Python binascii.unhexlify is converting linefeed characters. Can I prevent this?

Question

I have an string of pairs of characters representing hex numbers, (e.g. 0f means decimal 15). I need this in binary format, so I called binArray = binascii.unhexlify(finalString)

I have "bash on Ubuntu on Windows" installed, and when I perform this from there it works fine.

However, I need to invoke the script from a .bat file in the windows environment. When I call the exact same python program from the .bat file, if unhexlify sees '0a' in the hex string it converts it to 0d 0a (in the binary output). This is not a text file and the line-end conversion is corrupting my data!

Is there a way to convince unhexlify to stop doing this when I call it from the windows environment?

It would seem like a waste to have to roll-my-own conversion.

The above version is from when I run Python from the Ubunu shell — Randy Leberknight, Jun 02 '17 at 22:43
I think you need to add more details as to what exactly you are doing. — juanpa.arrivillaga, Jun 02 '17 at 22:43
When I run Python from a windows cmd shell I get a different python: — Randy Leberknight, Jun 02 '17 at 22:43
Python 2.7.13 (v2.7.13:a06454b1afa1, Dec 17 2016, 20:53:40) [MSC v.1500 64 bit (AMD64)] on win32 — Randy Leberknight, Jun 02 '17 at 22:44
That is all important to note, and you should add that to the question itself, but I mean you should elaborate what more details about your actual code. — juanpa.arrivillaga, Jun 02 '17 at 22:50

score 0 · Accepted Answer · answered Jun 13 '17 at 19:08

I found out why the 0x0A characters were getting converted to 0D0A (I.E. LF to CRLF)

It's not the fault of binascii. I used

outfile = open(scriptDir + "Output/NVRAM/NVDATAout", 'w') to open the file, which implies text mode, and therefore writes get linefeed conversion appropriate for the local system.

When I opened the output file in binary mode, this conversion stopped happening.

outfile = open(scriptDir + "Output/NVRAM/NVDATAout", 'wb')

I found this answer here: https://stackoverflow.com/a/9184137/7275012

Python binascii.unhexlify is converting linefeed characters. Can I prevent this?

1 Answers1