Identify WindowsTerminal process ID

[jdhitsolutions]

Description of the new feature/enhancement

I'd like a way to identify the process ID associated with a Windows Terminal session. In PowerShell, I can see the session and profile ID variables. And it is easy enough to run Get-Process and find the Windows Terminal process. But what if there are 2 instances running? How can I tell which ID goes with which?

Proposed technical implementation details (optional)

PowerShell has a built-in variable $pid that helps me identify the current PowerShell process. It would be nice to either create a variable like $wtpid. Or add another environment variable that identifies the process ID of this Windows Terminal instance.

[DHowett-MSFT]

Thanks for the request! I'm going to need a use case for this one o_O

[DHowett-MSFT]

(You can use (Get-Process -Id $PID).Parent to get at the WT hosting your powershell instance.)

[jdhitsolutions]

That PowerShell command only works in PowerShell 7, not Windows PowerShell. I am building a simple PowerShell tool that gets the Windows Terminal process and its children. This is not difficult if there is only one instance of Windows Terminal running. But I don't want to make that assumption.

[jdhitsolutions]

I have a viable workaround for my immediate need. Still, since you are already populating environment variables with profile_id and session, I'm hoping it isn't that hard to add wt_pid.

[oising]

Hey Jeff -- for windows powershell, use (gwmi win32_process -Filter "processid = $pid").parentprocessid

PS C:\Users\oisin> gps -id (gwmi win32_process -Filter "processid = $pid").parentprocessid

Handles  NPM(K)    PM(K)      WS(K)     CPU(s)     Id  SI ProcessName
-------  ------    -----      -----     ------     --  -- -----------
    675      37    55884      59052     307.84   6748   1 WindowsTerminal

[jdhitsolutions]

That's the workaround I'm using.

[oising]

That's the workaround I'm using.

Ok, but how does that depend on the assumption that there's only one WT running? I'm not following.

[jdhitsolutions]

This workaround using WMI also solves the multiple instances issue. I originally started with a simple Get-Process WindowsTerminal to get the process ID and go from there. That's when I realized that wouldn't work with I had 2 instances running. AND I realized the Parent property was added in PS7. I should have taken a little more time to think things through before posting. Personally, I'm set with the use case I posted.

But I still think it would be handy to have a variable of some sort to indicate the process id just as we do with $pid in PowerShell.

[DHowett-MSFT]

So, I've been hemming and hawing about this issue.

I don't want to introduce another environment variable exposing WT state for the following reasons:

• Every environment variable we expose is an API we need to continue supporting
  • You might think that a PID is going to be stable, but if we make any process model changes (the likes of which might support "tab tearoff", or "mixed elevation" (!)), the previously inviolate assumption that a single WT process is the host of your shell breaks down
  • (We can't poke a new value for WT_PID into each process running under terminal if it changes live; that's incredibly invasive!)
• Environment variables are, unfortunately, inherited . . . like, by code, and all the processes spawned in VSCode's integrated terminal.

I'm not sure the benefit here outweighs the cost, especially since there's a viable workaround 😄