Cron Every 3 Minutes

The cron expression */3 * * * * schedules a task to run once every three minutes, continuously throughout every day.

Field-by-field breakdown:

• */3 (Minute): Every 3rd minute, starting from minute 0. The step value /3 causes execution at minutes 0, 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, and 57.
• * (Hour): Every hour from 0 through 23. No restriction on which hour.
• * (Day of Month): Every day from 1 through 31. No restriction on the day of the month.
• * (Month): Every month from January through December. No restriction on the month.
• * (Day of Week): Every day of the week from Sunday through Saturday. No restriction on the day.

This means your task will execute 480 times per day (20 times per hour, 24 hours per day). This is a relatively aggressive schedule, sitting between every-2-minutes and every-5-minutes in frequency. The 3-minute interval is often chosen when every-5-minutes is too slow for responsiveness requirements but every-minute or every-2-minutes would create excessive load. Ensure your scheduled task completes well within 3 minutes to prevent overlapping executions. Consider using a lock file or flock to prevent concurrent runs if the task duration is variable. This expression is supported by standard cron on Linux/macOS, as well as cloud services like AWS CloudWatch, Google Cloud Scheduler, and GitHub Actions.