一.安装brew
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
二.安装composer
curl -sS https://getcomposer.org/installer | php mv composer.phar /usr/local/bin/composer
原文：https://www.cnblogs.com/300js/p/9432345.html