If your not already logged in, do so now and shutdown the database.
bash-2.05$ sqlplus /nolog SQL*Plus: Release 10.1.0.2.0 - Production on Wed Oct 6 11:25:46 2004 Copyright (c) 1982, 2004, Oracle. All rights reserved. SQL> connect sys/passwd as sysdba; Connected. SQL> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SQL> quit
There are a variety of different shutdown methods other than immediate. Using shutdown without an argument is rarely used because the database won't shutdown until all connections have been disconnected willingly, during which time it simply won't allow any new connections. The problems is that if a session is hung or a user went to lunch without disconnecting it could take a long long time. Shutdown immediate will safely close out all current connections regardless of whether or not they want to.