pulsar/script/utils/verify-requirements.js

var path = require('path');
var fs = require('fs');
var cp = require('child_process');
var execFile = cp.execFile;
var pythonExecutable = process.env.PYTHON;

module.exports = function(cb) {
  verifyNode();
  verifyPython27(cb);
};

function verifyNode() {
  var nodeVersion = process.versions.node.split('.');
  var nodeMajorVersion = +nodeVersion[0];
  var nodeMinorVersion = +nodeVersion[1];
  if (nodeMajorVersion === 0 && nodeMinorVersion < 10) {
    console.warn("node v0.10 is required to build Atom.");
    process.exit(1);
  }
}

function verifyPython27(cb) {
  if (false && process.platform !== 'win32') {
    cb();
  }
  else {
    if (!pythonExecutable) {
      var systemDrive = process.env.SystemDrive || 'C:\\';
      pythonExecutable = path.join(systemDrive, 'Python27', 'python.exe');

      if (!fs.existsSync(pythonExecutable)) {
        pythonExecutable = 'python';
      }
    }

    checkPythonVersion(pythonExecutable, cb);
  }
}

function checkPythonVersion (python, cb) {
  var pythonHelpMessage = "Set the PYTHON env var to '/path/to/Python27/python.exe' if your python is installed in a non-default location.";

  execFile(python, ['-c', 'import platform; print(platform.python_version());'], { env: process.env }, function (err, stdout) {
    if (err) {
      console.log("Python 2.7 is required to build Atom. An error occured when checking for python '" + err + "'");
      console.log(pythonHelpMessage);
      process.exit(1);
    }

    var version = stdout.trim();
    if (~version.indexOf('+')) {
      version = version.replace(/\+/g, '');
    }
    if (~version.indexOf('rc')) {
      version = version.replace(/rc(.*)$/ig, '');
    }

    // Atom requires python 2.7 or higher (but not python 3) for node-gyp
    var versionArray = version.split('.').map(function(num) { return +num; });
    var goodPythonVersion = (versionArray[0] === 2 && versionArray[1] >= 7);
    if (!goodPythonVersion) {
      console.log("Python 2.7 is required to build Atom. '" + python + "' returns version " + version);
      console.log(pythonHelpMessage);
      process.exit(1);
    }

    // Finally, if we've gotten this far, callback to resume the install process.
    cb();
  });
}