CODEWITHSUNDEEP
pythonloggingsubprocess
Alexis Eggermont
Alexis Eggermont

Reputation: 8145

redirect print to log files, in subprocesses too

I am using the following code to redirect my print statements into a text file.

old_stdout = sys.stdout
log_file = open("message.log","w")
sys.stdout = log_file
print "this will be written to message.log"

subprocess.call("iPython.exe", "script.py") #subprocesses here take this form

sys.stdout = old_stdout
log_file.close()

My problem is that this does not seem to apply to subprocesses. The print statements in "script.py" will not appear in "message.log". How can I make it so that they do?

Upvotes: 0

Views: 127

Answers (1)

VooDooNOFX
VooDooNOFX

Reputation: 4762

Use subprocess.Popen instead of subprocess.call, which allows you to redirect stdout and stderr.

import subprocess

with (open('message_stdout.log', 'w'), open('message_stderr.log', 'w')) as (stdout_file, stderr_file):
    my_process = subprocess.Popen(["iPython.exe", "script.py"],
                                   stdout=stdout_file,
                                   stderr=stderr_file)

You can also redirect stderr to stdout like this, so that all output from script.py is sent to a single file.

import subprocess

with open('message.log', 'w') as stdout_file:
    my_process = subprocess.Popen(["iPython.exe", "script.py"],
                                   stdout=stdout_file,
                                   stderr=subprocess.STDOUT)

However, subprocessing something which just calls iPython to load another script is an awful way to work. Instead, you should just call the script.py modules directly.

Upvotes: 1

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