文件系统的模拟本系统可以实现改变目录(cd)，创建文件(create)，删除文件(delete)，显示目录(dir)，创建目录(mkdir)以及退出系统(exit)。-The file system simulation of this system can bring about change directory (cd), create a file (create), delete the file (delete), which displays a directory (dir), c