Open your terminal of choice and login to your server via SSH. Ideally, you will want to login with the same user account as your webserver uses, or that your WHMCS installation uses. It is best to avoid using root during troubleshooting as a properly configured server does not utilize the root user to run the web server or cron processes.

Once logged into the server, simply execute the following command:

php -i | grep "Loaded Configuration File"

Doing this will show the configuration file that is being loaded when executing the php command. If you are forcing a specific version of PHP, or using the complete path you would simply substitute that for the php variable used above:

Another option to check this is via the Terminal option within cPanel. This feature was added in cPanel & WHM Version 72. Various settings must be set in order for your account to have the Terminal option. You can review the cPanel Documentation for this feature on their Documentation Site here.

Login to your cPanel and choose the Terminal option from the Advanced section.

Once the terminal is opened, the steps are identical to using the Computer-Based Terminal above.

One final option to check is via the cron engine itself. You can modify, or create, a cron job task to put this output to a file which can be read. For this example, we will be using cPanel.

First, Login to your cPanel and navigate to the Cron Jobs area, found under the Advanced section.

Once the cron job section is loaded, make note of the PHP path or variable being used by your existing WHMCS cronjob, as this is the path we will want to follow for troubleshooting.

This next step you have 2 options. You can modify the existing cronjob, or you can create a new one which is the preferred method. We will use the second option.

We will now create a new cronjob that runs every minute with a command similar to the one below:

php -i | grep "Loaded Configuration File" > /home/v76whmcssupport/public_html/whmcs/crons/phpoutput.txt

In this example, to make the file easy to find we are placing the output file in the same folder as the crons directory. In this case you would set that path to your crons directory path

We now want to head to the crons directory to look at the file output of the cron we just created. We will do this via the File Explorer in cPanel, but you could also check via FTP.

Note: The cron is setup to run 1 time per minute, so you must wait at least 1 minute (60 seconds) before the cron will be invoked or the output file will not be there.

We can now see the output by right clicking the file and choosing view:

In this example a PHP 5.6 environment is being used for the cron job.

After viewing the output, you should now remove the temporary cronjob to eliminate this unnecessary task from running.