(Login MCalkins) Moderator Posted Jul 1, 2012 1:42 PM
yeah, there are various ways of doing that.
Back in the old DOS days, when a file was modified the "A" (archive) attribute would be set. You could then copy all the files with the "A" attribute, and then remove the attribute from the source files.
You could write a QBASIC program to dump "dir" lists to files, and parse the files, looking for new files, or files with mismatching sizes and datestamps.
If you wanted to be extra sure, you could do binary comparisons of the files, or make a list of SHA-1 hashes of the backup files, then check the hashes of the new files against the list to see if there are new files. You could also use a list of hashes to detect duplicate files.
You might look into seeing if anyone else has written good synchronization software, rather that writing your own. (I know this is a programming forum with a strong hobby leaning, but sometimes it's easier and better to use someone else's program, unless you really want to write your own.)