Something like if you have a "Lecture Folder" shared on LAN but you also want a backup on your local HDD.
One thing a lame user will do is "copy and paste" which is pain in the ass.. There should be a automatic method..There is a software "rsync" which solves this problem. For ex.
$rsync -r --times --progress --verbose --update [source] [destination]This way whenever you run this command, it will only copy the files which are new.
You can also make a shell script for it.