The program 'php' is currently not installed.
ServerPilot uses its own PHP builds so you can have multiple versions of PHP on a server independent of what Ubuntu ships.
If you try to use php and get the following error:
~$ php The program 'php' is currently not installed. You can install it by typing: sudo apt-get install php5-cli
Do not try to install php5-cli.
ServerPilot has installed its PHP executables named as phpX.Y-sp.
~$ php5.4-sp -v PHP 5.4.25 (cli) (built: Feb 11 2014 02:04:13) Copyright (c) 1997-2014 The PHP Group Zend Engine v2.4.0, Copyright (c) 1998-2014 Zend Technologies
For more information, see What ServerPilot Installs, Why ServerPilot Installs Its Own Nginx, Apache, and PHP Packages, and How to Use the PHP CLI.