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I have a binary file from a mainframe which I'm trying to read using Python and produce a human readable text file. I'm still gathering more information about the file. What I do know is that the file serves as input to COBOL programs. I try to read the file into python like this:

with open('P_MF.DAT', mode='rb') as f:
    file_content = f.read(500)

When I print(file_content) I get something like:

b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00@@@@@@@@\x00\x00@@@\xf0\xf0\xf0\xf0\xf0\xf0\xf0\xf0\xf0\xf0\xf0\xf0\xf0\xf0\xf0@@@@\x00\x00\x00\x00\x00\x00\x00\x00@@@\x00\x00\x00\x00@@@@@@\xf0\xf0\xf0\xf4\x00\x00\x00\x00\x08\x02\x00\x00Q\x08c\x18\x1f\xc5@@@\x00\x00\x000\x00\x00\x0f\x00\x00\x00\x01\x11?\x00\x00\x10\x02F\x17o@@\xd5@\xc9\xd5\xc7\xd3\xc9\xe2@\xd4\xc1\xd9\xe8@@@@@@@@@@@@@@@@@@@@@@@@@@@@@\x00\x00\x00\x00\x00\x00\x00\x0c\x00\x00\x00\x00\x00\x00\x00'

Then I tried this using the codecs module which also gives me gibberish:

import codecs
file_content1 = codecs.decode(file_content, 'cp500')

But I can see a few readable characters in the output when I print(file_content1):

'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00 \x00\x00 000000000000000 \x00\x00\x00\x00\x00\x00\x00\x00 \x00\x00\x00\x00 0004\x00\x00\x00\x00\x97\x02\x00\x00é\x97Ä\x18\x1fE \x00\x00\x00\x90\x00\x00\x0f\x00\x00\x00\x01\x11\x1a\x00\x00\x10\x02ã\x87? N INGLIS MARY \x00\x00\x00\x00\x00\x00\x00\x0c\x00\x00\x00\x00\x00\x00\x00'

I've been googling around for a couple of days. Tried a number of things like this - Python read a binary file and decode I feel like I'm getting nowhere with this problem. I also plan to ask how this file looks if read in a mainframe. I'd appreciate any info/help/advice at this point. ​

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    Decoding implies text. Not all binary data is text data. You have a mix of binary and text data and must know the structure of the data and only decode the text portions. Commented Mar 30, 2021 at 22:55
  • Thanks @MarkTolonen. That makes a lot of sense. Will get the structure of the data and try it. Commented Mar 31, 2021 at 15:42
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