mysql启动时报 Bind on unix socket Address already in use的问题处理

一.问题描述： 版本:mariadb 10.0.19启动MySQL:/apps/svr/mariadb10/bin/mysqld_safe --defaults-file=/apps/dbdat/mariadb10_data3306/my.cnf  --socket=/tmp/mysql.sock &无法启动，mysql进程退出。

二.问题分析： 检查error log，如下：160826 15:33:33 [Note] Server socket created on ip: '0.0.0.0'.160826 15:33:33 [ERROR] Can't start server : Bind on unix socket: Address already in use160826 15:33:33 [ERROR] Do you already have another mysqld server running on socket: /tmp/mysql3306.sock ?160826 15:33:33 [ERROR] Aborting

160826 15:33:33 [Note] InnoDB: FTS optimize thread exiting.160826 15:33:33 [Note] InnoDB: Starting shutdown...160826 15:33:36 [Note] InnoDB: Shutdown completed; log sequence number 452295626292160826 15:33:36 [Note] /apps/svr/mariadb10/bin/mysqld: Shutdown complete

160826 15:33:36 mysqld_safe mysqld from pid file /apps/dbdat/mariadb10_data3306/mysql.pid ended

上面提示unix socket /tmp/mysql3306.sock 被占用，用ps -ef|grep mysql检查没有其它mysql进程.用netstat -an|grep 3306检查端口也不存在。对比分析，正常关闭mysql时，/tmp/mysql3306.sock文件是不存在的，而现在mysql已关闭后，还存在/tmp/mysql3306.sock文件。猜测是由于上次mysql未正常关闭或关闭异常引起。 

三.问题解决：  在root用户下，删除/tmp/mysql.sock文件，再重启mysql。