upgrade php on ubuntu, on nginx

sudo add-apt-repository ppa:ondrej/php
sudo apt-get update
sudo apt-get install php7.0-fpm
sudo apt-get install php7.0-mysql

Note: If you have made substantial modifications to any configuration files in /etc/php5/, those files are still in place, and can be referenced. Configuration files for PHP 7.0 now live in /etc/php/7.0.
Note2: Update your Nginx Site(s) to Use New Socket Path:
PHP5: /var/run/php5-fpm.sock
PHP7: /var/run/php/php7.0-fpm.sock
Change ‘fastcgi_pass unix:/var/run/php5-fpm.sock;’ to ‘unix:/var/run/php/php7.0-fpm.sock.’
Restart nginx:

sudo service nginx restart

Thanks to: https://www.digitalocean.com/community/tutorials/how-to-upgrade-to-php-7-on-ubuntu-14-04