Go to the Oracle XE web interface (running on http://localhost:8080/apex/ by default), and login with your username (not the system user).

Choose Utilities -> Generate DDL. Check the tables for which you want to export the DDL commands, and you are good to go.

Oracle XE export schema

Checking operating system version: must be redhat-3, SuSE-9, redhat-4, UnitedLinux-1.0, asianux-1 or asianux-2 Failed <<<<

To complete the install, run installer as ./runInstaller -ignoreSysPrereqs
(installation-oracle-on-suse-linux-enterprise-10)

To run Tora, add the following to your profile file

export LD_LIBRARY_PATH=$ORACLE_HOME/lib

And create a tnsnames.ora file in your ORACLE_HOME.
This file lists your Oracle services in the following format -

XE_192.168.1.1=

    (DESCRIPTION =

       (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.1.1)(PORT = 1521)))

       (CONNECT_DATA = (SID = xe) (SERVER = DEDICATED))

    )

(Re: Error connecting to an Oracle DB)

If Tora is still not connecting to oracle, try exporting TNS_ADMIN environment variable, pointing to the location of tnsnames.ora file -

export TNS_ADMIN=/usr/lib/oracle/xe/app/oracle/product/10.2.0/client/