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Re: Fwd: nounset option and arrays


From: Chet Ramey
Subject: Re: Fwd: nounset option and arrays
Date: Thu, 05 Feb 2009 14:54:53 -0500
User-agent: Thunderbird 2.0.0.19 (Macintosh/20081209)

> In the following example, I was expecting var2 not to be seen as an unbound 
> variable after it was declared.  Wouldn't it be more consistent with the 
> treatment of var1 not to issue the unbound variable error in this case?  What 
> is the rationale behind the current behavior?
> 
>     bash-3.2$ shopt -s -o nounset
>     bash-3.2$ declare var1
>     bash-3.2$ echo $var1
> 
>     bash-3.2$ declare -a var2
>     bash-3.2$ echo $var2
>     bash: var2: unbound variable
>     bash-3.2$ echo address@hidden
>     bash: address@hidden: unbound variable

The bug is actually that the reference to var1 doesn't cause the shell to
exit.  `declare' creates invisible "placeholder" variables that don't
actually exist until they're given a value.  Until they have a value, they
should be treated as if they're unset.

Bash-4.0 treats both cases (array and scalar) as unset.

Chet
-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer

Chet Ramey, ITS, CWRU    address@hidden    http://cnswww.cns.cwru.edu/~chet/




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