Common Interprocess Communication Methods in Linux

When preparing for interviews, many candidates encounter a flood of interview experiences, but understanding core interprocess communication (IPC) techniques provides lasting value.

1. Pipes

Pipes allow one‑way data flow where the output of one command becomes the input of another using the "|" symbol, known as an anonymous pipe. Named pipes (FIFOs) provide persistent files that can be listed with ls -l showing a "p" flag.

Example of writing to a pipe:

echo "666" > test

Reading from the pipe in another terminal:

cat < test

Advantages: simple and ubiquitous. Drawbacks: unidirectional and inefficient for frequent communication because the reader must wait for the writer to finish.

2. Message Queues

Message queues transmit data as discrete messages (message bodies) with defined sizes, allowing sender and receiver to agree on message types or formats. Unlike pipes, they can carry structured data and support multiple receivers.

Drawback: large messages require copying, which can affect performance.

3. Shared Memory

Shared memory lets processes map a common virtual address space to the same physical memory, enabling fast data exchange without copying. Created with shmget and inspected via ipcs . After use, the segment should be detached and removed.

Potential issue: concurrent writes can cause conflicts, requiring synchronization mechanisms.

4. Semaphores

Semaphores act as counters to enforce mutual exclusion and synchronization between processes. They provide two operations: P (decrement, acquire) and V (increment, release). They do not carry data themselves.

5. Signals

Signals are asynchronous notifications sent to a process to indicate events such as resource exhaustion or external interrupts. Each signal has a numeric value and an associated handler function that runs when the signal is received.

6. Sockets

Sockets enable communication between processes on different machines over a network, forming the basis of most client‑server applications, chat programs, and web requests.

7. Summary

The article reviews six IPC mechanisms, highlighting their use cases, strengths, and limitations, encouraging readers to understand the underlying concepts rather than memorizing them mechanically.