Two processes trying to talk

What this inter-process communication question tests

This is a hard operating-systems question that assesses your understanding of the different mechanisms by which isolated user-space processes can exchange data on Linux. It requires you to reason about the constraints, guarantees, and failure modes of each IPC primitive, rather than just recalling their names.

To solve it, you need to think carefully about whether each mechanism provides the necessary visibility between unrelated processes, whether the kernel enforces ordering guarantees, and what happens if one process crashes or never reads. The question rewards a systematic elimination process: for each scheme, ask whether both the sender and receiver can reliably access the same resource, and whether synchronisation alone is sufficient to make the transfer safe.

• Shared memory (mmap, System V, POSIX)
• Pipes and named pipes (FIFOs)
• Message queues and sockets
• Memory visibility and synchronisation primitives
• Kernel guarantees vs. userland assumptions