YUM (Yellowdog Updater Modified) — Package Management for Legacy RHEL Systems¶

YUM (Yellowdog Updater Modified) is the traditional package manager used by older versions of Red Hat Enterprise Linux (RHEL), CentOS, Oracle Linux, and other RPM-based Linux distributions. Although modern distributions use DNF as the default package manager, YUM remains important because many enterprise environments continue to run legacy Linux servers. Understanding YUM is essential for maintaining older production systems and supporting enterprise infrastructure.

Learning Path¶

Linux Mastery → Module 7: Package Management → Lesson 3

Difficulty: Beginner → Intermediate

Reading Time: 50 Minutes

Course Progress

Course: Linux Mastery

Module: Package Management

Lesson: 3 of 10

What You'll Learn¶

After completing this lesson, you'll be able to:

Understand YUM
Install and remove packages
Update software
Search package repositories
Manage repositories
View package history
Compare YUM and DNF
Maintain legacy Linux systems

Prerequisites¶

Complete:

Module 1 – Linux Fundamentals
Module 2 – Linux Command Line Essentials
Module 3 – Text Processing
Module 4 – File Management and Permissions
Module 5 – Users and Groups
Module 6 – Process Management
Module 7 Lessons 1–2

Why Learn YUM?¶

Although DNF has replaced YUM on modern systems, many organizations still run:

RHEL 7
CentOS 7
Oracle Linux 7
Legacy enterprise servers

As a Linux administrator or DevOps engineer, you'll often encounter environments where YUM is still the standard package manager.

What is YUM?¶

YUM stands for:

Yellowdog Updater Modified

It is a package manager for RPM-based Linux distributions.

YUM works with:

.rpm

packages and automatically:

Resolves dependencies
Downloads packages
Installs software
Removes packages
Updates software

Package Management Workflow¶

YUM Command
      │
      ▼
Repository
      │
      ▼
Download Package
      │
      ▼
Resolve Dependencies
      │
      ▼
Install Package
      │
      ▼
Ready to Use

Check for Available Updates¶

sudo yum check-update

This refreshes package metadata and displays available package updates.

Install a Package¶

Install NGINX.

sudo yum install nginx

Install multiple packages.

sudo yum install git curl vim

YUM automatically installs required dependencies.

Update Packages¶

Update all installed packages.

sudo yum update

Update a specific package.

sudo yum update nginx

Remove a Package¶

sudo yum remove nginx

Unused dependencies may remain and should be reviewed separately.

Search for Packages¶

yum search nginx

Example:

nginx

nginx-all-modules

nginx-filesystem

View Package Information¶

yum info nginx

Displays:

Version
Repository
Description
Size
Architecture

List Installed Packages¶

yum list installed

Find a package.

yum list installed | grep nginx

List Enabled Repositories¶

yum repolist

Example:

base

extras

updates

Clean Package Cache¶

Remove cached packages.

sudo yum clean packages

Remove all cached metadata and packages.

sudo yum clean all

Rebuild the cache.

sudo yum makecache

View Package History¶

Display transaction history.

yum history

View a specific transaction.

yum history info <ID>

Undo a transaction.

sudo yum history undo <ID>

Common Commands¶

Install package.

sudo yum install nginx

Update packages.

sudo yum update

Remove package.

sudo yum remove nginx

Search package.

yum search nginx

Package information.

yum info nginx

List repositories.

yum repolist

Real Production Examples¶

Install Git.

sudo yum install git

Install Apache.

sudo yum install httpd

Update production server.

sudo yum update

Install Docker.

sudo yum install docker

Production Perspective¶

YUM is commonly found on:

RHEL 7
CentOS 7
Oracle Linux 7
Older enterprise Linux servers
Legacy production environments

Although DNF is now the default package manager on newer releases, many enterprise systems continue to rely on YUM.

Hands-on Lab¶

Task 1¶

List enabled repositories.

yum repolist

Task 2¶

Search for Git.

yum search git

Task 3¶

View package details.

yum info git

Task 4¶

Check for updates.

sudo yum check-update

Task 5¶

Install Git (if not already installed).

sudo yum install git

Task 6¶

Verify installation.

git --version

Task 7¶

View package history.

yum history

Task 8¶

Clean the package cache.

sudo yum clean all

Command Deep Dive¶

Command	Purpose	Production Example
`yum install`	Install packages	Software deployment
`yum update`	Update packages	Security patching
`yum remove`	Remove packages	Cleanup
`yum search`	Search packages	Package discovery
`yum info`	Package details	Verification
`yum repolist`	View repositories	Repository management
`yum history`	View transactions	Auditing
`yum clean all`	Clear cache	Maintenance

YUM vs DNF¶

Feature	YUM	DNF
Default On	RHEL/CentOS 7	RHEL/Rocky/AlmaLinux 8+ and Fedora
Package Format	`.rpm`	`.rpm`
Dependency Resolution	Good	Improved
Performance	Good	Faster and more efficient
Transaction History	✅	✅
Active Development	Maintenance only	Active development

Production Troubleshooting Scenario¶

Scenario

A system administrator attempts to install Docker.

sudo yum install docker

Error:

No package docker available.

Investigation:

yum repolist

The required repository is not enabled.

After enabling the correct repository:

sudo yum makecache

sudo yum install docker

The installation completes successfully.

Best Practices¶

Apply package updates regularly.
Use only trusted repositories.
Clean the package cache periodically.
Review package dependencies before installation.
Plan migrations from YUM-based systems to DNF-supported platforms where appropriate.

Common Mistakes¶

❌ Using outdated repositories.

✅ Avoid using outdated repositories when a safer approach exists.

❌ Ignoring security updates.

✅ Always review security updates.

❌ Installing packages from untrusted sources.

✅ Avoid this mistake: installing packages from untrusted sources.

❌ Assuming every RPM-based distribution uses DNF.

✅ Older enterprise systems may still rely on YUM.

Interview Questions¶

Beginner¶

What does YUM stand for?
Which Linux distributions traditionally use YUM?
Which command installs a package?
How do you search for a package?

Intermediate¶

What is the difference between yum update and yum check-update?
How do you view enabled repositories?
How do you view package history?
How do you remove a package?

Architect Level¶

Why is YUM still relevant in enterprise environments?
How would you manage package updates across legacy RHEL servers?
What factors would you consider when migrating from YUM to DNF?

Summary¶

In this lesson, you learned:

YUM package management
Package installation
Package updates
Repository management
Package history
Cache management
Legacy enterprise Linux administration

YUM remains an important tool for maintaining older RPM-based Linux systems. While DNF has become the standard package manager on modern Red Hat-based distributions, understanding YUM enables you to support legacy enterprise environments and smoothly transition to newer platforms.

Key Takeaways¶

YUM is the traditional package manager for older RPM-based Linux distributions.
Use yum install to install software.
Use yum update to apply package updates.
Use yum search and yum info to discover packages.
Use yum repolist to view configured repositories.
Many enterprise environments continue to use YUM on legacy systems.

What's Next?¶

RPM (Red Hat Package Manager) — Managing RPM Packages in Linux

You'll explore:

What RPM is
Installing local RPM packages
Querying installed packages
Verifying package integrity
Viewing package contents
Differences between RPM and YUM/DNF
Production package management using RPM

Understanding RPM will help you work directly with package files and troubleshoot package-related issues on RPM-based Linux systems.