1、下载composer

php -r "copy('https://install.phpcomposer.com/installer', 'composer-setup.php');"

2、执行安装

php composer-setup.php

3、将composer放到系统环境变量中

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

4、修改镜像为阿里镜像

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

注意:第四步不能使用root执行。会报错

Do not run Composer as root/super user! See https://getcomposer.org/root for details