We have special measurement devices which connect through USB to a Windows PC. There's very limited software for those devices which only lets you configure the .txt file where the measured values are saved.
Said software puts every read value (read values are floats from 0 to 15) on the new line of .txt file. The values won't be read frequently (few times in an hour or so).
The software doesn't support timestamps so what we want to accomplish is having timestamps on every line with the time when the value was measured. It doesn't have to be exact time (few minutes there or there).
I was thinking of finding some kind of .txt file monitoring software and then adding current time to last line whenever it sees that file has been changed. What would be the most efficient and free way to accomplish such thing?