From mboxrd@z Thu Jan  1 00:00:00 1970
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In-Reply-To: <201107050956.18175.dexen.devries@gmail.com>
References: <201107050956.18175.dexen.devries@gmail.com>
Date: Sun, 10 Jul 2011 20:08:17 -0400
Message-ID: <CADSkJJXPSVkxjfyO_YJdDiLrW+CKMrbw3JMiEnyvskvNSZ4WeQ@mail.gmail.com>
Subject: Re: [9fans] grep (or perhaps regex(6)) question
From: Russ Cox <rsc@swtch.com>
To: Fans of the OS Plan 9 from Bell Labs <9fans@9fans.net>
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On Tue, Jul 5, 2011 at 3:56 AM, dexen deVries <dexen.devries@gmail.com> wro=
te:
> on plan9port:
> % echo foobar | 9 grep '$JUNK'
> =C2=A0-> foobar
>
> that is, p9p grep matches any line with regular expression in form of
> $ANY_REGEX
>
> why is it so?

It's an ancient bug in the Plan 9 grep, a complication
of the way Ken implemented ^ and $: as aliases for \n (!).
It looks like someone added a workaround for this one
case in the Plan 9 sources since I forked them for
plan9port seven years ago.  I pulled it in.

For fun, try seeing what matches '^$^$' across a
variety of grep implementations.

Russ