How to redirect the output of print to a TXT file

Question

I have searched Google, Stack Overflow and my Python users guide and have not found a simple, workable answer for the question.

I created a file c:\goat.txt on a Windows 7 x64 machine and am attempting to print "test" to the file. I have tried the following based on examples provided on StackOverflow:

At this point I don't want to use the log module since I don't understand from the documentation of to create a simple log based upon a binary condition. Print is simple however how to redirect the output is not obvious.

A simple, clear example that I can enter into my interperter is the most helpful.

Also, any suggestions for informational sites are appreciated (NOT pydocs).

import sys
print('test', file=open('C:\\goat.txt', 'w')) #fails
print(arg, file=open('fname', 'w')) # above based upon this
print>>destination, arg

print>> C:\\goat.txt, "test" # Fails based upon the above

Solution 1

If you're on Python 2.5 or earlier, open the file and then use the file object in your redirection:

log = open("c:\\goat.txt", "w")
print >>log, "test"

If you're on Python 2.6 or 2.7, you can use print as a function:

from __future__ import print_function
log = open("c:\\goat.txt", "w")
print("test", file = log)

If you're on Python 3.0 or later, then you can omit the future import.

If you want to globally redirect your print statements, you can set sys.stdout:

import sys
sys.stdout = open("c:\\goat.txt", "w")
print ("test sys.stdout")

Solution 2

To redirect output for all prints, you can do this:

import sys
with open('c:\\goat.txt', 'w') as f:
    sys.stdout = f
    print "test"

Solution 3

A slightly hackier way (that is different than the answers above, which are all valid) would be to just direct the output into a file via console.

So imagine you had main.py

if True:
    print "hello world"
else:
    print "goodbye world"

You can do

python main.py >> text.log

and then text.log will get all of the output.

This is handy if you already have a bunch of print statements and don't want to individually change them to print to a specific file. Just do it at the upper level and direct all prints to a file (only drawback is that you can only print to a single destination).

Solution 4

Building on previous answers, I think it's a perfect use case for doing it (simple) context manager style:

import sys

class StdoutRedirection:
    """Standard output redirection context manager"""

    def __init__(self, path):
        self._path = path

    def __enter__(self):
        sys.stdout = open(self._path, mode="w")
        return self

    def __exit__(self, exc_type, exc_val, exc_tb):
        sys.stdout.close()
        sys.stdout = sys.__stdout__

and then:

with StdoutRedirection("path/to/file"):
    print("Hello world")

Also it would be really easy to add some functionality to StdoutRedirection class (e.g. a method that lets you change the path)

Solution 5

Usinge the file argument in the print function, you can have different files per print:

print('Redirect output to file', file=open('/tmp/example.log', 'w'))

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