key

    The key for which the associated semaphore identifier is
    returned.

 nsems

    Value used to initialize the sem_nsems member of the semid_ds
    data structure. See the description.

 semflg

    Flag used to initialize the low-order 9 bits of the sem_perm.mode
    member of the semid_ds data structure associated with the new
    semaphore. See the description.

 value

    The initial value to be given to the semaphore. This argument is
    used only when the semaphore is being created.