1、检查是否安装
composer --version
2、下载安装
php -r "copy(‘https://install.phpcomposer.com/installer‘, ‘composer-setup.php‘);"
php composer-setup.php
All settings correct forusingComposerDownloading...Composer(version 1.6.5) successfully installed to:/root/composer.phar Use it: php composer.phar
3、移动 composer.phar，这样 composer 就可以进行全局调用：
mv composer.phar /usr/local/bin/composer
4、切换为国内镜像
composer config -g repo.packagist composer https://packagist.phpcomposer.com
5、更新 composer：
composer selfupdate
composer selfupdate原文：https://www.cnblogs.com/daizhongxing/p/11805108.html