def main():
    """Command line interface."""
    coloredlogs.install(level='debug')
    arguments = sys.argv[1:]
    if arguments:
        interpret_script(arguments[0])
    else:
        logger.notice(compact("""
            This script requires the 'urxvt' terminal emulator and the
            ImageMagick command line programs 'convert' and 'import' to be
            installed. Don't switch windows while the screenshots are being
            generated because it seems that 'import' can only take screenshots
            of foreground windows.
        """))
        generate_screenshots()