title: How can I interact with another program in Python?
body: <p>I want to write a Python script that runs another program, reading the output of the other program and manipulating it. The problem is that this program prompts for a password, and I cannot figure out how to supply it automatically. (For the purposes of this script, it really does not matter if the password is stored in plain-text in the script itself.) What I want to do is something like:</p>
  
  <pre><code>os.system('echo someinput | /var/local/bin/someprogram') 
  </code></pre>
  
  <p>Which results in someprogram giving me the unwanted password prompt, and also doesn't give me the program's output as the return value. Tragically, the program does not have a way to bypass this prompt.</p>
  
  <p>Unfortunately, I also have some restrictions as to how I can go about solving this problem. First, I'm stuck with Python 2.3 (so I cannot use the subprocess module). Second, I cannot install any new modules, (so no pexpect). Fortunately, it doesn't have to be particularly portable, so a Linux-only solution is fine.</p>
  
  <p>I've been trying to figure out the pty module, since it looks like it offers what I need, but after spending hours wrestling with it, I just cannot figure out how to get it to work the way I need it to.</p>