nix-config

A personal Nix flake managing system (NixOS) and user (Home Manager) configuration across several hosts and platforms: NixOS desktops/laptops, an aarch64 NixOS VM, macOS (aarch64-darwin), and Pop!_OS as a Home-Manager-only target.

There is no application code here — every change is configuration that gets evaluated by Nix and activated on a host.

Contents

• Overview
• Initial setup
• Installing Nix
• NixOS setup
• Home Manager (standalone)
• macOS setup
• Everyday commands
• Inspecting changes
• Services
• Application configuration
• License

Overview

Configuration is split into two output sets in flake.nix, keyed by host:

• nixosConfigurations.<host> — full NixOS systems.
• homeConfigurations."mir@<host>" — standalone Home Manager (used on macOS and Pop!_OS, and on NixOS hosts too, since Home Manager is not imported as a NixOS module here).

The repo is expected to live at ~/dev/nix-config. The bin/rename-and-link.sh helper backs up a system-generated file and replaces it with a symlink into this repo, bringing it under version control.

Initial setup

These steps are common to every platform.

Generate SSH keys

Generate a key on the new system so it can clone this repo from GitHub, then add the public key to your GitHub account.

ssh-keygen -t ed25519 -C "abcdef@gmail.com"
cat ~/.ssh/id_ed25519.pub

Clone the repository

git may not be available yet, so pull it into a temporary nix shell for the session instead of installing it.

nix shell --extra-experimental-features nix-command --extra-experimental-features flakes nixpkgs#git
git clone git@github.com:nazmir/nix-config.git

Installing Nix

NixOS already ships with Nix. On non-NixOS systems (macOS, Pop!_OS) install it first:

# Installs upstream Nix (not the Determinate distribution) via the
# Determinate Systems installer.
curl -fsSL https://install.determinate.systems/nix | sh -s -- install

NixOS setup

Bring the system-generated config files under repo control, then rebuild. The rename-and-link.sh script backs up the source file (arg 1) and links it to the target (arg 2).

Note: Don't rename the hardware config to a machine-specific name the way configuration.nix is renamed — keep it as hardware-configuration.nix.

sudo ~/dev/nix-config/bin/rename-and-link.sh /etc/nixos/configuration.nix ~/dev/nix-config/nixos/hosts/pc/configuration-pc.nix
sudo ~/dev/nix-config/bin/rename-and-link.sh /etc/nixos/hardware-configuration.nix ~/dev/nix-config/nixos/hosts/pc/hardware-configuration.nix
sudo nixos-rebuild switch --flake $HOME/dev/nix-config/.#mir-nixos-pc

Home Manager (standalone)

Used on every host (NixOS, macOS, Pop!_OS). Link the generated config into the repo before the first switch.

cd ~/dev/nix-config

# Initialize Home Manager; places a config at ~/.config/home-manager/home.nix
nix run home-manager/master -- init --switch

# Drop the generated flake and link our host file in its place
rm ~/.config/home-manager/flake.*
~/dev/nix-config/bin/rename-and-link.sh ~/.config/home-manager/home.nix ~/dev/nix-config/home-manager/hosts/home-nixos.nix

# Initial evaluation with flakes
home-manager switch --flake ~/dev/nix-config/.#mir@mir-nixos-pc

macOS setup

macOS (aarch64-darwin) follows the shared flow — Initial setup, Installing Nix, and Home Manager (standalone) — with the macOS-specific notes below.

1. git comes from the Xcode Command Line Tools

   xcode-select --install

2. Home Manager uses the macOS host file and flake target when you reach the Home Manager step:

   ~/dev/nix-config/bin/rename-and-link.sh ~/.config/home-manager/home.nix ~/dev/nix-config/home-manager/hosts/home-mac.nix
   home-manager switch --flake ~/dev/nix-config/.#mir@mir-m4pro-mbp

3. Set fish as the login shell — see Fish shell under Application configuration.

4. Ghostty — the nixpkgs ghostty package is Linux-only, so the app itself is installed via Homebrew (declared in macos/Brewfile, see below), while its configuration is managed declaratively by Home Manager in home-manager/hosts/home-mac.nix.

5. Non-Nix channels — on macOS this repo runs standalone Home Manager (no nix-darwin), so the flake only manages Nix packages. Homebrew, global uv tools, and hand-downloaded apps are tracked separately under macos/. After the Home Manager switch, run:

   # Homebrew formulae + casks (and uv tools) — adopts already-installed apps
   brew bundle install --file=~/dev/nix-config/macos/Brewfile
   
   # Global uv tools, if you skipped brew or want them brew-independent
   while read -r t; do [ -n "$t" ] && [ "${t#\#}" = "$t" ] && uv tool install "$t"; done \
     < ~/dev/nix-config/macos/uv-tools.txt
   
   # Hand-downloaded / App Store apps — open the checklist and reinstall each
   open ~/dev/nix-config/macos/apps.md

   See macos/README.md for the full bootstrap order, how to re-snapshot state after installing new things, and when adopting nix-darwin becomes worthwhile.

Everyday commands

The nh helper (installed via Home Manager) is the preferred entrypoint for rebuilds.

nh os switch --ask          # Ask for confirmation before applying
nh home switch --ask
#home-manager switch --flake '.#mir@mir-nixos-pc'
nh home switch -c mir@mir-nixos-pc ./

# Specify the flake explicitly:
nh os switch --ask ~/dev/nix-config/.#mir-nixos-thinkpad

# Use the current hostname with an explicit flake path:
nh os switch --ask ~/dev/nix-config/

Update flake inputs

nix flake update

Garbage collection

nh clean all     # Clean OS and Home profiles
nh clean user    # Clean user profiles

Clean a specific profile:

nix profile list
nh clean profile -a nixGL   # nixGL is the profile name; -a asks for confirmation

Rebuild without nh

If the nh helper isn't installed yet (e.g. a fresh install):

sudo nixos-rebuild switch --flake $HOME/dev/nix-config/.#mir-nixos-thinkpad
home-manager switch --flake $HOME/dev/nix-config/.#mir@mir-nixos-thinkpad

Inspecting changes

Build the result before switching, then diff it against the running system:

sudo nixos-rebuild build --flake $HOME/dev/nix-config/.#mir-nixos-thinkpad

nvd diff /run/current-system/ ./result/
nvd diff $(ls -d1v /nix/var/nix/profiles/system-*-link|tail -n 2)   # Compare after a switch

nvd wraps nix store diff-closures with improved reporting. The underlying command is:

nix store diff-closures $(ls -d1v /nix/var/nix/profiles/system-*-link|tail -n 2)

Services

Tailscale

sudo tailscale up -authkey tskey-auth-KEY   # Get the key from the Tailscale console

Application configuration

The shell prompt uses starship, configured declaratively in home-manager/common.nix — no manual setup step is required.

Fish shell

Fish is installed and configured for every host via home-manager/common.nix. To make it the login shell:

• On NixOS, set it declaratively in the system config (users.users.<name>.shell = pkgs.fish).

• On non-NixOS systems (macOS, Pop!_OS), register and switch to the Home-Manager-provided fish:

  sudo sh -c 'echo $HOME/.nix-profile/bin/fish >> /etc/shells'
  chsh -s $HOME/.nix-profile/bin/fish

Doom Emacs

Install Doom Emacs, then run doom doctor to check for issues. Back up an existing ~/.emacs.d first:

mv ~/.emacs.d ~/.emacs.d.orig

Link the Doom configuration into the repo:

~/dev/nix-config/bin/rename-and-link.sh ~/.config/doom/ ~/dev/nix-config/.config/doom

Sway

~/dev/nix-config/bin/rename-and-link ~/.config/sway/config ~/.config/sway/config

Kitty

~/dev/nix-config/bin/rename-and-link ~/.config/kitty/ ~/dev/nix-config/.config/kitty
# The result will be in the current folder

License

Released under the MIT License — free to use, copy, and adapt.