title: child_process.execSync('tty') causes error
body: <p>Anyone know why I get the following error, when I run</p>
  
  <pre><code>const cp = require('child_process');
  const _tty = cp.execSync('tty');
  </code></pre>
  
  <p>...we get this error:</p>
  
  <pre><code>Error: Command failed: tty
  
      at checkExecSyncError (child_process.js:488:13)
      at Object.execSync (child_process.js:528:13)
      at Server (/Users/Olegzandr/WebstormProjects/oresoftware/suman/lib/create-suman-server.js:52:13)
      at watch (/Users/Olegzandr/WebstormProjects/oresoftware/suman/lib/watching/add-watcher.js:84:3)
      at module.exports (/Users/Olegzandr/WebstormProjects/oresoftware/suman/lib/helpers/watch-init.js:56:41)
      at Object.&lt;anonymous&gt; (/Users/Olegzandr/WebstormProjects/oresoftware/suman/index.js:557:38)
      at Module._compile (module.js:573:32)
      at Object.Module._extensions..js (module.js:582:10)
      at Module.load (module.js:490:32)
      at tryModuleLoad (module.js:449:12) 
  </code></pre>
  
  <p>No idea why the error happens, since I can run "tty" from any terminal (without root permissions?)</p>