Bash 4.0+ case statement with fall-through: https://stackoverflow.com/questions/5562253/switch-case-with-fallthrough

default.sh

echo -en "Directory ~/bin already exists, overwrite it? [Y/n]: "
read -n 1 action; echo
case "$action" in
    '')   ;&
    [Yy]) rm -rf ~/bin;;
    *)    echo "Skipping directory ~/bin";;
esac