title: Sending two processes ouput pipes to a dual pipe input process
body: <p>I have two commands (command 1 and command2) that output to stdout (fd 1) and I'd like to send them to a new command3 that is prepared to receive them in two pipes, one on stdin from command1 and the other in any other file descriptor, i.e. in the fd 3, from command2. 
  How can I do this in bash ?</p>