Common NixOS instructions

• Update flake

$ sudo nix flake update

• Rebuilt flake

$ sudo nixos-rebuild switch --flake '.#ideapad'

• List generations

$ sudo nix-env -p /nix/var/nix/profiles/system --list-generations

• Remove old generations

$ sudo nix-env -p /nix/var/nix/profiles/system --delete-generations +3
$ sudo nix-env -p /nix/var/nix/profiles/system --delete-generations old
$ sudo nix-env -p /nix/var/nix/profiles/system --delete-generations 7d

• Free up some disk space

$ nix-collect-garbage