Am 11.01.2013 19:27, schrieb Dan Douglas:
> Bash treats the variable as essentially undefined until given at least an
> empty value.
>
> $ bash -c 'typeset -i x; [[ -v x ]]; echo "$?, ${x+foo}"; typeset -p x'
> 1,
> bash: line 0: typeset: x: not found
> $ ksh -c 'typeset -i x; [[ -v x ]]; echo "$?, ${x+foo}"; typeset -p x'
> 0,
> typeset -i x
>
> Zsh implicitly gives integers a zero value if none are specified and the
> variable was previously undefined. Either the ksh or zsh ways are fine IMO.
>
> Also I'll throw this in:
>
> $ arr[1]=test; [[ -v arr[1] ]]; echo $?
> 1
>
> This now works in ksh to test if an individual element is set, though it
> hasn't always. Maybe Bash should do the same? -v is tricky because it adds
> some extra nuances to what it means for something to be defined...
>
Personally I like the current behavior, disclaimer I use nounset.
I see no problem with getting people to initialize variables.
it is a more robust programming approach.
