说明：  实现linux的网卡的ip地址、掩码、默认路由的查询和修改程序，main函数是我测试用的，你可以按照main的写法任意使用其他函数
(Linux realize the network card ip address, netmask, default routing query and modify the program, main function is testing me, you can follow the main formulation of the arbitrary use of other functions)