Override invalid option message with getopts in bash

Question

I am using getopts to track options that are given to my script. However, I want to able to detect whether an option that was specified is invalid. I can do this, but it will always echo a message that I haven't written.

The result

my.sh: illegal option -- x
Error: Invalid option was specified --

What I want to achieve

Error: Invalid option was specified --

A snippet of my code

while getopts g:r: option; do
        case $option in
                g) guesses=$OPTARG;;
                r) range=$OPTARG;;
                ?) echo "Error: Invalid option was specified -- $OPTARG";;
        esac
done

How can I achieve the desired result?

Answer 1

Assuming you want two short options -g and -r, the following example will not trigger the illegal option message on passing -x:

while getopts ":g :r" option; do
    case $option in
        g) guesses=$OPTARG;;
        r) range=$OPTARG;;
        ?) echo "Error: Invalid option was specified -$OPTARG";;
    esac
done