On 7/18/2011 7:03 PM, Glenn Linderman wrote:

Wonder if there is a third party command line tool which augments them for reading/setting HCU Classes? Will search. I know there is a command line registry tool somewhere, but specifying the paths correctly would be onerous.

XP+ has REG and REGINI commands which can manipulate the registry from the command line, without resorting to third party applications. So a batch file could wrap them, to avoid mistyping keys, and one could make an FTYPE.CMD and ASSOC.CMD (I haven't, at least not yet).

Also <http://vim.wikia.com/wiki/Windows_file_associations> although specific to Vim, is addressing the general problem, and comments by readers on that page seem relevant:

The following is a "for reader's information" comment; not a suggestion that the tip be changed. In classic Microsoft style, using HKEY_CLASSES_ROOT is ambiguous. I do not know the details, but on at least some systems (after Windows 9x), I think the following is correct:

HKEY_LOCAL_MACHINE\Software\Classes : for all users

HKEY_CURRENT_USER\Software\Classes : for interactive user

HKEY_CLASSES_ROOT : merged view of above (and is used by Win9x apps)

I don't know what happens if you write to HKEY_CLASSES_ROOT (which does not exist). Perhaps (like installing some apps), if you are in the Administrators group, you will write to HKLM, otherwise you will write to HKCU. JohnBeckett 08:24, 2 July 2009 (UTC)

This is correct as far as I know. I wanted to include some information about how HKCR is a merged view of HKLM/Software/Classes and HKCU/Software/Classes, but doing so would beg information such as "what happens when I edit an entry that actually exists in HKCU?" etc. From experimentation, it seems that creating new keys in this area will always create it in HKLM (system-wide), and ftype and assoc certainly do that, but I don't really have any documentation of that fact, and I don't know what it will do for limited-privilege accounts. I also don't know what happens when you edit an existing key, but I imagine it will "do the right thing" and keep the original where it was. I don't know this for a fact though. For these reasons, I left out that tidbit. But if we can answer some of these questions, it would be a good thing to include.

So attempts by applications to use the HKEY_CLASSES_ROOT directly may result in variant behavior depending on the privilege of the application. My overall opinion? It is sad that M$ even invented the registry.