You can use cURL and CRON to run .php files at set times.
Here's an example of what cURL needs to run the .php file:
curl http://localhost/myscript.php
Then setup the CRON job to run the above cURL:
nano -w /var/spool/cron/root
or
crontab -e
Followed by:
01 * * * * /usr/bin/curl http://www.yoursite.com/script.php
For more info about, check out this post: https://www.scalescale.com/tips/nginx/execute-php-scripts-automatically-using-cron-curl/
For more info about cURL: What is cURL in PHP?
For more info about CRON: http://code.tutsplus.com/tutorials/scheduling-tasks-with-cron-jobs--net-8800
Also, if you would like to learn about setting up a CRON job on your hosted server, just inquire with your host provider, and they may have a GUI for setting it up in the c-panel (such as http://godaddy.com, or http://1and1.com/ )
NOTE: Technically I believe you can setup a CRON job to run the .php file directly, but I'm not certain.
Best of luck with the automatic PHP running :-)