Nix

nix-channel --add https://nixos.org/channels/nixpkgs-unstable
nix-channel --update

nix-env -qa PACKAGE_NAME
# or use nox, install with nix-env -iA nox
nox PACKAGE_NAME

nix-env -i PACKAGE_NAME

nix-env -e PACKAGE_NAME
# same as nix-env --uninstall PACKAGE_NAME

nix-collect-garbage -d

nix-env -q

vi /etc/nixos/configuration.nix
nixos-rebuild switch
nix-env --list-generations

ref:

http://nixos.org/nix/manual/#chap-quick-start

Select channel