    def _add_user_cmd_default(self):
        """Guess the most likely-to-work adduser command for each platform"""
        if sys.platform == 'darwin':
            raise ValueError("I don't know how to create users on OS X")
        elif which('pw'):
            # Probably BSD
            return ['pw', 'useradd', '-m', '-n']
        else:
            # This appears to be the Linux non-interactive adduser command:
            return ['adduser', '-q', '--gecos', '""', '--disabled-password']
Guess the most likely-to-work adduser command for each platform
jupyterhub/auth.py