说明：  这是基于linux的应用层的串口程序，根据linux的不同只需做设备的打开路径的修改即可，这是一个典型的字符设备的调用过程。对学习其他字符设备是很有帮助的。尤其对初学的人帮忙最大。
(This is based on the application layer linux serial procedures, according to the different linux just so equipment can open the path changes, this is a typical character called the process of equipment. Learn from other characters on the device is very useful. In particular, the greatest help the beginner.)