Ubuntu Patching

apt-get update first to get current packages available.

apt-get upgrade - man apt-get:- Using upgrade keeps to the rule: under no circumstances are currently installed packages removed, or packages not already installed retrieved and installed.

apt-get dist-upgrade will add or remove packages to satisfy dependancies, so dist-upgrade is more likely to fix issues with conflicting package versions.

do-release-upgrade will upgrade to the latest release.