how to read a text file as bytes

[killerrex]

The "per line" operator works with binary files using '\n' as separator, so you can do something like:

with open('input.bin', 'rb') as fd:
    for line in fd:
        for sub_line in line.split(b'\r'):
            # Take into account any single '\r'
            if not sub_line:
                # If you want to deal also with zero length groups, thsi must be improved...
                continue
            # Do something with the lines
            pass

If you can guarantee in the input format that splitting by '\n' is safe is a good way.
Other option is to use a memory map.