When you type your password, UNIX turns off echoing so what you type
won't show on the screen.
You can do the same thing in shell scripts with
trap 'stty echo; exit' 0 1 2 3 15
# use the right echo for your UNIX:
echo "Enter code name: \c"
#echo -n "Enter code name: "
The response is stored in
helps to make sure that, if the user presses
to abort the script, characters will be echoed again.