Re: Grep colors highlight all possible matches

[Pollock, Wayne]

Thanks, that would be helpful!  I already use sed, but the color option would 
work better for me.

-- 
Wayne Pollock

On Feb 20, 2013, at 6:16 AM, "Paolo Bonzini" <address@hidden> wrote:

> Il 10/02/2013 00:28, Pollock, Wayne ha scritto:
>> In teaching REs, I use grep and recently noticed
>> the colors highlight all possible matches, not
>> the one match as per POSIX's rules:
>> 
>>  echo 'abcdefabc' | grep '[abc]'
>> 
>> Should highlight only the first "a" (earliest match has
>> precedence, than longest).  Instead, every "a", "b", and
>> "c" is highlighted.  It would be my guess that grep historically
>> didn't need to know exactly what matched, just that something
>> did, so the code doesn't bother to apply any rules to determine
>> exactly what matched.
>> 
>> I don't mind the current behavior as a default, but there should
>> be some option to force grep to only highlight the one match,
>> as per BRE/ERE/PCRE rules of precedence.
>> 
> 
> We could add a --max-line-matches option.  It would affect --color and
> -o.  It would be mostly useful for -o, but would help you nicely as well. :)
> 
> For your task, in the meanwhile you can use
> 
>   echo 'abcdefabc' | sed 's/[abc]/|&|/'
> 
> Paolo

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