Oracle runInstaller Error

Many a times when you try to start runInstaller or DBCA, you see below error:

[oracle@abc database]$ ./runInstaller
Starting Oracle Universal Installer...

Checking Temp space: must be greater than 500 MB.   Actual 193971 MB    Passed

Checking swap space: must be greater than 150 MB.   Actual 19072 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

Step 1: X11 Forwarding is Enabled in PuTTY Settings

Open PuTTY settings >> SSH >> X11 >> Check Enable X11 forwarding

You can permanently save this setting by navigating to Session in the left hand menu, under Saved Session give a meaningful name and click on Save. So going forward, you can just double click on session name and X11 forward will be enabled by default.

Step 2: Make Sure Xming is Running

Just check your system task bar if Xming is up and running. If Xming is not running, the Linux GUI will not show up.

Step 3: Don't Switch Users

For X11 forwarding to work, you must open a new PuTTY session and directly connect with Oracle user. If you connect to PuTTY with root user and switch to Oracle user, THIS WILL THROW THE LINUX DISPLAY VARIABLE ERROR.

If you want to install Oracle software as Oracle user then

Take a new PuTTY session and connect with Oracle user. DON'T SWITCH FROM ROOT TO ORACLE.

If you want to install Grid software as Grid user then

Take a new PuTTY session and connect with Grid user. DON'T SWITCH FROM ROOT / ORACLE TO GRID USER.

The above 3 steps should resolve the Linux DISPLAY variable issue!