Simple Handlebars Compiler in command line.

Gruntfile.js

module.exports = function(grunt) {
  grunt.initConfig({
    pkg: grunt.file.readJSON('package.json'),
    handlebars: {
      all: {
        src:  ["app/assets/javascripts/templates"],
        dest: "app/assets/javascripts/templates/all.js"
      }
    }
  });

  grunt.registerMultiTask('handlebars', 'Precompile Handlebars template', function() {
    var done = this.async();

    var compiler = new HandlebarsCompiler({
      sources:     this.data['src'],
      destination: this.data['dest'],
      verbose:     this.data['verbose']
    });

    compiler.compile();
    done();
  });
};

handlebars_compiler.js

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

HandlebarsCompiler = function(options) {
    this.sources     = options.sources || [];
    this.destination = options.destination;
    this.extension   = options.extension || '*.hbs';
    this.verbose     = options.verbose || false;

    this.compile = function() {
      var compiler = this;

      if (this.sources == null || this.destination == null) {
        if (this.verbose) {
          console.log('Need to pass the sources and destination to compiler.');
        }
        return false;
      }

      this.sources.forEach(function(source) {
        var filePattern = __dirname + '/' + source + '/' + compiler.extension;
        var command = 'handlebars ' + filePattern + ' -f ' + compiler.destination;
        if (compiler.verbose) {
          console.log('Running command: ' + command);
        }

        exec(command, function(err, stdout, stderr) {
          if (err) {
            compiler.error  = true;
            compiler.stderr = stderr;
            return false;
          }
        });
      });

      return true;
    }
  }