When we create a shared-Memory we use shm_open() and ftruncate() function. According to my information shm_open() create a shared-memory region. And then we use ftruncate() function to configure the size of shared-memory region.
Well how does shm_open() creates the memory region in the first place when it doesn't yet know the size? And if this is not the case and I am totally wrong, then please tell me the purpose of shm_open() and ftruncate(). Thanks in Advance!!!