What do you do when you can’t login via sqlplus / as sysdba?  You try to connect and it just hangs. You can login with the -prelim option. It is a lightweight session and No SQL is allowed in the connected session.

$ sqlplus -prelim / as sysdba

SQL*Plus: Release 10.2.0.4.0 - Production on Thu Jul 2 03:32:26 2009

Copyright (c) 1982, 2007, Oracle.  All Rights Reserved.
SQL> shutdown abort;

ORACLE instance shut down.
SQL> exit
Disconnected from ORACLE
rac01.dbaexpert.com:/apps/oracle
DBATOOLS - oracle: sqlp

SQL*Plus: Release 10.2.0.4.0 - Production on Thu Jul 2 03:33:08 2009<

Copyright (c) 1982, 2007, Oracle.&nbsp; All Rights Reserved.

Connected to an idle instance.

SQL> startup
ORACLE instance started.

Total System Global Area&nbsp; 419430400 bytes
Fixed Size       2084456 bytes
Variable Size    155189656 bytes
Database Buffers 255852544 bytes
Redo Buffers     6303744 bytes
Database mounted.
Database opened.

Posted by Charles Kim, Oracle ACE