os.path.join (folder, filename) ensures the path is correct for the system. On Windows, it uses backslashes (reports\summary.txt); on Linux and macOS it uses forward slashes (reports/summary.txt).

The md5sum utility is used to calculate what is called the fingerprint of a file. A small tutorial for the program "md5" or "md5sum" commonly called "checksum". (The checksum is a value of 128 bits ...