php -v
PHP 5.4.4-14+deb7u4 (cli) (built: Aug 23 2013 14:37:41)

`sudo apt-get install -y php-pear`

sudo apt-get install -y build-essential php5-dev

sudo pecl install zendopcache-7.0.3

sudo find / -name 'opcache.so'

/usr/lib/php5/20100525/opcache.so

sudo vim /etc/php5/mods-available/opcache.ini

zend_extension=/usr/lib/php5/20100525/opcache.so # File path from above
opcache.memory_consumption=128
opcache.interned_strings_buffer=8
opcache.max_accelerated_files=4000
opcache.revalidate_freq=60
opcache.fast_shutdown=1
opcache.enable_cli=1

sudo ln -s /etc/php5/mods-available/opcache.ini /etc/php5/conf.d/20-opcache.ini

sudo service php5-fpm restart
sudo service apache2 restart

php -v

Zend Engine v2.4.0, Copyright (c) 1998-2013 Zend Technologies
    with Zend OPcache v7.0.3, Copyright (c) 1999-2014, by Zend Technologies

sudo apt-get remove --purge build-essential php5-dev

deb http://packages.dotdeb.org wheezy-php55 all
deb-src http://packages.dotdeb.org wheezy-php55 all

shtool at '/tmp/pear/temp/zendopcache/build/shtool' does not exist or is not executable.
Make sure that the file exists and is executable and then rerun this script.

mount -o remount,exec /tmp
pecl install zendopcache
mount -o remount,noexec /tmp

pecl install apc

apt-get install php5-apc