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

[Chet Ramey]

On 3/21/22 8:45 AM, Andreas Luik wrote:

> Bash Version: 4.4
> Patch Level: 20
> Release Status: release
>
> 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

This was changed in bash-5.0.

> echo "${myvar[@]:+nonnull}"
> nunnull -> likewise not OK, because "${myvar[@]}" is null

This is still kind of useless, but there are cases where bash doesn't
correctly propagate quoted null strings, and those need to be fixed.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/