Re: Empty array referenced by indirection reports unbound variable

[Chet Ramey]

On 4/5/21 4:45 PM, konsolebox wrote:
> set -u
> array=()
> __ref=array[@]
> : "${array[@]}" # Reports nothing

This is a special case, mirroring the special case that POSIX carved out
for $@ and $* in 2009.

> : "${!__ref}" # Unbound variable

But this is not. Bash looks for __ref, finds it with a value of array[@],
and attempts to expand that. It expands to null (internally), since there
are no array elements, which becomes the value of the parameter expansion.

Since the expansion (${!__ref}) resulted in the null string, `set -u' kicks
in and bash reports a fatal error.

--
``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/