In case you need an example about how to use one of these:
- Unix Message Queues
- Unix Sockets
- POSIX Threads
- Basic C usage
You may want to take a look at the source code of my toy project at GitHub. I don’t claim it to be good, bug free or even usable beyond what I need – much to the contrary: I don’t think I would show this at a job interview o.O. Anyway, feel free to check it out if you need an usage example of any of these technologies.