Ubuntu 20.04 Focal Fossa uses - like its ancestors - apt
Before you can upgrade your running system you need to update the package-cache for the repositories that are enabled on your system, by using:
sudo apt update
Once that is done, you have to upgrade - meaning applying the newly found patches to your system, by using:
sudo apt full-upgrade
This should be it, except if you are using packages that are not supported anymore and/or you made manual changes to packages that were regularly installed via apt from your current repositories/sources; In that case, you would have to use:
sudo apt upgrade
The difference to sudo apt full-upgrade
is that sudo apt upgrade
does not remove packages from your system; which would be done for example because those non-standard packages reached end-of-life, were replaced by another (meta-) package or do break the dependency chain, which you might have willfully ignored.
If you are new to Ubuntu, Distros based on Debian (using apt as a package manager) or in general to GNU/Linux Distributions, you can ignore the alternative method, namely sudo apt upgrade
, just use the first two commands mentioned:
sudo apt update && sudo apt full-upgrade
[ The &&
just chains commands, so you can write/copy-paste this one-liner.]