are u sure MySQL has not been started already?Check if there is any running MySQL process by using the following commands and kill all and restart.ps aux | grep mysqlif so, kill them and try start MySQL service
感谢回复，查看过了，没有mysql相关进程=。=，启动mysql服务的时候提示 The server quit without updating PID file (/var/run/mysqld/mysqld.pid).
see this as a ref:http://linuxadministrator.pro/blog/?p=225
see this as a ref:http://linuxadministrator.pro/blog/?p=225再次感谢你的热心回答，It works!说来惭愧，其实那个文章我看过了，尝试过删除/etc/my.cnf，但是没有用。这次我连/etc/mysql/my.cnf都删除了，没想到启动成功了，但是我还有一个疑惑，现在MySql的配置文件是哪个呢？没有生成新的配置文件。
The server quit without updating PID file (/var/run/mysqld/mysqld.pid).
see this as a ref:http://linuxadministrator.pro/blog/?p=225
see this as a ref:http://linuxadministrator.pro/blog/?p=225再次感谢你的热心回答，It works!说来惭愧，其实那个文章我看过了，尝试过删除/etc/my.cnf，但是没有用。这次我连/etc/mysql/my.cnf都删除了，没想到启动成功了，但是我还有一个疑惑，现在MySql的配置文件是哪个呢？没有生成新的配置文件。