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