可以实现下列几条命令：login 用户登录；dir列文件目录；create创建文件；delete删除文件；open打开文件；close关闭文件；read读文件；write写文件-Few can achieve the following command: login user login　dir List directory files　create create a file　delete delete files　open to open the file　close close the file　read read file　write write file