NixOS Crash Course

Introduction

Welcome to the NixOS Crash Course! Think of this as the Ron Popeil approach to Linux: "Set it and forget it." While NixOS may have a steeper learning curve than other distributions, it rewards you with unparalleled reproducibility and flexibility.

This guide will walk you through setting up NixOS from a fresh install, customizing it with packages, and leveraging Home Manager for user-level configuration. Let’s get started!

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Who Uses NixOS?

NixOS is popular among:

• Developers and DevOps Engineers who love reproducible builds and deployments.
• Linux Enthusiasts who enjoy tweaking and customizing their setups.
• System Administrators looking for a declarative approach to configuration.

If you value consistency and want your configurations to work across machines, NixOS might be for you!

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Prerequisites

Before diving in, ensure you have:

• A fresh NixOS installation. If you’re new to NixOS, check out the official installation guide or simply download the ISO from here.
  • Optional: A Linux-compatible Wi-Fi adapter like the Alfa AWUS036ACHM. NixOS requires an internet connection during installation. If you’re unsure whether your Wi-Fi card is supported by the Linux kernel, consider using an adapter.
  • Make sure to allow un-free software during installation unless you’re certain you don’t need it. This typically helps with drivers and hardware compatibility.
• A willingness to tinker and learn!

Note: Some configurations, like for older MacBooks (e.g., a 2015 MacBook Air), may require additional setup for components like webcams.

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NixOS Basics

Nix is a package manager, and NixOS is a Linux distribution built around it. Instead of manually managing configurations, you declare your system’s state in configuration files. Think of it as coding your system into existence.

Key concepts:

• Declarative Configuration: Define your system in files.
• Reproducibility: Replicate configurations on different machines.
• Atomic Upgrades and Rollbacks: Easily revert changes.

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Step-by-Step Guide

1. Install a Text Editor

For editing configuration files, you’ll need a text editor. If Nano isn’t your preference, install Vim temporarily:

nix-shell -p vim

This creates a temporary shell with Vim, removed after the session ends.

2. Change the Hostname

Set your system’s hostname in /etc/nixos/configuration.nix:

networking.hostName = "nebulaNugget";

Test the change:

sudo nixos-rebuild test

Apply it permanently:

sudo nixos-rebuild switch

3. Add Essential Packages

Add packages under environment.systemPackages in configuration.nix:

environment.systemPackages = with pkgs; [
  vim
  wget
  firefox
];

Rebuild your system:

sudo nixos-rebuild switch

Packages and options are found here. There are loads!:

• search.nixos.org

4. Edit Configurations as a User

For convenience, move your NixOS configuration directory to your home folder:

mkdir ~/etc
sudo mv /etc/nixos ~/etc/
sudo chown -R $(id -un):users ~/etc/nixos
sudo ln -s ~/etc/nixos /etc/

This lets you edit configurations without switching to root. I recommend initializing this folder as a private repository. This makes management really easy.

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Home Manager Setup

Home Manager allows you to manage user-level configurations declaratively. This method is installing Home Manager as a NixOS Module.

1. Add the Home Manager Channel

Add the Home Manager channel matching your NixOS version:

sudo nix-channel --add https://github.com/nix-community/home-manager/archive/release-24.11.tar.gz home-manager
sudo nix-channel --update

Learn more about channels here.

2. Enable Home Manager in configuration.nix

Add the Home Manager module to imports:

imports = [
  <home-manager/nixos>
];

3. Configure Home Manager

Define user-specific configurations:

home-manager.users.phil = {
  home.stateVersion = "24.11";
  programs.vscode = {
    enable = true;
    package = pkgs.vscodium;
    extensions = with pkgs.vscode-extensions; [
      bbenoist.nix
      kamadorueda.alejandra
    ];
  };
  programs.chromium = {
    enable = true;
    extensions = [
      "nngceckbapebfimnlniiiahkandclblb" # Bitwarden extension ID
    ];
  };
};

The VSCode extensions are from search.nixos.org, The Chrome extensions are the code at the end of its URL, like this for Bitwarden: nngceckbapebfimnlniiiahkandclblb

Apply changes:

sudo nixos-rebuild switch

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Maintenance Tips

Updating Channels and Packages

Keep your system up to date:

sudo nix-channel --update
sudo nixos-rebuild switch --upgrade

Garbage Collection

Remove unused packages and generations:

sudo nix-collect-garbage -d

Learn more here.

Rollbacks

If a configuration causes issues, revert to a previous generation via GRUB or:

sudo nix-env --rollback

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Resources

• Official Documentation: NixOS Manual
• Community Wiki: NixOS Wiki
• Support: Join the NixOS Discourse or Matrix chat.

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Conclusion

With this guide, you’re well on your way to mastering NixOS. Its declarative, reproducible approach can transform how you manage systems. Experiment, learn, and enjoy the journey!

Happy hacking!