title: Run subprocess.call(cmd) while the cmd is a text variable
body: <p>In python, is it possible to run a shell command, while the command stored in variable as text ?
  for example:</p>
  
  <pre><code>  self.command_editor = QTextEditor()
    self.command_editor.append("echo command")
    cmd = str(self.command_editor.toPlainText())
    call(cmd)
  </code></pre>
  
  <p>this code doesn`t work!</p>