- https://stackoverflow.com/questions/5656530how-to-use-shared-memory-with-linux-in-c (inside Solutions @shakram02)
- https://users.cs.cf.ac.uk/Dave.Marshall/C/node27.html Has Error((:(!):))
- https://users.cs.cf.ac.uk/Dave.Marshall/C/node27.html client-server OK
- https://users.cs.cf.ac.uk/Dave.Marshall/C/node27.html shmop(attach+detach) OK