APT (Advanced Package Tool)

APT is the command-line package management tool used by Debian, Ubuntu, Linux Mint, and their derivatives. It handles the retrieval, configuration, and installation of software packages from repositories.

How APT Works

APT does not install .deb files directly; it is a higher-level tool that interacts with dpkg (the underlying package manager). APT's main advantage is dependency resolution. If you install a package that requires three other libraries, APT automatically downloads and installs those libraries first.

Package repositories are configured in /etc/apt/sources.list and files within /etc/apt/sources.list.d/.

Essential Commands

# Update the local list of available packages (Do this before installing anything!)
sudo apt update

# Upgrade all installed packages to their latest versions
sudo apt upgrade

# Install a new package
sudo apt install nginx

# Remove a package (keeps configuration files)
sudo apt remove nginx

# Remove a package AND its configuration files
sudo apt purge nginx

# Remove dependencies that were automatically installed and are no longer needed
sudo apt autoremove

# Search for a package by name or description
apt search "web server"

apt vs. apt-get

You may see tutorials using apt-get. apt is a newer command designed specifically for interactive use by humans, combining the most commonly used features of apt-get and apt-cache and adding progress bars. For scripts, apt-get is still preferred as its output is more stable, but for daily use, prefer apt.