You need to use some sort of IPC between the processes involved.
http://en.wikipedia.org/wiki/Inter-process_communication[
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Every IPC type has positives and negatives, so read up on your options and implement one based on your research.
Edit: If your processes are simple and don't have to run concurrently, you can also pipe the output of one into another. That's the simple way of doing things. If they do have to run at the same time, you definitely need some sort of IPC.