重新安装mysql时，运行

systemctl status mysqld.service

报错。

[root@test-dcruxue ~]# systemctl start mysqld.service

Job for mysqld.service failed because the control process exited with error code. See "systemctl status mysqld.service" and "journalctl -xe" for details.

查看mysql服务状态

[root@test-dcruxue ~]# systemctl status mysqld.service

● mysqld.service - MySQL Server

Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)

Active: failed (Result: exit-code) since Tue 2018-07-17 16:14:22 CST; 8min ago

Docs: man:mysqld(8)

http://dev.mysql.com/doc/refman/en/using-systemd.html

Process: 17451 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=1/FAILURE)

Process: 17376 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)

Main PID: 16428 (code=exited, status=1/FAILURE)

Jul 17 16:13:41 test-dcruxue systemd[1]: Starting MySQL Server...

Jul 17 16:14:20 test-dcruxue mysqld[17451]: Initialization of mysqld failed: 0

Jul 17 16:14:20 test-dcruxue systemd[1]: mysqld.service: control process exited, code=exited status=1

Jul 17 16:14:22 test-dcruxue systemd[1]: Failed to start MySQL Server.

Jul 17 16:14:22 test-dcruxue systemd[1]: Unit mysqld.service entered failed state.

Jul 17 16:14:22 test-dcruxue systemd[1]: mysqld.service failed.

无果；

遂想到查看日志：cat /var/log/mysqld.log

2018-07-17T08:23:01.745601Z 0 [ERROR] Can't start server: Bind on TCP/IP port: Address already in use

2018-07-17T08:23:01.745607Z 0 [ERROR] Do you already have another mysqld server running on port: 3306 ?

2018-07-17T08:23:01.745619Z 0 [ERROR] Aborting

发现3306端口被占用

[root@test-dcruxue ~]# ps aux|grep mysql

root 9861 0.0 0.0 113252 1600 ? S 14:52 0:00 /bin/sh /usr/bin/mysqld_safe --skip-grant-table

mysql 10009 0.0 5.6 1585376 457120 ? Sl 14:52 0:03 /usr/sbin/mysqld --basedir=/usr --datadir=/var/lib/mysql --plugin-dir=/usr/lib64/mysql/plugin --user=mysql --skip-grant-table --log-error=/var/log/mysqld.log --pid-file=/var/run/mysqld/mysqld.pid --socket=/var/lib/mysql/mysql.sock

root 17563 0.0 0.0 112648 956 pts/2 R+ 16:32 0:00 grep --color=auto mysql

然后杀掉进程

[root@test-dcruxue ~]# kill -9 10009

就ok了

————————————————