安装php
composer install --ignore-platform-reqs
sudo add-apt-repository ppa:ondrej/php
sudo apt-get update
sudo apt-get upgrade
sudo apt-get install php7.1 # for PHP 7.1
sudo apt-get install php7.0 # for PHP 7.0
sudo apt-get install php5.6 # for PHP 5.6
安装扩展
sudo apt-cache search php7*
sudo apt-get install php7.2-curl php7.2-dev php7.2-gd php7.2-imap php7.2-intl php7.2-mbstring php7.2-mysql php7.2-xml php7.2-zip
切换版本
sudo update-alternatives --config php
