操作系统为centos，网站突然连接不上数据库,于是朋友直接重启了一下服务器。进到cli模式下，执行 service myqsld start 发现还是提示"mysql deamon failed to start"错误信息。
# /etc/init.d/mysqld start
MySQL Daemon failed to start.
Starting mysqld: [FAILED]
查看mysqld的log文件
#less /var/log/mysqld.log
141201 11:35:20 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended
141201 11:35:43 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
141201 11:35:43 [Warning] '--default-character-set' is deprecated and will be removed in a future release. Please use '--character-set-server' instead.
141201 11:35:43 InnoDB: Initializing buffer pool, size = 8.0M
141201 11:35:43 InnoDB: Completed initialization of buffer pool
141201 11:35:43 InnoDB: Started; log sequence number 0 44233
141201 11:35:43 [ERROR] Can't start server: Bind on TCP/IP port: Permission denied
141201 11:35:43 [ERROR] Do you already have another mysqld server running on port: 12345 ?
141201 11:35:43 [ERROR] Aborting
说明应该是SELINUX的权限限制了，需要关掉selinux
查看当前配置信息.
# getenforce
Enforcing
就表明SELinux已经启用.只需要关闭即可。
关闭方法：
/usr/sbin/setenforce 0（0|1 开|关）
或者
setsebool ftpd_disable_trans 1
//以下是修改配置文件重新启动系统的方法
需要修改： vi /etc/selinux/config
SELINUX=disabled
然后重启服务器即可