Oracle Message ORA-02708 - osnrntab: connect to host failed, unknown ORACLE_SID

ERRORosnrntab: connect to host failed, unknown ORACLE_SID
CAUSEThe invoked Unix two-task driver failed to find an entry in oratab for the sid you supplied.
ACTIONFirst, check whether you have read access to oratab, and see if the desired sid is there. Add an entry to oratab for the desired sid, if necessary.