nix-super/doc/manual/src/installation/upgrading.md

Upgrading Nix

Multi-user Nix users on macOS can upgrade Nix by running: sudo -i sh -c 'nix-channel --update && nix-env -iA nixpkgs.nix && launchctl remove org.nixos.nix-daemon && launchctl load /Library/LaunchDaemons/org.nixos.nix-daemon.plist'

Single-user installations of Nix should run this: nix-channel --update; nix-env -iA nixpkgs.nix nixpkgs.cacert

Multi-user Nix users on Linux should run this with sudo: nix-channel --update; nix-env -iA nixpkgs.nix nixpkgs.cacert; systemctl daemon-reload; systemctl restart nix-daemon