Comparing Unix/Linux IPC

Unix IPC

Here are the big seven:

1. Pipe

   Useful only among processes related as parent/child. Call pipe(2) and fork(2). Unidirectional.

2. FIFO, or named pipe

   Two unrelated processes can use FIFO unlike plain pipe. Call mkfifo(3). Unidirectional.

3. Socket and Unix Domain Socket

   Bidirectional. Meant for network communication, but can be used locally too. Can be used for different protocol. There's no message boundary for TCP. Call socket(2).

4. Message Queue

   OS maintains discrete message. See sys/msg.h.

5. Signal

   Signal sends an integer to another process. Doesn't mesh well with multi-threads. Call kill(2).

6. Semaphore

   A synchronization mechanism for multi processes or threads, similar to a queue of people waiting for bathroom. See sy