A process launcher that does what it says on the tin


A process launcher that does what it says on the tin

This project is a plugin for Grunt.JS that gives one the ability to spawn processes. This project has not been tested on windows but I am sure with all the heavy lifting the grunt team have done to make Grunt work everywhere, it might just work. The tests are not supported for windows.

You can install this plugin via the node package manager.

npm install grunt-cli -g
npm install grunt
npm install grunt-spawn

It is also good to create yourself a package.json file and emebed it in the dependencies or devDependencies section. For more please click here. Example below:

  "name": "my-project",
  "version": "0.0.1",
  "private": true,
  "author": "",
  "description": "my-project",
  "keywords": [
  "repository": {
    "type": "git",
    "url": ""
  "dependencies": {
  "devDependencies": {
    "grunt": "0.4.x",
    "grunt-spawn": "0.0.x"
  "scripts": {
    "test": "grunt spawn:test"
  "engines": {
    "node": "0.10.x"

You can use the following example to setup your grunt file. To get you started.

path = require("path");

module.exports = function(grunt) {
//grunt.option("force", true);

  pkg: grunt.file.readJSON("package.json"),

  jshint: {
    files: [

  spawn: {
    echo: {
      command: "echo",
      commandArgs: ["{0}"], 
      directory: "./tests",
      pattern: "**/*.js",
      useQuotes: true,
      quoteDelimiter: "\"",
      groupFiles: true,
      fileDelimiter: " ", 
      ignore: ["notNeededFile.js"]
    list: {
      command: "ls",
      commandArgs: ["-la", "{0}"], 
      directory: "./tests"
    test: {
      command: "mocha",
      commandArgs: ["--reporter", "spec", "{0}"],
      directory: "./tests",
      pattern: "**/*.js"

  release: {
    options: {
      bump: true,
      file: "package.json",
      add: true, 
      commit: true,
      tag: true,
      push: true,
      pushTags: true,
      npm: true



  grunt.registerTask("test", ["spawn:test"]);
  grunt.registerTask("default", ["spawn:test", "release"]);


Pay special attention to the spawn task above. There are two targets namely list which is merely a demonstration of a bare bones shell command and test which demonstrates how this plugin can be tweaked to do slightly more fine grained spawning. Grunt-cli commands below:

grunt spawn:echo


grunt spawn:list


grunt spawn:test

Here is a brief description of the elements involved:

  • command: "echo" -> Any command
  • commandArgs: ["{0}"] -> commandArgs where '{0}' is a placeholder for a file
  • directory: "./tests" -> Working directory
  • pattern: "*/.js" -> Globbing wildcard based on minimatch
  • useQuotes: true -> Whether to use the quote delimiter or not
  • quoteDelimiter: """ -> The actual quote delimiter if useQuotes = true
  • groupFiles: true -> Whether to group files into a single string
  • 'passThrough': good with groupFiles = true; removes lame file scanning.
  • fileDelimiter: " " -> The file delimiter if groupFiles = true
  • ignore: ["any.js"] -> The files you would like to exclude
  • opts: { cwd: process.cwd() } -> Pass through mechanism for passing 'opts' to grunt.spawn
  • dontWait: true | false -> To wait or not?

Here is a further example of how you would create a start/wait task for express. This was tested with express v4.11.0. Notice how we use opts to override stdio. This is passed to nodejs spawn.

If you are not scanning for any wildcard patterns and you would like to pass your arguments as a space separated array to a single command then you would need to set this option to true. If you dont, then each result found within the wildcard matching pattern will be run individually again the command. So if three files are found, the command will be run 3 times.

If you are not interested in scanning the filesystem and have a command that does not require any input from grunt-spawn then you can use this option. This will bypass any scanning done on the current directory. This can dramatically speed up what you are trying to do.

Here is an example that launches and provides feedback from express in a blocking way. You have to CTRL-C to exit.

module.exports = function(grunt) {

  // Project configuration.

    pkg: grunt.file.readJSON('package.json'),

    // *** - grunt-spawn: WebStart for Express {Start}
    spawn: {
      webstart: {
        command: 'node',
        commandArgs: ['{0}'],
        directory: './',
        groupFiles: true, 
        passThrough: false,
        pattern: 'www',
        opts: {
          stdio: 'inherit',
          cwd: __dirname + '/'
    // *** - grunt-spawn: WebStart for Express {End}

  // Grunt plugins.

  // Default task.
  grunt.registerTask('default', ['spawn:webstart']);


###Express example output

Included some example output from an express process.

Running "spawn:webstart" (spawn) task

<grunt-spawn/>: Launching child process
>> <grunt-spawn/>: Launching 'node bin/www' starting in '/usr/local/src/nodejs/poly-plates' overridden with cwd='/usr/local/src/nodejs/poly-plates/'
GET / 304 314.669 ms - -
GET /stylesheets/style.css 304 5.350 ms - -
GET /favicon.ico 404 57.264 ms - 1186

Any problems, please raise issues.