NixOS

$ nixos-rebuild --flake . switch

nix-darwin

Installation

First build/installation:

$ nix \
  --extra-experimental-features "nix-command flakes" \
  run nix-darwin/master#darwin-rebuild -- --flake . switch

Rebuilding

$ darwin-rebuild --flake . switch

home-manager-only

# Can't just use `--extra-experimental-features` for some reason because some
# subprocesses are invoked without passing along that arg.
mkdir -p ~/.config/nix/
echo "experimental-features = nix-command flakes" > ~/.config/nix/nix.conf

nix run home-manager/master -- --flake . switch