Sometimes you may get below error while starting Siebel.
ODBC error 08003 in SQLConnect:
[DataDirect][ODBC lib] Connection not open
(native error 0).
Unable to login using specified ODBC parameters.
Resolution :
1) Check ORACLE_HOME is set or not?
2) Check LD_LIBRARY_PATH is set or not?
3) Check TNS_ADMIN is set or not?
4) Check PATH is set in or not?
If all oracle parameters are not then set it.
Example :
bash-3.2$ export ORACLE_HOME=/app/oracle/product/11.2.0/client_32
bash-3.2$ export LD_LIBRARY_PATH=$ORACLE_HOME/lib:$LD_LIBRARY_PATH
bash-3.2$ export TNS_ADMIN=/app/oracle/product/11.2.0/client_32
bash-3.2$ export PATH=$ORACLE_HOME/bin:/usr/sbin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin