“Check if the DISPLAY variable is set” error – Installing Oracle Forms from a Mac

While installing Oracle Forms and Reports 11gR2 (11.1.2.0.0)  from a Mac (OS/x Mountain Lion) the following error occurred executing the runInstaller installation script:

$ ./runInstaller

Starting Oracle Universal Installer…

Checking Temp space: must be greater than 270 MB.   Actual 40478 MB    Passed

Checking swap space: must be greater than 500 MB.   Actual 4094 MB    Passed

Checking monitor: must be configured to display at least 256 colors

    >>> Could not execute auto check for display colors using command /usr/bin/xdpyinfo. Check if the DISPLAY variable is set.    Failed <<<<

Some requirement checks failed. You must fulfill these requirements before

continuing with the installation,

Continue? (y/n) [n] y

I have a remote session from my mac using terminal.  To export the display, I typed ssh -Y user@servername.

I have upgraded my O/S to Mountain Lion a couple of days ago.  So I though that might be the cause.  I tried to manually start X11 and I received the following message:

click on the continue button and get redirected  to the following URL: About X11 and OS X Mountain Lion explaining X11 is no longer part of the O/S and that I should use XQuartz from now on.

 download and Install XQuartz and there you go!

You can now continue with the rest of the Install via the Installer GUI.