YUM and DNF Package Managers 📦
DNF (Dandified YUM) is the next-generation package manager replacing YUM on RPM-based distributions (RHEL 8/9, Rocky Linux, AlmaLinux, Fedora, and Amazon Linux 2023). It resolves dependencies faster using libsolv, consumes less memory, and provides modular repository controls.
1. YUM vs DNF Comparison
| Feature | YUM (v3 - Legacy) | DNF (v4 / v5 - Modern) |
|---|---|---|
| Dependency Resolver | Python-based internal solver (slow) | libsolv C library (SAT-solver algorithm) |
| Memory Footprint | High (loads entire metadata into RAM) | Low (shared metadata caches) |
| Python API | Poorly documented Python 2/3 internals | Clean, stable C/Python API |
| Default Distributions | RHEL 7, CentOS 7, Amazon Linux 2 | RHEL 8/9, Rocky, Fedora, Amazon Linux 2023 |
| Command Compatibility | yum install pkg | Fully backward compatible (yum is a symlink to dnf) |
2. Core DNF Command Workflows
# Update repository metadata and upgrade installed packages
sudo dnf check-update
sudo dnf upgrade -y
# Search for packages by keyword or file path
dnf search nginx
dnf provides /usr/sbin/semanage # Find which package supplies a file
# Install and remove packages
sudo dnf install -y htop
sudo dnf remove -y httpd
# Clean cached metadata and packages
sudo dnf clean all
sudo dnf makecache
# Transaction History & Rollbacks
dnf history
sudo dnf history info 12
sudo dnf history undo 12 # Roll back specific installation transaction3. Repository Configuration (/etc/yum.repos.d/)
DNF reads .repo files from /etc/yum.repos.d/:
[custom-repo]
name=Custom Enterprise Repository
baseurl=https://packages.example.com/rhel/$releasever/$basearch/
enabled=1
gpgcheck=1
gpgkey=https://packages.example.com/RPM-GPG-KEY-custom
metadata_expire=6h
sslverify=1Managing Repositories via CLI
# List active repositories
dnf repolist
# Enable or disable repository on the fly
sudo dnf config-manager --set-enabled epel
sudo dnf config-manager --set-disabled crb
# Add a remote repo file
sudo dnf config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo4. DNF Modules & Application Streams
RHEL 8+ uses AppStreams to allow installing multiple versions of the same software (e.g., Node.js 18 vs 20):
# List available module streams
dnf module list nodejs
# Enable and install specific stream
sudo dnf module enable -y nodejs:20
sudo dnf module install -y nodejs:20/default
# Switch stream
sudo dnf module reset -y nodejs
sudo dnf module enable -y nodejs:22
sudo dnf distro-sync