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Re: Incorrect example for `[[` command.

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  Re: Incorrect example for `[[` command. Chet Ramey <chet.ramey@case.edu> - 2019-09-22 13:53 -0400

#15400 — Re: Incorrect example for `[[` command.

On 9/21/19 5:34 AM, Ilkka Virta wrote:
> On 21.9. 03:12, hk wrote:
>> Thanks for the reply. I was wrong in my report. It does match values like
>> aab and  aaaaaab  in its original form.
> 
> In some systems, yes. (It does that on my Debian, but doesn't work at all
> on my Mac.)
> 
>> It is syntatically correct as a regular expression. 
> 
> [[:space:]]*?(a)b  isn't a well-defined POSIX ERE:
> 
>   9.4.6 EREs Matching Multiple Characters
> 
>   The behavior of multiple adjacent duplication symbols ( '+', '*', '?',
>   and intervals) produces undefined results.

It's ambiguous, but it can be interpreted as valid. I wonder why they used
"undefined" instead of the usual "unspecified."


-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
		 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/

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