Set all configuration specified in :attr:`REQUIRED_SETTINGS`.

    Args:
        configuration (str): Configuration file content.

    Returns:
        str: Updated configuration.

def update_configuration(configuration):
    """
    Set all configuration specified in :attr:`REQUIRED_SETTINGS`.

    Args:
        configuration (str): Configuration file content.

    Returns:
        str: Updated configuration.
    """
    for key, val in REQUIRED_SETTINGS.items():
        if val in ["$username", "$groupname"]:
            val = get_username()

        configuration = conf_writer.add_or_update(configuration, key, val)

    return configuration