Rsync
Internal
Overview
rsync is a differential, recursive file transfer utility. rsync copies files to or from a remote host, or locally on the current host. It does not support copying files between two remote hosts. rsync may connect to the remote system either using a remote-shell programs, such as ssh or ssh, or directly to the rsync daemon running on the remote system, via TCP. The remote-shell transport is used whenever there is a ":" after the host specification. If not configured otherwise with RSYNC_RSH environment variable or with -e command line option, rsync uses ssh by default. The rsync daemon transport is used when there is a "::" separator after host specification, or when "rsync://" is explicitly specified. If neither the source or destination path specify a remote host, the copy occurs locally. For remote transfers, rsync must be installed on both the source and destination machines.
Organizatorium
If a single source argument is specified without a destination, the files are listed in an output format similar to "ls -l".