Oracle standalone instance, say 11gR2 on Linux, DBA mistakenly issues a SHUTDOWN in a production session rather than development as intended. It's been suggested to (1) be extra careful next time and (2) don't do it a second time :)
Would it be worth pursuing to add a BEFORE SHUTDOWN trigger that checks IF business day AND IF business hours, THEN RAISE EXCEPTION to check for some intervening control -- such as a global variable value, or file presence. IOW prevent an unscheduled outage during business hours unless there is an override.
It appears that the BEFORE DATABASE trigger syntax could accommodate either a PL/SQL procedure or an OS shell. But what kind of trace would be required to see where control would go after the SHUTDOWN is prevented?