Php – How to update Zend Engine API? Ubuntu

You're attempting to upgrade the package provided by the distribution. Often, distributions will not change the version but backport security fixes, which is done to maintain a more stable environment. As major revision changes can affect the operation of software, they typically will only be done between major revisions of the distribution.

If you want to run the latest PHP, you'll likely have to create your own package, locate a third party package, or compile from source making your own build standard.

Based on the output provided, it's reasonable to assume you're running the latest version of PHP available for the current distribution you're running.

It looks like the CentOS wiki has a walkthrough for updating to 5.2 using the development repo.

eaccelerator.shm_only="1" means that it won't write to the disk.