Oh god, you know you've become anal about bash when you can actually vaguely understand what is going on. I mean it's parameter expansion, just flip down to th

Oh god, you know you've become anal about bash when you can actually vaguely understand what is going on. I mean it's parameter expansion, just flip down to that section of the manpage, and then there is posix regex in there. Not too difficult to look up in the manpages.