# 下载composer.phar 
curl -sS https://getcomposer.org/installer | php
# 把composer.phar移动到环境下让其变成可执行 
mv composer.phar /usr/local/bin/composer
# 测试
composer -V 
# 输出：Composer version 1.8.4 2019-02-11 10:52:10