F_LOCK
case F_LOCK:
if (lockf(fileno(fp), F_LOCK, (off_t)0) == -1)
if (lockf(fd, F_LOCK, 0) == -1)
if (lockf(fd, F_LOCK, 0) == -1)
if (lockf(fd, F_LOCK, size) == -1)
i = lockf (fd, F_LOCK, 0);