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Garbage collection

glixos uses Nix's standard garbage collector. glix gc is a thin wrapper.

Common use​

Free space without deleting old generations:

glix gc

This is equivalent to nix-collect-garbage. Old generations stay, which means you can still roll back via nixos-rebuild --rollback.

Free more space by also removing old generations:

sudo glix gc -delete-old

Equivalent to nix-collect-garbage -d. After this, only the current generation is left; rollback is no longer possible.

When to run it​

  • After a glix update that pulled significant nixpkgs deltas.
  • After removing a large package that you don't plan to reinstall.
  • On low-disk-space alerts.

You don't need to run glix gc after every mutation. Generations are cheap; they only consume disk for whatever store paths they reference that aren't reachable from the current generation.

Scheduling​

If you want garbage collection on a timer, NixOS has it natively:

# hosts/laptop/default.nix
nix.gc = {
  automatic = true;
  dates = "weekly";
  options = "--delete-older-than 30d";
};

That's a host-level concern (not a glix package), so it belongs in hosts/<host>/default.nix, not in glix.toml.

Verifying​

nix-store --gc --print-roots | head
df -h /nix