Dotfiles

To Update Local Dotfiles / Installed Packages

Assuming if you have completed all of the Getting Started instructions below, you should be able to run the following command to apply the dotfiles / installed package changes.

home-manager switch --impure --flake .#$HOMECONFIG_NAME

# OR

nix build .#homeManagerConfigurations.$HOMECONFIG_NAME.activationPackage && ./result/activate

# OR After applying at least once, using the alias
hmapply $HOMECONFIG_NAME

To update the packages for home-manager, simply run the nix-channel update and flake-lock updates first, then run the home-manager switch command above.

nix-channel --update
nix flake update ~/.config/nixpkgs

# OR
nxup

To check the updated list of $HOMECONFIG_NAME, run the following command and use the name immediately after the homeConfigurations. prefix

$ awk '/^        ###### HOMECONFIG PROFILES START/{p=1;next};/^        ###### HOMECONFIG PROFILES END/{p=0};p' ~/.config/nixpkgs/flake.nix | awk -F'=' '{print $1}' | awk '{$1=$1;print}'
linux_64
linux_headless_64
darwin_64

# OR After applying at least once, using the alias
hmls

NB: A word about the impurity and the --impure flag

The above advocates for --impure purely because we are using our $HOME and $USER env vars to switch the home-manager config. We could probably remove --impure if we set the username and homeDirectory for the respective homeConfigurations available, or just define a new homeConfiguration that does not use those.

NB2: Errors on first application

When applying the home-manager switch, occasionally Nix will fail to install the new home manager profile. Due to the a file conflict between home-manager-path and nix. An example of such a scenario here: nix-community/home-manager#2995

A workaround is to set the priority of the corresponding nix package to be 0, taking higher priority than home-manager-path

nix-env --set-flag priority 0 nix-2.10.3

Rollbacks, cleanups and other miscelleanous ops info

Rollbacks & Cleanups

Relevant Link: https://nix-community.github.io/home-manager/index.html#sec-usage-rollbacks

Home Manager as of time of writing does not support rollbacks explicitly but the following steps can be used to help with this:

# 1. Run the following commands to see the generation you'll want to rollback to
$ home-manager generations
2022-07-31 11:44 : id 3 -> /nix/store/c4nxmvixgan6iw3h4qyb35mrllip4rzc-home-manager-generation
2022-07-30 23:54 : id 2 -> /nix/store/6ybk9xq9i44v9afy27wwjpk2wz92z0cr-home-manager-generation
2022-07-30 13:52 : id 1 -> /nix/store/qh89xz60pdiwizzr7q2mijm7iv8mh7dg-home-manager-generation

# 2. Copy the store path of the generation you'll like to rollback to and run its `activate` script
# For example if we want to rollback to generation 1
$ /nix/store/qh89xz60pdiwizzr7q2mijm7iv8mh7dg-home-manager-generation/activate
Starting home manager activation

Cleaning up unused nix stores can be done via the following:

# First cleanup home-generations, can replace `now` with relative days such as '-30days` etc
home-manager expire-generations now
# OR the folowing after applying once
hmclean


nix-store --gc
# Or the following after applying once
nxclean

# The following to erase every generation for nix-store
nix-collect-garbage -d
# Or the following after applying once
nxcleandeep

Misc Info 1: Imperative Operations

Taken from: https://nixos.wiki/wiki/Nix#Imperative_Operations

nix environments also technically allow imperative operations, although the home-manager switch .#$HOMECONFIG_NAME should overwrite this

Below are some nix-env common commands used to run imperatively

nix search packagename # Searching for packages
nix-env -iA packagename # Installing a package, for example in `nix-shell`, you can run `nix-env -iA nixpkgs.custom_python310_with_defaults`
nix-env -q # List installed packages
nix-env -e packagename # Uninstall packages
nix-env -u # Upgrade packages
nix-env --list-generations # see nix-env generations
nix-env --delete-generations +3 # remove every generation except current + 2 older
nix-env --delete-generations old # remove all old generations
nix-channel --list # list all installed channels
nix-channel --update # update all nix channels
nix-channel --remove channelname # remove channel
nix-channel --add CHANNEL_URL channel_name # add a new channel to track, e.g. nix-channel --add https://nixos.org/channels/nixpkgs-unstable nixpkgs-unstable

Misc Info 2: Temporary Shell

Sometimes you'll want to try out temporary builds and not overwrite the current system, in this case nix allows us to drop into a temporary shell environment via nix-shell.

To drop into this shell, with the project's overlays applied, do the following:

# cd into the nixpkgs path (i.e. ~/.config/nixpkgs), the path for this repo
cd ~/.config/nixpkgs

# drop into the environment, this should take a while if its your first time as
# the store will take a while to fetch / build
# the packages required
nix-shell --pure

Getting Started (1) - Nix/Flakes/Home-Manager Installation

Install nix, there several recommendation that NixOS has, you can check here: https://nixos.org/download.html

Here is a general gist of the installation process:

Nix Installations comes in different flavours, multi-user installation and single-user installation.

# Multi-user installation
sh <(curl -L https://nixos.org/nix/install) --daemon

# Single user installation
sh <(curl -L https://nixos.org/nix/install) --no-daemon

The choice of installations determine how nix will be run. Under a multi-user installation, the nix store is owned by root and builds are done via special user accounts. Unprivileged users forward nix-commands as actions to the nix-daemon.

Multi-user installations have a few pros and cons over a single-user installation.

Pros

• Better build isolation (and that is what Nix is all about)
• Better security (a build can not write somewhere in your home)
• Sharing builds between users

Cons

• Requires root to run the daemon
• More involved installation (creation of nixbld* users, installing a systemd unit, ...
• Harder to uninstall

Installation recommendations

Linux

• multi-user installation is recommended if you are on Linux running systemd, with SELinux disabled and you can authenticate with sudo.
• single-user is recommended otherwise. /nix will be owned by the invoking user. You should run this under your usual user account, not as root. The script will invoke sudo to create /nix if it doesn’t already exist.

Windows via Windows Subsystem for Linux (WSL2)

• single-user installation is recommended

MacOS

• multi-user installation is recommended

Checking Nix Installation

$ nix-env --version
nix-env (Nix) 2.3.15

nix-channel --list

# Add nixpkgs unstable if not added automatically
nix-channel --add https://nixos.org/channels/nixpkgs-unstable nixpkgs
nix-channel --update

Nix Flakes Installation

Nix Flakes allows us to specify our dependencies in a declarative way

Ensure that nix >= 2.4, then add this line in the config path ~/.config/nix/nix.conf

experimental-features = nix-command flakes

Restart the nix-daemon

# On linux
sudo systemctl restart nix-daemon.service

# On MacOS
sudo launchctl stop org.nixos.nix-daemon
sudo launchctl start org.nixos.nix-daemon

More recent installations of nix should already come with flakes installed. To verify, check with the following command:

nix flake --help

home-manager installation

Add the following Home Manager channel.

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

Run the Home Manager installation command and create the first Home Manager generation:

NIX_PATH=$HOME/.nix-defexpr/channels:/nix/var/nix/profiles/per-user/root/channels${NIX_PATH:+:$NIX_PATH} nix-shell '<home-manager>' -A install

Getting Started (2) - Git Clone

Clone the repository to the following path ~/.config/nixpkgs.

Overwrite the git name and git email for this as well in this step

git clone git@github.com:lohvht/dotfiles.git ~/.config/nixpkgs

git config --add user.name "Victor Loh"
git config --add user.email vic94loh@hotmail.com

After that, proceed with the home-manager switch instruction at the start of the document

Getting Started (3) - Non nix/home-manager related settings

This repository consists of packages and dotfiles installations that can only be done at the $HOME level, as this is not a NixOS module.

While certain tools and packages (such as some language support for Python/Golang/Rust etc) can be installed here, others tools may require installation at a system level, such as via either your native package manager or manual installation.

Below in the following section are some of the starting points for some tools that I use

Docker installation

Install docker desktop here: https://docs.docker.com/get-docker/

Change Default Shell

1. Add the full path of the desired shell to the end of the /etc/shells file

Adding preinstall hooks automatically via direnv

The .envrc

export FOO=foo > .envrc

e.g.

echo '/home/myunixusername/.nix-profile/bin/zsh' >> /etc/shells
echo '/home/myunixusername/.nix-profile/bin/bash' >> /etc/shells

2. Change shell with the following

chsh -s ~/.nix-profile/bin/fish

Updating nix / nix packages / flake lockfile

https://nixos.org/manual/nix/stable/installation/upgrading.html

Nix Updating

For updating nix itself, these are the commands to run: Multi-user Nix users on macOS can upgrade Nix by running:

sudo -i sh -c 'nix-channel --update && nix-env -iA nixpkgs.nix && launchctl remove org.nixos.nix-daemon && launchctl load /Library/LaunchDaemons/org.nixos.nix-daemon.plist'

Single-user installations of Nix should run this:

nix-channel --update; nix-env -iA nixpkgs.nix nixpkgs.cacert

Multi-user Nix users on Linux should run this with sudo:

nix-channel --update; nix-env -iA nixpkgs.nix nixpkgs.cacert; systemctl daemon-reload; systemctl restart nix-daemon

Flake update lockfile

nix flake update ~/.config/nixpkgs

# After first apply
nxup