Monday, November 2, 2009

The Windows 7 'reg' command

So I had a problem. I had a Topo 8 install on my old XP hard drive and wanted to transfer it to my new Windows 7 machine. No problem, just re-install, right? Well, that would be a problem alright, because my activation key for Delorme Netlink would not work in the new install -- Delorme links it to a single installation of Topo USA. Note that the licensing for Netlink allows me to run it on any computer that I own as long as it's just one computer at a time (i.e. I can't have it installed on more than two computers and can only use it on one computer at a time), but the actual implementation is similar to the lamentable Windows Activation in that it often disallows things that are allowed under your licensing agreement, requiring you to call in to a support center and have a database entry adjusted at the other end to allow activation.

So now let's talk about what actually happens on modern versions of Windows when you install a program. Things get placed into basically four areas:

  1. Start Menu folder -- usually a folder is created here with a new Shortcut to the application plus utilities. The location of the Start Menu folder differs wildly between Windows XP and Windows 7, but it's easy to find.
  2. Program Files -- usually a folder with the program and all its data is created here.
  3. Windows -- Any driver bundles are plopped into the appropriate folders here, as is installer/uninstaller info.
  4. Registry -- Configuration data and component registration.
Of these, the first three are easy to copy from one computer to another. But the registry entries... ah yes, now that is a problem!

The fundamental problem is that the registry is a database, and thus you can't simply use drag and drop to move entries from point A to point B, unlike with MacOS where you could just copy the appropriate directory from the old /System/Library/xxx to the new /System/Library/xxx and/or the old ~/Library/xxx to the new ~/Library/xxx to move the configuration data, or Linux where you could just copy the appropriate directory from the old /etc/xxx to the new /etc/xxx to move the configuration data. You have to use database tools, and the Windows database tools for accessing the registry are crude and primitive compared to the tools available for accessing file data. This is especially true for the 'regedit' GUI command which is utterly incapable of copying registry from place A in the registry tree to place B in the registry tree. But never fear: This is a capability that the command line 'reg' command has, and we're going to use it.

The first thing to do is to mount the old hard drive as your "D:" drive. Make sure you've added the 'Run' menu option to your Start Menu with the appropriate control panel entry (sorry, you've already seen my opinion of the Windows control panel, it's in there *somewhere* but you'll have to do like me and just dig until you find it!). Select 'Run' from your start menu, and go into 'Regedit'.

The next thing you'll need to do after that is import the HKLM hive into your registry. Click on the HKEY_LOCAL_MACHINE entry and select File->Load Hive. Browse over to D:\Windows\System32\config and select 'software' as the hive to import. Then give it a name, like OLD_SOFTWARE. Once you finish doing this, you'll find that OLD_SOFTWARE is now in your registry tree. You can now exit regedit, because regedit has no (zero) ability to copy subtrees from one place to another in your registry tree.

Now you'll need an administrative mode command prompt in order to operate. Now, I'm going to assume you have some basic Unix-compatible command line tools available using Cygwin or by copying files to MacOS or Linux via a network file share then executing Unix commands there, simply because there are no native Windows tools which will do the same command line parsing in as easy a manner, but it COULD be done with VBscript. It'd just be a lot more coding to make it work.

So: now that we have a command line,let's query out all the Delorme keys:

  • reg query HKLM\OLD_SOFTWARE /s /f delorme >\Delorme_keys
Then copy Delorme_keys someplace where you can run Unix commands on it:

  • grep "^HKEY" Delorme_keys >Delorme_keys2
  • vi Delorme_keys2
Take a look at those keys, and at the original file too, to see which ones you want. In general you will not want to completely replace the contents of all keys that have some data item related to your application, you'll want the Classes and any software-specific key. So I edited Delorme_keys2 to have the keys I wanted to copy from the old install, then:

  • awk ' { t=$0; sub("OLD_","",$0) ; printf("reg copy \"%s\" \"%s\" /s\n", t,$0); } ' Delorme_keys2 >DelormeRegCopy.bat
This gives me a file that has lines in it that look like this:
  • reg copy "HKEY_LOCAL_MACHINE\OLD_SOFTWARE\Classes\CLSID\{20016EDD-4CB6-11D3-A3FA-0000C0506658}" "HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{20016EDD-4CB6-11D3-A3FA-0000C0506658}" /s
The 'reg copy' command will copy both the key (and its data items) and any subkeys to the new location, assuming you provide the /s flag. Then I copy this .bat file back to the Windows 7 system, and from the Command prompt type "delormeregcopy.bat" and voila! Now my copy of the Delorme application works, Netlink works, and I can then re-install Topo 8 on top of this install to "repair" it (i.e., put the installer and driver bundles in the right place and verify that everything is registered properly) and the installation keys will still be there to keep my Netlink operational.

Note: As always, back up your registry before mucking around in it. And be *very* careful with any keys you copy in, I examined the contents of each key using regedit before I allowed it to stay in my final Delorme_keys2 file. The above is NOT the full directions for how to do this specific task, simply because I do not wish to enable software piracy, but, rather, an example of how to use the 'reg' command to copy critical registry entries from an old installation into a new installation. And the usual disclaimer "this might destroy your system!" applies.

Now: I could go off on a rant about how stupid the Windows registry is, how the tools to manipulate it are primitive and far inferior to the tools available to manipulate text files, blah blah blah, but we already all know about that. The "reg" command at least gives us some of the missing functionality that regedit doesn't have, even if it requires typing obscure commands at a command prompt. But then, "obscure" and "Windows Registry" do go together like "macaroni" and "cheese", eh?

-- EG

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