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

var fs = require("fs");
var path = require("path");
var devBundlePromise = require("./dev-bundle.js");
var Promise = devBundlePromise.constructor;
var binDirPromise = devBundlePromise.then(function (devBundleDir) {
  return path.join(devBundleDir, "bin");
});

exports.getCommandPath = function (command) {
  return binDirPromise.then(function (binDir) {
    return path.join(binDir, command);
  });
};

exports.getEnv = function() {
  return Promise.all([
    // When npm looks for node, it must find dev_bundle/bin/node.
    binDirPromise,
    devBundlePromise
  ]).then(function (paths) {
    var devBundleDir = paths[1];

    // Also make available any scripts installed by packages in
    // dev_bundle/lib/node_modules, such as node-gyp.
    paths[1] = path.join(devBundleDir, "lib", "node_modules", ".bin");

    var env = Object.create(process.env);

    var PATH = env.PATH || env.Path;
    if (PATH) {
      paths.push(PATH);
    }

    env.PATH = paths.join(path.delimiter);

    if (process.platform === "win32") {
      // On Windows we provide a reliable version of python.exe for use by
      // node-gyp (the tool that rebuilds binary node modules). #WinPy
      env.PYTHON = env.PYTHON || path.join(
        devBundleDir, "python", "python.exe");

      // We don't try to install a compiler toolchain on the developer's
      // behalf, but setting GYP_MSVS_VERSION helps select the right one.
      env.GYP_MSVS_VERSION = env.GYP_MSVS_VERSION || "2015";

      // While the original process.env object allows for case insensitive
      // access on Windows, Object.create interferes with that behavior,
      // so here we ensure env.PATH === env.Path on Windows.
      env.Path = env.PATH;
    }

    return env;
  });
};