Package Management

Beginner Linux Server
aptapt-getdpkgapt-cachesnap/etc/apt/sources.list

Objective

Install, update, remove, and manage software packages on Debian/Ubuntu using APT, understand repositories, and find package information.

Tools & Technologies

  • apt
  • apt-get
  • dpkg
  • apt-cache
  • snap
  • /etc/apt/sources.list

Key Commands

apt update && apt upgrade
apt install nginx
apt remove --purge nginx
dpkg -l | grep nginx
apt-cache search term

Architecture Overview

sequenceDiagram participant U as User participant APT as APT participant REPO as Repository\n(mirrors) participant DPKG as dpkg participant FS as Filesystem U->>APT: apt install nginx APT->>REPO: Download package index REPO-->>APT: Package metadata APT->>REPO: Download nginx.deb + deps REPO-->>APT: .deb files APT->>DPKG: Install packages DPKG->>FS: Extract files FS-->>U: nginx installed

Step-by-Step Process

01
Update & Upgrade

Always update the package index before installing or upgrading.

sudo apt update            # refresh package lists
sudo apt upgrade           # upgrade installed packages
sudo apt full-upgrade      # upgrade + remove blocking pkgs
sudo apt dist-upgrade      # similar, handles dependencies better
sudo apt autoremove        # remove unused dependencies
02
Install & Remove

Install individual packages or remove them cleanly.

sudo apt install nginx
sudo apt install -y curl wget git vim  # -y skips confirmation
sudo apt remove nginx               # remove but keep config
sudo apt remove --purge nginx       # remove including config
sudo apt autoremove                 # clean up orphaned deps
03
Search & Inspect

Find packages and get information about them.

apt-cache search nginx         # search by keyword
apt-cache show nginx           # package details
apt-cache depends nginx        # list dependencies
dpkg -l | grep nginx           # check if installed
dpkg -L nginx                  # list installed files
where-is nginx                 # find binary location
04
Manage Repositories

Add third-party repositories for software not in the main repo.

# View current repos
cat /etc/apt/sources.list
ls /etc/apt/sources.list.d/

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

# Add a repo manually
echo 'deb https://example.com/repo focal main' | sudo tee /etc/apt/sources.list.d/myrepo.list
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys KEYID
sudo apt update

Challenges & Solutions

  • apt update ≠ apt upgrade — update refreshes lists, upgrade installs updates
  • Removing without --purge leaves config files that may cause confusion on reinstall

Key Takeaways

  • apt list --upgradable shows pending updates
  • Hold a package at current version: apt-mark hold nginx