Error in installing Oracle11g on RedHat5: $ DISPALY not detected

When Oracle11g is installed on RedHatas5, the following error occurs when the GUI cannot be started: [oracle @ sensedisk1] $. /runInstallerStartingOracleUniversalInstaller... checkingTempspace: mustbegreaterthan80MB. when installing Oracle11g on RedHat as5, Actual1184MB cannot start the GUI and the following error is reported:
[Oracle @ sense disk1] $./runInstaller
Starting Oracle Universal Installer...

Checking Temp space: must be greater than 80 MB. Actual 1184 MB Passed
Checking swap space: must be greater than 150 MB. Actual 3027 MB Passed
Checking monitor: must be configured to display at least 256 colors
>>> Cocould 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, at which time they will be rechecked.

Continue? (Y/n) [n]
Solution:
Log out of the logon user and use oracle to install the user to log on to the system again. For example, if you have created oracle, you can use oracle to log on to the system to solve the problem.

[Oracle @ sense disk1] $./runInstaller
Starting Oracle Universal Installer...

Checking Temp space: must be greater than 80 MB. Actual 1184 MB Passed
Checking swap space: must be greater than 150 MB. Actual 3027 MB Passed
Checking monitor: must be configured to display at least 256 colors. Actual 16777216 Passed
Preparing to launch Oracle Universal Installer from/tmp/OraInstall2009-01-03_05-06-47PM. Please wait.