DNF Package Manager Basics on RHEL 9

dnf is the package manager on every RHEL-family distro from RHEL 8 onward — Rocky, Alma, Oracle Linux, Fedora. It replaced yum, though yum still exists as a symlink for muscle-memory. This guide covers the commands you will run weekly.

Prerequisites

• Rocky 9 / Alma 9 / RHEL 9 with sudo.
• Outbound HTTPS reachable for the configured mirrors.

Step 1: Refresh metadata and list updates

sudo dnf check-update              # exit code 100 = updates available
sudo dnf list --installed | wc -l
sudo dnf list --upgrades

Step 2: Install, remove, search

sudo dnf install -y vim git tmux
sudo dnf remove  -y unwanted-pkg
dnf search redis                  # search names + summaries
dnf info redis                    # detailed metadata
dnf provides /usr/bin/openssl     # which package owns this file?

Step 3: Upgrades

sudo dnf upgrade -y               # security + bugfix updates
sudo dnf upgrade --security -y    # security only
sudo dnf upgrade --refresh -y     # force a metadata refresh first

After kernel updates:

sudo dnf needs-restarting -r      # 0 = no reboot; 1 = reboot needed

Step 4: Repositories

dnf repolist                      # enabled repos
dnf repolist --all                # all configured repos (incl. disabled)
sudo dnf config-manager --enable crb       # enable CodeReady Builder
sudo dnf install -y epel-release           # add EPEL
sudo dnf config-manager --add-repo https://example.com/repo.repo

config-manager is in dnf-plugins-core on RHEL 9 — install it if missing.

Step 5: Modules and streams (AppStream)

RHEL 9 ships PHP, Node, Python, etc. as modules with selectable streams:

dnf module list nodejs
sudo dnf module enable -y nodejs:20
sudo dnf module install -y nodejs:20/common
sudo dnf module reset nodejs                 # back to default stream

Step 6: Clean and lock

Reclaim disk used by the package cache:

sudo dnf clean all
sudo dnf clean dbcache

Lock a package at a known version (useful for production stability):

sudo dnf install -y python3-dnf-plugin-versionlock
sudo dnf versionlock add postgresql-server
sudo dnf versionlock list

Verify

sudo dnf history list | head      # last transactions
sudo dnf history info 5           # what changed in transaction 5
sudo dnf history undo 5           # revert that transaction (carefully)

Conclusion

dnf is the same toolbox as apt on Debian/Ubuntu, just spelled differently. Learn check-update, upgrade, install, remove, info, provides, history, and you are 95 percent of the way to RHEL operations.

Next steps

• Set up firewalld zones for inbound rules.
• See Subscribe RHEL 9 to AppStream if you are on Red Hat proper rather than Rocky/Alma.
• Read the Fedora dnf vs yum post for the Fedora-specific differences.