Some of the things he mention have nothing to do with Unix or Posix. __sync_*, for example, are gcc-specific. Similarly, F_GETLEASE, F_SETLEASE, and F_NOTIFY are Linux-specific fcntl() operations. And as far as I can tell, the -T option isn't included in the Posix spec for mv, either (http://www.opengroup.org/onlinepubs/000095399/toc.htm).