cron job from php script - best example

here are the links to execute cronjob from php script

http://articles.sitepoint.com/article/introducing-cron
http://www.webmasterworld.com/php/3875021.htm

the best example from cPanel --- http://www.trap17.com/index.php/cron-jobs-cron-jobs-cpanel_t6321.html

google search string -- http://www.google.co.in/search?hl=en&source=hp&q=cronjob+using+php&meta=&aq=f&oq=