Why Does Nothing Work, 2024 ▶ NixOS Tutorials - Basic Maintenance

Basic NixOS skills to maintain your machine.

Tldr

After watching this I added automatic garbage collection, nix store optimization, and automatic upgrades to my nix config.

Timestamps

• YT=00:00 - Start of video

Notes

I dont feel like taking much notes since i can just write the code into my configuration and reference it later. i should still take some notes tho.

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Updates

Updating packages, channels, etc.

Manual

you can rebuild your system to upgrade the inputs: doas nixos-rebuild switch --flake ~/.dotfiles/#ThinkPad

Scheduled

system.autoUpgrade = {
    enable = true;
    flake = inputs.self.outPath; # for flake based systems
    flags = [
      "--update-input"
      "nixpkgs"
      "-L" 
    ];
    dates = "09:00";
    randomizedDelaySec = "45min";
  };

to check the upgrade status run: systemctl status nixos-upgrade.service

---

Rollbacks (Generations)

Rollbacks can roll back to a working generation but it doesnt roll back:

• Config files
• documents
• etc

Commands:

• List generations & current generation: nixos-rebuild list-generations
• Rollback (without reboot): nix-env --switch-generation 60 -p /nix/var/nix/profiles/system
  • Rollback (with reboot): reboot then pick a generation to boot into.
• set current generation to default boot: /run/current-system/bin.switch-to-configuration boot

roll back by rebooting and choosing a generation. you can make this the default generation to boot from by running: /run/current-system/bin.switch-to-configuration boot

Another way to check which generation you are running:

1. run ls /var/run/*system -lah which will return generations and hashes.
2. run ls -lah /nix/var/nix/profiles/|grep HASH replacing HASH with the hash you are checking.

---

Garbage Collection

Manual

• run the gc: nix-collect-garbage --delete-older-than 10d

Scheduled

nix.gc = {
    automatic = true;
    dates = "02:05";
    randomizedDelaySec = "45min";
    options = "--delete-older-than 365d";
  };

---

Nix Store Optimization

Manual

• to optimize: “

Scheduled

nix.optimise = {
    automatic = true;
    dates = [ "01:05" ];
  };