subprocess.kill should ignore signal argument on Windows

Version

v18.0.0

Platform

Microsoft Windows NT 10.0.19044.0 x64

Subsystem

child_process

What steps will reproduce the bug?

The documentation about subprocess.kill([signal]) says:

On Windows, where POSIX signals do not exist, the signal argument will be
ignored, and the process will be killed forcefully and abruptly (similar to
'SIGKILL').

This does not seem to match the current behavior, where the signal argument is not ignored on Windows, and it can lead in fact to different results. A minimal repro:

// test.mjs - Run on Windows

import { spawn } from 'child_process';

spawn(process.execPath, ['-v']).kill('SIGKILL'); // ok
spawn(process.execPath, ['-v']).kill('SIGHUP'); // throws ENOSYS

How often does it reproduce? Is there a required condition?

Always on Windows

What is the expected behavior?

If the documentation is right, invoking kill('SIGHUP') on a subprocess on Windows should work exactly like kill('SIGKILL').

What do you see instead?

The signal argument is not currently ignored on Windows. I can't decide if this behavior is intended and the documentation is wrong or if the documentation is right and the behavior is incorrect.

Additional information

If someone could clarify me about the expectations of running subprocess.kill on Windows, I would be glad to submit a PR to fix the code or the documentation.

This seems a fairly significant issue, in the sense that anybody that is triggering a signal with process.kill without knowing this issue is probably doing it in a problematic way for Windows.

src: fix kill signal on Windows

src: fix kill signal 0 on Windows

@StefanStojanovic

@StefanStojanovic Thanks for fixing subprocess.kill(0)!

However, subprocess.kill('SIGWINCH') is still having this problem, as mentioned in earlier messages from this issue. Therefore I believe this issue should remain open?

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`subprocess.kill` should ignore `signal` argument on Windows #42923

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How often does it reproduce? Is there a required condition?

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What do you see instead?

Additional information

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subprocess.kill should ignore signal argument on Windows #42923

Description

Version

Platform

Subsystem

What steps will reproduce the bug?

How often does it reproduce? Is there a required condition?

What is the expected behavior?

What do you see instead?

Additional information

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fabiospampinato commented on Dec 9, 2023

3 remaining items

ehmicky commented on Oct 26, 2025

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`subprocess.kill` should ignore `signal` argument on Windows #42923