Unable to execute child_process.exec("node child.js")

Question

I have two files under a folder with names "app.js" and "child.js". The Node is running on Windows OS. The app.js file:

;(function() {
    var http = require("http"),
    child_process = require("child_process"),
    exec = child_process.exec;

    http.createServer(function(request, response) {
        response.writeHead(200, {"content-type": "text/plain"});
        exec('node child.js', {env: {number: 1234}}, function(error, stdout, stderror) {
            if(error) throw error;
            console.log(stdout);
            console.log(stderror);
        });
        response.write("Hello world!!!");
        response.end();
    }).listen(8000);
    console.log("The server has started listening to the port: 8000");
})();

The child.js file:

;(function() {
    var envVar = process.env.envVar;
    console.log("Type of envVar: " + typeof envVar);
    console.log("The value of envVar is: " + parseInt(envVar, 10));
})();

I am attempting to execute an external command via "exec" method.
But when I run:

node app.js

I receive the error:

Command failed: 'node' is not recognized as an internal or external command, operable program or batch file.

What wrong am I doing here?

@Alex: I have the node installed. When I write "node" on my command line, i get the REPL. — Anup Vasudeva
– Anup Vasudeva, Commented Mar 22, 2013 at 8:11
you should use fork instead of exec to launch node processes. nodejs.org/api/… — generalhenry
– generalhenry, Commented Mar 22, 2013 at 8:24
@generalhenry: If I write exec("dir *.*", function(err, stdout, stderr) {}), it works fine. I am not able to understand why it fails for the situation mentioned above. — Anup Vasudeva
– Anup Vasudeva, Commented Mar 22, 2013 at 8:29
Maybe node is not in the PATH, try exec("path", function(err, stdout, stderr) {}), and print to the console what's in your path. You can also specifiy the whole path of node, like c:\Program Files\nodejs\node.exe child.js. — balazs
– balazs, Commented Mar 22, 2013 at 8:39

balazs · Accepted Answer · 2013-03-22 10:05:11Z

So if you want to exec a command, try this:

var http = require("http"),
    child_process = require("child_process"),
    exec = child_process.exec;
    http.createServer(function(request, response) {
        response.writeHead(200, {"content-type": "text/plain"});
        exec( '"' + process.execPath + '" child.js', {env: {number: 1234}}, function(error, stdout, stderror) {
            if(error) throw error;
            console.log(stdout);
            console.log(stderror);
        });
        response.write("Hello world!!!");
        response.end();
    }).listen(8000);
    console.log("The server has started listening to the port: 8000");

the process.execPath contains the full path of node.exe, the " should be there, because directory names can contain spaces like Program files.

the child process is the same, I just changed process.env.envVar to process.env.number, because you set that in exec options.

var envVar = process.env.number;
    console.log("Type of envVar: " + typeof envVar);
    console.log("The value of envVar is: " + parseInt(envVar, 10));

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