Using APT (Debian/Ubuntu)

APT (Advanced Package Tool) is the package manager for Debian, Ubuntu, and related distributions. It's what you'll use most often.

Essential APT Commands

Command	Description
apt update	Update package list
apt upgrade	Upgrade installed packages
apt install	Install packages
apt remove	Remove packages
apt search	Search for packages
apt show	Show package info

Updating Package Lists

Always update before installing:

sudo apt update

This downloads the latest package information from repositories, but doesn't install anything.

Installing Packages

sudo apt install package-name
sudo apt install vim git curl

Install Specific Version

sudo apt install package=version

Install Without Prompts

sudo apt install -y package-name

Upgrading Packages

Upgrade All

sudo apt upgrade

Full Upgrade (handles dependencies better)

sudo apt full-upgrade

Upgrade Specific Package

sudo apt install --only-upgrade package-name

Removing Packages

Remove Package (keep config)

sudo apt remove package-name

Remove Package and Config

sudo apt purge package-name

Remove Unused Dependencies

sudo apt autoremove

Searching for Packages

apt search keyword
apt search "web server"

Package Information

apt show package-name
apt policy package-name    # Shows versions

Listing Packages

apt list --installed          # All installed
apt list --upgradeable        # Can be upgraded
apt list package-name         # Specific package

Common apt Commands

Update and Upgrade Together

sudo apt update && sudo apt upgrade -y

Install Build Tools

sudo apt install build-essential

Install Development Headers

sudo apt install libssl-dev

Clean Up

sudo apt autoremove           # Remove unused
sudo apt autoclean            # Clear old packages
sudo apt clean                # Clear all cached packages

apt vs apt-get

apt is newer and combines features:

apt	apt-get/apt-cache
apt install	apt-get install
apt search	apt-cache search
apt show	apt-cache show
apt list	dpkg -l

Use apt for interactive use, apt-get in scripts.

Handling Errors

Broken Packages

sudo apt --fix-broken install

Lock File Error

# Wait for other apt to finish, or:
sudo rm /var/lib/dpkg/lock-frontend
sudo dpkg --configure -a

Practical Examples

Install LAMP Stack

sudo apt update
sudo apt install apache2 mysql-server php

Install Node.js

sudo apt install nodejs npm

Install Python Tools

sudo apt install python3 python3-pip python3-venv

Key Takeaways

• Always apt update before installing
• Use apt install to add packages
• Use apt remove or apt purge to remove
• apt autoremove cleans up unused dependencies
• Combine commands: apt update && apt upgrade -y