我是在vps（國外服務器）安裝php7的時候遇到這個問題，始終提示：
Couldn't find any package by regex 'php7.0'
Unable to locate package php7.0
找了很久，網上很多解決方案都是：
$ sudo add-apt-repository ppa:ondrej/php
$ sudo apt-get update
之後執行安裝
$ sudo apt-get install -y php7.0 php7.0-mysql php7.0-curl php7.0-json php7.0-cgi
但是我執行了代碼之後，仍然提示：
Couldn't find any package by regex 'php7.0'
Unable to locate package php7.0
最後找到解決方案，說是apt源不對，換成了阿里雲的源
cp /etc/apt/sources.list /etc/apt/sources.list.bak
vi /etc/apt/sources.list
sources.list內容如下：
deb-src http://archive.ubuntu.com/ubuntu xenial main restricted #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-updates main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates universe
deb http://mirrors.aliyun.com/ubuntu/ xenial multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-updates multiverse
deb http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-backports main restricted universe multiverse #Added by software-properties
deb http://archive.canonical.com/ubuntu xenial partner
deb-src http://archive.canonical.com/ubuntu xenial partner
deb http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted
deb-src http://mirrors.aliyun.com/ubuntu/ xenial-security main restricted multiverse universe #Added by software-properties
deb http://mirrors.aliyun.com/ubuntu/ xenial-security universe
deb http://mirrors.aliyun.com/ubuntu/ xenial-security multiverse
保存之後執行更新命令，更新apt源：
sudo apt-get update
更新apt源之後，然後添加第三方源支持，並且再次更新apt源：
add-apt-repository ppa:ondrej/php
sudo apt-get update
最後執行php的安裝：
sudo apt-get install -y php7.0 php7.0-mysql php7.0-curl php7.0-json php7.0-cgi
