来自: http://blog.csdn.net//wgw335363240/article/details/41984341
1.进入要安装composer的目录,如果没有则新建一个目录
cd :/home/wuguowei/software/composer
2.安装composer
sudo curl -s https://getcomposer.org/installer | sudo php
3.设置执行权限
sudo chmod a+x composer.phar
4.更新composer版本
sudo composer.phar self-update