nixconf

update existing machine

nixos-rebuild switch --flake .#hostname --target-host root@hostname --build-host root@hostname --use-remote-sudo --substitute-on-destination

boot into NixOS install media, configure networking, set a password for root
set up partitioning, mount everything under /mnt as normal
on the new machine, run nixos-generate-config --root /mnt and copy the resulting /mnt/etc/nixos/hardware-configuration.nix into the system dir in this repo

then, to run the install:

nix run github:nix-community/nixos-anywhere -- --flake .#hostname --phases install root@ipaddress

check everything looks good, then reboot