[BUG] Newlines are handled differently between node and `npm exec` on powershell

Is there an existing issue for this?

• I have searched the existing issues

This issue exists in the latest npm version

• I am using the latest npm

Current Behavior

Using the following script:

#!/usr/bin/env node
console.log(process.argv[process.argv.length - 1]);

and package.json with "bin": "./index.js",.

When I run the script with multiline arguments in node and npx, I get the different results on Powershell:

PowerShell 7.4.5/Windows 11
Note there is a missing second line on the npx output

PS > node .\index.js "a`nb"
a
b
PS > npx . "a`nb"
a

bash/linux

root@host:/app# node index.js $'a\nb'
a
b
root@host:/app# npx . $'a\nb'
a
b

Expected Behavior

Since I'm writing a CLI tool that relies heavily on multiline arguments, I expected the same behaviour between shells:

PowerShell 7.4.5/Windows 11

PS > node .\index.js "a`nb"
a
b
PS > npx . "a`nb"
a
b

bash

root@host:/app# node index.js $'a\nb'
a
b
root@host:/app# npx . $'a\nb'
a
b

A similar bug was fixed under bash at some time, however, it persists in windows environments.

Steps To Reproduce

1. Use the script provided above
2. Run sample commands

Environment

• npm: 10.8.2
• Node.js: v20.18.0 and v22.8.0 (managed with nvm-windows)
• OS Name: Windows 11
• System Model Name: Custom Desktop PC
• Terminal: Windows Terminal
• Shell: PowerShell 7.4.5
• npm config:

//registry.npmjs.org/:_authToken = (protected)

Start with the provided index.js and package.json, then reproduce the commands in PowerShell and bash to compare node with npx. Trace npm exec's Windows argument-forwarding path and verify that a multiline argument retains both lines, matching direct node execution.