[Bug?]: Combining redirections (>&) does not work

[jeffrson]

Self-service

• [ ] I'd be willing to implement a fix

Describe the bug

@yarnpkg/shell supports redirection of stdout and stderr: "command > stdout.txt 2> stderr.txt"

Apparently, combining those into one stream is also implemented. However, it does not work as intended. Given this "command > stdout.txt 2>&1" it should be expected, that both standard output and standard error are written to stdout.txt. However, standard error is not redirected, but written to "real" standard out of process. A bit of a mess...

To reproduce

// I'm sorry - it's not really sherlock - don't know how to demonstrate shell redirection

import {PassThrough} from 'stream'

import {execute} from '@yarnpkg/shell'

const stdout = new PassThrough()
const stderr = new PassThrough()

const stdoutChunks = []
const stderrChunks = []

stdout.on(`data`, chunk => stdoutChunks.push(chunk))
stderr.on(`data`, chunk => stderrChunks.push(chunk))

const command = 'node -e "console.log(\\"stdout\\"); console.error(\\"stderr\\")" > out1 2>&1'

execute(command, [], {stdout, stderr})
.then((exitCode => {
  const output = Buffer.concat(stdoutChunks).toString()
  const error = Buffer.concat(stderrChunks).toString()

  console.log('out: ' + output) // output should be empty, but isn't - contains "stderr"
  console.log('err: ' + error)  // error should be empty and is
}))

Environment

System:
    OS: Linux 5.10 Debian GNU/Linux 11 (bullseye) 11 (bullseye)
    CPU: (16) x64 Intel(R) Core(TM) i7-10875H CPU @ 2.30GHz
  Binaries:
    Node: 16.13.2 - /tmp/xfs-e70720b2/node
    Yarn: 3.1.1 - /tmp/xfs-e70720b2/yarn
    npm: 6.14.16 - ~/.nvm/versions/node/v16.13.2/bin/npm

Additional context

No response

[yarnbot]

Hi! 👋

This issue looks stale, and doesn't feature the reproducible label - which implies that you didn't provide a working reproduction using Sherlock. As a result, it'll be closed in a few days unless a maintainer explicitly vouches for it or you edit your first post to include a formal reproduction (you can use the playground for that).

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[vegerot]

I can reproduce this.

Use this package.json

{
  "scripts": {
    "stdout-and-stderr": "(echo out; type stderr) 1>/dev/null 2>&1"
  }
}

Now try running this script with different package runners:

$ npm run stdout-and-stderr

> PageBank@1.0.0 stdout-and-stderr
> (echo out; type stderr) 1>/dev/null 2>&1

$ bun run stdout-and-stderr
$ (echo out; type stderr) 1>/dev/null 2>&1
error: script "stdout-and-stderr" exited with code 1

$ deno task stdout-and-stderr
Task stdout-and-stderr (echo out; type stderr) 1>/dev/null 2>&1
error: Error parsing script 'stdout-and-stderr'.

Caused by:
    Multiple redirects are currently not supported.
      1>/dev/null 2>&1
      ~

$ yarn stdout-and-stderr
/usr/bin/type: line 4: type: stderr: not found

You can see that yarn does not respect the 2>&1. However, if I change the script to

    "stdout-and-stderr": "(echo out; type stderr) 1>/dev/null 2>/dev/null"

It works correctly

$ yarn stdout-and-stderr