Rsync helps you to keep two folders in sync. This is possible over the network or local.

over the network

The following command sends the directory /srv/www/htdocs over to server:

rsync -avv --stats <acronym title="show a progress">--progress</acronym></html> --partial /srv/www/htdocs server:/srv/www

locally

Copy a folder .VirtualBox to /root:

rsync -avv --stats --progress --partial .VirtualBox/ /root/.VirtualBox