Windows processes launched from WSL do not terminate when killed from WSL

[cspotcode]

Your Windows build number:

Microsoft Windows [Version 10.0.15063]

What you're doing and what's happening:

# At WSL bash prompt
/mnt/c/Windows/System32/cmd.exe &
sleep 1
# Do one of the following:
kill $!
# ...or
kill -9 $!
# Confirm that Linux cmd.exe process is terminated
ps
# In Windows Task Manager, cmd.exe process is still running

I see the same behavior when running python.exe or notepad.exe.

What's wrong / what should be happening instead:

Starting a Windows command-line process from WSL and then sending SIGTERM, SIGKILL, or pressing Ctrl+C terminates the Linux process but does not terminate the Windows process. I am expecting the Windows process to be terminated. Is the behavior I'm seeing by design or a bug?

[therealkenc]

Oddly this kind of goes to #2110. FWIW, you can't kill -9 a Windows process in Cygwin/MSYS2 either. Which isn't the least bit surprising; because win32 processes "don't work like that". But it would be academically interesting to see how far the WSL guys want to take this in the hypothetically distant future.

[cspotcode]

When you launch a Windows process from WSL, you do see a Linux process appear in WSL. And it is different from the process in Windows. (different PIDs) #2110 is talking about how the ps command doesn't list windows processes, but in the situation I'm describing, something does appear in ps output.

Since a Linux process with PID is created (different from the corresponding Windows PID) I would hope that sending SIGTERM to the Linux process would send a corresponding termination request to the Windows process.

Pressing Ctrl+C does terminate the Linux process. I assume this means it's listening for SIGTERM and exiting when it gets it. However, it doesn't send the Windows process a SIGINT signal, WM_CLOSE or WM_QUIT message.

I'm sure I'm oversimplifying, but here's my best guess equivalence between Linux and Windows:

Linux	Windows
SIGTERM	SIGINT signal for CONSOLE subsystem, WM_CLOSE* message for WINDOWS subsystem
SIGKILL	TerminateProcess()

*This post says that TaskKill.exe will send WM_CLOSE when the /F flag is omitted.

[benhillis]

Thanks for posting. This is the same request as #1614. Support for this is on my backlog - marking this thread as a duplicate.