Minimizing dowload amount on "nixos-rebuild switch"

Hi, I would like to minimize the network traffic.

I sometimes only want to change the configuration in /etc/nixos/configuration.nix and then only make the configuration changes available by “nixos-rebuild switch” or maybe another command.

But everytime it updates the whole system. What, if I have no internet? Does then the configuration change not apply?

How can I switch off these updates?

Kind Regards

How are you running nixos-rebuild? There should only be updates if your channels are updated, since the package set does not change without a channel update (unless you changed NIX_PATH to point somewhere else). nixos-rebuild --upgrade and nix-channel --update update the channel.

You could can check the channel version using:

nix eval nixpkgs.lib.version