1from time to time run the following commands to remove stuff from old generations
 2```
 3# list old generations
 4sudo nix-env --list-generations --profile /nix/var/nix/profiles/system
 5
 6# remove old generations
 7sudo nix-env --profile /nix/var/nix/profiles/system --delete-generations 9 10 11 12 13 X...
 8
 9# remove old generations except the last 5 generations
10sudo nix-env --profile /nix/var/nix/profiles/system --delete-generations +5
11
12
13# to remove old programs
14nix-collect-garbage --delete-old
15```
16
17When stting up the config files in a system, remember to rename either the file `thinkpad-configuration.nix` or `surface-configuration.nix` files into `configuration.nix`.