Interprocess Communication (IPC) in C

on: 5 minutes id: c-interprocess-communication-ipc-in-c language: c module: c-advanced order: 6 publishDate: 2025-07-17 slug: c-interprocess-communication-ipc-in-c title: Interprocess Communication (IPC) in C

Welcome back, aspiring coder.Let us now take a dive into the World of Interprocess Communication. IPC is a set of methods for exchanging data among multiple threads in one or more processes. In C, this can be crucial when your application spans multiple processes and you need them to work together.

Understanding IPC Techniques

• Shared Memory: Allows multiple processes to access a common memory space. It’s fast as there’s no kernel involvement in the data transfer once the memory is mapped.
• Message Queues: Enable processes to communicate with each other by sending and receiving messages, managed by the kernel.

Exercise

After learning the basics, it’s time for you to do a task on shared memory implementation, where you will:

• Use the shmget system call to allocate a shared memory segment.
• shmat attaches the shared memory segment to the process’s address space.
• Have one process write data to the shared memory, and another process read this data.

Example:

// Writer process
int shmid = shmget(key, SIZE, IPC_CREAT | 0666);
char *shm = shmat(shmid, NULL, 0);
// Write something to the memory
sprintf(shm, "Hello World");

// Reader process
int shmid = shmget(key, SIZE, 0666);
char *shm = shmat(shmid, NULL, SHM_RDONLY);
// Read from the shared memory
printf("%s\n", shm);

Your next task is to do a message queue implementation, where you will:

• Use msgget to create a message queue.
• Define a message structure and use msgsnd to send messages and msgrcv to receive them.

Example:

struct msg_buffer {
long msg_type;
char msg[100];
} message;
// Sending a message
msgsnd(msgid, &message, sizeof(message), 0);
// Receiving a message
msgrcv(msgid, &message, sizeof(message), 1, 0);

Next, it’s time for you to test your IPC mechanism, for that you should:

• Compile and run your processes.
• Verify that data is correctly transmitted between processes using your chosen IPC method.

Hints for the Exercise:

• For shared memory, ensure you handle the creation and destruction of the memory segment correctly.
• With message queues, be mindful of the message structure and the types of messages being sent and received.
• Consider edge cases such as what happens if the reader tries to access data before the writer has written it.

Conclusion

Mastering IPC techniques like shared memory and message queues is pivotal in developing complex C applications that require efficient process communication. These techniques open doors to creating more robust and interactive systems, where separate processes can work in unison, sharing information seamlessly. Keep exploring these powerful communication methods to enhance your applications’ capabilities.