1. $ nix-channel --list
  2. nixos https://nixos.org/channels/nixos-unstable
  3. nixos-unstable https://nixos.org/channels/nixos-unstable
  4. $ sudo nix-channel --list
  5. nixos https://nixos.org/channels/nixos-unstable
  6. nixos-unstable https://nixos.org/channels/nixos-unstable