[python] How to save python screen output to a text file

I'm new to Python. I need to query items from a dict and save the result to a text file. Here's what I have:

import json
import exec.fullog as e

input = e.getdata() #input now is a dict() which has items, keys and values.

#Query

print 'Data collected on:', input['header']['timestamp'].date()
print '\n CLASS 1 INFO\n'

for item in input['Demographics']:
    if item['name'] in ['Carly', 'Jane']:
        print item['name'], 'Height:', item['ht'], 'Age:', item['years']

for item in input['Activity']:
    if item['name'] in ['Cycle', 'Run', 'Swim']:
       print item['name'], 'Athlete:', item['athl_name'], 'Age:', item['years']

How do I save the printed output to a text file?

I found a quick way for this:

log = open("log.txt", 'a')

def oprint(message):
    print(message)
    global log
    log.write(message)
    return()

code ...

log.close()

Whenever you want to print something just use oprint rather than print.

Note1: In case you want to put the function oprint in a module then import it, use:

import builtins

builtins.log = open("log.txt", 'a')

Note2: what you pass to oprint should be a one string (so if you were using a comma in your print to separate multiple strings, you may replace it with +)

A quick and dirty hack to do this within the script is to direct the screen output to a file:

import sys 

stdoutOrigin=sys.stdout 
sys.stdout = open("log.txt", "w")

and then reverting back to outputting to screen at the end of your code:

sys.stdout.close()
sys.stdout=stdoutOrigin

This should work for a simple code, but for a complex code there are other more formal ways of doing it such as using Python logging.

Here's a really simple way in python 3+:

f = open('filename.txt', 'w')
print('something', file = f)

^ found that from this answer: https://stackoverflow.com/a/4110906/6794367

You would probably want this. Simplest solution would be

Create file first.

open file via

f = open('<filename>', 'w')

or

f = open('<filename>', 'a')

in case you want to append to file

Now, write to the same file via

f.write(<text to be written>)

Close the file after you are done using it

#good pracitice
f.close()

This is very simple, just make use of this example

import sys
with open("test.txt", 'w') as sys.stdout:
    print("hello")

What you're asking for isn't impossible, but it's probably not what you actually want.

Instead of trying to save the screen output to a file, just write the output to a file instead of to the screen.

Like this:

with open('outfile.txt', 'w') as outfile:
    print >>outfile, 'Data collected on:', input['header']['timestamp'].date()

Just add that >>outfile into all your print statements, and make sure everything is indented under that with statement.

More generally, it's better to use string formatting rather than magic print commas, which means you can use the write function instead. For example:

outfile.write('Data collected on: {}'.format(input['header']['timestamp'].date()))

But if print is already doing what you want as far as formatting goes, you can stick with it for now.

What if you've got some Python script someone else wrote (or, worse, a compiled C program that you don't have the source to) and can't make this change? Then the answer is to wrap it in another script that captures its output, with the subprocess module. Again, you probably don't want that, but if you do:

output = subprocess.check_output([sys.executable, './otherscript.py'])
with open('outfile.txt', 'wb') as outfile:
    outfile.write(output)

abarnert's answer is very good and pythonic. Another completely different route (not in python) is to let bash do this for you:

$ python myscript.py > myoutput.txt

This works in general to put all the output of a cli program (python, perl, php, java, binary, or whatever) into a file, see How to save entire output of bash script to file for more.

python script_name.py > saveit.txt

Because this scheme uses shell command lines to start Python programs, all the usual shell syntax applies. For instance, By this, we can route the printed output of a Python script to a file to save it.

We can simply pass the output of python inbuilt print function to a file after opening the file with the append option by using just two lines of code:

with open('filename.txt', 'a') as file:
    print('\nThis printed data will store in a file', file=file)

Hope this may resolve the issue...

Note: this code works with python3 however, python2 is not being supported currently.