Installing an Existing Host

1. Boot into the NixOS Live USB.

2. Verify target disk ID: Ensure the disk ID in hosts/desktop/disko.nix or hosts/laptop/disko.nix matches your target drive:

   ls -l /dev/disk/by-id/

3. Partition, format, and mount with Disko:

   sudo nix --extra-experimental-features "nix-command flakes" run github:nix-community/disko/latest -- --mode disko --flake github:fumoctl/ultix#<hostname>

   (Or clone the repo locally and use --flake .#<hostname>)

4. Initialize persistent user password:

   Because users.mutableUsers = false and hashedPasswordFile = "/persist/passwords/fumoctl" are enforced, you must seed the password hash into /persist before installing, or the account will be locked on first boot:

   sudo mkdir -p /mnt/persist/passwords
   

   nix-shell -p mkpasswd --run 'mkpasswd -m sha-512' | sudo tee /mnt/persist/passwords/fumoctl
   

   sudo chmod 600 /mnt/persist/passwords/fumoctl
   

5. (Optional) Restore SOPS Age master key:

   If you are setting up your own machine, restore your Age key before installing so private keys decrypt on first boot:

   sudo mkdir -p /mnt/persist/sops
   sudo nano /mnt/persist/sops/fumosops.key   # paste your AGE-SECRET-KEY-1...
   sudo chown -R 1000:1000 /mnt/persist/sops
   sudo chmod 700 /mnt/persist/sops
   sudo chmod 600 /mnt/persist/sops/fumosops.key

   Note: If installing without this key, the system still builds and installs completely fine; secrets decryption is skipped automatically.

6. Install NixOS:

   sudo swapon /mnt/.swapvol/swapfile
   sudo mkdir -p /mnt/var/tmp/nix-build
   sudo TMPDIR=/mnt/var/tmp/nix-build nixos-install --flake github:fumoctl/ultix#<hostname>

   (setting tmpdir avoids out of memory errors when building from source)

7. Reboot:

   reboot