With Oracle Database XE in production, it is even easier to install Oracle on Ubuntu. There is now an apt-get repository up on oss.oracle.com for XE. Just add:
deb http://oss.oracle.com/debian unstable main non-free
to /etc/apt/sources.list and then:
# useradd -m oracle
# passwd oracle
# wget http://oss.oracle.com/el4/RPM-GPG-KEY-oracle ; -O- | sudo apt-key add -
# apt-get update
# apt-get install oracle-xe
(Note: You will need to 'sudo' or have 'root' privileges to install XE.)
if all of above was finished then:
# /etc/init.d/oracle_x configure
and add
# .bash_profile
# Get the aliases and functions
if [-f ~/.bashrc]; then
.~/.bashrc
fi
# User specific environment and startup programs
PATH=$PATH:$ORACLE_HOME/bin
unset USERNAME
export ORACLE_SID=XE
export ORACLE_BASE=/usr/lib/oracle
export ORACLE_HOME=/usr/lib/oracle/xe/app/oracle/product/10.2.0/server
export PATH
to /home/oracle/.bash_profile and add :

ORACLE_HOME=/usr/lib/oracle/xe/app/oracle/product/10.2.0/server
ORACLE_SID=XE
LD_LIBRARY_PATH=$ORACLE_HOME/lib:$LD_LIBRARY_PATH
TNS_ADMIN=/usr/lib/oracle

to /etc/environment and add :$ORACLE_HOME/bin to PATH with /etc/environment

at last restart the server of ORACLE

# /etc/init.d/oracle_x restart

Catch-all disclaimer: These steps worked for me on my configuration; they might not work on yours.

I'm new guy,this is my first install oracle on LINUX OS.If any problems please let me know.