[kwlug-disc] Running multiple versions of Firefox on Linux

[Thomas McKee]

Having dipped my toes in the water with Nix, perhaps it can help you?

The `nix shell` command can construct a temporary environment with a given
package installed. The trick[2] is to make sure you're using the right
version of the nixpkgs repository that happens to include the version of
Firefox that you care about. Linked from [2], there's a handy lookup site
to track down such nixpkgs version hashes for a given package. It even
links to shell snippets like

```
nix shell
github:nixos/nixpkgs/e6f23dc08d3624daab7094b701aa3954923c6bbb#firefox ;
firefox
``` [4]

which I just used to run Firefox at version 139.0.4 (I use Arch, btw 🙃).

I expect this would need a fair bit of network transfer so, beware!

Cheers,
- Tom

My research breadcrumbs:
[1]: google search
<https://www.google.com/search?q=nix-shell+run+package+at+specific+version&oq=nix-shell+run+package+at+specific+version&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIHCAEQIRigATIHCAIQIRigATIHCAMQIRigAdIBCDg3MTJqMGo3qAIAsAIA&sourceid=chrome&ie=UTF-8>
[2]: blog post
<https://lazamar.github.io/download-specific-package-version-with-nix/>
[3]: nixpkgs version for each firefox version
<https://lazamar.co.uk/nix-versions/?channel=nixpkgs-unstable&package=firefox>
[4]: shell command for 139.0.4
<https://lazamar.co.uk/nix-versions/?package=firefox&version=139.0.4&fullName=firefox-139.0.4&keyName=firefox&revision=e6f23dc08d3624daab7094b701aa3954923c6bbb&channel=nixpkgs-unstable#instructions>

On Wed, Apr 1, 2026 at 4:03 PM Paul Nijjar via kwlug-disc <
kwlug-disc at kwlug.org> wrote:

> Tragically, I need to run multiple versions of Firefox on the same
> laptop for some debugging. What is the easiest acceptable way to do
> this? Set up a Docker container for the alternative versions?
> Something else?
>
> I don't care about syncing user profiles -- everything runs in private
> browsing mode. For now I only need to run Linux Firefox. I do need to
> be able to control the versions of Firefox I am running.
>
> The distribution is Debian stable, if that matters.
>
> - Paul
>
> _______________________________________________
> kwlug-disc mailing list
> To unsubscribe, send an email to kwlug-disc-leave at kwlug.org
> with the subject "unsubscribe", or email
> kwlug-disc-owner at kwlug.org to contact a human being.
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.kwlug.org/pipermail/kwlug-disc_kwlug.org/attachments/20260401/76b21fb4/attachment.htm>