Install 5.6 on Ubuntu using password 'password'

install-mysql-5.6.sh

dpkg -s mysql-client >/dev/null 2>&1 &&
  sudo apt-get -y remove mysql-client
dpkg -s mysql-server >/dev/null 2>&1 &&
  sudo apt-get -y remove mysql-server
command -v debconf-set-selections ||
  sudo apt-get -y install debconf-utils
sudo debconf-set-selections <<< "mysql-server-5.6 mysql-server/root_password password password"
sudo debconf-set-selections <<< "mysql-server-5.6 mysql-server/root_password_again password password"
command -v add-apt-repository ||
  sudo apt-get -y install software-properties-common
sudo add-apt-repository -y ppa:ondrej/mysql
sudo apt-get update
export DEBIAN_FRONTEND=noninteractive 
sudo apt-get -y install mysql-client-5.6 mysql-server-5.6