報錯信息：ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
[root@mysql5 ~]# mysql -uroot -pxxxx
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
[root@mysql5 ~]#
[root@mysql5 ~]#
[root@mysql5 ~]#
[root@mysql5 ~]# service mysqld3306 restart
ERROR! MySQL server PID file could not be found!
Starting MySQL. ERROR! The server quit without updating PID file (/data/mysql3306/data/mysql5.5.pid).
[root@mysql5 ~]#
確定是配置文件有錯誤，注意查看配置的更改：
[root@mysql5 ~]#
[root@mysql5 ~]# service mysqld3306 start
Starting MySQL. ERROR! The server quit without updating PID file (/data/mysql3306/data/mysql5.5.pid).
[root@mysql5 ~]#
[root@mysql5 ~]# vi /etc/my.cnf
[root@mysql5 ~]# service mysqld3306 start
Starting MySQL.. SUCCESS!
[root@mysql5 ~]#
其實我們可以通過查看報錯日誌來確定是哪裏的錯誤：
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150815 03:23:07 mysqld_safe mysqld from pid file /data/mysql3306/data/mysql5.5.pid ended
150815 03:23:16 mysqld_safe Starting mysqld daemon with databases from /data/mysql3306/data
150815 3:23:16 [Note] Plugin 'FEDERATED' is disabled.
150815 3:23:16 [Note] Plugin 'InnoDB' is disabled.
150815 3:23:16 [ERROR] Unknown/unsupported storage engine: InnoDB
150815 3:23:16 [ERROR] Aborting
150815 3:23:16 [Note] /usr/local/mysql/bin/mysqld: Shutdown complete
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也可以是其他的報錯信息，注意查找error報錯信息即可。