Install-PHP-7

Test OS: Ubuntu 15.10

apt-get install software-properties-common
add-apt-repository ppa:ondrej/php
apt-get update
apt-get install php7.0 -y --force-yes

Test OS: Debian 8 x64 (jessie)

Edit /etc/apt/sources.list, replacing <distribution> with either sequeeze, wheezy, jessie.

deb http://packages.dotdeb.org <distribution> all
deb-src http://packages.dotdeb.org <distribution> all

Add the GPG key:

#download gpg
wget https://www.dotdeb.org/dotdeb.gpg
#when you added it, you can delete it as you like
sudo apt-key add dotdeb.gpg

Install:

sudo apt-get update
sudo apt-get install php7.0

PS: If you meet some problems when you excute apt-get update, you may need to check /etc/apt/sources.list.

root@Ubuntu:~# php -v


PHP 7.0.6-13+donate.sury.org~wily+1 (cli) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2016 Zend Technologies
    with Zend OPcache v7.0.6-dev, Copyright (c) 1999-2016, by Zend Technologies

root@Ubuntu:~# apt-cache search php7-*


php-radius - radius client library for PHP
php-http - PECL HTTP module for PHP Extended HTTP Support
php-uploadprogress - file upload progress tracking extension for PHP
php-mongodb - MongoDB driver for PHP
php7.0-common - documentation, examples and common module for PHP
libapache2-mod-php7.0 - server-side, HTML-embedded scripting language (Apache 2 module)
php7.0-cgi - server-side, HTML-embedded scripting language (CGI binary)
php7.0-cli - command-line interpreter for the PHP scripting language
php7.0-phpdbg - server-side, HTML-embedded scripting language (PHPDBG binary)
php7.0-fpm - server-side, HTML-embedded scripting language (FPM-CGI binary)
libphp7.0-embed - HTML-embedded scripting language (Embedded SAPI library)
php7.0-dev - Files for PHP7.0 module development
php7.0-curl - CURL module for PHP
php7.0-enchant - Enchant module for PHP
php7.0-gd - GD module for PHP
...

Install specific modules with command below:

apt-get install php7.0-mysql php7.0-curl

apt-get install nginx
apt-get install php7.0-fpm

Edit /etc/nginx/sites-enabled/default, check the configuration below for advisory optinoin purpose.

server {
    ...

    location ~ \.php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass unix:/var/run/php/php7.0-fpm.sock;
        fastcgi_index index.php;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        include fastcgi_params;
    }
}

1. http://tecadmin.net/install-php-7-on-ubuntu/
2. https://www.colinodell.com/blog/2015-12/installing-php-7-0-0
3. https://www.digitalocean.com/community/tutorials/how-to-upgrade-to-php-7-on-ubuntu-14-04