SQL>
SQL> set feedback on
SQL> set pages 9999 serveroutput off
SQL>
SQL> BEGIN
2 DBMS_OUTPUT.PUT_LINE('Oh...');
3 END;
4 /
PL/SQL procedure successfully completed.
SQL>
SQL>
SQL> set serveroutput on
SQL>
SQL> /
Oh...
PL/SQL procedure successfully completed.
SQL>
SQL>