How to redirect stdout to both file and console with scripting?

I want to run a python script and capture the output on a text file as well as want to show on console.

I want to specify it as a property of the python script itself. NOT to use the command echo "hello world" | tee test.txt on command prompt every time.

Within script I tried:

sys.stdout = open('log.txt','w')

But this does not show the stdout output on screen.

I have heard about logging module but I could not get luck using that module to do the job.

You can use shell redirection while executing the Python file:

python foo_bar.py > file

This will write all results being printed on stdout from the Python source to file to the logfile.

Or if you want logging from within the script:

import sys

class Logger(object):
    def __init__(self):
        self.terminal = sys.stdout
        self.log = open("logfile.log", "a")
   
    def write(self, message):
        self.terminal.write(message)
        self.log.write(message)  

    def flush(self):
        # this flush method is needed for python 3 compatibility.
        # this handles the flush command by doing nothing.
        # you might want to specify some extra behavior here.
        pass    

sys.stdout = Logger()

Now you can use:

print "Hello"

This will write "Hello" to both stdout and the logfile.

I got the way to redirect the out put to console as well as to a text file as well simultaneously:

te = open('log.txt','w')  # File where you need to keep the logs

class Unbuffered:

   def __init__(self, stream):

       self.stream = stream

   def write(self, data):

       self.stream.write(data)
       self.stream.flush()
       te.write(data)    # Write the data of stdout here to a text file as well



sys.stdout=Unbuffered(sys.stdout)

Use logging module to debug and follow your app

Here is how I managed to log to file and to console / stdout

import logging
logging.basicConfig(level=logging.INFO,
                    format='%(asctime)s - %(levelname)s - %(message)s',
                    filename='logs_file',
                    filemode='w')
# Until here logs only to file: 'logs_file'

# define a new Handler to log to console as well
console = logging.StreamHandler()
# optional, set the logging level
console.setLevel(logging.INFO)
# set a format which is the same for console use
formatter = logging.Formatter('%(asctime)s - %(levelname)s - %(message)s')
# tell the handler to use this format
console.setFormatter(formatter)
# add the handler to the root logger
logging.getLogger('').addHandler(console)

# Now, we can log to both ti file and console
logging.info('Jackdaws love my big sphinx of quartz.')
logging.info('Hello world')

read it from source: https://docs.python.org/2/howto/logging-cookbook.html

Based on Amith Koujalgi's answer, here's a simple module you can use for logging -

transcript.py:

"""
Transcript - direct print output to a file, in addition to terminal.

Usage:
    import transcript
    transcript.start('logfile.log')
    print("inside file")
    transcript.stop()
    print("outside file")
"""

import sys

class Transcript(object):

    def __init__(self, filename):
        self.terminal = sys.stdout
        self.logfile = open(filename, "a")

    def write(self, message):
        self.terminal.write(message)
        self.logfile.write(message)

    def flush(self):
        # this flush method is needed for python 3 compatibility.
        # this handles the flush command by doing nothing.
        # you might want to specify some extra behavior here.
        pass

def start(filename):
    """Start transcript, appending print output to given filename"""
    sys.stdout = Transcript(filename)

def stop():
    """Stop transcript and return print functionality to normal"""
    sys.stdout.logfile.close()
    sys.stdout = sys.stdout.terminal