实现DOS COPY.EXE 的部分功能 执行时文件源和目标在命令行参数指定，文件源可以是[路径\文件名] 目标可以是[路径名（包括当前路径"." ）]，或[路径\文件名]-File the DOS COPY.EXE some functions to perform source and destination in the command-line argument to specify the source of the file can be a [path \ filenam