fetch_github_key() 
{
  read -p "Enter Github Username: " github_username
  GITHUB_KEY=$(curl https://github.com/${github_username}.keys)
  if [ -z $(grep "$GITHUB_KEY" ~/.ssh/authorized_keys) ]; then 
    echo "$GITHUB_KEY" >> ~/.ssh/authorized_keys
    echo 'key added.'
  fi
}

read -t10 -p "Download github public key for ssh? (Y/N): "
if [ $? -gt 128 ]; then
  echo "Timed out waiting for input. Defaulting to N!"
  break
fi

case $REPLY in
[yY]*)
  fetch_github_key
  break
  ;;
*)
  break
  ;;
esac