rsync
- used for transferring and synchronizing files between computers or storage devices
Examples
rsync everything from ~/ComputerScience to flash drive named CS_BACKUP:
rsync -avP --delete ~/ComputerScience/ /Volumes/CS_BACKUP/ComputerScience/
rsync over the internet
rsync -avz -e "ssh -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null" --progress /root/bigfile.txt username@198.211.117.129:/