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Managing software on Red Hat Enterprise Linux (RHEL) relies on YUM (Yellowdog Updater, Modified) or its successor, dnf. In this guide, you’ll learn how to register your system, configure repositories, and install, update, or remove packages. Most yum commands work identically with dnf; just replace yum with dnf where desired.
If you prefer dnf over yum, you can use it interchangeably, for example:
sudo dnf install httpd

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1. Registering with Red Hat Subscription Management

Before accessing Red Hat repositories, register and attach your system to a subscription. 
sudo subscription-manager register \
  --username your-redhat-developer-username \
  --password your-redhat-password
Once registered, attach the system automatically: 
sudo subscription-manager attach --auto
Ensure your subscription is active; expired subscriptions will prevent you from installing or updating packages.

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2. Listing and Inspecting Repositories

A repository (repo) is a storage location—online or on your network—containing RPM packages, metadata, and signing keys.

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2.1 View Enabled Repositories

sudo yum repolist
Sample output: 
repo id                             repo name
rhel-8-for-x86_64-appstream-rpms    Red Hat Enterprise Linux 8 for x86_64 - AppStream (RPMs)
rhel-8-for-x86_64-baseos-rpms       Red Hat Enterprise Linux 8 for x86_64 - BaseOS (RPMs)

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2.2 View Repository Details

Add -v for verbose details, including each repo’s URL and configuration file: 
sudo yum repolist -v
Key fields in the output:
  • Repo-baseurl: URL where YUM fetches packages
  • Repo-filename: Local file under /etc/yum.repos.d/

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3. Enabling and Disabling Repositories

Some packages reside in optional or specialized repos.

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3.1 List All Repositories

sudo yum repolist --all

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3.2 Using Subscription Manager

Enable or disable by repo ID: 
sudo subscription-manager repos --enable   rhel-8-for-x86_64-codeready-builder-rpms
sudo subscription-manager repos --disable  rhel-8-for-x86_64-codeready-builder-rpms

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3.3 Using yum-config-manager

First, install yum-utils: 
sudo yum install yum-utils
Then enable or disable: 
sudo yum-config-manager --enable  some-repo-id
sudo yum-config-manager --disable some-repo-id

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4. Adding a Custom Repository

To add a third-party or local repo: 
sudo yum install yum-utils
sudo yum-config-manager --add-repo https://download.docker.com/linux/rhel/docker-ce.repo
# Or from a local network path
sudo yum-config-manager --add-repo http://192.168.1.220/BaseOS.repo
This creates a .repo file in /etc/yum.repos.d/. Verify it: 
sudo yum repolist -v | grep Repo-filename

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5. Understanding a .repo File

Open the Docker repo for inspection: 
sudo vi /etc/yum.repos.d/docker-ce.repo

[docker-ce-stable]
name=Docker CE Stable - $basearch
baseurl=https://download.docker.com/linux/rhel/$releasever/$basearch/stable
enabled=1
gpgcheck=1
gpgkey=https://download.docker.com/linux/rhel/gpg
FieldDescription
[repo-id]Unique identifier in brackets
name=Human-readable repository name
baseurl=URL to fetch packages
enabled=1 to enable, 0 to disable
gpgcheck=1 enforces GPG signature checking (recommended)
gpgkey=URL or file path to the GPG public key
To completely remove a repository, delete its file: 
sudo rm /etc/yum.repos.d/docker-ce.repo

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6. Searching for Packages

If you’re unsure of the exact name, use yum search. Single terms match any, quotes require both terms. 
# Matches "web" OR "server"
sudo yum search web server

# Matches packages containing both "web" AND "server"
sudo yum search 'web server'
Example result: 
nginx.x86_64 : A high performance web server and reverse proxy server

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7. Viewing Package Information

Inspect a package before installation: 
sudo yum info nginx
Sample output: 
Name        : nginx
Version     : 1.20.1
Release     : 1.el8
Architecture: x86_64
Summary     : High performance web server and reverse proxy
Description : NGINX is a web server and a reverse proxy server for HTTP, SMTP, POP3 and
              IMAP protocols with a focus on high concurrency, performance and low
              memory usage.

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8. Installing, Reinstalling, and Removing Packages

Install a new package: 
sudo yum install nginx
Reinstall (e.g., to restore missing config files): 
sudo yum reinstall nginx
Remove a package and its dependencies: 
sudo yum remove nginx
Clean up unneeded dependencies: 
sudo yum autoremove

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9. Managing Package Groups

YUM supports predefined groups (e.g., “Server with GUI”).
CommandDescription
sudo yum group listList available groups
sudo yum group list --hiddenInclude hidden groups
sudo yum group install 'Group Name'Install a specific group
sudo yum group remove 'Group Name'Remove a specific group
Example: 
sudo yum group install 'Server with GUI'

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10. Installing from a Local RPM File

After downloading an RPM: 
sudo wget https://download.nomachine.com/download/7.7/Linux/nomachine_7.7.4_1_x86_64.rpm
sudo yum install ./nomachine_7.7.4_1_x86_64.rpm
Remove it when no longer needed: 
sudo yum remove nomachine

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11. Updating and Upgrading Packages

Check for available updates: 
sudo yum check-update
Apply all updates: 
sudo yum update
If a kernel or critical component is updated, reboot to ensure changes take effect:
sudo reboot

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