Linux Package Managers

On Linux, you rarely download a .exe or .dmg installer. Instead, you use a package manager — a tool that downloads, installs, upgrades, and removes software while automatically handling all dependencies. It's like an app store, but for your entire system.

What is a Package?

A package is a compressed archive containing: the program's binary files, configuration files, documentation, and metadata (name, version, description, dependencies). Two major formats:

Format	Extension	Used by	Low-level tool
Debian	.deb	Ubuntu, Debian, Mint	dpkg
RPM	.rpm	Fedora, RHEL, openSUSE	rpm
Pacman	.pkg.tar.zst	Arch, Manjaro	pacman

Repositories — Where Packages Come From

Where does apt actually download software from? From repositories — servers maintained by your distribution. Ubuntu's official repos are at archive.ubuntu.com. The list of repos your system knows about lives in /etc/apt/sources.list and /etc/apt/sources.list.d/.

# View configured repos (Ubuntu/Debian)
cat /etc/apt/sources.list

# Add a third-party PPA (Ubuntu)
sudo add-apt-repository ppa:deadsnakes/ppa

# View repo list (Fedora)
dnf repolist

APT — Debian and Ubuntu

# Update local package index (always do this first)
sudo apt update

# Upgrade all installed packages
sudo apt upgrade

# Install a package
sudo apt install nginx

# Remove a package (keep config files)
sudo apt remove nginx

# Remove package AND config files
sudo apt purge nginx

# Search for a package
apt search python3

# Show package info
apt show nginx

# List installed packages
dpkg -l

apt update doesn't install anything — it just refreshes the local database of what versions are available. Always run it before installing.

DNF (Fedora) and Pacman (Arch)

# DNF (Fedora/RHEL)
sudo dnf update          # update all packages
sudo dnf install nginx   # install
sudo dnf remove nginx    # remove
dnf search nginx         # search

# Pacman (Arch Linux)
sudo pacman -Syu         # sync + update all
sudo pacman -S nginx     # install
sudo pacman -R nginx     # remove
sudo pacman -Ss nginx    # search

Dependency Resolution

What happens when a package needs another package? The package manager reads each package's dependency list and automatically installs everything needed. If you install a web app that needs Python, nginx, and PostgreSQL, the package manager figures out the full dependency tree and installs them all in the right order.

This is why package managers are so powerful compared to manual installs — you never end up with "DLL hell" where software can't find the libraries it needs.

Universal Formats: Snap, Flatpak, AppImage

These newer formats bundle all dependencies into one package, working across distributions:

Format	Company	Sandboxed?	Best for
Snap	Canonical (Ubuntu)	Yes	Desktop apps, servers
Flatpak	Community	Yes	Desktop GUI apps
AppImage	Community	No	Portable, no install needed