Cron Expression 6 Fields (With Seconds)

Standard Unix cron uses 5 fields, but some systems use 6 or 7 fields. The most common 6-field format is Quartz Scheduler, which prepends a seconds field: second minute hour day-of-month month day-of-week. AWS EventBridge appends a year field instead: minute hour day-of-month month day-of-week year.

The Quartz seconds field (0-59) enables sub-minute scheduling — something standard cron cannot do. For example, */30 * * * * * in Quartz fires every 30 seconds. Spring's @Scheduled annotation uses this same format. The trade-off is that Quartz expressions are NOT compatible with standard crontab.

When working with 6-field expressions, always check which format your system uses. Quartz puts seconds first (second minute hour...), while AWS puts year last (minute hour ... year). Getting the field order wrong is a common source of bugs. SimpleCronTab auto-detects the format and shows the correct field labels.