http://www.linuxidc.com/Linux/2015-07/120833.htm
Systemctl是一個systemd工具,主要負責控制systemd系統和服務管理器。
Systemd是一個系統管理守護進程、工具和庫的集合,用於取代System V初始進程。Systemd的功能是用於集中管理和配置類UNIX系統。
在Linux生態系統中,Systemd被部署到了大多數的標准Linux發行版中,只有為數不多的幾個發行版尚未部署。Systemd通常是所有其它守護進程的父進程,但並非總是如此。

使用Systemctl管理Linux服務
本文旨在闡明在運行systemd的系統上“如何控制系統和服務”。
Systemd初體驗和Systemctl基礎
1. 首先檢查你的系統中是否安裝有systemd並確定當前安裝的版本
# systemd --versionsystemd 215+PAM +AUDIT +SELINUX +IMA +SYSVINIT +LIBCRYPTSETUP +GCRYPT +ACL +XZ -SECCOMP -APPARMOR
上例中很清楚地表明,我們安裝了215版本的systemd。
2. 檢查systemd和systemctl的二進制文件和庫文件的安裝位置
# whereis systemdsystemd:/usr/lib/systemd /etc/systemd /usr/share/systemd /usr/share/man/man1/systemd.1.gz# whereis systemctlsystemctl:/usr/bin/systemctl /usr/share/man/man1/systemctl.1.gz
3. 檢查systemd是否運行
# ps -eaf | grep [s]ystemdroot 10016:27?00:00:00/usr/lib/systemd/systemd --switched-root --system --deserialize 23root 4441016:27?00:00:00/usr/lib/systemd/systemd-journaldroot 4691016:27?00:00:00/usr/lib/systemd/systemd-udevdroot 5551016:27?00:00:00/usr/lib/systemd/systemd-loginddbus 5561016:27?00:00:00/bin/dbus-daemon --system --address=systemd:--nofork --nopidfile --systemd-activation
注意:systemd是作為父進程(PID=1)運行的。在上面帶(-e)參數的ps命令輸出中,選擇所有進程,(-a)選擇除會話前導外的所有進程,並使用(-f)參數輸出完整格式列表(即 -eaf)。
也請注意上例中后隨的方括號和例子中剩余部分。方括號表達式是grep的字符類表達式的一部分。
4. 分析systemd啟動進程
# systemd-analyzeStartup finished in487ms(kernel)+2.776s(initrd)+20.229s(userspace)=23.493s
5. 分析啟動時各個進程花費的時間
# systemd-analyze blame8.565s mariadb.service7.991s webmin.service6.095s postfix.service4.311s httpd.service3.926s firewalld.service3.780s kdump.service3.238s tuned.service1.712s network.service1.394s lvm2-monitor.service1.126s systemd-logind.service....
6. 分析啟動時的關鍵鏈
# systemd-analyze critical-chainThe time after the unit is active or started is printed after the "@" character.The time the unit takes to start is printed after the "+" character.multi-user.target @20.222s└─mariadb.service @11.657s+8.565s└─network.target @11.168s└─network.service @9.456s+1.712s└─NetworkManager.service @8.858s+596ms└─firewalld.service @4.931s+3.926s└─basic.target @4.916s└─sockets.target @4.916s└─dbus.socket @4.916s└─sysinit.target @4.905s└─systemd-update-utmp.service @4.864s+39ms└─auditd.service @4.563s+301ms└─systemd-tmpfiles-setup.service @4.485s+69ms└─rhel-import-state.service @4.342s+142ms└─local-fs.target @4.324s└─boot.mount @4.286s+31ms└─systemd-fsck@dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d19608096└─dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d196080964.device@4
重要:Systemctl接受服務(.service),掛載點(.mount),套接口(.socket)和設備(.device)作為單元。
7. 列出所有可用單元
# systemctl list-unit-filesUNIT FILE STATEproc-sys-fs-binfmt_misc.automount staticdev-hugepages.mount staticdev-mqueue.mount staticproc-sys-fs-binfmt_misc.mount staticsys-fs-fuse-connections.mount staticsys-kernel-config.mount staticsys-kernel-debug.mount statictmp.mount disabledbrandbot.path disabled.....
8. 列出所有運行中單元
# systemctl list-unitsUNIT LOAD ACTIVE SUB DESCRIPTIONproc-sys-fs-binfmt_misc.automount loaded active waiting ArbitraryExecutableFileFormatsFileSystesys-devices-pc...0-1:0:0:0-block-sr0.device loaded active plugged VBOX_CD-ROMsys-devices-pc...:00:03.0-net-enp0s3.device loaded active plugged PRO/1000 MT DesktopAdaptersys-devices-pc...00:05.0-sound-card0.device loaded active plugged 82801AA AC'97 Audio Controllersys-devices-pc...:0:0-block-sda-sda1.device loaded active plugged VBOX_HARDDISKsys-devices-pc...:0:0-block-sda-sda2.device loaded active plugged LVM PV Qzyo3l-qYaL-uRUa-Cjuk-pljo-qKtX-VgBQ8sys-devices-pc...0-2:0:0:0-block-sda.device loaded active plugged VBOX_HARDDISKsys-devices-pl...erial8250-tty-ttyS0.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS0sys-devices-pl...erial8250-tty-ttyS1.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS1sys-devices-pl...erial8250-tty-ttyS2.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS2sys-devices-pl...erial8250-tty-ttyS3.device loaded active plugged /sys/devices/platform/serial8250/tty/ttyS3sys-devices-virtual-block-dm\x2d0.device loaded active plugged /sys/devices/virtual/block/dm-0sys-devices-virtual-block-dm\x2d1.device loaded active plugged /sys/devices/virtual/block/dm-1sys-module-configfs.device loaded active plugged /sys/module/configfs...
9. 列出所有失敗單元
# systemctl --failedUNIT LOAD ACTIVE SUB DESCRIPTIONkdump.service loaded failed failed Crash recovery kernel armingLOAD =Reflects whether the unit definition was properly loaded.ACTIVE =The high-level unit activation state, i.e. generalization of SUB.SUB =The low-level unit activation state, values depend on unit type.1 loaded units listed.Pass--all to see loaded but inactive units, too.To show all installed unit files use'systemctl list-unit-files'.
10. 檢查某個單元(如 cron.service)是否啟用
# systemctl is-enabled crond.serviceenabled
11. 檢查某個單元或服務是否運行
# systemctl status firewalld.servicefirewalld.service - firewalld -dynamic firewall daemonLoaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled)Active: active (running) since Tue2015-04-2816:27:55 IST;34min agoMain PID:549(firewalld)CGroup:/system.slice/firewalld.service└─549/usr/bin/python -Es/usr/sbin/firewalld --nofork --nopidApr2816:27:51 tecmint systemd[1]:Starting firewalld -dynamic firewall daemon...Apr2816:27:55 tecmint systemd[1]:Started firewalld -dynamic firewall daemon.
使用Systemctl控制並管理服務
12. 列出所有服務(包括啟用的和禁用的)
# systemctl list-unit-files --type=serviceUNIT FILE STATEarp-ethers.service disabledauditd.service enabledautovt@.service disabledblk-availability.service disabledbrandbot.service staticcollectd.service disabledconsole-getty.service disabledconsole-shell.service disabledcpupower.service disabledcrond.service enableddbus-org.Fedoraproject.FirewallD1.service enabled....
13. Linux中如何啟動、重啟、停止、重載服務以及檢查服務(如 httpd.service)狀態
# systemctl start httpd.service# systemctl restart httpd.service# systemctl stop httpd.service# systemctl reload httpd.service# systemctl status httpd.servicehttpd.service -TheApache HTTP ServerLoaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)Active: active (running) since Tue2015-04-2817:21:30 IST;6s agoProcess:2876ExecStop=/bin/kill -WINCH ${MAINPID}(code=exited, status=0/SUCCESS)Main PID:2881(httpd)Status:"Processing requests..."CGroup:/system.slice/httpd.service├─2881/usr/sbin/httpd -DFOREGROUND├─2884/usr/sbin/httpd -DFOREGROUND├─2885/usr/sbin/httpd -DFOREGROUND├─2886/usr/sbin/httpd -DFOREGROUND├─2887/usr/sbin/httpd -DFOREGROUND└─2888/usr/sbin/httpd -DFOREGROUNDApr2817:21:30 tecmint systemd[1]:StartingTheApache HTTP Server...Apr2817:21:30 tecmint httpd[2881]: AH00558: httpd:Couldnot reliably determine the server's fully q...ssageApr 28 17:21:30 tecmint systemd[1]: Started The Apache HTTP Server.Hint: Some lines were ellipsized, use -l to show in full.
注意:當我們使用systemctl的start,restart,stop和reload命令時,我們不會從終端獲取到任何輸出內容,只有status命令可以打印輸出。
14. 如何激活服務並在啟動時啟用或禁用服務(即系統啟動時自動啟動服務)
# systemctl is-active httpd.service# systemctl enable httpd.service# systemctl disable httpd.service
15. 如何屏蔽(讓它不能啟動)或顯示服務(如 httpd.service)
# systemctl mask httpd.serviceln -s '/dev/null''/etc/systemd/system/httpd.service'# systemctl unmask httpd.servicerm '/etc/systemd/system/httpd.service'
16. 使用systemctl命令殺死服務
# systemctl kill httpd# systemctl status httpdhttpd.service -TheApache HTTP ServerLoaded: loaded (/usr/lib/systemd/system/httpd.service; enabled)Active: failed (Result:exit-code) since Tue2015-04-2818:01:42 IST;28min agoMain PID:2881(code=exited, status=0/SUCCESS)Status:"Total requests: 0; Current requests/sec: 0; Current traffic: 0 B/sec"Apr2817:37:29 tecmint systemd[1]: httpd.service:Got notification message from PID 2881, but recepti...bled.Apr2817:37:29 tecmint systemd[1]: httpd.service:Got notification message from PID 2881, but recepti...bled.Apr2817:37:39 tecmint systemd[1]: httpd.service:Got notification message from PID 2881, but recepti...bled.Apr2817:37:39 tecmint systemd[1]: httpd.service:Got notification message from PID 2881, but recepti...bled.Apr2817:37:49 tecmint systemd[1]: httpd.service:Got notification message from PID 2881, but recepti...bled.Apr2817:37:49 tecmint systemd[1]: httpd.service:Got notification message from PID 2881, but recepti...bled.Apr2817:37:59 tecmint systemd[1]: httpd.service:Got notification message from PID 2881, but recepti...bled.Apr2817:37:59 tecmint systemd[1]: httpd.service:Got notification message from PID 2881, but recepti...bled.Apr2818:01:42 tecmint systemd[1]: httpd.service: control process exited, code=exited status=226Apr2818:01:42 tecmint systemd[1]:Unit httpd.service entered failed state.Hint:Some lines were ellipsized,use-l to show in full.
使用Systemctl控制並管理掛載點
17. 列出所有系統掛載點
# systemctl list-unit-files --type=mountUNIT FILE STATEdev-hugepages.mount staticdev-mqueue.mount staticproc-sys-fs-binfmt_misc.mount staticsys-fs-fuse-connections.mount staticsys-kernel-config.mount staticsys-kernel-debug.mount statictmp.mount disabled
18. 掛載、卸載、重新掛載、重載系統掛載點並檢查系統中掛載點狀態
# systemctl start tmp.mount# systemctl stop tmp.mount# systemctl restart tmp.mount# systemctl reload tmp.mount# systemctl status tmp.mounttmp.mount -TemporaryDirectoryLoaded: loaded (/usr/lib/systemd/system/tmp.mount; disabled)Active: active (mounted) since Tue2015-04-2817:46:06 IST;2min48s agoWhere:/tmpWhat: tmpfsDocs: man:hier(7)http://www.freedesktop.org/wiki/Software/systemd/APIFileSystemsProcess:3908ExecMount=/bin/mount tmpfs /tmp -t tmpfs -o mode=1777,strictatime (code=exited, status=0/SUCCESS)Apr2817:46:06 tecmint systemd[1]:MountingTemporaryDirectory...Apr2817:46:06 tecmint systemd[1]: tmp.mount:Directory/tmp to mount over isnot empty, mounting anyway.Apr2817:46:06 tecmint systemd[1]:MountedTemporaryDirectory.
19. 在啟動時激活、啟用或禁用掛載點(系統啟動時自動掛載)
# systemctl is-active tmp.mount# systemctl enable tmp.mount# systemctl disable tmp.mount
20. 在Linux中屏蔽(讓它不能啟用)或可見掛載點
# systemctl mask tmp.mountln -s '/dev/null''/etc/systemd/system/tmp.mount'# systemctl unmask tmp.mountrm '/etc/systemd/system/tmp.mount'
使用Systemctl控制並管理套接口
21. 列出所有可用系統套接口
# systemctl list-unit-files --type=socketUNIT FILE STATEdbus.socket staticdm-event.socket enabledlvm2-lvmetad.socket enabledrsyncd.socket disabledsshd.socket disabledsyslog.socket staticsystemd-initctl.socket staticsystemd-journald.socket staticsystemd-shutdownd.socket staticsystemd-udevd-control.socket staticsystemd-udevd-kernel.socket static11 unit files listed.
22. 在Linux中啟動、重啟、停止、重載套接口並檢查其狀態
# systemctl start cups.socket# systemctl restart cups.socket# systemctl stop cups.socket# systemctl reload cups.socket# systemctl status cups.socketcups.socket - CUPS PrintingServiceSocketsLoaded: loaded (/usr/lib/systemd/system/cups.socket; enabled)Active: active (listening) since Tue2015-04-2818:10:59 IST;8s agoListen:/var/run/cups/cups.sock (Stream)Apr2818:10:59 tecmint systemd[1]:Starting CUPS PrintingServiceSockets.Apr2818:10:59 tecmint systemd[1]:Listening on CUPS PrintingServiceSockets.
23. 在啟動時激活套接口,並啟用或禁用它(系統啟動時自啟動)
# systemctl is-active cups.socket# systemctl enable cups.socket# systemctl disable cups.socket
24. 屏蔽(使它不能啟動)或顯示套接口
# systemctl mask cups.socketln -s '/dev/null''/etc/systemd/system/cups.socket'# systemctl unmask cups.socketrm '/etc/systemd/system/cups.socket'
服務的CPU利用率(分配額)
25. 獲取當前某個服務的CPU分配額(如httpd)
# systemctl show -p CPUShares httpd.serviceCPUShares=1024
注意:各個服務的默認CPU分配份額=1024,你可以增加/減少某個進程的CPU分配份額。
26. 將某個服務(httpd.service)的CPU分配份額限制為2000 CPUShares/
# systemctl set-property httpd.service CPUShares=2000# systemctl show -p CPUShares httpd.serviceCPUShares=2000
注意:當你為某個服務設置CPUShares,會自動創建一個以服務名命名的目錄(如 httpd.service),里面包含了一個名為90-CPUShares.conf的文件,該文件含有CPUShare限制信息,你可以通過以下方式查看該文件:
# vi /etc/systemd/system/httpd.service.d/90-CPUShares.conf[Service]CPUShares=2000
27. 檢查某個服務的所有配置細節
# systemctl show httpdId=httpd.serviceNames=httpd.serviceRequires=basic.targetWants=system.sliceWantedBy=multi-user.targetConflicts=shutdown.targetBefore=shutdown.target multi-user.targetAfter=network.target remote-fs.target nss-lookup.target systemd-journald.socket basic.target system.sliceDescription=TheApache HTTP ServerLoadState=loadedActiveState=activeSubState=runningFragmentPath=/usr/lib/systemd/system/httpd.service....
28. 分析某個服務(httpd)的關鍵鏈
# systemd-analyze critical-chain httpd.serviceThe time after the unit is active or started is printed after the "@" character.The time the unit takes to start is printed after the "+" character.httpd.service +142ms└─network.target @11.168s└─network.service @9.456s+1.712s└─NetworkManager.service @8.858s+596ms└─firewalld.service @4.931s+3.926s└─basic.target @4.916s└─sockets.target @4.916s└─dbus.socket @4.916s└─sysinit.target @4.905s└─systemd-update-utmp.service @4.864s+39ms└─auditd.service @4.563s+301ms└─systemd-tmpfiles-setup.service @4.485s+69ms└─rhel-import-state.service @4.342s+142ms└─local-fs.target @4.324s└─boot.mount @4.286s+31ms└─systemd-fsck@dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d196080964.service@4.092s+149ms└─dev-disk-by\x2duuid-79f594ad\x2da332\x2d4730\x2dbb5f\x2d85d196080964.device@4.092s
29. 獲取某個服務(httpd)的依賴性列表
# systemctl list-dependencies httpd.servicehttpd.service├─system.slice└─basic.target├─firewalld.service├─microcode.service├─rhel-autorelabel-mark.service├─rhel-autorelabel.service├─rhel-configure.service├─rhel-dmesg.service├─rhel-loadmodules.service├─paths.target├─slices.target│├─-.slice│└─system.slice├─sockets.target│├─dbus.socket....
30. 按等級列出控制組
# systemd-cgls├─1/usr/lib/systemd/systemd --switched-root --system --deserialize 23├─user.slice│└─user-0.slice│└─session-1.scope│├─2498 sshd: root@pts/0│├─2500-bash│├─4521 systemd-cgls│└─4522 systemd-cgls└─system.slice├─httpd.service│├─4440/usr/sbin/httpd -DFOREGROUND│├─4442/usr/sbin/httpd -DFOREGROUND│├─4443/usr/sbin/httpd -DFOREGROUND│├─4444/usr/sbin/httpd -DFOREGROUND│├─4445/usr/sbin/httpd -DFOREGROUND│└─4446/usr/sbin/httpd -DFOREGROUND├─polkit.service│└─721/usr/lib/polkit-1/polkitd --no-debug....
31. 按CPU、內存、輸入和輸出列出控制組
# systemd-cgtopPathTasks%CPU MemoryInput/s Output/s/831.0437.8M--/system.slice -0.1---/system.slice/mariadb.service 20.1---/system.slice/tuned.service 10.0---/system.slice/httpd.service 60.0---/system.slice/NetworkManager.service 1----/system.slice/atop.service 1----/system.slice/atopacct.service 1----/system.slice/auditd.service 1----/system.slice/crond.service 1----/system.slice/dbus.service 1----/system.slice/firewalld.service 1----/system.slice/lvm2-lvmetad.service 1----/system.slice/polkit.service 1----/system.slice/postfix.service 3----/system.slice/rsyslog.service 1----/system.slice/system-getty.slice/getty@tty1.service 1----/system.slice/systemd-journald.service 1----/system.slice/systemd-logind.service 1----/system.slice/systemd-udevd.service 1----/system.slice/webmin.service 1----/user.slice/user-0.slice/session-1.scope3----
控制系統運行等級
32. 啟動系統救援模式
# systemctl rescueBroadcast message from root@tecmint on pts/0(Wed2015-04-2911:31:18 IST):The system is going down to rescue mode NOW!
33. 進入緊急模式
# systemctl emergencyWelcome to emergency mode!After logging in, type "journalctl -xb" to viewsystem logs,"systemctl reboot" to reboot,"systemctl default" to try againto boot intodefault mode.
34. 列出當前使用的運行等級
# systemctl get-defaultmulti-user.target
35. 啟動運行等級5,即圖形模式
# systemctl isolate runlevel5.target或# systemctl isolate graphical.target
36. 啟動運行等級3,即多用戶模式(命令行)
# systemctl isolate runlevel3.target或# systemctl isolate multiuser.target
36. 設置多用戶模式或圖形模式為默認運行等級
# systemctl set-default runlevel3.target# systemctl set-default runlevel5.target
37. 重啟、停止、掛起、休眠系統或使系統進入混合睡眠
# systemctl reboot# systemctl halt# systemctl suspend# systemctl hibernate# systemctl hybrid-sleep
對於不知運行等級為何物的人,說明如下。
- Runlevel 0 : 關閉系統
- Runlevel 1 : 救援?維護模式
- Runlevel 3 : 多用戶,無圖形系統
- Runlevel 4 : 多用戶,無圖形系統
- Runlevel 5 : 多用戶,圖形化系統
- Runlevel 6 : 關閉並重啟機器
到此為止吧。保持連線,進行評論。別忘了在下面的評論中為我們提供一些有價值的反饋哦。喜歡我們、與我們分享,求擴散。
via: http://www.tecmint.com/manage-services-using-systemd-and-systemctl-in-linux/
作者:Avishek Kumar 譯者:GOLinux 校對:wxy
