[NBC1700155 mysql]# systemctl start mysqld
Job for mysqld.service failed because the control process exited with error code.
See "systemctl status mysqld.service" and "journalctl -xe" for details.
[NBC1700155 mysql]# systemctl status mysqld
● mysqld.service - MySQL Server
Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor pres>
Active: failed (Result: exit-code) since Wed 2019-11-06 21:14:40 CST; 8s ago
Docs: man:mysqld(8)
http://dev.mysql.com/doc/refman/en/using-systemd.html
Process: 3107 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0>
Process: 3128 ExecStart=/usr/bin/mysqld $MYSQLD_OPTS (code=exited, status=127)
Main PID: 3128 (code=exited, status=127)
11月 06 21:14:40 NBC1700155 systemd[1]: mysqld.service: Service RestartSec=100m>
11月 06 21:14:40 NBC1700155 systemd[1]: mysqld.service: Scheduled restart job, >
11月 06 21:14:40 NBC1700155 systemd[1]: Stopped MySQL Server.
11月 06 21:14:40 NBC1700155 systemd[1]: mysqld.service: Start request repeated >
11月 06 21:14:40 NBC1700155 systemd[1]: mysqld.service: Failed with result 'exi>
11月 06 21:14:40 NBC1700155 systemd[1]: Failed to start MySQL Server.
[NBC1700155 mysql]#
https://blog.csdn.net/uniondong/article/details/98392738
看mysql的错误日志，里面有详细的报错信息。