本教程介紹如何使用systemctl工具列出啟動失敗的systemd管理的各個服務(wù)
列出啟動失敗的服務(wù)
[root@localhost ~]# systemctl list-units --state failed
? UNIT? ? ? ? ? LOAD? ACTIVE SUB? ? DESCRIPTION
● httpd.service loaded failed failed The Apache HTTP Server
LOAD? = 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'.
可以發(fā)現(xiàn)，有個一個服務(wù)啟動失敗了孕似。
is-failed選項
可以使用is-failed選項檢查指定的服務(wù)是否啟動失敗阴绢。如果啟動失敗欠动，結(jié)果是failed装蓬。如果啟動沒有問題灿渴，結(jié)果是active下梢。
[root@localhost ~]# systemctl is-failed httpd
failed
[root@localhost ~]# systemctl is-failed vsftpd
active
檢查服務(wù)的狀態(tài)
可以使用status選項全肮，查看服務(wù)啟動失敗的原因悬钳，下面狀態(tài)信息里面告訴我們盐捷，是httpd.conf配置文件354行有語法錯誤柬脸。
May 26 09:22:05 localhost httpd[2958]: httpd: Syntax error on line 354 of /etc/httpd/conf/httpd.conf: /...osed.
[root@localhost ~]# systemctl status httpd
● httpd.service - The Apache HTTP Server
? Loaded: loaded (/usr/lib/systemd/system/httpd.service; disabled; vendor preset: disabled)
? Active: failed (Result: exit-code) since Tue 2020-05-26 09:22:05 CST; 18min ago
? ? Docs: man:httpd(8)
? ? ? ? ? man:apachectl(8)
Main PID: 2958 (code=exited, status=1/FAILURE)
May 26 09:22:05 localhost systemd[1]: Starting The Apache HTTP Server...
May 26 09:22:05 localhost httpd[2958]: httpd: Syntax error on line 354 of /etc/httpd/conf/httpd.conf: /...osed.
May 26 09:22:05 localhost systemd[1]: httpd.service: main process exited, code=exited, status=1/FAILURE
May 26 09:22:05 localhost kill[2959]: kill: cannot find process ""
May 26 09:22:05 localhost systemd[1]: httpd.service: control process exited, code=exited status=1
May 26 09:22:05 localhost systemd[1]: Failed to start The Apache HTTP Server.
May 26 09:22:05 localhost systemd[1]: Unit httpd.service entered failed state.
May 26 09:22:05 localhost systemd[1]: httpd.service failed.
Hint: Some lines were ellipsized, use -l to show in full.
使用journalctl查看服務(wù)的啟動日志
如果使用systemctl status [unit]沒有找到服務(wù)啟動失敗的原因，可以使用journalctl查看更多的啟動日志毙驯。
下面操作是過濾出所有帶有error的行倒堕，可以找到啟動失敗的服務(wù)。
[root@localhost ~]# journalctl |grep 'error'May 26 09:22:05 localhost httpd[2958]: httpd: Syntax error on line 354 of /etc/httpd/conf/httpd.conf: /etc/httpd/conf/httpd.conf:354: was not closed.
也可以使用journalctl -u [unit]只查看某一個服務(wù)的啟動日志：
[root@localhost ~]# journalctl -u httpd.service -- Logs begin at Sun 2020-05-24 06:52:52 CST, end at Tue 2020-05-26 09:48:03 CST. --May 26 09:22:05 localhost systemd[1]: Starting The Apache HTTP Server...May 26 09:22:05 localhost httpd[2958]: httpd: Syntax error on line 354 of /etc/httpd/conf/httpd.conf: /etc/httpd/conf/httpd.conf:354: was not closed.
May 26 09:22:05 localhost systemd[1]: httpd.service: main process exited, code=exited, status=1/FAILURE
May 26 09:22:05 localhost kill[2959]: kill: cannot find process ""
May 26 09:22:05 localhost systemd[1]: httpd.service: control process exited, code=exited status=1
May 26 09:22:05 localhost systemd[1]: Failed to start The Apache HTTP Server.
May 26 09:22:05 localhost systemd[1]: Unit httpd.service entered failed state.
May 26 09:22:05 localhost systemd[1]: httpd.service failed.
#過濾出有錯誤的信息爆价。
[root@localhost ~]# journalctl -u httpd.service |grep 'error'
May 26 09:22:05 localhost httpd[2958]: httpd: Syntax error on line 354 of /etc/httpd/conf/httpd.conf: /etc/httpd/conf/httpd.conf:354:? was not closed.
發(fā)現(xiàn)?/etc/httpd/conf/httpd.conf配置文件的354行垦巴，Directory標(biāo)簽沒有關(guān)閉，返現(xiàn)原因了铭段，就馬上修改吧骤宣。
總結(jié)
我們學(xué)習(xí)了如何使用systemctl命令顯示在Linux上運行失敗的服務(wù)/單元。有關(guān)詳細信息序愚，請查看systemctl手冊憔披。
