Why has the sql statement been extucted two times in shell script?

Question

I tried to test rac load balance using the following shell script on suse 10 + oracle 10g rac.
oracle@SZDB:~> more load_balance.sh
#!/bin/bash
for i in {1..20}
do
echo $i
sqlplus -S system/oracle@ORA10G <<EOF
select instance_name from v\$instance;
EOF
sleep 1
done
exit 0After execute shell script, I got the follow result.
oracle@SZDB:~> ./load_balance.sh
1
INSTANCE_NAME
ora10g2
INSTANCE_NAME
ora10g2
2
INSTANCE_NAME
ora10g1
INSTANCE_NAME
ora10g1
3
INSTANCE_NAME
ora10g1
INSTANCE_NAME
ora10g1Seem the sql statement has been executed two times in each loop. If you feel free please help to have a look. Thanks in advance.
Robinson

Answer 1

You can end a SQL command in one of three ways:
* with a semicolon (;)
* with a slash (/) on a line by itself
* with a blank line
A semicolon (;) tells SQL*Plus that you want to run the current command that was entered. SQL*Plus processes the command and also stores the command in the SQL buffer.
A blank line in a SQL statement or script tells SQL*Plus that you have finished entering the command, but do not want to run it yet, but it's stored the command on SQL Buffer.
A slash (/) on a line by itself tells SQL*Plus that you wish to run the command stored on SQL buffer.