How to save python screen output to a text file

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.

If you want the output to go to stdout and to the file, you can use tee:

$ python myscript.py | tee myoutput.txt

For more on tee, see: How to redirect output to a file and stdout

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.

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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.

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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)

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.

Let me summarize all the answers and add some more.

• To write to a file from within your script, user file I/O tools that are provided by Python (this is the f=open('file.txt', 'w') stuff.

• If don't want to modify your program, you can use stream redirection (both on windows and on Unix-like systems). This is the python myscript > output.txt stuff.

• If you want to see the output both on your screen and in a log file, and if you are on Unix, and you don't want to modify your program, you may use the tee command (windows version also exists, but I have never used it)

• Even better way to send the desired output to screen, file, e-mail, twitter, whatever is to use the logging module. The learning curve here is the steepest among all the options, but in the long run it will pay for itself.