apt / dpkg
# run update
export DEBIAN_FRONTEND=noninteractive
LANG=en_US.UTF-8 sudo apt-get update -y && sudo apt-get dist-upgrade -y && sudo apt-get autoremove -y && sudo apt-get clean -y
# allow unauthenticated repository
apt-get update --allow-unauthenticated
# list updatable packages
apt list --upgradable
# view avaiable package version
apt-cache show wget
apt-cache madison wget
# install specific version
apt-get install package name=version
apt-get install wget=1.6
# install from specific repository
apt-get install -t squeeze-backports wget
# view available versions