GNU bug report logs - #23676
Seems egrep violates simple rules of regexps

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Package: grep;

Reported by: Марк Коренберг <socketpair <at> gmail.com>

Date: Wed, 1 Jun 2016 19:35:02 UTC

Severity: normal

Done: Paul Eggert <eggert <at> cs.ucla.edu>

Bug is archived. No further changes may be made.

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Report forwarded to bug-grep <at> gnu.org:
bug#23676; Package grep. (Wed, 01 Jun 2016 19:35:02 GMT) Full text and rfc822 format available.
Acknowledgement sent to Марк Коренберг <socketpair <at> gmail.com>:
New bug report received and forwarded. Copy sent to bug-grep <at> gnu.org. (Wed, 01 Jun 2016 19:35:02 GMT) Full text and rfc822 format available.

Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Марк Коренберг <socketpair <at> gmail.com>
To: bug-grep <at> gnu.org
Subject: Seems egrep violates simple rules of regexps
Date: Thu, 2 Jun 2016 00:33:54 +0500

Example:

$ echo qwerty | egrep -o 'we|wert'
wert
$ echo qwerty | egrep -o 'wert|we'
wert

The same in Javascript:

/we|wert/.exec('qwerty')
["we"]
/wert|we/.exec('qwerty')
["wert"]

http://stackoverflow.com/questions/2394931/regex-is-behaving-lazy-should-be-greedy

$ egrep --version
grep (GNU grep) 2.25


-- 
Segmentation fault
Reply sent to Paul Eggert <eggert <at> cs.ucla.edu>:
You have taken responsibility. (Wed, 01 Jun 2016 19:48:01 GMT) Full text and rfc822 format available.
Notification sent to Марк Коренберг <socketpair <at> gmail.com>:
bug acknowledged by developer. (Wed, 01 Jun 2016 19:48:02 GMT) Full text and rfc822 format available.

Message #10 received at 23676-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Марк Коренберг <socketpair <at> gmail.com>,
 23676-done <at> debbugs.gnu.org
Subject: Re: bug#23676: Seems egrep violates simple rules of regexps
Date: Wed, 1 Jun 2016 12:47:41 -0700

On 06/01/2016 12:33 PM, Марк Коренберг wrote:
> Example:
>
> $ echo qwerty | egrep -o 'we|wert'
> wert
> $ echo qwerty | egrep -o 'wert|we'
> wert

That's not a bug; it's a feature. See, for example:

https://swtch.com/~rsc/regexp/regexp1.html
bug archived. Request was from Debbugs Internal Request <help-debbugs <at> gnu.org> to internal_control <at> debbugs.gnu.org. (Thu, 30 Jun 2016 11:24:05 GMT) Full text and rfc822 format available.
This bug report was last modified 8 years and 362 days ago.

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