Re: backreferences

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On Oct 15,  6:16pm, Ray Andrews wrote:
} Subject: Re: backreferences
}
}     if [[ "$sstring" = (#b)([(^(edcba))]*)(edcba)(*) ]];

Umm, no. [(^(edcba))] is still a character class (open paren, caret,
e,d,c,b,a, close paren).  Just (^(edcba)) without the square brackets.
And you have more parens then, so your $match[] indexes are wrong.

	if [[ "$sstring" = (#b)((^(edcba))*)(edcba)(*) ]]

There are 5 sets of parens, and you care about $match[1], $match[4],
and $match[5].  $match[2] is the prefix of $match[1] that was not
consumed by the middle *, and $match[3] is an empty substring of
$match[2] (because it was excluded from matching).  Count off the
open parens left to right to see this.

In fact you don't even need the middle * because (^edcba) will eat
an arbitrarily long string as long as it is not literally "edcba".
So you can reduce this to

	if [[ "$sstring" = (#b)(^edcba)(edcba)(*) ]]

and then you're back to only needing $match[1,3].