I recently saw an issue on one of our servers where we were trying to enable Zend Optimizer and IonCube Loaders, but they just won’t show up on a phpinfo page despite showing up via command line:

-bash-3.2# php -v
PHP 4.4.9 (cli) (built: May 4 2010 13:55:07)
Copyright (c) 1997-2008 The PHP Group
Zend Engine v1.3.0, Copyright (c) 1998-2004 Zend Technologies
with the ionCube PHP Loader v3.3.14, Copyright (c) 2002-2010, by ionCube Ltd., and
with Zend Optimizer v3.3.3, Copyright (c) 1998-2007, by Zend Technologies

After toggling around with this and finally getting cPanel installed, one of their techs (Kyle P.) figured out that the problem is with PHP being built with the versioning extension, which can apparently cause dynamic modules not to load when PHP is invoked as a DSO (and likely as CGI, but couldn’t reproduce it). The CPanel documentation also recommends against it:

“Versioning – The PHP versioning option was intended to allow the same sort of functionality that the concurrent DSO patches allow. It does not work well and is not recommended by cPanel or the PHP developers.”

Quite honestly, I never used versioning on a server and I knew it wasn’t something that was recommended, but at least now we know why!