Redirect STDOUT and STDERR to python logger and also to jupyter notebook

问题

Important to know: I am working on jupyter notebook.

I want to create a logger to which I will redirect the STDOUT and STDERR but I also want to see those outputs on the jupyter notebook output console.

So far what I have implemented is:

import logging
import sys

class StreamToLogger(object):
    """
    Fake file-like stream object that redirects writes to a logger instance.
    """
    def __init__(self, logger, log_level=logging.INFO):
        self.logger = logger
        self.log_level = log_level
        self.linebuf = ''

    def write(self, buf):
        for line in buf.rstrip().splitlines():
            self.logger.log(self.log_level, line.rstrip())

    def flush(self):
        pass

logging.basicConfig(filename='my_log.log',
                    filemode='a',
                    # stream=sys.stdout,
                    level=logging.DEBUG,
                    format='%(asctime)s;%(name)s;%(levelname)s;%(message)s')

# redirect stdout and stderr to logger
stdout_logger = logging.getLogger('STDOUT')
sl = StreamToLogger(stdout_logger, logging.INFO)
sys.stdout = sl

stderr_logger = logging.getLogger('STDERR')
s2 = StreamToLogger(stderr_logger, logging.ERROR)
sys.stderr = s2

log = logging.getLogger('my_log')

# An info log
log.info('This is an info')

# A stdout message
print("This is an STDOUT")

# A stderr message
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First Question: The previous code, if stored on a .py file, is able to redirect the stdout and stderr to the my_log.log file. But I lose track of the messages in a normal terminal console.

What I would like is to have both the stderr and stdout redirected to the log file and also be able to see them on the console.

Second Question: I am working on jupyter notebooks and I would like to be able to log from there. This means all the stdout and stderr redirected from jupyter notebook output to the log file, but also keep it on the jupyter notebook console. I realized that the code above, redirects the stdout to the log file but not the stderr, and as a result all my prints('XX') are in my log file and my exceptions are still on the notebook console.

Seems like jupyter notebooks deals in a different way with STDOUT and STDERR

Thanks for your help

来源：https://stackoverflow.com/questions/60281623/redirect-stdout-and-stderr-to-python-logger-and-also-to-jupyter-notebook

标签

python

logging

jupyter-notebook

stdout

stderr