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JSI Tip 1867. What switches were used to boot this Windows NT instance?

When you install your first copy of Windows NT on a computer, two boot.ini entries are created.

You can install many other Windows NT instances. Additionally, you can have many boot entires for each instance, each with differing switches.

To determine which instance of Windows NT you booted to, open a CMD prompt and type:

@echo %SystemRoot%

This will display the full path of the booted instance.

To determine which set of switches were used, inspect the string value at:


To use this in a batch, run the freeware REGfree program:

for /f "tokens=1*" %%i in ('regfree -Quiet -ListValue hklm\system\currentcontrolset\control\SystemStartOptions') do set bootsw=%%j

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