title: feedback stdin and stdout of two processes
body: <p>I have two processes that interface with one another over stdin and stdout.</p>
  
  <p>Suppose I have process A and process B. The stdout of B needs to feed into the stdin of A, and the stdout of A needs to feed in to that of process B.</p>
  
  <p>Is there a simple way to express this relationship in a simple command, or is there a basic shell script that can enable this?</p>
  
  <p>Thanks in advance.</p>