scrapy中如何进行自定制命令？

在spiders同级创建任意目录，如：commands
在其中创建'crawlall.py'文件（此处文件名就是自定义的命令）
from scrapy.commands import ScrapyCommand
    from scrapy.utils.project import get_project_settings
    class Command(ScrapyCommand):
        requires_project = True
        def syntax(self):
            return '[options]'
        def short_desc(self):
            return 'Runs all of the spiders'
        def run(self, args, opts):
            spider_list = self.crawler_process.spiders.list()
            for name in spider_list:
                self.crawler_process.crawl(name, **opts.__dict__)
            self.crawler_process.start()
在'settings.py'中添加配置'COMMANDS_MODULE = '项目名称.目录名称''
在项目目录执行命令：'scrapy crawlall'