The output file option is for the exec component to consider the content of that file as the "reply" message. So in the Camel route the message will then read the content of that output file as the new message content.
Does the md5sum.exe create an output file at all?
And maybe the path of the output file should use absolute as well? eg c:/temp/md5sum.log
1. No. md5sume.exe does not create output file.
2. Path is not the problem.
The outputFile is only to be used, if you execute some process that creates an output file, which you want to have Camel "read" as the result.
So if the md5sum.exe do not create any output file, then do not use that option. Instead Camel will use the output on the console as the "result".