错误如下：

Ignoring required pre-requisite failures. Continuing...
Preparing to launch Oracle Universal Installer from /tmp/OraInstall2015-01-29_03-14-51AM. Please wait ...
DISPLAY not set. Please set the DISPLAY and try again.
Depending on the Unix Shell, you can use one of the following commands as examples to set the DISPLAY environment variable:
- For csh:                      % setenv DISPLAY 192.168.1.128:0.0
- For sh, ksh and bash:         $ DISPLAY=192.168.1.128:0.0; export DISPLAY
Use the following command to see what shell is being used:
        echo $SHELL
Use the following command to view the current DISPLAY environment variable setting:
        echo $DISPLAY
- Make sure that client users are authorized to connect to the X Server.
To enable client users to access the X Server, open an xterm, dtterm or xconsole as the user that started the session and type the following command:
% xhost +
To test that the DISPLAY environment variable is set correctly, run a X11 based program that comes with the native operating system such as ‘xclock‘:
        % <full path to xclock.. see below>
If you are not able to run xclock successfully, please refer to your PC-X Server or OS vendor for further assistance.
Typical path for xclock: /usr/X11R6/bin/xclock

【解决办法】：

切换到root用户，执行以下命令：

[root@localhost ~]# export DISPLAY=:0.0

[root@localhost ~]# xhost +

access control disabled, clients can connect from any host

[root@localhost ~]#

执行以上命令后，再次切换到oracle用户执行安装即可。

[oracle@localhost database]# ./runInstaller

转载：http://blog.csdn.net/aovenus/article/details/8680468

Linux下安装oracle数据库提示DISPLAY not set. Please set the DISPLAY and try again。