Suppose you have two files named "dick" and "jane", and you
want to interchange them, so that "dick" contains whatever
was originally in "jane", and "jane" contains what was in "dick".
Will this sequence of commands do the job?
There are two files named "john" and "mary"
in this directory, if you wish to experiment.
When you have decided, type yes or no.
this is originally file john
this is originally file mary