nix-env with quiet option. By default, nix is extremely verbose and prints the build log of every package to stderr. This tells nix to
    only show changes.

def _nix_env():
    '''
    nix-env with quiet option. By default, nix is extremely verbose and prints the build log of every package to stderr. This tells nix to
    only show changes.
    '''
    nixhome = os.path.join(os.path.expanduser('~{0}'.format(__opts__['user'])), '.nix-profile/bin/')
    return [os.path.join(nixhome, 'nix-env')]