So I am running CentOS 6.8 with php upgraded to 5.6.0, and you have to set up a chronjob in /etc/crontab in order for some WHMCS functions to work correctly. So I looked up online and found a form with instructions, and this is what I did. CentOS 6.8 uses SysVInit/UpStart, NOT Systemd. Here is what I did...
Edited /etc/crontab to have the following contents,
Set crond to start on boot, by doing "chkconfig --levels 235 crond on"
Then start it, "service crond start"
and it says successfully started.
Then I noticed it was not running, I kept checking to see if it made that file and it wasn't, I rebooted the machine and still nothing. If anyone has any suggestions or help to get the cronjobs running please let me know, I literally have been battling WHMCS for a week now trying to get it working.