Re: 4.4 change in behavior from 4.3: how to catch unset when using ${#length}

[Chet Ramey]

On 10/21/16 5:41 PM, L. A. Walsh wrote:
> On 4.3 and earlier, at least on arrays, one could have
> the illusion of this working w/o complaint -- and returning
> 0 when the array was 0-len or unset, or the array length,
> otherwise:
> 
> 
>  echo ${#array[@]:-0}
> 
> But I note it only seemed to work in arrays, and in 4.4 gets a
> syntax error:
> 
>  echo ${#array[@]:-0}   bash: ${#array[@]:-0}: bad substitution

Because it is a syntax error, and if it were not it would be ambiguous.
The ${param:-word} word expansion takes a parameter, not another word
expansion, as the object to be expanded.

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