Communicate multiple times with a process without breaking the pipe?

Question

I think you misunderstand communicate…

http://docs.python.org/library/subprocess.html#subprocess.Popen.communicate

communicate sends a string to the other process and then waits on it to finish… (Like you said waits for the EOF listening to the stdout & stderror)

What you should do instead is:

proc.stdin.write('message')

# ...figure out how long or why you need to wait...

proc.stdin.write('message2')

(and if you need to get the stdout or stderr you’d use proc.stdout or proc.stderr)