2019-07-29 实测成功 - Ubuntu 18.04 安

sudo apt update
sudo apt-get install software-properties-common
sudo add-apt-repository ppa:ondrej/php
sudo apt update
sudo apt install php7.1-fpm php7.1-mcrypt php7.1-cli php7.1-xml php7.1-mysql php7.1-gd php7.1-imagick php7.1-recode php7.1-tidy php7.1-xmlrpc php7.1-mbstring php7.1-curl

确认安装成功

php -v
PHP 7.1.17-1+ubuntu18.04.1+deb.sury.org+1 (cli) (built: May 5 2018 04:56:28) ( NTS )
Copyright (c) 1997-2018 The PHP Group
Zend Engine v3.1.0, Copyright (c) 1998-2018 Zend Technologies
with Zend OPcache v7.1.17-1+ubuntu18.04.1+deb.sury.org+1, Copyright (c) 1999-2018, by Zend Technologies