-b, --backup
With this option, preexisting destination files are renamed
as
each file is transferred or deleted. You can control where
the
backup file goes and what (if any) suffix gets appended
using
the --backup-dir and --suffix options.
-From the man page for rsync
I think this just renames a copy of each destination file so they don't get
overwritten by mistake. If you have ever used Windows and download something
more than once you get:
file file(1) file(2) file(3)
Or, using emacs it makes backups with ~ :
file file~
But it is important that you RTFM or STFW or you may lose your data! Have
you used this program before? Why do you want to use this option?
