1. wget直接下载composer.phar直接下载composer.phar部署目录：(版本下载地址获取)

    wget 'https://getcomposer.org/download/1.8.5/composer.phar'

2.将composer部署到全局  

mv composer.phar /usr/local/bin/composer

3.设置权限

sudo chmod  XXX /usr/local/bin/composer

4.若php安装位置不在/usr/local/bin/,则设置软连接

sudo ln /usr/local/php/bin/php /usr/local/bin/php

5.修改为阿里云镜像

composer config -g repo.packagist composer https://mirrors.aliyun.com/composer/

6.windows下载composer

https://developer.aliyun.com/article/1076259