How to determine if I'm in powershell or cmd?

Question

I've been playing with OpenSSH on Windows and it looks like the normal Unix aliases are missing. I'm not sure whether it's starting powershell or cmd when I log in to a Windows machine via SSH. What's the correct way to see the currently running shell on Windows?

Answer 1

All credit goes to PetSerAl, this had to be posted as an aswer:

(dir 2>&1 *`|echo CMD);&<# rem #>echo PowerShell

Within Win32-OpenSSH this command also works, and outputs CMD.

NB : Win32-OpenSSH seems a bit limited, cd is not recognized on my system.

Answer 2

I'd like to expand on @sodawillow's answer to also distinguish between using Powershell (powershell.exe) known as Desktop and PWSH (pwsh.exe) known as Core.

(dir 2>&1 *`|echo CMD);&<# rem #>echo ($PSVersionTable).PSEdition
# Returns one of: CMD, Core, Desktop

This works in all instances where a sub-shell is not instantiated. What that means is that it does not work from opening a default sub-process in Python, as it always uses CMD when interacting with windows. This is actually set by the Windows environment variable: ComSpec always pointing to C:\Windows\system32\cmd.exe.

For example:

(Starting the python interpreter from a pwsh shell.)

>>> import os, subprocess
>>> c="(dir 2>&1 *`|echo CMD);&<# rem #>echo($PSVersionTable).PSEdition"
>>> subprocess.call(c,shell=True)
CMD

For other Python shell detection schemes, please see this good post.

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UPDATE: 2020-05-01

I managed to get the above working, but with the obnoxious side effect of always loading the powershell profile, before executing. The trick was to specify execute=<path-to-powershell-exe> like this:

(Start a python CLI.)

import os, subprocess
c="(dir 2>&1 *`|echo CMD);&<# rem #>echo($PSVersionTable).PSEdition"
e="C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\powershell.exe"
subprocess.call(c, shell=True, executable=e)

# output:
# <blah blah from profile>
# Desktop
# 0

I have not been able to circumvent the powershell profile issue. But apparently it is something being worked on. See here and here.