How do I Suppress "PL/SQL procedure successfully completed" message in sqlplus?

Use the command:

SET FEEDBACK OFF

before running the procedure. And afterwards you can turn it back on again:

SET FEEDBACK ON

This has worked well for me in sqlplus, but I did just notice that "set feedback off" suppresses errors in Sql Developer (at least version 17.2.0.188). Just something to be aware of if you use Sql Developer:

create or replace procedure test_throw_an_error as buzz number; begin dbms_output.put_line('In test_throw_an_error. Now, to infinity!'); buzz:=1/0; end;
/
set serveroutput on
set feedback off
exec test_throw_an_error;
exec dbms_output.put_line('Done, with feedback off');
set feedback on
exec test_throw_an_error;
exec dbms_output.put_line('Done, with feedback on');

Result:

Procedure TEST_THROW_AN_ERROR compiled

In test_throw_an_error. Now, to infinity!

Done, with feedback off

In test_throw_an_error. Now, to infinity!


Error starting at line : 11 in command -
BEGIN test_throw_an_error; END;
Error report -
ORA-01476: divisor is equal to zero
ORA-06512: at "ECTRUNK.TEST_THROW_AN_ERROR", line 1
ORA-06512: at line 1
01476. 00000 -  "divisor is equal to zero"
*Cause:    
*Action:
Done, with feedback on

PL/SQL procedure successfully completed.