Upgrading NixOS/changing channels

Note: sudo is usually needed for NixOS installations in the commands below. Check if the first command returns a valid url without using sudo. If yes, you probably don't have to/shouldn't use sudo from the following commands!

# View current NixOS channel
sudo nix-channel --list | grep nixos

# Set new NixOS channel/upgrade NixOS
sudo nix-channel --add https://channels.nixos.org/nixos-25.11 nixos

# Rebuild with --upgrade, set on boot to be thorough
sudo nixos-rebuild boot --upgrade

# Reboot the system
sudo reboot now

You can view the latest stable channel from the manual link below or checking the channel options in search.nixos.org!

Using packages from other channels

{ config, pkgs, ... }:

let
  unstable = import (builtins.fetchTarball
    "https://github.com/NixOS/nixpkgs/archive/nixos-unstable.tar.gz"
  ) {
    config.allowUnfree = true;
  };
in
{
  # Method 1: singular package from another channel 
  environment.systemPackages = with pkgs; [
    alacritty  # Default channel
    unstable.hyprlock  # From unstable
  ] ++ (with unstable; [
    # Method 2: Multiple packages from another channel
    stremio-linux-shell
    discord
  ]);
}