I deliberately didn&#x27;t write that to avoid the page going stale when OS X adds it. But OS X is behind the times and that&#x27;s harmful. POSIX 2008 has been out for years and most of the lacking features are trivial to add. They&#x27;re being actively harmful to Unix software by not having modern interfaces, forcing portable software to be worse. The purpose of the article is to highlight the interfaces, and when they&#x27;re suited, rather than being a replacement for your system manual page or a portability guide. Since OS X isn&#x27;t a free software Unix (though its libc is), I don&#x27;t really consider it among the relevant modern Unix systems. Linux, the BSDs, and so on all have the POSIX 2008 features mentioned here.