Talking to programs

[jonas karlsson]

How do  i call a program from a function, have the function respond to 
the various prompts, give the correct replies, and catch the output?
Someone suggested using socketpairs, fork off a child that dup2's standard in 
and out into one half of the socketpairs, and then execv'ing the program
(basically).  I tried following his suggestions, with no success. 
could someone please give me a detailed description (or code) on
how to do this?

tnx
-j