Install PHP Composer on CentOS 7 failed

I'm trying to install Magento 2.1 using PHP composer.

http://idroot.net/tutorials/how-to-install-php-composer-on-centos-7/

I found the url above to install PHP composer for Centos 7.

on step 2 it failed:

curl -sS https://getcomposer.org/installer | php

this is the error I get

"curl: (6) Could not resolve host: php; Name or service not known

Thanks for the help guys!