PHP.INI settings Disable exec, shell_exec, system, popen and Other Functions To Improve Security

Originally published at: https://www.cyberciti.biz/faq/linux-unix-apache-lighttpd-phpini-disable-functions/

I run a small Apache based web-server for my personal use, and it is shared with friends and family. However, most script kiddie try to exploit php application such as WordPress using exec(), passthru(), shell_exec(), system() functions. How do I disable these functions to improve my php script security?