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0 0/5 * * * Cron

5 min read Jul 03, 2024
0 0/5 * * * Cron

Understanding 0 0/5 * * * in Cron Jobs

In the world of Linux and Unix-like systems, cron jobs are used to schedule tasks to run at specific times or intervals. One of the most common and confusing parts of cron jobs is the timing syntax, specifically the 0 0/5 * * * pattern. In this article, we'll break down what each part of this syntax means and how it's used to schedule tasks.

The Five Asterisks

The first thing to notice about the 0 0/5 * * * syntax is the five asterisks. These asterisks represent five different fields that define when the task should be executed. The fields are, in order:

  • Minute: specifies the minute of the hour when the task should run
  • Hour: specifies the hour of the day when the task should run
  • Day of the month: specifies the day of the month when the task should run
  • Month: specifies the month when the task should run
  • Day of the week: specifies the day of the week when the task should run

The 0 0/5 Part

Now, let's focus on the 0 0/5 part of the syntax. This is where things can get a bit confusing.

  • 0: This is the minute field. In this case, it's set to 0, which means the task will run at the beginning of the hour (e.g., 12:00, 1:00, 2:00, etc.).
  • 0/5: This is the hour field, but it's not as simple as just specifying an hour. The / symbol is called a "step value" and it means "every X units". In this case, 0/5 means "every 5 hours starting from 0". This means the task will run at 0:00, 5:00, 10:00, 15:00, and so on.

The * * * Part

The remaining three asterisks (* * *) are the day of the month, month, and day of the week fields, respectively. In this case, each of these fields is set to *, which means "any" or "every". This means the task will run regardless of the day of the month, month, or day of the week.

Putting it All Together

So, what does the entire 0 0/5 * * * syntax mean? It means the task will run:

  • At the beginning of every hour (minute 0)
  • Every 5 hours (hour 0/5)
  • Regardless of the day of the month
  • Regardless of the month
  • Regardless of the day of the week

In practice, this means the task will run every 5 hours, 24/7. For example, the task will run at 0:00, 5:00, 10:00, 15:00, 20:00, and so on.

Conclusion

The 0 0/5 * * * syntax may seem daunting at first, but once you break it down, it's actually quite straightforward. By understanding each field and how they work together, you can create complex schedules for your cron jobs with ease.

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