Zsh Mailing List Archive
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Re: bad math expression: illegal character: "
> On Jun 18, 2020, at 7:19 AM, Mikael Magnusson <mikachu@xxxxxxxxx> wrote:
>> On 6/18/20, Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> wrote:
>>> On Fri, Jun 5, 2020 at 2:02 PM Lawrence Velázquez <vq@xxxxxxxxx> wrote:
>>>> On Jun 5, 2020, at 2:18 PM, Artur Renault <Artur.Renault@xxxxxxxxxxxxx>
>>>> 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 $?
> $ 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 $?'
% /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 $?'
% /opt/local/bin/bash -c 'echo $(( "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.
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