cron job：定时任务。
例：
Consider adding a cron job to remind yourself to check your backups at least once per month.
考虑添加cron作业来提醒自己每月至少检查一次备份。
相关介绍
Instead, a ZODB administrator will typically establish a cron job to perform the operation regularly.
相反，ZODB管理员通常将建立一个cron作业来定期执行该操作。
Specifying the full path in your batch or cron job will help ensure proper execution regardless of the user that executes the job.
在批处理或cron作业中指定完整路径将帮助确保正确执行，而不管执行作业的是哪个用户。
The preceding example is intended as a replacement for the normal line in/ etc/ crontab that runs the daily Cron job.
前例的目的是替换运行日常Cron作业的/etc/crontab中的普通代码行。
