Honestly that page isn't great at showing up in search results, but in any case -- POSIX can be too restrictive. I don't specifically recall an example for awk, but when every implementation supports something then it's a de-facto standard. If you follow POSIX then you become over-restricted compared to any shell you'll actually encounter. It'd be really nice if there was a page that showed the actual common features between various implementations of POSIX tools, not just the POSIX official features...
> I have twenty years of experience in getting that page to show up in search results. :)
Haha! I love that you acknowledge this because usually people just ignore all the experience they have in getting to the right page and make it look like you're dumb for not being able to find it. Thanks for the pointer! :-)
Before POSIX merged with the Single Unix Specification, I used to search using "single unix spec version 2" type queries; and that one brings us back to 1997:
It's the first search result for "awk posix" for me and the fourth for "awk standard".
But yes, sometimes POSIX or the C standard or whatever is too restrictive, but it's still a good starting point for figuring out how to write portable code.
You'll know anything it doesn't cover is implementation-specific, and then either decide it's not worth it to pursue it, or if it is figure out whether the implementations you're targeting support the feature.
