[Tutor] piping continuous output

[Koen Bossers]

Hi,

I'm trying some stuff with popen2.

The thing is that I want to parse the output from a program (will be the
output of cdrecord or similar progams) that runs for a while (in this
example indefinitely) and print out a progress indicator or something
like that. For this purpose I created the following two scripts:


[print_messages.py]
#! /usr/bin/python

import time, os

counter = 0
while 1:
    counter += 1
    print 'Hello from process', os.getpid()
    print '%d'%counter,
    time.sleep(0.05)


[popentest.py]
#! /usr/bin/python

## test popen with continuing output

import os, time
import popen2


(output, input) = popen2.popen2('./print_messages.py')

count = 0

print "starting...", os.getpid()
listing = ''

while 1:
    test = output.read(1000)     ## read next 1000 bytes
    listing += test

    if not test:                         ## wait for sufficient output
        time.sleep(0.5)
        listing = ''

    print listing
    print "\nRun",count

    count += 1

This works for me. The only thing is I find this a very dirty hack. Are
there other ways to achieve the same result?

Thanks,

Koen Bossers