So, I’ve been stuck on a build from March because any later builds break jackd. It seems that this means that, not only am I completely unable to update pkgs, I can’t even change my system configuration.
Is it possible to work out the commit of my channel and pin to that? If so, might that free me to to install packages and, more importantly, change my system config.
You can just use -I nixpkgs=https://github.com/nixos/nixpkgs/archive/22a3bf9fb9e.tar.gz with the nixos-rebuild command.
Timestamp may be good for you to know when you built that system but what really matters is the nixpkgs hash (and the starting point of version is good to give you idea about ordering among those hashes).