如果以下步骤安装7.2失败，可以尝试安装7.0版本。
sudo apt-get install software-properties-common python-software-properties
sudo add-apt-repository ppa:ondrej/php && sudo apt-get update
sudo apt-get -y install php7.2
若之前有其他版本PHP，则先卸载
sudo apt-get autoremove php5 php5-fpm php7
安装常用扩展
sudo apt-get install -y php7.2-fpm php7.2-mysql php7.2-curl php7.2-json php7.2-mbstring php7.2-xml php7.2-intl
安装其他扩展（按需安装）
sudo apt-get install php7.2-gd
sudo apt-get install php7.2-soap
sudo apt-get install php7.2-gmp
sudo apt-get install php7.2-odbc
sudo apt-get install php7.2-pspell
sudo apt-get install php7.2-bcmath
sudo apt-get install php7.2-enchant
sudo apt-get install php7.2-imap
sudo apt-get install php7.2-ldap
sudo apt-get install php7.2-opcache
sudo apt-get install php7.2-readline
sudo apt-get install php7.2-sqlite3
sudo apt-get install php7.2-xmlrpc
sudo apt-get install php7.2-bz2
sudo apt-get install php7.2-interbase
sudo apt-get install php7.2-pgsql
sudo apt-get install php7.2-recode
sudo apt-get install php7.2-sybase
sudo apt-get install php7.2-xsl
sudo apt-get install php7.2-cgi
sudo apt-get install php7.2-dba
sudo apt-get install php7.2-phpdbg
sudo apt-get install php7.2-snmp
sudo apt-get install php7.2-tidy
sudo apt-get install php7.2-zip
sudo apt-get install php7.2-redis
sudo apt-get install php7.2-memcached
sudo apt-get install php7.2-mongodb
sudo apt-get install php7.2-mongo
如果报以下错误：
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/20151012/mbstring.so' - /usr/lib/php/20151012/mbstring.so: cannot open shared object file: No such file or directory in Unknown on line 0
则安装mbstring扩展即可:
sudo apt-get install php7.0-mbstring
参考文章：
1. Deepin 添加 apt 软件源：
https://blog.csdn.net/one312/article/details/104893204
2. ubuntu14.04 安装 php7.2：
https://blog.csdn.net/hanzengyi/article/details/83034987
3. deepin/ubuntu apt-get快速安装的apache、php7.2和nginx和：
php7.2https://blog.csdn.net/ZHANG_TIMI/article/details/89853129
