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 ?

laconbass · Accepted Answer · 2020-11-22T18:19:01.643

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?

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})` — jlyonsmith, Nov 14 '17 at 23:03

damphat · Answer 2 · 2014-12-31T08:02:11.283

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 '14 at 08:02

answered Dec 29 '13 at 12:43

damphat

18,246
8
45
59

I have test this on my server, are you sure you can run `node` from terminal? – damphat Dec 29 '13 at 13:59
I'm running from iterm, when I use `console.log(process.env)`, it gives iterm environment variables. – aacanakin Dec 29 '13 at 14:18
If you want to use the parent process' environment, just leave it undefined. – Alan Mar 04 '14 at 21:14

score 8 · Answer 3 · edited Dec 31 '14 at 05:49

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 '14 at 05:49

laconbass

17,080
8
46
54

answered Sep 14 '14 at 01:24

John Papa

21,880
4
61
60

score 0 · Answer 4 · answered Jun 09 '17 at 02:15

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 09 '17 at 02:15

Augustine

49
3

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. – thewaywewere Jun 09 '17 at 02:34
1

see nodejs api: https://nodejs.org/api/child_process.html#child_process_spawning_bat_and_cmd_files_on_windows – Augustine Jun 12 '17 at 08:58
You just copied and pasted the code which doesn't explained well. Looks like better one but please explain it – M. Inam Jun 19 '21 at 13:04
this nodes official docs may help: https://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options – Augustine Jul 09 '21 at 12:14

Using spawn function with NODE_ENV=production

4 Answers4

Linked