Log Micropython console text to file

Here is a small snippet, how you can write everything what you get on console to file in your Micropython device. This may help you to debug long running devices.

import io, os
 
class logToFile(io.IOBase):
    def __init__(self):
        pass
 
    def write(self, data):
        with open("logfile.txt", mode="a") as f:
            f.write(data)
        return len(data)
 
# now your console text output is saved into file
os.dupterm(logToFile())
 
# disable logging to file
os.dupterm(None)

micropython, python, tutorial, console, log, file, tip

Martin Ortiz, 2021/08/01 10:23

hi, I tried and worked perfect. but i would like to understand how as I need to make some changes on it, for instead be sure to flush the file when/before to reboot/deepsleep-.

Also I would like to name the file adding a _YYMMDDHHMMSS ending, or just pass a name as a additional parameter.

I was reading about io.IOBase for an ESP32 https://docs.micropython.org/en/latest/library/uos.html?highlight=iobase and at https://pydocs2cn.readthedocs.io/projects/pydocs2cn/en/latest/library/io.html.

any hint?

Ignas, 2021/08/16 11:03, 2021/09/06 16:23

You may give filename custom name based on date via following name:

    def write(self, data):
        logFileName = 'info_{}.log'.format(strftime('%d_%m_%Y_%T'))
        with open(logFileName, mode="a") as f:
            f.write(data)
        return len(data)

You may use all date and time variable (google strftime function ), just avoid slashes and backslashes, semicolon and other special symbols in file name.

Tony, 2022/08/04 10:10

Hey there,

Just for the people that are interested for creating separate log files for each time the device reboots / deepsleeps, I have made the following alteration that keeps the logfiles from being overwritten every reboot/deepsleep. Notice that this solution does not need any time keeping (and therefore an internet connection to synchronize time). I hope that it helps anyone facing debugging issues on long running devices where serial connections over longer periods do not make sense. Cheers.

https://pastebin.com/cFgnvYqi