Just illustrating and example of how this might be done when a bash or ksh script needs a little more scripting muscle. It merely illustrates a method for leveraging PERL within bash or shell of choice, when OS utilities fall a little short. No one tool can do it all, though PERL comes very close, but, when it can't... the illustration offers by example an enhancement to your existing tools out of the box.
roboticus, Sorry we don't share the same out-of-box thinking. I have seen other requests for this type of method. Merely fulfilling a need to know, whether you agree or not.