Rsync
rsync copies files and directories. It is often used for backups, or duplicating directory contents on a remote server. rsync can copy only changed files, and can use SSH to securely copy the file.
Common Options
-a - Combo flag, same as -rlptgoD (recursive; copies symlinks; preserve: permissions, modification times, group, and owner; device/special)
-v - verbose
-n - do a "dry run". Together with -v, -n shows what rsync will copy, but doesn't actually copy anything
dir vs dir/:
dir - Copy the directory
dir/ - Copy the contents of the directory
Sync Directories on the same computer
rsync -a dir1/ dir2 - Copies the contents of dir1 into dir2
Copy files to a remote system
rsync -a ~/dir1 username@remote_host:destination_directory - Copies the entire specified directory to the destination on the server.
Example: rsync - /docs bob@example.com:/home/bob/public_html