📦 Day 3 of #150DaysOfDevOps – Introduction to Linux Package Management

Package management is at the heart of Linux system administration. Whether you're installing software, updating dependencies, or maintaining a clean environment, package managers make life easier for DevOps professionals.

In this blog, we'll cover key package managers used in Debian-based and RedHat-based Linux distributions:

🤔 What is a Package?

A package is a compressed archive that contains all the files needed for a software to run: binaries, libraries, config files, metadata, and more.

For example:

• gimp.deb → for Debian-based systems

• firefox.rpm → for RedHat-based systems

⚙️ Why Package Managers?

With hundreds of Linux distributions and diverse libraries/tools, direct installation of packages often fails due to dependency hell. Package managers:

• Automate dependency resolution

• Ensure system compatibility

• Streamline software installation and upgrades

🐧 Package Managers by Distribution

🔴 RPM (Red Hat Package Manager)

RPM is a low-level tool used in RedHat-based distributions.

Common Commands:

# Install a package
sudo rpm -ivh package.rpm

# Remove a package
sudo rpm -e package-name

# Query installed packages
rpm -qa | grep wget

❌ Limitation:

Does not resolve dependencies on its own.

🟠 YUM (Yellowdog Updater Modified)

YUM is a high-level package manager that wraps RPM and handles dependencies automatically.

YUM Commands:

# Install
sudo yum install httpd -y

# Remove
sudo yum remove httpd

# Update one package
sudo yum update telnet

# Update all packages
sudo yum update

# List repositories
yum repolist

# Check package for a command
yum provides scp

Repository Location:

/etc/yum.repos.d/*.repo

🟢 DPKG (Debian Package Manager)

DPKG is the low-level tool for .deb packages.

Common Commands:

# Install a package
sudo dpkg -i package.deb

# Remove a package
sudo dpkg -r package-name

# List installed packages
dpkg -l

# Show package status
dpkg -s package-name

❌ Limitation:

No dependency management — installs fail if dependencies are missing.

🔵 APT (Advanced Package Tool)

APT is a high-level tool for Debian-based systems that resolves dependencies automatically.

APT Commands:

# Update repo index
sudo apt update

# Upgrade all packages
sudo apt upgrade

# Install a package
sudo apt install gimp

# Remove a package
sudo apt remove gimp

# Search a package
apt search telnet

Repository File:

/etc/apt/sources.list

⚔️ APT vs APT-GET

🔍 Final Thoughts

• Use RPM + YUM on RHEL/CentOS

• Use DPKG + APT on Ubuntu/Debian

• Prefer high-level tools (yum, apt) for easier dependency handling

• Know the config files: /etc/yum.repos.d/, /etc/apt/sources.list

🧠 Advanced Tips

✅ Using yum history to track package operations

# View YUM transaction history
yum history

# Undo a transaction (e.g., ID 15)
yum history undo 15

✅ Cleaning up unused packages and cache

# Remove old/unused packages
sudo yum autoremove

# Clean up YUM cache
sudo yum clean all

# Clean up APT cache
sudo apt autoremove
sudo apt clean

✅ Simulating package installation (dry-run)

# Simulate with APT (dry-run)
sudo apt install <package-name> --dry-run

# With YUM (dry-run equivalent using --assumeno)
sudo yum install <package-name> --assumeno

✅ Lock a package version (APT-based)

# Prevent a package from upgrading
sudo apt-mark hold <package-name>

# Remove the lock
sudo apt-mark unhold <package-name>

✅ Find which package owns a file

# RPM-based
rpm -qf /bin/ls

# APT-based
dpkg -S /bin/ls