I have a magento site hosted on a hostgator shared plan. It only allows me to run cron jobs which are more than 15 mins. I have used the following format to run the cron job.
*/15 * * * * php /home/username/public_html/path/cron.php
Still my 'cron_schedule' table is empty. I have also set the cron.php file permission to 755. (Magento ver. 18.104.22.168)
Contacted hostgator, They ran the script manually and still the 'cron_schedule' table is empty.