meteor/tools/cli/dev-bundle-bin-commands.js

// Note that this file is required before we install our Babel hooks in
// ../tool-env/install-babel.js, so we can't use ES2015+ syntax here.

// The dev_bundle/bin command has to come immediately after the meteor
// command, as in `meteor npm` or `meteor node`, because we don't want to
// require("./main.js") for these commands.
var devBundleBinCommand = process.argv[2];
var args = process.argv.slice(3);

function getChildProcess() {
  if (typeof devBundleBinCommand !== "string") {
    return Promise.resolve(null);
  }

  var helpers = require("./dev-bundle-bin-helpers.js");

  return Promise.all([
    helpers.getDevBundle(),
    helpers.getEnv()
  ]).then(function (devBundleAndEnv) {
    var devBundleDir = devBundleAndEnv[0];
    var cmd = helpers.getCommand(devBundleBinCommand, devBundleDir);
    if (! cmd) {
      return null;
    }

    var env = devBundleAndEnv[1];
    var child = require("child_process").spawn(cmd, args, {
      stdio: "inherit",
      env: env
    });

    require("./flush-buffers-on-exit-in-windows.js");

    child.on("error", function (error) {
      console.log(error.stack || error);
    });

    child.on("exit", function (exitCode) {
      process.exit(exitCode);
    });

    return child;
  });
}

module.exports = getChildProcess();