[Tutor] How to get messages from stderr

[klappnase]

Hello everyone,

I try to get progress messages from a shell command on the fly while the process is still running
for use in a progress window. The problem is that most of these messages are printed to stderr.
Now I tried something like:

def runcmd(self):
	self.pp = popen2.Popen4(cmd)
	self.ppp = self.pp.fromchild
	self.frame.after(100, self.getprogress)

def getprogress(self):
	self.progress = self.ppp.read()
	self.frame.after(100, self.getprogress)

but I found that I only got any output after the child process had finished.
It seems to work as long as I only get the output from stdout with Popen3, but I need the stderr messages.
Does anyone know a way to get the output from stderr while the child process is still running?
Any help would be very appreciated.

Thanks

Michael