Closed
Description
- Version: v15.3.0
- Platform: macOS Darwin
- Subsystem: process (or maybe streams?)
What steps will reproduce the bug?
In v15, if process.stdin is referenced, and is not a TTY or Pipe, then its data will be not be seen when passed to a child process. It's almost like it's already consumed or something.
$ node -v
v15.3.0
$ cat shell.js
const { spawn } = require('child_process')
// just reference the object, don't do anything with it
if (process.env.LOAD_STDIN === '1')
process.stdin
const child = spawn(process.env.SHELL, [], { stdio: 'inherit' })
child.on('close', (code, signal) => console.error({ code, signal }))
$ cat cmd.sh
#!/bin/bash
echo "hello from node's child shell"
$ node shell.js < cmd.sh
hello from node's child shell
{ code: 0, signal: null }
## This is the error:
$ LOAD_STDIN=1 node shell.js < cmd.sh
{ code: 0, signal: null }
## but this works, which is interesting?
$ cat cmd.sh | LOAD_STDIN=1 node shell.js
hello from node's child shell
{ code: 0, signal: null }
$ nave use 14
$ node -v
v14.15.1
$ node shell.js < cmd.sh
hello from node's child shell
{ code: 0, signal: null }
$ LOAD_STDIN=1 node shell.js < cmd.sh
hello from node's child shell
{ code: 0, signal: null }
$ cat cmd.sh | LOAD_STDIN=1 node shell.js
hello from node's child shell
{ code: 0, signal: null }
How often does it reproduce? Is there a required condition?
100% of the time on node 15. Not in any prior version tested (14, 12, and 10).
What is the expected behavior?
Stdin data should not be consumed when process.stdin is merely referenced. This causes problems when a script checks process.stdin.isTTY to print a helpful message prior to opening a shell in a child process.
What do you see instead?
Stdin data is not passed to child process if stdin is referenced, and not a Pipe or TTY.
Additional information
This kind of is a pain for npm exec. It means you can't do something like npx some-interactive-thing < list-of-commands.