From: Gregory Heytings <gregory@heytings.org>
To: "Mattias Engdegård" <mattiase@acm.org>
Cc: Po Lu <luangruo@yahoo.com>, emacs-devel@gnu.org
Subject: Re: grep: RE error in ^*** ADVICE-ON-FAILURE-: repetition-operator operand invalid
Date: Sat, 19 Nov 2022 12:49:05 +0000 [thread overview]
Message-ID: <518ded72c37a0afa121d@heytings.org> (raw)
In-Reply-To: <67089852-8265-4EE5-8234-F2F135A60949@acm.org>
>> I just checked, it was not incorrect. POSIX says that in BREs the '*'
>> is special, except wen used:
>>
>> - in a bracket expression
>> - as the first character of an entire BRE (after an initial '^', if any)
>> - as the first character of a subexpression (after an initial '^', if any)
>
> That just means that the first of the three asterisks is literal. The
> other two are special and indicate repetition of the literal asterisk.
>
Hmmm, you're correct. '^**' would be correct (matching zero or more
asterisks), but '^***' is not, because POSIX also says that "multiple
adjacent duplication symbols produces undefined results".
>
> (And even if the three asterisks were interpreted literally, it would be
> bad style.)
>
It's better if the expression is correctly matched by more grep's, indeed.
Anyway, bug closed.
next prev parent reply other threads:[~2022-11-19 12:49 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <87fsef9pms.fsf.ref@yahoo.com>
2022-11-19 10:59 ` grep: RE error in ^*** ADVICE-ON-FAILURE-: repetition-operator operand invalid Po Lu
2022-11-19 11:24 ` Gregory Heytings
2022-11-19 11:35 ` Mattias Engdegård
2022-11-19 11:49 ` Gregory Heytings
2022-11-19 12:05 ` Eli Zaretskii
2022-11-19 11:57 ` Po Lu
2022-11-19 12:00 ` Po Lu
2022-11-19 12:14 ` Mattias Engdegård
2022-11-19 12:26 ` Gregory Heytings
2022-11-19 12:42 ` Mattias Engdegård
2022-11-19 12:49 ` Gregory Heytings [this message]
2022-11-19 11:45 ` Eli Zaretskii
2022-11-19 14:06 ` Gregory Heytings
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