安装swoole扩展，怎么安装到7.0下去了，我本来编译的版本是7.19版本，但是没吃
升级步骤
$ sudo add-apt-repository ppa:ondrej/php
$ sudo apt-get update
$ sudo apt-get upgrade php
直接安装提示这个：
www@TinywanAliYun:~$ pecl install swoole
The program 'pecl' is currently not installed. To run 'pecl' please ask your administrator to install the package 'php-pear'
sudo apt-get install php-pear
错误提示：
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/20160303/xml.so' - /usr/lib/php//xml.so: cannot open shared object file: No such file or directory in Unknown on line
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/20160303/dom.so' - /usr/lib/php//dom.so: cannot open shared object file: No such file or directory in Unknown on line
开始了
1、软连接
sudo ln -s /usr/local/php-7.1./bin/php /usr/bin/php
2、php7.1-dev
sudo apt search php7 sudo apt-get install php7.-dev