title: Store subprocess.call stdout in a variable and load it back as json
body: <p>I want to run a subprocess command, store stdout in a variable and later load into json</p>
  
  <pre><code>variable=""
  subprocess.call('command',stdout=variable,shell=True)
  instance_details=json.loads(variable)
  
  Error:
  AttributeError: 'str' object has no attribute 'fileno'
  </code></pre>