Hands-On System Programming with Linux

Crude IPC

Think about it, it's quite simple: processes A and B are part of a multi-process application. Now process A wants to inform process B that it has completed some work; upon receiving this information, we expect process B to acknowledge the same.

We can devise a simple IPC scheme via signaling as follows:

• Process A is performing its work.
• Process B is performing its work (they run in parallel of course).
• Process A reaches a milestone; it informs process B of this by sending it SIGUSR1 (via the kill(2)).
• Having trapped the signal, process B enters its signal handler and verifies things as required.
• It acknowledges the message by sending process A, say, SIGUSR2 (via the kill(2)).
• Having trapped the signal, process A enters its signal ...