无法理解cron-job时间

Question

我有类似0,30 * * * * /some/command这样的东西，我不确定，这是每隔30分钟执行一次吗？

Answer 1

是的，该命令每30分钟执行一次。

0,30      <---------------    execute at 0 minutes and 30 minutes into the hour. 
*         <---------------    every hour in the day
*         <---------------    every day of the month
*         <---------------    every month
*         <---------------    every day of the week

https://en.wikipedia.org/wiki/Cron