It seems that this should be a common question, but I did not find a definite answer via Google search. I saw solutions to only scan files in the last 60 days, but it is not difficult for a virus file to change date, isn't it? I can think of to maintain hash table with file name and its checksum, but looks like this should be a functionality of the clamav itself. How do you do it? Just do a full scan every time? Thanks.