`pip env shell`, launches the wrong shell.

[dopry]

Issue description

When I launch pipenv shell, it opens a different shell than the one I am running. I use windows and typically use either powershell or bash, with a strong preference for bash with my python projects. When I run pipenv shell it launchs cmd.exe. I've tried setting PYENV_SHELL_EXPLICIT, but that doesn't work.

Expected result

I expect that if a new subshell to be the same shell I'm currently running or the shell in PYENV_SHELL_EXPLICIT. It might be nice to have a pipenv activate/deactivate instead. I don't usually launch a new shell just to load my virtual environments. seem like a bit of overkill.

Actual result

It launches cmd.exe

Steps to replicate

launch git bash or powershell
cd to a folder with a pipfile
pipenv shell

voila, you're in cmd.

[oz123]

I am not familiar with pyenv, neither windows tbh, but this seems wrong

 PYENV_SHELL_EXPLICIT

This is PIPENV not pyenv...

[dopry]

Doesn't change the fact the the wrong shell is launched when it is not set. I don't want to have to set that env var every time I switch shell. I think shellingham is doing a poor job of shell detection for this use case. It searches the process tree and returns the first shell it finds. When using pyenv it returns cmd, because the pyenv shims are CMD. This could probably be pre-empted by checking for $SHELL first which will be set in most posix shells, even those ported to windows, then falling back to shellingham detection.

dopry@Quasar MINGW64 ~
$ python
Python 3.10.8 (tags/v3.10.8:aaaf517, Oct 11 2022, 16:50:30) [MSC v.1933 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import shellingham
>>> shellingham.detect_shell()
('cmd', 'C:\\Windows\\System32\\cmd.exe')
>>> import os
>>> os.getenv('SHELL')
'C:\\Program Files\\Git\\usr\\bin\\bash.exe'
>>>

PS C:\Users\dopry> python
Python 3.10.8 (tags/v3.10.8:aaaf517, Oct 11 2022, 16:50:30) [MSC v.1933 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import shellingham
>>> shellingham.detect_shell
<function detect_shell at 0x000001B7D9D46B90>
>>> shellingham.detect_shell()
('cmd', 'C:\\Windows\\System32\\cmd.exe')
>>>

[oz123]

Well, thanks for doing that hard work finding the root cause. Now, please open the issue (and a PR) in Shellingham repo.

[dopry]

I have, but I'm not convinced its a shellingham issue. Shellingham's purpose is to identify the shell the current process is running in, which it does. Pipenv shell on the other hand should be focused on preserving the interactive shell the user is using, which isn't always the same shell that is executing the process. Shellingham also does purport any compatibility with pyenv, which pipenv does.