Oracle database consists of a collection

An Oracle database consists of a collection of data managed by an Oracle database management system. You can download Oracle Database XE server for Debian, Mandriva, Novell, Red Hat and Ubuntu Linux distributions. First you need to get databases up and running in order to use Oracle. The Oracle database has had a reputation among new Linux users as difficult to install on Linux systems. Now Oracle Corporation has packaged recent versions for several popular Linux distributions in an attempt to minimize installation challenges beyond the level of technical expertise required to install a database server.

Make sure you have enough disk space and memory

If you have less than 1GB memory run the following commands to create swap space:
$ sudo dd if=/dev/zero of=/swpfs1 bs=1M count=1000
$ sudo mkswap /swpfs1
$ sudo swapon /swpfs1
Debian / Ubuntu Oracle installation

First modify /etc/apt/sources.list file:
$ sudo vi /etc/apt/sources.list

Append following line:
deb http://oss.oracle.com/debian unstable main non-free

Save and close the file. Next import GPG key:
$ wget http://oss.oracle.com/el4/RPM-GPG-KEY-oracle -O- | sudo apt-key add -

Update package database:
$ sudo apt-get update

Finally install Oracle:
$ sudo apt-get install oracle-xe

Output:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
linux-headers-2.6.20-15-generic linux-headers-2.6.20-15
Use 'apt-get autoremove' to remove them.
The following extra packages will be installed:
libaio
The following NEW packages will be installed:
libaio oracle-xe
0 upgraded, 2 newly installed, 0 to remove and 2 not upgraded.
Need to get 221MB/221MB of archives.
After unpacking 405MB of additional disk space will be used.
Do you want to continue [Y/n]? y
Get:1 http://oss.oracle.com unstable/non-free oracle-xe 10.2.0.1-1.1 [221MB]
....
....
Post-install configuration

You must configure Oracle TCP/IP port and other parameters. Simply type the following command:
$ sudo /etc/init.d/oracle-xe configure

Output:
Oracle Database 10g Express Edition Configuration
-------------------------------------------------
This will configure on-boot properties of Oracle Database 10g Express
Edition. The following questions will determine whether the database should
be starting upon system boot, the ports it will use, and the passwords that
will be used for database accounts. Press to accept the defaults.
Ctrl-C will abort.

Specify the HTTP port that will be used for Oracle Application Express [8080]: [Enter key]

Specify a port that will be used for the database listener [1521]:[Enter key]

Specify a password to be used for database accounts. Note that the same
password will be used for SYS and SYSTEM. Oracle recommends the use of
different passwords for each database account. This can be done after
initial configuration:secret
Confirm the password:secret

Do you want Oracle Database 10g Express Edition to be started on boot (y/n) [y]:y

Starting Oracle Net Listener...Done
Configuring Database...Done
Starting Oracle Database 10g Express Edition Instance...Done
Installation Completed Successfully.
To access the Database Home Page go to "http://127.0.0.1:8080/apex"

To access the Database Home Page go to http://127.0.0.1:8080/apex. Open a web browser and type url (you need to use username "system" and password setup earlier)