If your only copying a files why not use java.io instead?

Basiaclly my doubt  is not on file  system. My doubt was in the RunTime. i.e. how
to capture  the question  message from a process? I used copy  command as an
example only.

The Runtime.exec() methods all return a process  instance. The Process
class includes methods for retrieving the error stream, input stream and
output stream of the process. You would need to try to read data from
the output stream and then send the appropriate data back to the process
through the input stream.

Is this like writing a pipe?

We have to link input/output of process.

I would like to know.