On Nov 18, 5:22 pm, Tim Harig <user...@ilthio.net> wrote: > On 2010-11-18, noydb <jenn.du...@gmail.com> wrote: > > > import subprocess > > pig = subprocess.Popen(["C:\Halls\hallbig2.exe"], > > stdin=subprocess.PIPE, stdout=subprocess.PIPE) > > result = pig.communicate(input='C:\Halls\Input\Ea39j.txt')[-1] #I need > > to capture the, what I think is the, last output > > From the subprocess documentation: > > [62]communicate() returns a tuple (stdoutdata, stderrdata). > Note that if you want to send data to the process's stdin, > you need to create the Popen object with stdin=PIPE. Similarly, > to get anything other than None in the result tuple, you need > to give stdout=PIPE and/or stderr=PIPE too. > > By using index [-1] you are accessing the processes stderr stream. I am > not really sure why you changed it. It doesn't give you the last output. > Index 0 gives you *all* of stdout and index 1 gives you *all* of stderr, > period. If you wish to further disect the output to get say the last line, > then you will need to parse it separately.
Okay, I see now. I did run it to start with 0 -- still same result no matter if 0 or -1. So, what is result (stdout, using [0]) in this case? (yes, i know I sound dumb - programming is not my background, obviously). A list, tuple??? How do you access stdout (or is it stdoutdata?) results? I have tried, get errors with all attempts. The exe gui returns several statistical values uopn inputing a text file (containing numerous lines of <value> <frequency>) and clicking compute - I want just one of the values. > > > print result > > print pig.returncode > >>> None > >>> 0 > > > So the tuple is empty. ?? The exe executes fine and returns output in > > th exe tool itself. The python script seems to execute fine, no > > errors, '...returned exit code 0'. Any ideas/suggestions? > > No the tuple contains two items (stdout, stderr). The first is what the > program printed to its stdout stream (which is most likely the output you > see if you run the command at a terminal/console). The second is what it > printed to its > stderr stream which is a channel used for out of band data such as error or > status messages. In this case, it is None, because you did open stderr as a > subprocess.PIPE. -- http://mail.python.org/mailman/listinfo/python-list
