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Chapter 10.1 - apt (Debian/Ubuntu)

Learning Objectives​

By the end of this chapter, you will be able to:

  • Use apt to install packages
  • Update the system
  • Manage repositories
  • Resolve dependencies
  • Search for packages
  • Understand apt vs apt-get

What is apt?​

apt (Advanced Package Tool) is the package manager for Debian and Ubuntu.

Functions:

  • Package Installation/Removal
  • System Update
  • Dependency Management
  • Package Search

Basic Commands​

Update​

# Update package list
sudo apt update

# Upgrade installed packages
sudo apt upgrade

# Full upgrade (includes dependency changes)
sudo apt full-upgrade

# Update and upgrade in one command
sudo apt update && sudo apt upgrade

Installation​

# Install a package
sudo apt install package-name

# Install multiple packages
sudo apt install package1 package2 package3

# Install without confirmation
sudo apt install -y package-name

# Install specific version
sudo apt install package-name=version

Removal​

# Remove package (keeps config)
sudo apt remove package-name

# Remove package and config
sudo apt purge package-name

# Remove unused dependencies
sudo apt autoremove

# Clean cache
sudo apt clean
sudo apt autoclean

Search and Information​

# Search for package
apt search keyword

# Search by exact name
apt search --names-only package-name

# View package information
apt show package-name

# List installed packages
apt list --installed

# List available packages
apt list --upgradable

Information​

# Detailed information
apt show package-name

# Dependencies
apt depends package-name

# Dependent packages
apt rdepends package-name

# Package contents
dpkg -L package-name

Repositories​

Configuration Files​

# List repositories
cat /etc/apt/sources.list
ls /etc/apt/sources.list.d/

# Format
deb http://archive.ubuntu.com/ubuntu/ jammy main restricted
deb-src http://archive.ubuntu.com/ubuntu/ jammy main restricted

Add Repository​

# Method 1: File in sources.list.d/
echo "deb http://repo.example.com/ubuntu jammy main" | \
    sudo tee /etc/apt/sources.list.d/my-repo.list

# Add GPG key
wget -qO - http://repo.example.com/key.gpg | sudo apt-key add -

# Update
sudo apt update

PPA Repository (Ubuntu)​

# Add PPA
sudo add-apt-repository ppa:name/ppa

# Remove PPA
sudo add-apt-repository --remove ppa:name/ppa

# Update
sudo apt update

apt vs apt-get​

apt (Modern)​

# Modern interface, recommended
sudo apt update
sudo apt install
sudo apt upgrade
sudo apt search

apt-get (Classic)​

# Still functional
sudo apt-get update
sudo apt-get install
sudo apt-get upgrade

Difference:

  • apt is more user-friendly (progress bar, colors)
  • apt-get is more low-level
  • Use apt for daily use

Practical Examples​

Complete Installation​

# Update
sudo apt update

# Install package
sudo apt install nginx

# Verify installation
systemctl status nginx

# Check version
nginx -v

System Update​

#!/bin/bash
# Update script

echo "Updating package list..."
sudo apt update

echo "Upgrading packages..."
sudo apt upgrade -y

echo "Cleaning up..."
sudo apt autoremove -y
sudo apt autoclean

echo "Done!"

Search and Install​

# Search
apt search nginx

# View information
apt show nginx

# Install
sudo apt install nginx

# Verify
dpkg -l | grep nginx

Troubleshooting​

Broken Dependencies​

# Fix dependencies
sudo apt --fix-broken install

# Fully repair
sudo apt --fix-missing install
sudo dpkg --configure -a

Corrupted Cache​

# Clean cache
sudo apt clean
sudo apt autoclean

# Rebuild cache
sudo apt update

Locked Package​

# See processes using package
sudo lsof | grep package-name

# Force installation
sudo dpkg --force-depends -i package.deb

Summary​

In this chapter, you learned:

apt: Debian/Ubuntu package manager
Commands: update, upgrade, install, remove, search
Repositories: sources.list, sources.list.d/, PPA
Search: search, show, list
Problems: --fix-broken, clean, dpkg
Practice: Installation, update, maintenance

Next Steps​

Chapter 10.2: yum/dnf (Red Hat/CentOS)
Chapter 10.3: Compilation from Source

Chapter created on: December 2024