instead of "/home/etc....", try explicitly telling to use php to execute your phtml file, ie... "/usr/bin/php /home/path/to/myfile.phtml"...
The /usr/bin/php is the full path to where your php binary is located, if you are unsure just run a "find . -name php" from /, the second is to tell php what to parse, ie the phtml file you want. I'm not sure if that may work at all, but hey it's worth a shot 😉.
You may be able to use just "php /home/path/to/myfile.phtml" instead if the php binary is residing in one of your directories specified in your path environmental variable...