From: "Lawrence Velázquez" <vq@larryv.me>
To: Mikael Magnusson <mikachu@gmail.com>
Cc: Bart Schaefer <schaefer@brasslantern.com>, zsh-workers@zsh.org
Subject: Re: bad math expression: illegal character: "
Date: Fri, 19 Jun 2020 02:38:15 -0400 [thread overview]
Message-ID: <C7887F95-23FE-45E6-A1FF-0DF0996892AA@larryv.me> (raw)
In-Reply-To: <CAHYJk3SZRufTJqZPLKdzzSDG6FCfjbMq-kH=+eDBFDusAixUVg@mail.gmail.com>
> On Jun 18, 2020, at 7:19 AM, Mikael Magnusson <mikachu@gmail.com> wrote:
>
>> On 6/18/20, Bart Schaefer <schaefer@brasslantern.com> wrote:
>>
>>> On Fri, Jun 5, 2020 at 2:02 PM Lawrence Velázquez <vq@larryv.me> wrote:
>>>
>>>> On Jun 5, 2020, at 2:18 PM, Artur Renault <Artur.Renault@microsoft.com>
>>>>
>>>> while (( "$#" )); do
>>>>
>>>> repro.sh:1: bad math expression: illegal character: "
>>>
>>> For what it's worth, dash also rejects this. I assume that it and
>>> zsh are just more strict about what constitutes a math expression.
>>
>> Does anybody know if this is something we should change for sh
>> emulation, or is it merely another unspecified POSIX corner-case?
>
> If this is a POSIX requirement, it must have been very specific about
> when quotes should be allowed (bash):
>
> $ (( "0" )); echo $?
> 1
> $ echo $(( "0" ))
> bash: "0" : syntax error: operand expected (error token is ""0" ")
Looks like the bash behavior changed at some point?
% /bin/bash --version | head -n 1
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin18)
% /bin/bash -c '(( "0" )); echo $?'
1
% /bin/bash -c 'echo $(( "0" ))'
/bin/bash: "0" : syntax error: operand expected (error token is ""0" ")
% /opt/local/bin/bash --version | head -n 1
GNU bash, version 5.0.17(1)-release (x86_64-apple-darwin18.7.0)
% /opt/local/bin/bash -c '(( "0" )); echo $?'
1
% /opt/local/bin/bash -c 'echo $(( "0" ))'
0
Anyway, unless I'm missing something, POSIX seems pretty clear about
this, as far as $((...)) goes:
The expression shall be treated as if it were in double-quotes,
except that a double-quote inside the expression is not treated
specially. The shell shall expand all tokens in the expression
for parameter expansion, command substitution, and **quote
removal**. [Emphasis mine.]
Next, the shell shall treat this as an arithmetic expression
and substitute the value of the expression.
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_04
vq
next prev parent reply other threads:[~2020-06-19 6:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-05 18:18 Artur Renault
2020-06-05 21:01 ` Lawrence Velázquez
2020-06-17 23:21 ` Bart Schaefer
2020-06-18 11:19 ` Mikael Magnusson
2020-06-19 6:38 ` Lawrence Velázquez [this message]
2020-06-19 15:35 ` Sebastian Gniazdowski
2020-06-19 15:55 ` Peter Stephenson
2020-06-22 11:11 ` Peter Stephenson
2020-06-23 23:51 ` Bart Schaefer
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