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Date: Fri, 15 Sep 2006 09:21:17 -0700
From: Zak Johnson <zakj@nox.cx>
To: Volodymyr Kostyrko <arcade@synergetica.dn.ua>
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Cc: freebsd-standards@freebsd.org
Subject: Re: find regular expression question
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Volodymyr Kostyrko wrote:
>   Just stumbled upon some inconsistences in find(1) regular expressions 
> parsing:
> 
> [code]
> > :>a
> > find . -regex '^\./a\?$'
> > find . | grep '^\./a\?$'
> ./a
> [/code]

Find uses basic (obsolete) regular expressions by default; '?' is an
ordinary character.  You can use either of the following instead:

find . -regex '^\./a\{0,1\}$'
find -E . -regex '^\./a?$'

find's '-E' option makes -regex use the extended regular expression
syntax, documented in re_format(7).  GNU grep uses its own---slightly
different---re syntax, described in grep(1).

-Zak