title: File writing command in pexpect not behaving as I thought it would
body: <p>There is a process that i can run from the command line which writes data to a file continuously until i tell it to stop, and can be accessed (read) while the process is running.</p>
  
  <p>However, if I run the same command through pexpect, the file stays empty (although can be read) until I stop the pexpect instance.  Only then will the file fill up with the data.</p>
  
  <p>Is this just a feature of pexpect or am I doing something wrong here?</p>
  
  <p>pexpect command:</p>
  
  <pre><code>child = pexpect.spawn('airodump-ng', ['-a', '-w', '/root/Desktop/TEST', '--output-format', 'csv', INTERFACE])
  </code></pre>