Powershell executing python: redirect print statements only?

Question

Is there a way in Powershell to redirect the print statements from python one place and the return statements to another place?

For instance i'm trying

$ python myPythonScript.py args >> logFile

I get print statement output in my log file (though it looks awful, cleaning will be the next job)

However, i do not get the return statement values from the python in the output. Nor do i catch them if I use *>>

Any ideas what's happening?

Python Example:

def main(args)
     print "This goes to file"
     #parse flags...
     #do something here...
     MyVar = "Please " + "Work"

     return MyVar #doesn't go anywhere
if(__name__ == '__main__':
     main(sys.argv)

You can only return integers from your application, so you won't be able to get that string. You use echo %errorlevel% to print the returned int value of your python script. I will make an answer. — Fabien
– Fabien, Commented Jul 13, 2017 at 2:17

Fabien · Accepted Answer · 2017-07-13 02:41:10Z

1

The return value of a program (or exit code) can only be an integer, not a string.

First, ensure you return an int, or do exit(n) where n is an int.

You might want to also fix:

if(__name__ == '__main__'):
     return main(sys.argv)

You can then access the return value of your program (script) in Powershell with echo %errorlevel%

If you really want a string to be used by powershell, you should:

print your logs on stderr instead of stdout
print the filename on stdout at end of execution
redirects stderr to your logfile and stdout to a powershell pipe | if you want a redirection - or you can execute the python script within parentheses $() so the result can be used on command line

edited Jul 13, 2017 at 2:41

answered Jul 13, 2017 at 2:21

Fabien

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3 Comments

Jamie Marshall Over a year ago

Thanks Fabien. How do I get the string I need though? In my actual program the string I need back is a file name - an integer won't work.

Jamie Marshall Over a year ago

I'm playing with this now. How do I direct one to log-file and one to pipe? There's good examples here, but how do direct to two separate places on one call? -RedirectStandardOutput seems to only accept a file?

Fabien Over a year ago

What you do is redirect stderr only, and stdout is naturally conveyed through a pipe. I recommend you also try the $() feature, it is helpful.

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