Bug report

Transferred tohttps://discuss.python.org/t/support-for-file-urls-in-webbrowser-open/81612 until consensus is reached.

Bug description:

In the code:

importwebbrowserfrompathlibimportPathindex_html=Path.cwd()/"index.html"webbrowser.open(index_html.as_uri())

It is common forxdg-open (on linux) oropen location (on mac) oros.startfile (on windows) to be selected as the default browser. This is great and simple forhttp[s] urls, but when these are passedfile:// urls, all of the above select the default opener for HTMLfiles, which may not be a browser at all (commonly a text editor for developer systems).

I don't know if there's a way to indicate that Browser entries can handle given URL schemes, but when selecting a browser from the try list, ideally these generic 'open' mechanisms should be skipped forfile: URLs. Even better, use standard APIs to lookup the default browsers forhttp[s] and invoke that explicitly, rather than relying on an interpretation of "open URL" which is only valid for http URLs.

I believeURLForApplicationToOpenURL is the current macOS API to look up the application forhttp:, which could be used to launch explicitly with a browser. I guessxdg-settings get is already the equivalent for most linux situations and preferred if available, which is great. I'm not sure there's a more general way to discover whatxdg-open will do withhttp://, but we haveoccasional reports wherexdg-settings get default-web-browser doesn't work andxdg-open is invoked and doesn't launch a browser (or launches adifferent browser). I've no idea what the Windows call would be, butthis looks like the same question.

This appears to have been opened long ago as#37540 and erroneously closed as an Apple bug (all platforms exhibit this behavior, and I think the bug is pretty clearly in webbrowser's assumption that "open file://path.html" means "open file://path.html with a web browser" which does not appear to be what any of the platforms mean by the chosen API).

CPython versions tested on:

3.9, 3.10, 3.11, 3.12

Operating systems tested on:

Linux, macOS, Windows

Linked PRs

• gh-128540: Fixedwebbrowser.open withfile: URLs may launching editor instead of browser #130031
• gh-128540: lookup default webbrowser on macOS #130535
• gh-128540: lookup default webbrowser on Windows #130538
• gh-128540: launch default browser more often on Linux #130541