crontab utility helps to set up tasks to run automatically in the background at regular intervals, as specified in the schedule.
You can use cron.allow and cron.deny files under /usr/lib/cron directory to control access to the cron.
crontab -e Edit crontab file, or create one if it doesn’t already exist.
crontab -l Display crontab file.
crontab -r Remove your crontab file.
crontab -v Display the last time the crontab file is edited
The following is the crontab file syntax
* * * * * command
- – - – -
+—– day of week (0 – 6) (Sunday=0)
+——- month (1 – 12)
+——— day of month (1 – 31)
+———– hour (0 – 23)
+————- min (0 – 59)
Example
Crontab entry for health check report that runs every night at 11.30pm
30 23 * * * /home/oracle/monitoring/health.sh > /logs/health.log 2>&1
