This is experimental and assumes you are already familiar with ClearOS. This will upgrade all your server, so only use if all your PHP apps support PHP 5.5 You should test this on a backup, as there is no rollback to PHP 5.3
Special thanks to Rémi Collet
You can skip some of these steps if you are deploying on an existing system which already has PHP & MySQL.
cd /var/www/html wget --output-document=tiki-check.php https://svn.code.sf.net/p/tikiwiki/code/trunk/tiki-check.php
visit example.org/tiki-check.php to check PHP version. You will be at 5.3.x
cd /root wget http://rpms.famillecollet.com/RPM-GPG-KEY-remi rpm --import RPM-GPG-KEY-remi
cd /root wget http://dl.fedoraproject.org/pub/epel/6/i386/epel-release-6-8.noarch.rpm wget http://rpms.famillecollet.com/enterprise/remi-release-6.rpm rpm -Uvh remi-release-6*.rpm epel-release-6*.rpm
yum --enablerepo=remi-php55,remi,clearos-core update php*
You will see a lot of warnings. At this point, PHP 5.5 is installed but you need to reboot server. Just restarting Apache is not enough.
visit example.org/tiki-check.php to confirm you are now at PHP 5.5.x
# php -v PHP 5.5.14 (cli) (built: Jul 16 2014 11:10:19) Copyright (c) 1997-2014 The PHP Group Zend Engine v2.5.0, Copyright (c) 1998-2014 Zend Technologies
yum install --enablerepo=remi,remi-php55 install php-opcache service httpd restart