Yes, you can script it with direct registry manipulation.
The Short Answer
Copy each of the following into .reg
files (such as firefox.reg
, chrome.reg
, ie.reg
) and run them when you want to switch (or, script with reg.exe
).
For Firefox:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\http\UserChoice]
"ProgId"="FirefoxURL"
For Chrome:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\http\UserChoice]
"ProgId"="ChromeHTML"
For IE9:
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations\http\UserChoice]
"ProgId"="IE.HTTP"
The Long Answer
Windows stores per-user standard protocol Default Registrations under the UrlAssociations
key, found at
HKEY_CURRENT_USER\Software\Microsoft\Windows\Shell\Associations\UrlAssociations
Similar to file associations, there can be a "Default Program" for links. This is sort of jargon terminology that references the UserChoice
key- there is also a standard file association-like shell registration under the http
ProgId which can also be changed, but the proximal configuration for browsers is via Default Programs (see bottom for an additional comment on this).
What I'm talking about here is what you're changing when you go to the Default Programs section of the Control Panel to set a browser:
![Default Programs for Protocols in the Control Panel](https://i.imgur.com/DehDA.png)
To configure this directly in the registry, let's first inspect that's already there. In this screenshot I've navigated to that key in regedit.exe
, and Chrome is my default browser, designated by the ChromeHTML
ProgId value.
![Navigating to the UrlAssociations subkey in regedit](https://i.stack.imgur.com/Gm8jb.png)
The minimum change you need to make to switch which browser opens when you click a link is to change the ProgId
value under the UserChoice
subkey on each protocol you want to change (probably http
and https
will be the same, but if for some reason you wanted to make each of those open in separate browsers, you could).
Now it's just a matter of determining what to use for Firefox, IE, and any other browser you may want to switch to. If you wanted to determine this programmatically, you could do so by digging into the Capabilities
key of the browser registration, found here for Firefox:
HKEY_LOCAL_MACHINE\SOFTWARE\Clients\StartMenuInternet\FIREFOX.EXE\Capabilities\URLAssociations
HKEY_LOCAL_MACHINE\SOFTWARE\Clients\StartMenuInternet
is where all the browsers are listed, and each one should have the above structure.
![Navigating to the Capabilities key in regedit](https://i.stack.imgur.com/TBcON.png)
You can see from inspection that if I wanted to switch to Firefox, I'd use the FirefoxURL
ProgId value back up in UrlAssociations.
(However, if you didn't want to dig around like this, there's a quick cheat: Just set whatever browser you want as default, and refresh regedit to see what the browser has set for the UserChoice
!)
All we need to do is change that key value to FirefoxURL
, and now links open in Firefox. After doing so you can either click a link or double check in the control panel that the right default is registered:
![Double checking the default program in the Control Panel](https://i.stack.imgur.com/DFVxE.png)
Now if you've been paying close attention, you might have noticed a couple flaws with all of this:
IE doesn't have a URLAssociations
subkey under it's browser registration in StartMenuInternet
, so where does the ProgId value come from? Answer: I don't know, at least not without more research. It may be hardcoded or found in another key I haven't found yet.
Firefox's ProgId's under it's URLAssociations
are FirefoxURL
, but when you click to register in the options in the browser itself, it uses FirefoxHTML
as the ProgId instead! Why? Again, I don't know. They both work because they both exist and point to Firefox. Maybe it's intentional, but it's probably just a bug with no effect.
What happens when there's no UserChoice
Default Program? Answer: the "regular" file association for the protocol (eg, http
) is used. This is found at the standard ProgId locations just like file associations (HKCU\Software\Classes
, HKLM\Software\Classes
, and the view at HKCR
). At least Chrome sets it's info there, I think, but Firefox doesn't seem to, at least in my tests.
I recommend that if you want this added to Default Programs Editor, you should suggest and upvote it on that application's UserVoice Feedback page. I have it on good authority that the application author pays attention to that feedback when deciding how to spend his development time!
Paste the following into notepad
Windows Registry Editor Version 5.00
[-HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.exe]
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.exe]
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.exe\OpenWithList]
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.exe\OpenWithProgids]
"exefile"=hex(0):
In notepad On the File menu, click Save as
Select All Files in the Save as type list, and then type Exe.reg in the File name box.
Select Unicode in the Encoding list. Save it and remember the file location.
Go to the file location and right click on the EXE.reg file and select "merge"
Restart the PC.
For alternative ways to fix this issue and a bit more info view this page from Microsoft
Best Answer
You can always approach it by going to the Registry Editor. If you aren't familiar with editing the registry, I suggest you back it up first before attempting anything.
You can find the extension at HKEY_CLASSES_ROOT\.yourextension
For example, let's take WinRAR's .RAR extension. For that, I'd have to go to HKEY_CLASSES_ROOT\.rar on the Registry Editor. As you can see on the screenshot below, the (Default) REG_SZ key points to WinRAR.
Now we will go to the registry key that actually contains the application information. That is WinRAR and it should be located on HKEY_CLASSES_ROOT as well. So it will be located under HKEY_CLASSES_ROOT\WinRAR. As you can see on the image below, under the WinRAR key, you can jump directly to shell\open\command.
As shown above, you just edit the (Default) key and place the path to your application inside double quotes then a space and followed by %1 inside double quotes as well. %1 denotes the path to your file.
I hope this somewhat lengthy explanation can serve as a template for you to be able to easily remap your file extension to your newly updated executable. Once you get the hang of this, it should be pretty easy from here-on out.