I am testing something out*, and I want to make sure the newly built configuration is sane before even trying to switch to it. I started by running
sudo nixos-rebuild build and verifying that it returned exit code 0. But now I can’t find the result - I expected that command to create a new generation, but
sudo nix-env --list-generations doesn’t show it. So where do I find the build results, how do I verify which packages it contains, and how do I switch to it without building again?
* It’s probably not relevant, but I’ve split my configuration.nix into common and machine-specific files, and I want to make sure that multiple
environment.systemPackages instances are merged rather than overridden.