Using spawn function with NODE_ENV=production

Question

I'm currently trying to run process using spawn. What I am trying to run from shell is the following;

NODE_ENV=production node app/app.js

Here's the code to run that;

var spawn = require('child_process').spawn;
var start = spawn('NODE_ENV=production',['node','app/app.js']);

However, I got the following error;

events.js:72
        throw er; // Unhandled 'error' event
              ^
Error: spawn ENOENT
    at errnoException (child_process.js:980:11)
    at Process.ChildProcess._handle.onexit (child_process.js:771:34)

How can I do that using spawn ?

Pier · Accepted Answer · 2023-09-26 22:24:06Z

117

Your usage of spawn is not correct:

spawn( command, args, options ):

Launches a new process with the given command, with command line arguments in args. If omitted, args defaults to an empty Array.

The third argument is used to specify additional options, which defaults to:

{ cwd: undefined, env: process.env }

Use env to specify environment variables that will be visible to the new process, the default is process.env.

So the env variable NODE_ENV should be provided on the options argument:

// ES6 Object spread eases extending process.env
spawn( 'node', ['app.js'], { env: { ...process.env, NODE_ENV: 'test' } })

See also How do I debug "Error: spawn ENOENT" on node.js?

edited Sep 26, 2023 at 22:24

Pier

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answered Dec 31, 2014 at 6:02

laconbass

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1 Comment

jlyonsmith Over a year ago

With ES6/7 Stage 3 syntax you can do this in one line using object spread syntax - spawn('node', ['app.js'], {...process.env, NODE_ENV: 'test})

damphat · Accepted Answer · 2014-12-31 08:02:11Z

16

Syntax: spawn(command, [args], [options])

var spawn = require('child_process').spawn;
var start = spawn('node', ['app.js'], {env: {NODE_ENV: 'production'}});

Or keep default ENV variables:

var spawn = require('child_process').spawn;

var productionEnv = process.env; // TODO should clone process.env like utils.extend
productionEnv.NODE_ENV = 'production';

var start = spawn('node', ['app.js'], {env: productionEnv});

My test:

app.js

console.log(process.env);

spawn.js

var spawn = require('child_process').spawn;
var start = spawn('node', ['app.js'], {env: {NODE_ENV: 'production'}});

start.stdout.pipe(process.stdout);

from terminal:

node spawn

output:

{ NODE_ENV: 'production' }

edited Dec 31, 2014 at 8:02

answered Dec 29, 2013 at 12:43

damphat

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3 Comments

damphat Over a year ago

I have test this on my server, are you sure you can run node from terminal?

aacanakin Over a year ago

I'm running from iterm, when I use console.log(process.env), it gives iterm environment variables.

Alan Over a year ago

If you want to use the parent process' environment, just leave it undefined.

laconbass · Accepted Answer · 2014-12-31 05:49:40Z

8

This worked for me

var spawn = require('child_process').spawn;
var productionEnv = Object.create(process.env);
productionEnv.NODE_ENV = 'production';
var start = spawn('node', ['app.js'], {env: productionEnv});

this did not

var spawn = require('child_process').spawn;
var start = spawn('node', ['app.js'], {env: {NODE_ENV: 'production'}});

edited Dec 31, 2014 at 5:49

laconbass

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answered Sep 14, 2014 at 1:24

John Papa

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2 Comments

Aral Roca Over a year ago

I don't understand anything. I have this console.log: console.log({ NODE_ENV: process.env.NODE_ENV, env: process.env }), and NODE_ENV gives 'development', but env is an object that has NODE_ENV as 'production'. I don't understand what could be happening?

KernelDeimos Over a year ago

@AralRoca I'm very curious to know what this is when you find out. My best guess is that something else is interfering.

Augustine · Accepted Answer · 2017-06-09 02:15:46Z

0

add shell option worked for me

gulp.task('xxx', function (callback) {
    process.chdir('xxx/');
    var spawn = require('child_process').spawn;
    var productionEnv = Object.create(process.env);
    // var jekyll = spawn('gulp', ['stylecheck'], {stdio: 'inherit', env: productionEnv});
    var jekyll = spawn('gulp', ['stylecheck'], {stdio: 'inherit', env: productionEnv, shell: true});

    jekyll.on('exit', function (code) {
        console.log(arguments);
    });
});

answered Jun 9, 2017 at 2:15

Augustine

493 bronze badges

4 Comments

thewaywewere Over a year ago

While this code may answer the question, providing additional context regarding how and/or why it solves the problem would improve the answer's long-term value.

Augustine Over a year ago

see nodejs api: nodejs.org/api/…

M. Inam Over a year ago

You just copied and pasted the code which doesn't explained well. Looks like better one but please explain it

Augustine Over a year ago

this nodes official docs may help: nodejs.org/api/…

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