PHP and Shared Memory

What's the difference between the SEM and SHMOP functions in PHP? Are SEM functions exclusive for System V and SHM开发者_运维技巧OP for UNIX?

SHMOP functions are for UNIX systems only.

SHMOP functions can be used in *NIX and Windows environments. Semaphore is not available in Windows at all however, which also includes ftok().

If you check out the PHP documentation user comments for SHMOP, there are workarounds for getting a key to use with SHMOP in Windows without ftok().