crontab

* * * * *  /home/amitkumar/anisble/crontab.sh #every minute

* * * * *  sleep 30; /home/amitkumar/anisble/crontab.sh #every 30 seconds
* * * * * sleep 00; timeout 15s /home/amitkumar/anisble/crontab.sh
* * * * * sleep 15; timeout 15s /home/amitkumar/anisble/crontab.sh #15seconds
* * * * * sleep 30; timeout 15s /home/amitkumar/anisble/crontab.sh
* * * * * sleep 45; timeout 15s /home/amitkumar/anisble/crontab.sh

This command allows cron to execute on first Saturday of every month.

0 2 * * sat  [ $(date +%d) -le 06 ] && /script/script.sh