The goal of this is to provide a quick introduction to the fedora package manager dandified yum (dnf) and a few of its useful commands.
Pretty much the definitive guide to DNF can be found here which is an well put together comprehensive reference to have if you use dnf frequently.
Basic Package Management
Most commands in dnf are self explanatory. The follow an English language type syntax.
These are probably the most common day to day ones you would use:
dnf search <package>
dnf install <package>
dnf remove <package>
dnf upgrade
Each do what you would expect.
Dnf has some globing ability when searching and installing packages. Globbing essentially allows you to specify things like wildcards when searching for packages.
For example if you wanted to search for all non C++ linux-gnu cross compilers
dnf search gcc-[!c++]*-linux-gnu
Group Packages
Dnf has package groups like you’d expect in most package managers. Common groups are used to install
Desktop Enviroments or programming tool chains etc.
You can list groups via dnf group list. Install via dnf group install "Package Group Name"
You can get information about what a group is and what will be installed by using dnf group info "Package Group Name"
Some Useful Options
There’s a few common options that you may find use for on occasion, among them are the following.
--refresh Allows for you to re-download the latest package metadata. This can be useful on occasion if the meta data is slightly old and you are testing updates from updates-testing, or if you are trying to solve any issues and want to ensure the data is completely refreshed.
-y or --assumeyes will automatically accept any queries from dnf, for example to answer yes to proceed to install updates. Useful for scripts, etc.
Security Updates Options
There are some security related specific options, useful for when you want to upgrade packages with security patches, but don’t want to update the system for any other reason.
--security will include packages with security updates-testing
--sec-severity=<severity> where <severity> can be 'Critical', 'Important', 'Moderate', 'Low' will update packages that meet the specified security severity.
--cve=<cve> where <cve> corresponds to the CVE you want to patch (assuming there is a patch available)
The are used as such: dnf upgrade --sec-severity=Critical
Package History
DNF provide package install history information using dnf history, allowing you to check what actions you have taken and if necesary rollback actions you took.
For example: dnf histroy
[root@jupiter]# dnf history
Last metadata expiration check: 1:20:50 ago on Fri May 19 01:44:32 2017 BST.
ID | Command line | Date and time | Action(s) | Altered
-------------------------------------------------------------------------------
71 | update | 2017-05-18 18:23 | Update | 1 EE
You can get the specific information for a transaction by specifying the following command with the id number of the transaction
dnf history info 71
[root@jupiter]# dnf history info 71
Last metadata expiration check: 1:24:47 ago on Fri May 19 01:44:32 2017 BST.
Transaction ID : 71
Begin time : Thu May 18 18:23:42 2017
Begin rpmdb : 5840:6a1bb0fa948a57d1374a54b5db89abc485484497
End time : 18:23:50 2017 (8 seconds)
End rpmdb : 5840:32a1749248a39c64cdac79b37d54a785711794ea **
User : ---
Return-Code : Success
Command Line : update
Transaction performed with:
Installed dnf-2.4.1-1.fc26.noarch @updates-testing
Installed rpm-4.13.0.1-4.fc26.x86_64 @updates-testing
Packages Altered:
Upgraded google-chrome-unstable-60.0.3095.5-1.x86_64 @google-chrome-unstable
Upgrade 60.0.3100.0-1.x86_64 @google-chrome-unstable
Scriptlet output:
1 Redirecting to /bin/systemctl start atd.service
This will show you what was installed, how it’s installed, and any other actions taken post installation. This can be useful to identify post installation actions that failed to run properly.
History can also be used to undo changes made.
dnf history undo <transaction id>
Or to redo a transaction
dnf history redo <transaction id>
##Fedora Release Upgrades
You can upgrade to the next Fedora release from within DNF without new install media, reinstalling, etc. This has become pretty stable with the last few releases.
One caveat I would suggest for a smooth upgrade is the following
If you have third party repositories installed they should support the new release first. The upgrade should disable them, but you can have unintended consequences if you have a lot of unsupported exotic packages installed that don’t yet support a new release.
Generally rpmfusion is supported and will quickly support new releases.
Prerequisits
You need to install the following package.
dnf install dnf-plugin-system-upgrade
Prepare the Upgrade
dnf system-upgrade download --refresh --releasever=26
--releasever=<ver> is used to specify the specific version you want to upgrade to, this can be for example a new release (if going from 24 -> 25 you would specify 25), to a beta release in this example 26 which is near release but currently in testing. Or for example ‘rawhide’ which is Fedora rolling branch.
You may find you need to also specify --allow-erasing in an upgrade if you are upgrading your system that includes packages that don’t have an upgrade path. You need to check this carefully.
Upgrade the system
To complete the upgrade:
dnf system-upgrade reboot
But, what is the