How to get information about the user who called shutdown in the BEFORE SHUTDOWN ON DATABASE trigger and put his name in the table?

Question

Oracle

Hello everyone, I just started to study triggers in Oracle, I want to enter information about the user who caused the shutdown in the table,
I wrote something like this:
CREATE TABLE user_inf
(
Event_type VARCHAR2(150)
);
CREATE OR REPLACE TRIGGER STOP_SCRIPT BEFORE SHUTDOWN ON DATABASE
BEGIN
insert into user_inf (Event_type) values ​​(SYS_CONTEXT('USERENV', 'OS_USER'));
END;
The trigger for some reason does not fire on shutdown immediate.