crc32sum - Print CRC-32 (binary mode) checksums with Python on Linux.

https://github.com/thingsiplay/crc32sum

 undefined

    
# usage: crc32sum [-h] [-r] [-i] [-u] [--version] [path ...]

crc32sum *.sfc
2d206bf7  Chrono Trigger (USA).sfc

  

Previously I used a Bash script to filter out the checksum from 7z output. That felt always a bit hacky and the output was not very flexible. Plus the Python script does not rely on any external module or program too. Also the underlying 7z program call would automatically search for all files in sub directories recursively when a directory was given as input. This would require some additional rework, but I decided it is a better idea to start from scratch in a programming language. So I finally wrote this, to have a bit better control. My previous Bash script can be found here, in case you are curious: https://gist.github.com/thingsiplay/5f07e82ec4138581c6802907c74d4759

BTW, believe it or not, the Bash script running multiple commands starts and executes faster than the Python instance. But the difference is negligible, and the programmable control in Python is much more important to me.

What is this program for?

Calculates the CRC hash for each given file, using Python's integrated zlib module. It has a similar use like MD5 or SHA, but is way, way weaker and simpler. It's a quick and easy method to verify the integrity of files, in example after downloading from the web, to check data corruption from your external drives or when creating expected files.

It is important to know and understand that CRC-32 is not secure and should never be used cryptographically. It's use is limited for very simple use cases.

Linux does not have a standard program to calculate the CRC. This is a very simple program to have a similar output like md5sum offers by default. Why use CRC at all? Usually and most of the time CRC is not required to be used. In fact, I favor MD5 or SHA when possible. But sometimes, only a CRC is provided (often used by the retro emulation gaming scene). Theoretically CRC should also be faster than the other methods, but no performance comparison has been made (frankly the difference doesn't matter to me).