Well I tried with -o file command and without and no file was saved when the key was found, then I tried the same in the latest version and it worked perfectly.
When I tried on Windows to run the original bitcrack, it saved output file in windows/system32.
Try naming the file non-standard way, run bc, and then searching for the file in system.
Tried and no textfile was found in system32. I really wish someone can add -r to the latest version.