Can [ruby] on rails do this --- crazy request

Have you looked at the Ruby shell library? It is part of the standard
installation. On Linux you'll find it at
/usr/lib/ruby/1.8/shell

You can look up the Shell class and its methods at
http://www.ruby-doc.org/core/

You can do anything you'd from the command line and pass values back and forth.
You can write your own classes and put the file in the RAILS_ROOT/lib dir.

I am using it to do some file format conversions. To see how shell is
used you can look into the doc_convert library to see how shell is
used. That's what I did.
http://raa.ruby-lang.org/project/doc_convert/

Hope this helps,

bakki