Colors from child scripts not being used in logged output

[kentcdodds]

Thanks for this tool! I think it's great! I'm not getting colorized output when running concurrently on a script that is outputing stuff with chalk. Here's a repo that reproduces the issue: https://github.com/kentcdodds/chalk-concurrently-bug

It's pretty simple. color-red.js is:

#!/usr/bin/env node
const chalk = require('chalk')

console.log(chalk.red(process.argv.slice(2).join(' ')))

Any ideas? This is sort of a blocker for p-s dropping the --parallel option and recommending people just use concurrently. (more info).

[gustavohenke]

Hi @kentcdodds! Thanks for the report.
After some research, I think that this is a standard behavior of Node itself.

See:

• http://stackoverflow.com/questions/18825493/retaining-output-colors-when-shelling-out-to-node
• http://stackoverflow.com/questions/7725809/preserve-color-when-executing-child-process-spawn

You can, however, use the --raw flag. Under the hoods, the behavior of --raw is to simply use stdio: "inherit", when spawning the child process.
I was able to always retain the colors when using it, even though the output is less cooler :)

[kentcdodds]

Ah! I found this which explains what's going on quite nicely.

I think that a solution could be to simply add FORCE_COLOR = 1 to the env that you spawn the script with. Right around here we could probably change that to:

var spawnOpts = config.raw
  ? {stdio: 'inherit'}
  : {
      env: Object.assign({FORCE_COLOR: 1}, process.env)
    };

I'd be happy to make a PR to do this!

[gustavohenke]

Hmm, yes, this makes more sense 😁
btw, I just checked the other issues, and... #49 is a duplicate, and this exact solution has been proposed there.

I think it's better if we don't force colors everytime.
Instead, we should test whether colors are supported by the terminal running concurrently in order to set FORCE_COLOR env.

This way we can avoid strange ASCII chars in some cases.

[okonet]

You can check if it's TTY and only force colors in this case. This solved CI and similar cases:

https://github.com/okonet/lint-staged/blob/master/src/index.js#L18

[kentcdodds]

We could just use https://www.npmjs.com/package/supports-color :) That's the same thing that chalk uses.

var spawnOpts = config.raw
  ? {stdio: 'inherit'}
  : {
      env: Object.assign({FORCE_COLOR: Boolean(supportsColor)}, process.env)
    };

[gustavohenke]

Exactly what I thought 👍

If you have the time to send such PR, please go ahead.
Otherwise I'll do it later and push a new version.

[kentcdodds]

Writing tests for this is pretty difficult and would require a bit of a rewrite of how tests work. So I'm not going to add tests to my changes.

[gustavohenke]

Published v3.2.0!

[sinedied]

Using concurrently 8.8.2 I don't have any colors from my child scripts, unless I use --raw. Is this a regression?

[gustavohenke]

Hi @sinedied, unlikely to be a regression, maybe it's something in your environment. But please open a new issue so that I can help diagnose.