Installing Application Express with Oracle 10g Express Edition on Ubuntu is as easy as installing on Windows.

I have comprehended the steps to install Oracle Express Edition along with APEX 3.2 in Ubuntu.

UPDATE: The same procedure works for upgrading to APEX 4.0 from APEX 3.2 or directly installing 4.0 over Oracle XE as well.

1) Download Oracle XE universal .deb file from oracle.com

Download apex_3.2.zip from oracle.com

2)  Double click the .deb file and install the package.

then in Terminal window type:
Type:

 sudo /etc/init.d/oracle-xe configure 

Follow the instructions given there to complete the installation of Oracle 10g.

3) Setting the Oracle Path:
Edit your .bashrc file to include the lines:

ORACLE_HOME=/usr/lib/oracle/xe/app/oracle/product/10.2.0/server
PATH=$PATH:$ORACLE_HOME/bin
export ORACLE_HOME
export ORACLE_SID=XE

export PATH

4) UPGRADING TO APEX 3.2
Place apex_3.2.zip in folder /tmp.
In terminal:

cd /tmp
unzip apex_3.2.zip
cd /tmp/apex
sqlplus /nolog 

Type:

connect sys as sysdba

Note: Prompt for password of database admin login
Type:

 @apexins SYSAUX SYSAUX TEMP /i/ 

This will take several minutes for installation.

5) Setting the Images folder
In terminal Type inside /tmp/apex directory:

sqlplus /nolog

In sqlplus:

connect sys as sysdba
@apxldimg.sql /tmp

6) Enable remote http connections:

SQL>

 exec dbms_xdb.setListenerLocalAccess (l_access => FALSE);

Login

URL: http://127.0.0.1:8080/apex

Workspace: Internal

Username: Admin

Password: password

Source:

http://ubuntuforums.org/showthread.php?t=899926

https://help.ubuntu.com/community/Oracle10g

and Apex Documentation

Ubuntu 9.10 is finally out

and the .iso file can be downloaded here from the web
You can Request  for a free cd here (www.shipit.ubuntu.com)

For IIT Guwahati’s Intranet – Click here

Don’t forget to bypass the proxy before downloding)

Installing:

1) You can directly burn the .iso image onto a CD and then insert the CD for installation.
2) If you  are a windows user (Not having ubuntu at all),  then you can save the  cost of a CD by
»mounting the .iso image by using daemon tools or related software and then in the auto-run window,
»choose  “Install inside windows” – Preferably select a hard drive not having windows
»Then Install and reboot – your Ubuntu 9.10 will be installed in minutes

Note: Installing inside windows – All your harddisk information is retained -

-No formatting