NixOS Documentation

Complete reference for NixOS and the Nix ecosystem, auto-generated from official repositories:

• nix.dev — tutorials, guides, best practices
• NixOS Manual — from NixOS/nixpkgs
• Nix Pills — progressive learning series
• Release Wiki — NixOS release process

The references/ directory contains full, unmodified documentation from those sources, updated daily.

Directives

• Base all answers on the official NixOS documentation in the reference files below.
• Use correct Nix language syntax (attribute sets, let-in, with, inherit, etc.).
• Distinguish between NixOS module options (services.nginx.enable = true;) and Nix language expressions (pkgs.mkDerivation { ... }).
• Show configuration examples using current NixOS syntax (configuration.nix or flake-based configs).
• When flakes are relevant, show both the classic (channels) and flakes approach if applicable.
• For packaging, prefer the callPackage pattern over raw import.

Reference Files

Identify the topic from the user's question, then read the matching reference file:

Getting Started

Nix Language & Concepts

NixOS Configuration

NixOS Administration

NixOS Development

Packaging & Build

Tutorials

Guides & Recipes

Release Process

Live Fetching

When reference files are insufficient, fetch the latest docs from raw GitHub:

nix.dev

https://raw.githubusercontent.com/NixOS/nix.dev/master/source/<path>.md

NixOS Manual (nixpkgs)

https://raw.githubusercontent.com/NixOS/nixpkgs/master/nixos/doc/manual/<section>/<file>.md

Nix Pills

https://raw.githubusercontent.com/NixOS/nix-pills/master/pills/<NN>-<slug>.md

Strategy

1. Identify the topic from the user's question.
2. Read the matching reference file from the tables above.
3. Answer with correct Nix syntax and configuration.nix / flake.nix examples.
4. If more detail is needed, fetch from the corresponding raw GitHub URL.
5. For beginners, recommend starting with references/first-steps.md or references/nix-pills.md.
6. For troubleshooting, check references/troubleshooting.md and references/faq.md first.
7. For NixOS system issues, check references/nixos-administration.md.

Quick Reference

Config file location

/etc/nixos/configuration.nix (classic) or flake.nix (flakes)

Rebuild system

sudo nixos-rebuild switch          # apply config
sudo nixos-rebuild test            # apply without adding to bootloader
sudo nixos-rebuild build           # build only
sudo nixos-rebuild boot            # apply on next boot

Nix shell (ad-hoc packages)

nix-shell -p python3 git vim       # classic
nix shell nixpkgs#python3 nixpkgs#git  # flakes

Nix develop (dev environment)

nix develop                        # from flake.nix devShell
nix-shell                          # from shell.nix

Search packages

nix search nixpkgs firefox
# or https://search.nixos.org/packages

Garbage collection

nix-collect-garbage -d             # delete all old generations
nix store gc                       # flakes equivalent
sudo nix-collect-garbage -d        # also clean system profiles

Flake basic structure

{
  inputs = {
    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
  };
  outputs = { self, nixpkgs }: {
    nixosConfigurations.hostname = nixpkgs.lib.nixosSystem {
      system = "x86_64-linux";
      modules = [ ./configuration.nix ];
    };
  };
}

NixOS module syntax

{ config, pkgs, ... }:
{
  services.nginx.enable = true;
  environment.systemPackages = with pkgs; [ vim git firefox ];
  networking.firewall.allowedTCPPorts = [ 80 443 ];
  users.users.myuser = {
    isNormalUser = true;
    extraGroups = [ "wheel" "networkmanager" ];
  };
}