SHELL

bash user input yes no

### simple yes no question
read -p "Are you sure? " -n 1 -r
echo    # (optional) move to a new line
if [[ ! $REPLY =~ ^[Yy]$ ]]
then
    exit 1
fi

### most widely used method
while true; do
    read -p "Do you wish to install this program?" yn
    case $yn in
        [Yy]* ) make install; break;;
        [Nn]* ) exit;;
        * ) echo "Please answer yes or no.";;
    esac
done

### select from yes/no menu
echo "Do you wish to install this program?"
select yn in "Yes" "No"; do
  case $yn in
    Yes ) make install;;
    No ) exit;;
  esac
done