Using shared memory between unrelated processes
In the previous recipe, we used shared memory between a child and a parent. In this recipe, we'll learn how to use a file descriptor to mapped memory to share that memory between two unrelated processes. Using shared memory in this way automatically creates an underlying file for the memory in the
/dev/shm directory, where shm stands for shared memory.
Knowing how to use shared memory between unrelated processes widens your use of this IPC technique.
For this recipe, you'll only need the GCC compiler and the Make tool.
How to do it…
First, we'll write a program that opens and creates a file descriptor for shared memory and also maps the memory. Then, we'll write another program that reads the memory area. Instead of just a message, as we did in the previous recipe, we'll write and retrieve an array of three floating-point numbers here.
Creating the writer