title="Select example"
prompt="Pick an option:"
options=("A" "B" "C")

echo "$title"
PS3="$prompt "
select opt in "${options[@]}" "Quit"; do 

    case "$REPLY" in

    1 ) echo "You picked $opt which is option $REPLY";;
    2 ) echo "You picked $opt which is option $REPLY";;
    3 ) echo "You picked $opt which is option $REPLY";;

    $(( ${#options[@]}+1 )) ) echo "Goodbye!"; break;;
    *) echo "Invalid option. Try another one.";continue;;

    esac

done


while opt=$(zenity --title="$title" --text="$prompt" --list \
                    --column="Options" "${options[@]}"); do

    case "$opt" in
    "${options[0]}" ) zenity --info --text="You picked $opt, option 1";;
    "${options[1]}" ) zenity --info --text="You picked $opt, option 2";;
    "${options[2]}" ) zenity --info --text="You picked $opt, option 3";;
    *) zenity --error --text="Invalid option. Try another one.";;
    esac

done