sudo apt-get update
sudo apt-get upgrade
sudo apt-get remove --purge `dpkg -l | grep php | grep -w 5.5 | awk '{print $2}' | xargs`
sudo apt-get purge apache2 php5 libapache2-mod-php5
sudo sed -i.bak "s/trusty/precise/g" /etc/apt/sources.list
sudo apt-get update
sudo apt-get install apache2 apache2-suexec libapache2-mod-fcgid php5-cgi
sudo apt-get install php5-mysql php5-curl php5-gd php5-intl php-pear php5-imagick php5-imap php5-mcrypt php5-memcache php5-xmlrpc php5-xsl php5-xdebug
sudo sed -i "s/precise/trusty/g" /etc/apt/sources.list
dpkg --get-selections | egrep '^(apache|php)' | sed 's/install/hold/g' | sudo dpkg --set-selections
sudo apt-get update