Shell Programming and Scripting

export ORACLE_SID=DB1
sqlplus / as sysdba << EOF
whenever sqlerror exit sql.sqlcode;
whenever oserror exit FAILURE

set define off
set head off
set feedback off
set echo off
set pagesize 0
set pages 0
set linesize 200
set timing off

spool DB1.txt
select * from v$instance;

EOF

for DB in DB1 DB2 etc; do
  ORACLE_SID=$DB
  sqlplus / as sysdba << EOF
  ...
  spool $DB
  ...
EOF
done