How to redirect stdout to both file and console with scripting

Question

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

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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

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I devised an easier solution  Just define a function that will print to file or to screen or to both of them  In the example below I allow the user to input the outputfile name as an argument but that is not mandatory   OutputFile  args Output File OF   open OutputFile   w    def printing text       print text     if args Output File          OF write text     n     After this  all that is needed to print a line both to file and or screen is      printing Line to be printed

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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

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Here is a simple context manager that prints to the console and writes the same output to an file  It also writes any exceptions to the file   import traceback import sys    Context manager that copies stdout and any exceptions to a log file class Tee object       def   init   self  filename           self file   open filename   w           self stdout   sys stdout      def   enter   self           sys stdout   self      def   exit   self  exc type  exc value  tb           sys stdout   self stdout         if exc type is not None              self file write traceback format exc            self file close        def write self  data           self file write data          self stdout write data       def flush self           self file flush           self stdout flush     To use the context manager   print  Print   with Tee  test txt        print  Print Write       raise Exception  Test   print  Print

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This way worked very well in my situation  I just added some modifications based on other code presented in this thread  import sys  os   orig stdout   sys stdout    capture original state of stdout  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                                                  Feel free to use print function                                              print  quot Here is an Example    quot                                                Feel free to use print function                                                   Stop capturing printouts of the application from Windows CMD sys stdout   orig stdout    put back the original state of stdout te flush      forces python to write to file te close      closes the log file    read all lines at once and capture it to the variable named sys prints with open  log txt    r    as file      sys prints   file readlines       erase the file contents of log file open  log txt    w   close

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Based on Brian Burns edited answer  I created a single class that is easier to call   class Logger object                Class to log output of the command line to a log file      Usage      log   Logger  logfile log       print  inside file       log stop       print  outside file       log start       print  inside again       log stop                def   init   self  filename           self filename   filename      class Transcript          def   init   self  filename               self terminal   sys stdout             self log   open filename   a           def   getattr   self  attr               return getattr self terminal  attr          def write self  message               self terminal write message              self log write message          def flush self               pass      def start self           sys stdout   self Transcript self filename       def stop self           sys stdout log close           sys stdout   sys stdout terminal

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You can use shell redirection while executing the python file   python foo bar py  gt  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

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I ve tried a few solutions here and didn t find the one that writes into file and into console at the same time  So here is what I did  based on this answer   class Logger object       def   init   self           self terminal   sys stdout      def write self  message           with open   logfile log    a   encoding    utf-8   as self log                          self log write message          self terminal 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        This solution uses more computing power  but reliably saves all of the data from stdout into logger file and uses less memeory  For my needs I ve added time stamp into self log write message  aswell  Works great

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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

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To redirect output to a file and a terminal without modifying how your Python script is used outside  you could use pty spawn itself       usr bin env python    Redirect stdout to a file and a terminal inside a script     import os import pty import sys  def main        print  put your code here    if   name       main         sentinel option    --dont-spawn      if sentinel option not in sys argv            run itself copying output to the log file         with open  script log    wb   as log file              def read fd                   data   os read fd  1024                  log file write data                  return data              argv    sys executable    sys argv    sentinel option              rc   pty spawn argv  read      else          sys argv remove sentinel option          rc   main       sys exit rc    If pty module is not available  on Windows  then you could replace it with teed call   function that is more portable but it provides ordinary pipes instead of a pseudo-terminal -- it may change behaviour of some programs   The advantage of pty spawn and subprocess Popen -based solutions over replacing sys stdout with a file-like object is that they can capture the output at a file descriptor level e g   if the script starts other processes that can also produce output on stdout stderr  See my answer to the related question  Redirect stdout to a file in Python

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from IPython utils io import Tee from contextlib import closing  print  This is not in the output file             with closing Tee  outputfile log    w   channel  stdout    as outputstream      print  This is written to the output file and the console          raise Exception  The file  outputfile log  is closed anyway    print  This is not written to the output file          Output on console    This is not in the output file    This is written to the output file and the console    This is not written to the output file     Content of file outputfile txt    This is written to the output file and the console    The Tee class in IPython utils io does what you want  but it lacks the   enter   and   exit   methods needed to call it in the with-statement  Those are added by contextlib closing

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you can redirect the output to a file by using      python with print rint s  chevron  syntax as indicated in the docs  let see   fp open  test log   a       take file  object reference  print  gt  gt  fp    hello world              use file object with in print statement  print  gt  gt  fp    every thing will redirect to file   fp close       close the file    checkout the file test log you will have the data  and to print on console just use plain print statement

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I tried this       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  sys stderr         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     sys stderr   sys stderr terminal

[python] How to redirect stdout to both file and console with scripting?

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