On 4/17/15 5:12 AM, isabella parakiss wrote:
> I need to check if an element in an associative array is set. What's the
> correct way to test it?
If *any* element is set, or if a particular element is set?
>
>
> $ declare -A arr=([x]=y); var=*
> $ [[ -v arr["$var"] ]]; echo $?
> 0
> $ [[ ${arr["$var"]} ]]; echo $?
> 1
>
>
> The former seems wrong, the glob is expanded even if "$var" is quoted.
It's not a glob. The array subscripts `@' and `*' are special and expand
to all elements of an array.
> The latter works but it doesn't distinguish between unset and empty.
The distinction is murky. A variable is not set unless it has been
assigned a value. Has an array variable that has no elements been
assigned a value? Is the concept of a=() meaningful and useful?
> Is there a way to test it with ''[[ -v'' ?
Are you interested in whether or not an array has been declared or whether
it has any elements?
> Also this one seems wrong, found by geirha:
>
> $ declare -A a=([x]=y); [[ -v a ]]; echo $?
> 1
> $ declare -A a=(["0"]=y); [[ -v a ]]; echo $?
> 0
Referencing an array without a subscript is equivalent to referencing
element 0.
Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU c...@case.edu http://cnswww.cns.cwru.edu/~chet/
