[BUG] npm run on Windows mishandles backslash escaping

[iamdennshi]

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

package.json

{
    "scripts": {
        "test": "printf '%s' '\\\\' | od -c"
    }
}

Using npm run

$ npm run test

> test
> printf '%s' '\\' | od -c

0000000   \
0000001

Using git-bash

$ printf '%s' '\\' | od -c
0000000   \   \
0000002

Expected Behavior

$ npm run test

> test
> printf '%s' '\\' | od -c

0000000   \   \
0000002

In Linux (Ubuntu 24.04.2 LTS) this works as expected

Steps To Reproduce

See Current Behavior section

Environment

• npm: 11.11.1
• Node.js: v24.14.0
• OS Name: Windows 11 Pro