. 列出当前使用的运行等级

  1. # systemctl get-default

  2. multi-user.target

35. 启动运行等级5，即图形模式

  1. # systemctl isolate runlevel5.target
  2. 或
  3. # systemctl isolate graphical.target

36. 启动运行等级3，即多用户模式（命令行）

  1. # systemctl isolate runlevel3.target
  2. 或
  3. # systemctl isolate multiuser.target

36. 设置多用户模式或图形模式为默认运行等级

  1. # systemctl set-default runlevel3.target

  2. # systemctl set-default runlevel5.target

37. 重启、停止、挂起、休眠系统或使系统进入混合睡眠

  1. # systemctl reboot

  2. # systemctl halt

  3. # systemctl suspend

  4. # systemctl hibernate

  5. # systemctl hybrid-sleep

对于不知运行等级为何物的人，说明如下。

  • Runlevel 0 : 关闭系统
  • Runlevel 1 : 救援？维护模式
  • Runlevel 3 : 多用户，无图形系统
  • Runlevel 4 : 多用户，无图形系统
  • Runlevel 5 : 多用户，图形化系统
  • Runlevel 6 : 关闭并重启机器

到此为止吧。保持连线，进行评论。别忘了在下面的评论中为我们提供一些有价值的反馈哦。喜欢我们、与我们分享，求扩散。

via: http://www.tecmint.com/manage-services-using-systemd-and-systemctl-in-linux/

作者：Avishek Kumar 译者：GOLinux 校对：wxy

本文由 LCTT 原创翻译，Linux中国 荣誉推出

参考原文：http://www.tecmint.com/manage-services-using-systemd-and-systemctl-in-linux/作者： Avishek Kumar
编译文章：LCTT  https://linux.cn/article-5926-1.html译者： GOLinux

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