File Synchronization

Unison is a file-synchronization tool for Unix and Windows. It allows two replicas of a collection of files and directories to be stored on different hosts (or different disks on the same host), modified separately, and then brought up to date by propagating the changes in each replica to the other.


Unison shares a number of features with tools such as configuration management packages (CVS, PRCS, Subversion, BitKeeper, etc.), distributed filesystems (Coda, etc.), uni-directional mirroring utilities (rsync, etc.), and other synchronizers (Intellisync, Reconcile, etc).

Other applications

Linux

rsync is an open source utility that provides fast incremental file transfer.
In Ubuntu you can install from the application menu Grsync, a simple graphical interface for rsync.

Windows

SyncToy is a free PowerToy designed by Microsoft that provides an easy to use graphical user interface that can automate synchronizing files and folders. It is written using Microsoft's .NET framework.