Linux Basic — cron Expressions
cron Expressions
Beyond single values and *, cron supports ranges, lists, and steps.
Ranges: -
# 9 AM to 5 PM, every hour
0 9-17 * * * /opt/work-hours.sh
# weekdays only (Mon–Fri)
0 9 * * 1-5 /opt/weekday-job.sh
Lists: ,
# at 9 AM, noon, and 6 PM
0 9,12,18 * * * /opt/check.sh
# on Jan, Apr, Jul, Oct (quarterly)
0 0 1 1,4,7,10 * /opt/quarterly.sh
Steps: /
# every 15 minutes
*/15 * * * * /opt/frequent.sh
# every 2 hours
0 */2 * * * /opt/bihouly.sh
# every 5 minutes during business hours
*/5 9-17 * * 1-5 /opt/monitor.sh
*/N means “every Nth value”. */15 in the minute field = 0, 15, 30, 45.
Combining
# every 10 minutes, 9 AM–5 PM, weekdays
*/10 9-17 * * 1-5 /opt/office-hours-check.sh
# 6 AM and 6 PM every day
0 6,18 * * * /opt/twice-daily.sh
Examples
| Schedule | Expression |
|---|---|
| Every minute | * * * * * |
| Every 5 minutes | */5 * * * * |
| Top of every hour | 0 * * * * |
| Daily at 3:30 AM | 30 3 * * * |
| Sundays at noon | 0 12 * * 0 |
| Weekdays at 8 AM | 0 8 * * 1-5 |
| 1st and 15th at midnight | 0 0 1,15 * * |
Testing cron Expressions
Use crontab.guru to validate and translate expressions into plain English.
Next → crontab -e & Shortcuts
