Re: parameter expansion null check fails for arrays when [*] or [@] is used

[L A Walsh]

On 2022/03/21 05:45, Andreas Luik wrote:
> Description:
>         Bash fails to correctly test for parameter to be unset or null when the 
> parameter is an array reference [*] or [@].
>
> Repeat-By:
>
> myvar[0]=
> echo "${myvar[0]:+nonnull}"
> <empty> -> OK
> echo "${myvar[*]:+nonnull}"
> nunnull -> not OK, because "${myvar[*]}" is null
>   
myvar[*] = ('', )  element 0 contains an empty string, so not null.

> echo "${myvar[@]:+nonnull}"
> nunnull -> likewise not OK, because "${myvar[@]}" is null
>   
myvar[@] = ''  (displays all elements, each quoted.  Since
element 1 contains an empty string, it is quoted and isn't null.


>