Re: capturing sub-expressions?

[Bernd Eggink]

Linda Walsh schrieb:
> I was wondering -- in the bash substitute commands ${..%%|##|//} etc,
> is there a way to "capture" a subexpression, so that I can
> use the subexpression in the replacement string so I can
> end up 'only' with the the subexpression?
>
> If the full expression was in a shellvar "Options", I thought about
> using something like:
>     ${Option//!(expr)}
> which I hoped would have "!(expr) match anything but my desired
> expression, and the double "/" would say allow it to match multiple
> times, but it appears the "!()" construct is limited to pathname
> expansion?  Presuming that is true (limited to pathname expansion),
> is there anyway to do it on Shell vars?
>
> I keep confusing the path-matching regular expressions with
> string-matching expressions and keep getting disappointed when I'm
> re-reminded of the limitation...:-(

There should be no difference between path-matching and string-matching 
expressions. Normally even nested extended patterns work with string 
matching. But, in fact, !(...) appears to not work like one would 
expect. The only case that looked correct to me is the trivial one 
${x//!(*)}, which leaves $x unchanged.

I'm not sure whether this is a bug or I (we) miss something. 
Interestingly, ksh behaves the same way. Can anybody clarify this?

Regards,
Bernd

--
Bernd Eggink
monoped@sudrala.de
http://sudrala.de