yum replaced by dnf
yum package manager has been replaced in Fedora 22 by its successor, dnf. The yum fork has been available in Fedora for testing since Fedora 18, and is now the default command line package manager.
Most dnf commands use directives that are familiar to yum users, and it uses the same RPM package repositories. Behind the scenes, dnf uses an improved dependency solver,
hawkey, along with
librepo for repository operations and
libcomps for package groups.
The behavior of dnf differs from yum in some areas:
Updates that don't work are skipped
If a portion of a transaction is not viable, dnf will automatically exclude it and transparently continue with the portions that will work. For example, if a package has unmet dependencies during a
dnf updateaction, that package will not be updated, but others will. This is similar to yum's "--skip-broken" directive, but evaluates the impact of the problem against the entire transaction.
To review details about a problematic package direction, you can use the "--best" option.
dnf update --best will force dnf to resolve the transaction using the latest versions of involved packages, and report any problems instead of skipping them.
Clean on remove
When removing a package, dnf will automatically remove any dependent packages that were not explicitly installed by the user. If a package was independently installed, it won't be uninstalled this way.
This behavior is configured by the "clean_requirements_on_remove" option in /etc/dnf/dnf.conf.
Repo cache refresh schedule
By default, dnf will check for updates in configured repositories hourly, starting ten minutes after the system boots. The action is controlled by a systemd timer unit, /usr/lib/systemd/system/dnf-makecache.timer.
To adjust this, copy the timer file to /etc/systemd/system/dnf-makecache.timer and edit it.
Alternatively, setting the metadata_timer_sync in /etc/dnf/dnf.conf to a number of seconds configures the minimum number of seconds between makecache operations. If the timer has not expired,
dnf makecache will exit immediately.
dnf will also honor the metadata_expire option set in individual repo configs, and refresh repo metadata at runtime if it is too old. This option is described in
Repository Actions =
The "repository-packages" directive can be used to search for or get info about packages in a specific repository, list installed packages frrom that repository, and more. This simplifies operations that would have required use of "--excluderepo" and "--includerepo" options with yum, and is especially useful for managing similar packages from different repositories.