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Reply-To: moss@cs.umass.edu
Subject: Re: bug with grep 3.0.2 in cygwin 3.0.7
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From: Eliot Moss <moss@cs.umass.edu>
Message-ID: <806ab587-a07c-1616-1486-ebb258ace1d9@cs.umass.edu>
Date: Thu, 29 Aug 2019 21:42:46 -0400
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On 8/29/2019 3:08 PM, Andrey Repin wrote:
> Greetings, akiki@free.fr!
> 
>> Hi,
>> I encounter some problem with grep option -E on cygwin 3.0.7
> 
> 
>> echo "a^b" | grep "a^b" #answer a^b ie it's OK
>> but
>> echo "a^b" | grep -E "a^b" #answer nothing " for me it's KO
> 
> That's an expected result of an impossible constraint.
> 
>> I have to backslash ^ to be OK like : grep -E 'a\^b'
> 
> Yes.
> 
>> Is-it a bug ?
> 
> No.
> 
>> I don't know if all versions of cygwin and grep are concerned.
> 
> RTFM, this is regexp basics.

There was a really great answer to this earlier.  I tried an
answer, but was wrong.  One has to read the "fine print" really
carefully.  At first I thought it was a bug, at least in the
documentation, but the meaning of a^b, when ^ is the metacharacter,
is kind of subtle (IMO at least).  It's easy to miss that
subtlety and think that if ^ is not at the beginning of an
expression it will be treated as an ordinary character ...

But my main point is that RTM would be enough; RTFM seemed
to me perhaps a little more rude than necessary.

Regards - EM

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