Re: status on $[arith] for eval arith vsl $((arith))??

[Pierre Gaston]

On Sun, Apr 8, 2012 at 12:50 AM, Linda Walsh <bash@tlinx.org> wrote:
>
>
> Mike Frysinger wrote:
>
>> On Saturday 07 April 2012 16:45:55 Linda Walsh wrote:
>>>
>>> Is it an accidental omission from the bash manpage?
>>
>>
>> it's in the man page.  read the "Arithmetic Expansion" section.
>> -mike
>
>
>
> ====
> My 4.2 manpage says:
>
>   Arithmetic Expansion
>       Arithmetic  expansion allows the evaluation of an arithmetic
> expression
>       and the substitution of the result.  The format for  arithmetic
>  expan-
>       sion is:
>
>              $((expression))
>
>       The  expression  is  treated  as if it were within double quotes, but
> a
>       double quote inside the parentheses  is  not  treated  specially.
> All
>       tokens in the expression undergo parameter expansion, string
> expansion,
>       command substitution, and quote removal.  Arithmetic expansions may
>  be
>       nested.
>
>       The  evaluation  is performed according to the rules listed below
> under
>       ARITHMETIC EVALUATION.  If expression is invalid, bash prints a
> message
>       indicating failure and no substitution occurs.
>
> ----------
> No mention of square brackets.
>
> What's yours say?
>
Some linux distributions patch the man page and document $[ ] as deprecated.

The SUS rationale says:

In early proposals, a form $[expression] was used. It was functionally
equivalent to the "$(())" of the current text, but objections were
lodged that the 1988 KornShell had already implemented "$(())" and
there was no compelling reason to invent yet another syntax.
Furthermore, the "$[]" syntax had a minor incompatibility involving
the patterns in case statements.