ERROR! MySQL is running but PID file could not be found

/etc/init.d/mysql status
提示
ERROR! MySQL is running but PID file could not be found
先打印MYSQL进程
ps aux | grep mysql
然后KILL进程
kill -9 pid1 pid2 …
再启动MYSQL
/etc/init.d/mysql start
再检查mysql运行状态
/etc/init.d/mysql status