Introduction

Linux has many many many (and many more) distributions. Needless to say, you have a lot of options to choose from. NixOS is one of those choices and in this article I will articulate my thought on why it is one of the better ones.

What is Nix?

All Linux distributions use a package manager to manage installed software on the system. Debian based distros use apt, Arch based systems use pacman, Fedora uses dnf and openSUSE uses zypper for package management. These package managers require you to imperatively install packages that you would like to use, either through an app store or the terminal.

The nix package manager however, allows you to declaratively manage your packages in a reproducible manner. This means that every single package can be declared in a file, and the package is installed based on the configuration. You could even take the same file to another system that has the nix package manager install all the software used in the first system through a single command.

What is NixOS?

NixOS is a free and open source Linux distribution based on the nix package manager. What makes it unique in the sea of available distributions is that the system can be configured in the same manner you would configure packages in the nix package manager.

Imagine that!! Declaratively configuring your system in a functional and reproducible manner! You can configure your own hardware, software, services, and so much more, giving an easy way to control your system.

Nix also allows you to create and manage development environments through nix-shell which means you can do away with Docker.

One of the biggest advantages of nix is that if you ever have a system crash due to any reason whatsoever, and are unable to get into your system, you can always roll back to a previous version of your system. This gives you the freedom to experiment without the worry that you might end up having to reinstall your operating system and setting it up all over again.

The one con against all its pros is that this reproducibility and customizability comes at the cost of a steep learning curve, which I believe is a barrier that stops many from either trying it out or sticking with NixOS long enough to feel the benefits. This is made worse at times by the lack of documentation and learning resources. But with more learning resources coming up, that disadvantage no longer remains.

Installing NixOS

To install NixOS, you need a bootable drive with the NixOS iso image on it. Installing is as simple as plugging in the drive and booting the system from it. You can then follow the installation prompts and you will have your NixOS system in a few minutes. You will need an internet connection for the setup to complete.

Reboot your system after removing the boot drive and you can start playing around with your system configuration.

Searching Nix packages

After installing NixOS, you need to add packages that you wish to install. First you need to find the name of the package as is referenced in the nix repository. You can do this in a few ways.

1. Using the website

   You can open the website at search.nixos.org an search for any packages that you wish to install. This does require an internet connection.

2. Using the nix-env -qaP command

   If you want to look up packages without an internet connection, you can follow this method, though it is slow and takes up a lot of memory. Once the list is open, you can search for the package by typing / followed by the package name. To exit, press q.

3. Using the nix REPL

   Start the nix REPL using the command nix repl. Then type :load <nixpkgs> when the prompt for nix repl appears. This will load up all the packages in the nix repository. Type the name of the pagkage you want to search and use tab completion to see the available options.

Installing Packages

Once you have the name of the package you want to install, open up the file at /etc/nixos/configuration.nix with admin priviledges using the following command:

sudo nano /etc/nixos/configuration.nix

This file may look complex right now, but you only need to bother yourself with the packages section for now. Press Ctrl+F to search for environment.systemPackages and then press enter.

Here, you need to enter the name of the package you wish to install, say neovim. Once you have done that, it should look something like this:

environment.systemPackages = with pkgs; [
    neovim
];

Save this to the file using Ctrl+x. When prompted for the file name, press enter to keep the same name.

You can now install your package using this command:

sudo nixos-rebuild switch

This command will build a new version of your system and install. You don’t even need to reboot!

When you do reboot, you will see a new version of your system in the boot menu. By default, the latest build that you switch to is the one that is used to boot up.

Configuring the System

With NixOS, you can configure your system extensively by enabling or disabling services, hardware and programs. This means everything from boot configuration to network management is possible declaratively. You just need to know where to look.

The best advice I can give you is to open up the man page for NixOS Configuration by using man configuration.nix in your terminal and search for whatever you can think of editing.

Enabling services, hardware and more is as easy as below:

services.<service-name>.enable = true;
hardware.<hardware-name>.enable = true;

where <service-name> and <hardware-name> are the name of the service and hardware you want to enable respectively.

There might be more options you might want to configure, in which case you need to pass an attribute set to the element you want to configure. For example, if you want to configure your firewall,

networking.firewall = {
    enable = true;
    allowedTCPPorts = {};
    allowedUDPPorts = {};
}

To see what attributes you can configure, you need to look up the man pages, same as to look for what to enable.

One more thing you want to note is that apart from system packages, there are also user packages which can only be accessed by a specific user. In the base configuration, it looks something like this:

users.users.wrothmir = {
    isNormalUser = true;
    description = "wrothmir";
    extraGroups = [ "networkmanager" "wheel" ];
    packages = with pkgs; [
    ];
    shell = pkgs.zsh;
};

So you have the ability to set both system-wide and user-only installations and configure them how the user sees fit!

End Remarks

You now have enough knowledge to get started on tinkering with NixOS. I highly encourage you to use NixOS and tweak the system as much as you like to get one that is suited perfectly to you. If you would like to learn more about Nix and NixOS, do go through the listed learning resources below.

1. Nix Language Basics
2. A Tour of Nix
3. Nix Language Reference
4. Noogle