POSIX Shared Memory

POSIX shared memory is actually a variation of mapped memory (see "Creating and Using Mappings"). The major differences are to use shm_open(3R) to open the shared memory object (instead of calling open(2)) and use shm_unlink(3R) to close and delete the object (instead of calling close(2) which does not remove the object). The options in shm_open(3R) are substantially fewer than the number of options provided in open(2).