*/30 * * * *frequency
Every 30 Minutes (*/30 * * * *)
Executes twice every hour (at :00 and :30). Commonly used for cache invalidation and session cleanup.
Crontab Expression Syntax Breakdown
*/30 * * * *
Standard 5-part cron syntax: Minute [0-59] | Hour [0-23] | Day of Month [1-31] | Month [1-12] | Day of Week [0-6]
Linux Crontab Entry Example
Paste this line into your system crontab file (crontab -e):
*/30 * * * * /usr/bin/php /var/www/script.php >> /var/log/cron.log 2>&1
AWS EventBridge Rate Expression
Equivalent AWS CloudWatch / EventBridge scheduled rule syntax:
cron(?/30 ? ? ? ?)
Projected Execution Timeline
- Today at 14:00:00 UTC
- Today at 14:05:00 UTC
- Today at 14:10:00 UTC
- Today at 14:15:00 UTC
- Today at 14:20:00 UTC
Test or Customize Cron Schedules
Use Teksolvr's interactive Cron Builder and Crontab Validator tools to generate custom expressions.