How to set up Xdebug for PHP5-FPM on Ubuntu

Install required packages:

sudo apt-get install php5-dev php-pear
sudo pecl install xdebug

Open file /etc/php5/fpm/php.ini and add the following line to the "Dynamic Extensions" section:

zend_extension="/usr/lib/php5/20121212/xdebug.so"

Restart PHP:

sudo service php5-fpm restart