Antw: Re: "set -u" and empty arrays

[Ulrich Windl]

>>> Chet Ramey <chet.ramey@case.edu> schrieb am 13.05.2019 um 21:44 in Nachricht
<ead04541-953d-f1ba-f021-5c6938063f53@case.edu>:
> On 5/9/19 7:07 AM, Ulrich Windl wrote:
>> Bash Version: 4.3
>> Patch Level: 48
>> Release Status: release
>> 
>> Hi!
>> 
>> Is this intended with "set -u":
>> # set -u
>> # declare -a INSTANCES
>> # echo ${INSTANCES[*]}
>> bash: INSTANCES[*]: unbound variable
>> # INSTANCES=()
>> # echo ${INSTANCES[*]}
>> bash: INSTANCES[*]: unbound variable
>> # echo ${INSTANCES[@]}
>> bash: INSTANCES[@]: unbound variable
> 
> This was changed late in the bash-4.4 development cycle (July, 2016). From
> bash-4.4/CHANGES:
> 
> a.  Using ${a[@]} or ${a[*]} with an array without any assigned elements 
> when
>     the nounset option is enabled no longer throws an unbound variable 
> error.

Thanks for the info! Actually it seems "${#a[*]}" is also affected:
v04:~> declare -a a
v04:~> echo ${#a[@]}
0
v04:~> set -u
v04:~> echo ${#a[@]}
bash: a: unbound variable
v04:~> a=()
v04:~> echo ${#a[@]}
0
v04:~> echo $BASH_VERSION
4.3.48(1)-release

Regards,
Ulrich