.The server quit without updating PID file (/var/lib/mysql/pc.pid).

启动Mysql是报错

[root@pc mysql]# mysql start
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/lib/mysql/mysql.sock' (2)
[root@pc mysql]# service mysql start
Starting MySQL.......................................................................................................The server quit without updating PID file (/var/lib/mysql/pc.pid).

原因是 mysql重复启动，上次启动未关闭mysql 

ps -ef | grep mysql    查看运行的mysql进程       kill   -9   进程号     杀死进程、

在使用 service mysql start   启动mysql即可