How to upgrade a Debian-based Linux distribution–let me count the ways. There’s an apt-get upgrade, apt-get dist-upgrade, and do-release-upgrade. Say what? Why are there three different paths to upgrading an operating system? Truth be told, each of those commands does different things. Confused?
Let me explain.
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apt-get upgrade vs. apt-get dist-upgrade
Let’s first look at the difference between apt-get upgrade and apt-get dist-upgrade (as that is where much of the confusion lies). When you run apt-get upgrade, it only upgrades that which has a new release available to the platform, as defined in /etc/apt/sources.list or in /etc/apt/sources.list.d/.
However, when you run apt-get dist-upgrade, it will intelligently install or remove packages as needed, in order to complete the upgrade. Apt-get dist-upgrade has a smart conflict resolution system, so it will attempt to upgrade the most important packages, at the expense of those deemed less important.
Apt-get upgrade does not remove packages, it only upgrades. Can you use sudo apt-get dist-upgrade as your regular upgrade tool? Certainly. Just remember, it will delete software–if it is required to complete the process.
The do-release-upgrade command, on the other hand, is responsible for upgrading from one release to another. So if you want to upgrade from Ubuntu 18.10 to 19.04, you use do-release-upgrade.
However, in order to use this command, the system must first be fully upgraded. To do that, you should first run sudo apt-get upgrade, followed by sudo apt-get dist-upgrade. When those two complete, you can then run sudo do-release-upgrade and wait for the magic to complete.
The difference between these commands is important. In fact, you might want to read up on the apt-get and do-release-upgrade man pages to find out more. To do that, issue the commands man apt-get and man do-release-upgrade. Enjoy the read.