def untar_cmd(src, dest):
    """ Create the tar commandline call

    Args:
        src (str): relative or full path to source tar file
        dest (str): full path to output directory

    Returns:
        str: the tar command ready for execution

    Examples:
        >>> untar_cmd('my.tar.gz', '/path/to/place')
        'tar --directory /path/to/place -xvf my.tar.gz'
    """
    return ' '.join(['tar', '--directory', dest, '-xvf', src])