Saturday, June 14, 2008

Windows Vista - Choosing Timeout and Default OS with bcdedit

Now that we're experts on identifying OS entries, let's return to some nuts and bolts. As with boot.ini, Windows Boot Manager's main jobs are to define a timeout value and a default. (Clearly there are also other things that Windows Boot Manager does, but I'm trying to cover just the essentials here.)

Changing the Boot Manager Timeout

To change the timeout value, type bcdedit /timeout numberofseconds to set the number of seconds that Windows Boot Manager waits before choosing the default operating system entry. For example, to tell Windows Boot Manager to wait 15 seconds, you'd type

bcdedit /timeout 15

The adjustment you'll want to do more often is probably choosing the default operating system instance.

Changing the Default Boot Manager Entry

You'd think the second task-telling Boot Manager which OS entry to load by default-would be a snap. It is, almost; you can pick any OS entry and make it the default, but, as you'd probably guess by now, you've got to refer to that OS entry by an identifier, and the chances are good that you'll have to use its GUID.

As we've already seen, the new "Vista without DEP" OS entry on my system got a GUID of {}.


Even if you type into your system exactly the same commands that I've typed, you will not get the same GUID, as they're random. So if your GUIDs look different than mine, don't panic, it's supposed to work out that way.

Using that GUID, I can then make that entry the default by typing bcdedit /default { guid }, so for example to make "Vista without DEP" the default, I'd type

bcdedit /default {}

Again, you can do something similar on your system; just remember that you'll have to retrieve the particular GUID of your "Vista without DEP" OS entry; simply typing bcdedit by itself will, recall, show you your OS entries and their GUIDs. And don't forget to surround the GUID with curly braces; bcdedit won't work without them. Then, after typing bcdedit all by itself a second time, I'll see the same output, except in the "identifier" line the {} will be replaced by {default}. The other OS entry, the "Microsoft Windows Vista" one, will have an identifier of {current}.

*.* Source of Information : Administering Windows Vista Security: The Big Surprises

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