wsl.exe Windows command never exits when run using child_process.spawn

[centsi]

• Version: v9.3.0
• Platform: Windows 10 Fall Creators 64 bit
• Subsystem: child_process

Running a command in Ubuntu on Windows using the "wsl" command works fine except the exit and / or close events never occur, and the script remains running until forcibly closed. I've specifically tested using child_process.spawn, but I believe it's the same with exec and execFile.

Example code follows (works fine if the wsl command is substituted with the "dir" windows command - and of course the first argument removed):

const child_process = require( 'child_process' );

const child = child_process.spawn( "C:\\Windows\\System32\\wsl.exe", [ "ls", "/" ] );

child.stdout.pipe( process.stdout );
child.stderr.pipe( process.stderr );

//Never fires
child.on( 'exit', function() {
	console.log( 'Exited.' );
});


//Never fires
child.on( 'close', function() {
	console.log( 'Closed.' );
});

Thanks - Lawrence

[bzoz]

This reproduces back to v6.0.0. Using spawnSync works as expected.

/cc @nodejs/platform-windows

[seishun]

That's because wsl doesn't exit, you can see it in Task Manager. Probably a wsl bug.

[bzoz]

Investigated this. WSL is waiting for the stdin pipe to be closed. Adding child.stdin.end(); to the code solves this.

I think it is not an issue with Node, its only the way WSL handles its stdin.

[benhillis]

This is microsoft/WSL#4424, fix is inbound.

[corydorning]

this same issue occurs when using windows powershell. exit never occurs. not using wsl