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Re: Use of double parentheses
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From: |
Paul Eggert |
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Subject: |
Re: Use of double parentheses |
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Date: |
Mon, 01 Aug 2011 08:51:50 -0700 |
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User-agent: |
Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.18) Gecko/20110617 Thunderbird/3.1.11 |
On 08/01/11 08:21, Eric Blake wrote:
>>>> && ( (unset $as_var) || exit 1)>/dev/null 2>&1&& unset $as_var || :
>>> ...
>>> It's not a bug in pdksh - POSIX was recently reworded to allow (( to
>>> introduce arithmetic parsing on any shell that wants to provide it as an
>>> extension.
> http://austingroupbugs.net/view.php?id=217
Thanks for mentioning that; I didn't know it. However,
from that URL it still appears that pdksh is buggy.
The new rule says that '((FOO))' is special if FOO
is a syntactically valid arithmetic expression.
But in the above example, the expression '((unset $asvar) ...)'
surely would not be syntactically valid to pdksh,
and therefore '((' should not be special there.