Can I run a PHP script on cron?

Yes, you can run a PHP script on cron. Look here to see how to setup your own crontab.

If your PHP scripts do not have executable permissions, 644 or -rw-r--r-- for example, then as part of the command portion of the cron line, you must specify the php interpreter and pass it the filename of the PHP script (including full path to the script from your home directory) that you want executed, like so:

28 14 * * * /usr/local/bin/php -q /myscript.phtml
6 3 20 4 * /usr/local/bin/php -q /htdocs/www/x.php

The first cron line above will run myscript.phtml located in your home directory every day at 2:28PM. The second line will run the script x.php from your /htdocs/www/ directory once a year on April 20th at 3:06AM.

When you explicitly specify the php interpreter /usr/local/bin/php your scripts need not have filenames ending in .php .phtml .php3 .php4. Conversely, if your script filenames do not end in one of those PHP extensions, then you must explicitly use the php interpreter in the command portion of your cron as above.

The -q flag suppresses HTTP header output. As long as your script itself does not send anything to stdout, -q will prevent cron from sending you an email every time the script runs. For example, print and echo send to stdout. Avoid using these functions if you want to prevent cron from sending you email.

If your PHP scripts do have executable permissions like 755 or -rwxr-xr-x and they have one of the PHP filename extensions above, then you do not need to specify the php interpreter in the command portion of your cron line, like this:

5 17 * * 2 /myscript.php

The above cron would run myscript.php in your home directory every Tuesday at 5:05PM.
courtsy: modwest.com