RED HAT ENTERPRISE LINUX

Package Management
with DNF

Installing, Updating, and Managing Software

CIS126RH | RHEL System Administration 1
Mesa Community College

Learning Objectives

Understand RPM packages

Know the RPM package format and naming conventions

Manage packages with DNF

Search, install, update, and remove software packages

Configure repositories

Enable, disable, and add software repositories

Use Application Streams

Work with DNF modules for multiple software versions

We have four main learning objectives for this module. First, we'll understand RPM packages - the fundamental unit of software distribution in RHEL. You'll learn the package naming conventions and what information is contained in an RPM. Second, we'll master DNF for package management - searching for software, installing it, keeping it updated, and removing what you don't need. DNF handles dependencies automatically, making software management straightforward. Third, we'll configure repositories - the sources from which DNF downloads packages. You'll learn about Red Hat's standard repositories and how to add third-party sources when needed. Fourth, we'll explore Application Streams and DNF modules, which allow RHEL to provide multiple versions of software like Python, Node.js, or PostgreSQL simultaneously. This is how RHEL delivers newer software versions while maintaining its stable base.

Package Management Overview

Repository

→

DNF

→

System

Repositories contain packages → DNF downloads and installs → Software runs on system

RPM

Package format containing software, metadata, and installation scripts

DNF

High-level package manager that handles dependencies automatically

Repository

Collection of packages with metadata, hosted on a server

Module

Set of packages representing an application or version stream

Let's understand the package management ecosystem in RHEL. At the foundation, we have RPM (Red Hat Package Manager) packages. An RPM file contains the software files, metadata about the package, and scripts that run during installation or removal. RPM is the format; you can install packages directly with the rpm command, but it doesn't handle dependencies. DNF (Dandified YUM) is the high-level package manager that sits above RPM. When you ask DNF to install a package, it figures out what other packages are required (dependencies), downloads everything from repositories, and installs them in the correct order. DNF makes package management practical. Repositories are collections of packages stored on servers. Red Hat provides official repositories; organizations may host internal repositories; third-party projects like EPEL provide additional software. DNF is configured to know about repositories and fetches packages from them. Modules are a newer concept introduced with Application Streams. A module groups related packages and can provide multiple versions (streams) of software. For example, the nodejs module might offer Node.js 16, 18, and 20 as different streams you can choose from.

RPM Package Format

An RPM package is a file containing software, metadata (name, version, dependencies), and scripts for installation and removal.

httpd-2.4.57-5.el9.x86_64.rpm

Component	Example	Description
Name	httpd	Software name
Version	2.4.57	Upstream software version
Release	5.el9	Package build number and distribution (el9 = RHEL 9)
Architecture	x86_64	CPU architecture (x86_64, aarch64, noarch)

Understanding RPM naming conventions helps you identify packages and their versions. The format is name-version-release.architecture.rpm. The name identifies the software - httpd is the Apache web server. The version is the upstream software version - the version Apache developers released. The release is Red Hat's build number, including distribution identification. The "5.el9" means it's the fifth Red Hat build for Enterprise Linux 9. When Red Hat backports a security fix, they increment the release number while keeping the version the same. The architecture indicates which CPU type the package is compiled for. x86_64 is standard 64-bit Intel/AMD processors. aarch64 is 64-bit ARM. noarch means the package works on any architecture - typically scripts, documentation, or configuration files. When you see a package like "kernel-5.14.0-362.el9.x86_64", you can decode it: kernel software, version 5.14.0, Red Hat build 362 for RHEL 9, compiled for 64-bit x86. This naming is consistent across all RPM-based distributions.

DNF Basic Commands

Command	Description
dnf search keyword	Search for packages by name or description
dnf info package	Display detailed package information
dnf install package	Install a package and dependencies
dnf remove package	Remove a package
dnf update	Update all installed packages
dnf update package	Update a specific package
dnf list installed	List all installed packages
dnf list available	List packages available to install
dnf provides /path/file	Find which package provides a file

These are the DNF commands you'll use most frequently. "dnf search" finds packages matching a keyword in the name or description. This is your starting point when you know what you want but don't know the exact package name. "dnf info" shows detailed information about a package - description, version, size, repository source, and dependencies. Useful for learning about a package before installing. "dnf install" installs packages along with any required dependencies. DNF calculates what's needed and prompts for confirmation. "dnf remove" uninstalls a package. By default, it also removes packages that depended on the removed package if they're no longer needed. "dnf update" without arguments updates all installed packages to their latest versions. With a package name, it updates just that package. This is how you apply security patches and bug fixes. "dnf list installed" shows what's currently installed. "dnf list available" shows what's available in configured repositories. You can combine these: "dnf list installed 'http*'" shows installed packages starting with http. "dnf provides" is extremely useful - give it a file path, and it tells you which package contains that file. Perfect for when a command is missing and you need to know what to install.

Searching for Packages

# Search by keyword (searches name and description)
[root@server ~]# dnf search web server
======================== Name & Summary Matched: web, server =========================
httpd.x86_64 : Apache HTTP Server
nginx.x86_64 : A high performance web server and reverse proxy server

# Search only in package names
[root@server ~]# dnf search --names-only httpd

# Get detailed information about a package
[root@server ~]# dnf info httpd
Name         : httpd
Version      : 2.4.57
Release      : 5.el9
Architecture : x86_64
Size         : 59 k
Source       : httpd-2.4.57-5.el9.src.rpm
Repository   : rhel-9-for-x86_64-appstream-rpms
Summary      : Apache HTTP Server
URL          : https://httpd.apache.org/
License      : ASL 2.0

# Find what package provides a command
[root@server ~]# dnf provides /usr/bin/vim
vim-enhanced-2:9.0.1712-1.el9.x86_64 : A version of the VIM editor which includes recent enhancements
Repo        : rhel-9-for-x86_64-appstream-rpms
Matched from:
Filename    : /usr/bin/vim

Let's explore searching for packages in detail. "dnf search" is flexible - it searches both package names and summaries/descriptions. Searching "web server" finds httpd, nginx, and other packages with those terms. For more targeted searches, --names-only restricts to package names only. This is useful when you know part of the package name and don't want irrelevant description matches. "dnf info" provides comprehensive details. You see the full name-version-release-architecture, the repository it comes from, size, license, and description. This helps you verify you're installing the right package and understand what it is. The "provides" command is invaluable. When you try to run a command and get "command not found," use "dnf provides /usr/bin/commandname" to find which package contains it. You can also use wildcards: "dnf provides */vim" finds packages containing any file named vim. This works for configuration files too - if you need to know which package owns /etc/httpd/conf/httpd.conf, provides will tell you. The output shows which repository contains the package, helping you understand your system's software sources.

Installing Packages

# Install a single package
[root@server ~]# dnf install httpd
Dependencies resolved.
================================================================================
 Package          Arch      Version              Repository                Size
================================================================================
Installing:
 httpd            x86_64    2.4.57-5.el9         rhel-9-appstream          59 k
Installing dependencies:
 apr              x86_64    1.7.0-11.el9         rhel-9-appstream         127 k
 apr-util         x86_64    1.6.1-20.el9         rhel-9-appstream          98 k
 httpd-filesystem x86_64    2.4.57-5.el9         rhel-9-appstream          18 k
 httpd-tools      x86_64    2.4.57-5.el9         rhel-9-appstream          84 k
 
Transaction Summary
================================================================================
Install  5 Packages

Total download size: 386 k
Is this ok [y/N]: y

# Install without confirmation prompt
[root@server ~]# dnf install -y nginx

# Install multiple packages
[root@server ~]# dnf install vim wget curl

# Install a package group
[root@server ~]# dnf group install "Development Tools"

Installing packages with DNF is straightforward, but understanding the output is important. When you run "dnf install httpd," DNF resolves dependencies - it determines what other packages httpd needs to function. The transaction summary shows everything that will be installed. In this example, httpd requires apr (Apache Portable Runtime), apr-util, httpd-filesystem (directory structure), and httpd-tools (utilities). All five packages will be installed to satisfy the request. You're prompted for confirmation (y/N) before proceeding. The -y flag skips confirmation and answers yes automatically. Use this in scripts or when you're confident about what you're installing. Don't use it casually - you want to review what's being installed in most cases. You can install multiple packages in one command. "dnf install vim wget curl" installs all three packages and their combined dependencies in one transaction. This is more efficient than separate install commands. Package groups bundle related packages together. "Development Tools" includes compilers (gcc), make, and development headers. Use "dnf group list" to see available groups. Groups are convenient for setting up development environments or server roles.

Updating Packages

# Check for available updates
[root@server ~]# dnf check-update
kernel.x86_64                    5.14.0-362.18.1.el9_3       rhel-9-baseos
openssl.x86_64                   1:3.0.7-25.el9_3            rhel-9-baseos
vim-enhanced.x86_64              2:9.0.2081-1.el9            rhel-9-appstream

# Update all packages
[root@server ~]# dnf update

# Update specific package
[root@server ~]# dnf update openssl

# Update with automatic yes
[root@server ~]# dnf update -y

# Security updates only
[root@server ~]# dnf update --security

# Download updates without installing
[root@server ~]# dnf update --downloadonly

# View update changelog
[root@server ~]# dnf updateinfo list
[root@server ~]# dnf updateinfo info RHSA-2024:0001

Keeping systems updated is critical for security. "dnf check-update" shows available updates without installing anything. The exit code is 100 if updates are available, 0 if the system is up to date - useful in scripts. "dnf update" without arguments updates all installed packages to their latest versions from enabled repositories. This is the standard way to apply patches. On production systems, you might schedule this during maintenance windows. Updating specific packages is useful when you need a particular fix but want to minimize changes. "dnf update openssl" updates only OpenSSL and any new dependencies it might require. The --security flag restricts updates to only those addressing security vulnerabilities. This is useful when you need to patch security issues but want to minimize other changes that might require additional testing. The --downloadonly flag downloads packages without installing them. This is useful for pre-staging updates or for reviewing exactly what will change before actually installing. "dnf updateinfo" provides information about updates including security advisories. You can see which CVEs are addressed by updates and make informed decisions about update urgency.

Removing Packages

# Remove a package
[root@server ~]# dnf remove httpd
Dependencies resolved.
================================================================================
 Package              Arch     Version              Repository            Size
================================================================================
Removing:
 httpd                x86_64   2.4.57-5.el9         @rhel-9-appstream     155 k
Removing dependent packages:
 mod_ssl              x86_64   1:2.4.57-5.el9       @rhel-9-appstream     298 k
Removing unused dependencies:
 apr                  x86_64   1.7.0-11.el9         @rhel-9-appstream     289 k
 apr-util             x86_64   1.6.1-20.el9         @rhel-9-appstream     211 k

Transaction Summary
================================================================================
Remove  4 Packages

# Remove without dependency removal
[root@server ~]# dnf remove --noautoremove httpd

# Clean up unneeded dependencies
[root@server ~]# dnf autoremove

# Remove a group
[root@server ~]# dnf group remove "Development Tools"

⚠ Caution: DNF removes packages that depend on what you're removing. Always review the transaction before confirming!

Package Managementwith DNF

Installing, Updating, and Managing Software

Learning Objectives

Package Management Overview

RPM

DNF

Repository

Module

RPM Package Format

DNF Basic Commands

Searching for Packages

Installing Packages

Updating Packages

Removing Packages

Package Management
with DNF