processing stdout in python

Question

I have a script that keeps on dumping some values to the screen. Lets call this script 1

I need the values that gets dumped to the screen to be processed by another python script.Lets call this script2. I Script1 cant be stopped

I currently use python 2.2 so it would be great if someone could provide an example without using subprocess

script 1 looks something like this

import sys
import os
i = 0
while 1:
    print i
    sys.stdout.write(str(i)+"\n")
        i = i + 1

I need to write script2 such that every output generated by script1 is processed by script2

-- edit --

I need it to run on a legacy implementation ie no power shell just the command prompt available in Windows XP

What operating system are you using?

GWW
– GWW

2011-04-05 14:41:13 +00:00
Commented Apr 5, 2011 at 14:41 — GWW
– GWW, Commented Apr 5, 2011 at 14:41

Gustav Larsson · Accepted Answer · 2011-04-05 14:44:36Z

7

I'm not going to say anything about code design here, because I really don't know what you are working on.

But for script2.py:

import sys
for line in sys.stdin:
    print "From stdin:", line

And then run (at least on unix/linux, if you are on windows, google "piping in powershell"):

python script1.py | python script2.py

Or did you want to do it within one python script? You could re-pipe sys.stdout, by simply replacing it with a class that has all the necessary methods (write, etc.).

answered Apr 5, 2011 at 14:44

Gustav Larsson

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tokland · Accepted Answer · 2011-04-05 14:48:51Z

2

I guess you want to process line by line:

# script2.py
import sys

for line in sys.stdin:
     print line # do something here with line

[edit] Finally, you simply pipe them:

python script1.py | python script2.py

edited Apr 5, 2011 at 14:48

answered Apr 5, 2011 at 14:43

tokland

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