Arrays have indexes for indexing each of the elements. Ordinary and associative arrays differ in terms of index type.

Obtain the list of indexes in an array.

$ echo ${!array_var[*]}

Alternatively, we can also use the following command:

$ echo ${!array_var[@]}

In the previous fruits_value array example, consider the following command:

$ echo ${!fruits_value[*]}
orange apple

This will work for ordinary arrays too.