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+
+## Two stage update
+
+The configuration is split into two parts to allow for two stage updates to conserve space
+on storage-limited systems.
+
+To run a two stage update do:
+```shell
+  $ sudo NIX_LIGHTWEIGHT=1 nixos-rebbuild switch
+  $ reboot
+```
+then:
+```shell
+  $ sudo nix-collect-garbage --delete-old
+  $ sudo nixos-rebbuild switch
+```
+
+