1.Remove ORACLE_SID, ORACLE_HOME variablesin .profile.
2.Add the following in.profile
PATH=/usr/local/bin:$PATH
export PATH
echo " the SIDS on this machine are:"
cat /var/opt/oracle/oratab |awk -F: '{print $1}' |grep -v
ORAENV_ASK="YES"
. /usr/local/bin/oraenv
....
3.During oracle user login, there will be a prompt to choose which ORACLE_SID you want to use, so choose what you want, and oraenv will automatically setup ORACLE_HOME for this specific ORACLE_SID.
Note: the above is for Sun Solaris. For other unix,please refer to ORACLE DOC for Unix
