bug#63819: Gnu `grep '.*'` does not match an empty string.

[Bob Vincent Il (US)]

Okay, but `echo ''` does not output an empty string. It outputs a line feed 
character.


Bob Vincent (US-TSO)

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________________________________
From: Paul Eggert <eggert@cs.ucla.edu>
Sent: Wednesday, May 31, 2023 8:42:47 PM
To: Bob Vincent Il (US) <robert.a.vincent.ii@pwc.com>
Cc: 63819@debbugs.gnu.org <63819@debbugs.gnu.org>
Subject: Re: bug#63819: Gnu `grep '.*'` does not match an empty string.

On 2023-05-31 10:18, Bob Vincent Il (US) via Bug reports for GNU grep wrote:
> I discovered only today that the following commands all behave identically:
>
>    *   grep -q '.*'
>    *   grep -q '.\+'
>    *   grep -q .
>    *   grep -qE '.*'
>    *   grep -qE '.+'
>    *   grep -qE .

No they don't. For example:

$ echo '' | grep -q . ; echo $?
1
$ echo '' | grep -q '.*' ; echo $?
0


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