is it possible u misunderstood what u have to edit?
maybe u have to add a ORACLE_HOME_DIR or sth like that to your
/home/username/.bash_profile or /.bashrc
seems more likely to me.
sth like
export ORACLE_HOME=/path/to/your/oracle
after u have saved that u may
'source /home/username/.bash_profile'
to make the environment variable visible to your system
but i may be wrong...
good luck,
jens