1.
sudo aptitude purge `dpkg -l | grep php| awk '{print $2}' |tr "\n" " "`
查询卸载已安装php
sudo add-apt-repository ppa:ondrej/php
sudo apt-get update
sudo apt-get install php5.6
ubuntu 16.04 卸载php7.0 安装 php5.6
1.
sudo aptitude purge `dpkg -l | grep php| awk '{print $2}' |tr "\n" " "`
sudo apt-get update
sudo apt-get install php5.6