The point of shm_open() is the relaxed guarantees as opposed to plain open() - primarily these two: It is unspecified whether the name appears in the file syst

The point of shm_open() is the relaxed guarantees as opposed to plain open() - primarily these two: It is unspecified whether the name appears in the file system and is visible to other functions that take pathnames as arguments. It is unspecified whether the name and shared memory object state remain valid after a system reboot. That gives the implementation wider latitude in how it implements the function, for example shm_open() objects may be entirely in-memory.