$
$ cat test.sh
sqlplus -S /nolog <<EOF
conn / as sysdba
set serverout on
exec dbms_output.put_line('sussed');
EOF

$
$ sh test.sh
sussed

PL/SQL procedure successfully completed.

$
$

C:\tmp>
C:\tmp>type test.bat
sqlplus -S /nolog <<EOF
conn / as sysdba
set serverout on
exec dbms_output.put_line('sussed');
EOF



C:\tmp>
C:\tmp>.\test.bat
<< was unexpected at this time.

C:\tmp>sqlplus -S /nolog <<EOF

C:\tmp>

U:\>type test.cmd
(
echo conn user^/pass@test
echo set serverout on
echo exec dbms_output.put_line('sussed'^^^);
) | sqlplus /nolog

U:\>test.cmd

U:\>(
echo conn user/pass@test
echo set serverout on
echo exec dbms_output.put_line('sussed'^);
)  | sqlplus /nolog

SQL*Plus: Release 9.2.0.8.0 - Production on Thu Jan 14 13:56:50 2016

Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.


Connected to:
Oracle Database 11g Release 11.2.0.3.0 - 64bit Production

SQL> Connected.
SQL> SQL> sussed

PL/SQL procedure successfully completed.

SQL> Disconnected from Oracle Database 11g Release 11.2.0.3.0 - 64bit Production


U:\>