How to copy files from one directory to another on application server?

Hi,

I have some files on application server i.e. /usr/abc/xyz/1.txt

/usr/abc/xyz/2.txt etc.

Now I need to copy these files in different directory with different names i.e./usr/abc/xyz_copy/1_copy.txt

/usr/abc/xyz_copy/2_copy.txt

How can i do that in function module in ABAP instead of open dataset?

Can anybody tell me how to use unix command like cp(for COPY) in ABAP?

Thanks and regards,

Deepak