实验要求

编写类似于DOS，UNIX的命令行解释程序

（1）自行定义系统提示符

（2）自定义命令集（8-10个）

（3）用户输入HELP以查找命令的帮助

（4）列出命令的功能，区分内部还是外部命令

（5）用户输入QUIT退出

（6）内部命令有dir, cd, md, rd, cls, date, time, ren, copy等。

-The experiment requires the preparation is similar to the DOS, UNIX command line interpreter (1) self-help (4) define the system prompt (2) custom command set (8-10) (3) user input HELP to find the command listed command functions, the distinction between internal or external command (5) user input QUIT exit (6) internal commands dir, cd, md, rd, cls, date, time, ren, copy, etc..