Why use apt-get upgrade instead of apt-get dist-upgrade?

I usually use apt-get update && apt-get upgrade to run my updates and upgrades instead of the GUI because it seems to run more quickly.

However, I've noticed lately that I often get a message that one of my upgrades was held back. I then usually run dist-upgrade to run it through and it works fine. As far as I can tell after reading this question and its answers, dist-upgrade does all the same things and then some.

So, my question is: Why use apt-get upgrade at all? Why not use apt-get dist-upgrade all the time? Why does apt-get upgrade even exist?

4 Answers

I typically upgrade my machines with:

sudo apt-get update && time sudo apt-get dist-upgrade

Below is an excerpt from 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. If that's important to you, use apt-get upgrade. If you want things to "just work", you probably want apt-get dist-upgrade to ensure dependencies are resolved.

To expand on why you'd want upgrade instead of dist-upgrade, if you are a systems administrator, you need predictability. You might be using advanced features like apt pinning or pulling from a collection of PPAs (perhaps you have an in-house PPA), with various automations in place to inspect your system and available upgrades instead of always eagerly upgrading all available packages. You would get very frustrated when apt performs unscripted behavior, particularly if this leads to downtime of a production service.

upgrade upgrade is used to install the newest versions of all packages currently installed on the system from the sources enumerated in /etc/apt/sources.list. Packages currently installed with new versions available are retrieved and upgraded; under no circumstances are currently installed packages removed, or packages not already installed retrieved and installed. New versions of currently installed packages that cannot be upgraded without changing the install status of another package will be left at their current version. An update must be performed first so that apt-get knows that new versions of packages are available.
dist-upgrade dist-upgrade in addition to performing the function of upgrade, also intelligently handles changing dependencies with new versions of packages; apt-get has a "smart" conflict resolution system, and it will attempt to upgrade the most important packages at the expense of less important ones if necessary. So, dist-upgrade command may remove some packages. The /etc/apt/sources.list file contains a list of locations from which to retrieve desired package files. See also apt_preferences(5) for a mechanism for overriding the general settings for individual packages.

I know this question has been answered and is a year old, but I feel this needs to be said. Ubuntu 14.04 and later (and Debian Jessie and later, for those finding this from Google) uses APT 1.0, which allows the command apt instead of apt-get and apt-cache for some operations.

• apt-get upgrade will not change what is installed (only versions),
• apt-get dist-upgrade will install or remove packages as necessary to complete the upgrade,
• apt upgrade will automatically install but not remove packages.
• apt full-upgrade performs the same function as apt-get dist-upgrade.

The upgrade option only installs new version of the packages that are already installed on the system (and yes, kernel updates belong to them).

However, sometimes the updates change dependencies: for example, a new version of a package will no longer depend on a library that you have installed, or will require installation of additional libraries. The upgrade option will never remove installed packages that you no longer actually need.

However, the dist-upgrade option can "intelligently" handle changes in the dependencies system. This includes removing packages that are no longer necessary or resolve conflicts between packages that arose because of changes in the dependencies.

Users might have come to rely on packages that were installed implicitly because of other (explicitly installed) packages' dependency on them. Thus the packaging system cannot be aware of a user/administrator desire to retain certain functionality that might otherwise be removed via dist-upgrade.