title: merging big binary files using python 3
body: <p>How can I merge a few big files into 1 using python 3?
  it should work like the bash command</p>
  
  <pre><code>cat * &gt; outfile
  </code></pre>
  
  <p>but it should work on Linux, Windows and OS X.</p>
  
  <p>If I use</p>
  
  <pre><code>outfile = open("outfile", "wb")
  for file in os.listdir():
      outfile.write(file.read())
  </code></pre>
  
  <p>it uses too much RAM</p>