The difference between REGEDIT and REGEDT32
When Windows 95 came out, the registry was one of the big new features offered with that operating system. Instead of storing system and application configuration information in a whole slew of .INI files scattered across the hard drive, the registry moved all of that information into one place. Knowing how to plow through the registry is probably something any decent Windows NT/ Windows 2000 sysadmin should know about.
One of the not-very-well-explained quirks about editing the registry is that there are two tools available by default for doing this in NT and 2K: REGEDIT and REGEDT32. The two have some marked differences that need to be kept in mind.
REGEDIT is basically a copy of the original registry-editing utility found in Windows 95, and is kept around in other versions of Windows for the sake of backward compatibility. REGEDT32, on the other hand, was only shipped with NT, 2K and XP. The main difference between the two is that REGEDT32 allows you to set and clear permissions in the registry, while REGEDIT doesn't.
Each key in the registry in NT and 2K (and XP, of course) has an access control list or ACL -- in exactly the same manner that files and folders on an NTFS volume have ACLs. The reason for this applies as it does on files and folders: to allow or deny access to certain objects based on a given user's credentials. This way a given user could be provided access to one particular subtree of the registry, but not another.
To edit the permissions for a particular key in REGEDT32, right-click on the key in the left-hand pane and select Permissions. A dialog box similar to the kind used to set permissions on files and folders will come up. This lets you set basic or advanced permissions, and also set or reset the inheritability of those permissions on any subkeys of the key you're editing. You may need to clear permissions for a subkey if you are, for instance, trying to uninstall an application from another user account and need to purge the keys as an administrator to do it.
On the whole, then, use REGEDT32 to set or clear registry keys when you use Windows NT, 2K or XP.
Bear in mind that when you apply permissions to any object, the most restrictive set of permissions supersedes all others.
Serdar Yegulalp is editor of the Windows 2000 Power Users Newsletter.