Cron expressions
Learn the cron expression format used by @robojs/cron.
Cron expressions define when a job runs. The plugin uses the croner library, which supports a six-field format with seconds precision.
Format
A cron expression consists of six fields separated by spaces:
┌──────── second (0-59)
│ ┌────── minute (0-59)
│ │ ┌──── hour (0-23)
│ │ │ ┌── day of month (1-31)
│ │ │ │ ┌ month (1-12)
│ │ │ │ │ ┌ day of week (0-6, Sunday = 0)
│ │ │ │ │ │
* * * * * *The seconds field is optional. When only five fields are provided, they represent minute hour day-of-month month day-of-week (the standard cron format).
Special characters
| Character | Meaning | Example |
|---|---|---|
* | Every value | * * * * * * — every second |
*/N | Every N units | */5 * * * * * — every 5 seconds |
N,M | Specific values | 0,30 * * * * * — at second 0 and 30 |
N-M | Range of values | 0-5 * * * * * — seconds 0 through 5 |
N-M/S | Range with step | 0-30/10 * * * * * — every 10 seconds from 0 to 30 |
Common examples
| Expression | Schedule |
|---|---|
* * * * * * | Every second |
*/5 * * * * * | Every 5 seconds |
*/30 * * * * * | Every 30 seconds |
0 * * * * * | Every minute (at second 0) |
0 */5 * * * * | Every 5 minutes |
0 */15 * * * * | Every 15 minutes |
0 */30 * * * * | Every 30 minutes |
0 0 * * * * | Every hour |
0 0 */2 * * * | Every 2 hours |
0 30 * * * * | Every hour at minute 30 |
0 0 0 * * * | Daily at midnight |
0 0 12 * * * | Daily at noon |
0 30 14 * * * | Daily at 2:30 PM |
0 0 9 * * 1-5 | Weekdays at 9 AM |
0 0 0 * * 0 | Every Sunday at midnight |
0 0 0 1 * * | First of each month at midnight |
0 0 0 1 1 * | January 1 at midnight |
Tips
- Seconds precision. Unlike standard Unix cron (five fields), this plugin supports a sixth field for seconds. Use it for sub-minute schedules.
- System timezone. Jobs run in the system's local timezone. Keep this in mind when scheduling across time zones.
- Prefer Patterns. For most schedules, the Patterns helper is easier to read and less error-prone than raw expressions.
- Validate expressions. Invalid expressions throw an error at job creation time. Use Crontab Guru to verify your expressions (note: Crontab Guru uses five-field format without seconds).