question about double using a thread

[Ronald Bultje <rbultje ronald bitfreak net>]

For a simple application, I use the call:

system("a_command");

this runs this application. Now, this application needs some simple user
input ("press enter to do this", etc). I tried creating a second thread to
do this, but this will not press enter for this thread but for its own. So
the a_command programm still thinks enter wasn't pressed.
Can someone think of a way to give this user input without having to do it
console by hand? (I mean, I try to make a GUI! :) )

Thnx,

Ronald