https://stackoverflow.com/a/54649402/292166

gistfile1.txt

joseph@button:~$ python3
Python 3.4.2 (default, Sep 16 2019, 12:55:35)
[GCC 4.9.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import time
>>> import sys
>>>
>>> class TimestampFilter:
...     # pending_output stores any output passed to write where a \n has not yet been found
...     pending_output = ''
...     def write(self, message):
...         output = self.pending_output + message
...         (output, not_used, self.pending_output) =  output.rpartition('\n')
...         if output != '':
...             timestamp = time.strftime("%Y-%m-%d %X")
...             output = timestamp + " " + output.replace("\n", "\n"+timestamp+" ")
...             print(output, file=sys.__stdout__)
...             sys.__stdout__.flush()
...
>>> sys.stdout = TimestampFilter()
>>> print('hi')
2020-06-09 09:21:13 hi
>>>