linux出现错误：Bringing up interface eth0: Error: Connection activation failed: Device not managed by NetworkManager or unavailable
解决办法：
# service NetworkManager stop 停止NetworkManager 服务
# chkconfig NetworkManager off 关闭NetworkManager随系统启动
# service network restart 重启网络服务
# chkconfig network on 网络服务设为开机自动启动