Thanks Perderabo for your reply, what I am sure about is that i have no clue about what you mean by saying your program seems to require tty input and how that would make a difference, trying to give more information:
the program is a third party application running on AIX, tcsh, it ask user interactively for the options he may need to check.

Anyways, I will search for expect now. hope to find what i need :-)
thanks again.