Linux系统是通过提供套接字(socket)来进行网络编程的.网络程序通过socket和其它几个函数的调用,

会返回一个 通讯的文件描述符,我们可以将这个描述符看成普通的文件的描述符来操作,这就是linux的设备无关性的好处.

-Linux system is by providing socket (socket) for network programming. Network program through the socket and several other function calls,

Returns a communication file descr iptor, we can put this descr iptor as common file descr iptor to operation, this is the Linux device independence benefits.