rsync is a program that behaves in much the same way that rcp does, but has many more options and uses the rsync remote-update protocol to greatly speed up file transfers when the destination file already exists.
The rsync remote-update protocol allows rsync to transfer just the differences between two sets of files across the network link, using an efficient checksum-search algorithm described in the technical report that accompanies this package.
Debian or Ubuntu Linux
apt-get install rsync
sudo apt-get install rsync
Red Hat Enterprise Linux (RHEL)
CentOS/Fedora Core Linux
yum install rsync