I need to back up my whole hard drive to an external drive. There is so many files that it has frozen a few times, and I'm afraid some files have only been partially copied. There has also been some changes made to some files on the hd that is to be backed up.
How can I copy all new files, and overwrite all those files that are only partially copied or that has had changes (e.g. are of differing file size) but skip those that are of the same size?
Merging directories (with the tack "do this to all") and skipping files with the same name (with the tack "do this to all") did not work, it skipped all files that had the same name (even if they were of different size).
EDIT: I am using Ubuntu 16.04 and the program "Files".