转载来源：吴家伟的博客 原文 一、数据成员
               
                termios 函数族提供了一个常规的终端接口，用于控制非同步通信端口。 这个结
                构包含了至少下列成员：
                tcflag_t c_iflag;     
                tcflag_t c_oflag;     
                tcflag_t c_cflag;     
                tcflag_t c_lflag;     
                cc_t c_cc[NCCS];      
               
                struct termios
                {unsigned short c_iflag;
                unsigned short c_oflag;
                unsigned short c_cflag;
                unsigned short c_lflag;
                unsigned char c_line;