CODEWITHSUNDEEP
node.jsexecchild-process
mayorbyrne
mayorbyrne

Reputation: 507

Display running child process' output in nodejs (windows)

For example sake, I'm running the most basic webServer in node (I'm using windows) with the following code (named server.js):

    var http = require('http');
       http.createServer(function (req, res) {
         res.writeHead(200, {'Content-Type': 'text/plain'});
         res.end('Hello World\n');
       }).listen(1337, '127.0.0.1');
    console.log('Server running at http://127.0.0.1:1337/');

I would like to run this as a child process, and am successfully doing so with the following:

var exec = require('child_process').exec;
var serv = exec('node server.js', function(error, stdout, stderr){
    console.log('outputs & errors:' + error, stdout, stderr);
});

However, I receive nothing once I run the second file. No "outputs & errors", no "Server running at...". If I type localhost:1337 in a browser, I get "hello world" though, so I know it's running. Is there a way to pipe that "server running..." so I can be "sure" it's listening?

Upvotes: 20

Views: 18787

Answers (3)

Qwertiy
Qwertiy

Reputation: 21380

Just specify that you want the child process to inherit stdio of parent one:

require('child_process').exec('node server.js', { stdio: 'inherit' });

Upvotes: 1

Verdigrass
Verdigrass

Reputation: 1301

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

//The following is on windows and I record stdout and stderr to my logger

var proc = spawn('cmd.exe', ['/S', '/C', script_path]);
proc.stdout.on('data', function(data) {
       logger(logtag, 'proc_stdout: ' + data);
});

proc.stderr.on('data', function(data) {
    logger(logtag, 'proc_stderr: ' + data);
});

Upvotes: 2

topek
topek

Reputation: 18979

Exec will return STDOUT and STDERR when the child finishes, see exec. That's why you do not see any output, when the server starts.

What you want is fork, which automatically connects the child process STDOUT and STDERR to your parent's. This is the preferred way if your child process is a node process.

If you want to use exec you can use the child processe's streams to get your data, e.g.:

child.stdout.pipe(process.stdout);
child.stderr.pipe(process.stderr);

Upvotes: 29

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