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From: Harald van Dijk <harald@gigawatt.nl>
To: Christoph Anton Mitterer <calestyo@scientia.org>, dash@vger.kernel.org
Subject: Re: possible wrong behaviour with patterns using a quoted ^ at the start of a bracket expression
Date: Wed, 12 Jan 2022 18:17:28 +0000	[thread overview]
Message-ID: <944ee473-9ad6-c13f-48cb-690086c2c902@gigawatt.nl> (raw)
In-Reply-To: <4a139aa29e7ccaf561d93cd400e37d60feb7bebc.camel@scientia.org>

On 12/01/2022 17:47, Christoph Anton Mitterer wrote:
> On Wed, 2022-01-12 at 17:20 +0000, Harald van Dijk wrote:
>> However, whether this is the correct approach is a matter of opinion:
>> dash could alternatively choose to always take ^ as a literal and
>> always
>> escape it before passing it on to fnmatch()
> 
> Well I personally think the best would to *always* take ^ literally,
> whether quoted or not.
> 
> That would match the behaviour of bash and klibc sh, and also seems
> more in the spirit of POSIX (which, while saying that an unquoted ^
> produces undefined behaviour, also says that:
> "( '!' ) shall replace the <circumflex> character ( '^' )""
> 
> ... "replace", not complement.

Actually, in bash, unquoted ^ does act as negation. Same in ksh, which 
is the basis for a lot of POSIX. As for the spirit of POSIX, POSIX does 
say in the rationale that it's unspecified specifically in order to 
allow that:

   The restriction on a <circumflex> in a bracket expression is to allow
   implementations that support pattern matching using the <circumflex>
   as the negation character in addition to the <exclamation-mark>.

But personally, I have no opinion on which action dash should take, as 
long as it gets the right results for quoted ^.

Cheers,
Harald van Dijk

  reply	other threads:[~2022-01-12 18:17 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-12 16:25 Christoph Anton Mitterer
2022-01-12 17:20 ` Harald van Dijk
2022-01-12 17:47   ` Christoph Anton Mitterer
2022-01-12 18:17     ` Harald van Dijk [this message]
2022-01-12 18:21       ` Christoph Anton Mitterer
2022-01-18  6:13   ` [PATCH] expand: Always quote caret when using fnmatch Herbert Xu
2022-01-18  8:44     ` Harald van Dijk
2022-01-19  5:37       ` [v2 PATCH] " Herbert Xu
2022-02-20  7:15         ` Stephane Chazelas
2022-02-21 16:39           ` Eric Blake
2022-02-21 17:06             ` Harald van Dijk
2022-02-21 19:15               ` Stephane Chazelas
2022-01-18 14:29     ` [PATCH] " Christoph Anton Mitterer
2022-01-18 14:54       ` Chet Ramey
2022-01-18 22:33       ` Herbert Xu

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