I have a large number of files (text files, swx files, etc.) which changes frequently. New files are added on a regular basis. I back up these files regularly (onto a separate hard disk), but would like to be able to back up only what has changed (i.e. only the files which have been added). Is there a simple way to do this, so I don't have to back up the whole archive every single time? Any suggestions would be appreciated.