Package 'php5' has no installation candidate

原因：

ubuntu16.04默认自带php7，所以php5安装会提示Package php5 have no installation candidate

解决办法：

        sudo add-apt-repository ppa:ondrej/php
	sudo apt-get update
	sudo apt-get install php5.6

如果找不到 add-apt-repository命令报错：add-apt-repository: command not found 先安装add-apt-repository

          sudo apt-get install software-properties-common python-software-properties