实例如下:
vim /var/spool/cron/root
* * * * * sleep 10; /usr/bin/curl http://localhost/index.php
* * * * * sleep 20; /usr/bin/curl http://localhost/index.php
* * * * * sleep 30; /usr/bin/curl http://localhost/index.php
* * * * * sleep 40; /usr/bin/curl http://localhost/index.php
* * * * * sleep 50;