Source: http://www.syahzul.com/2016/04/06/how-to-install-oci8-on-ubuntu-14-04-and-php-5-6/
First, run:
$ composer config --list --global //this will get the composer home path.
[home] /root/.composer //it's my composer home path.
And then, edit the config.json in [home]
directory, make it like this:
{
"config": {
"github-protocols": [