I have a new article on different ways in which you can synchronize your Unix files. From the intro:

There are many tools available that allow you to synchronize files across UNIX directories, but doing it effectively, and securely, takes a little bit more effort. This article looks at solutions for synchronizing files across UNIX filesystems and different computer systems securely, and at solutions that allow you to synchronize encrypted versions of your files for the purposes of backup.File synchronization is the process of adding, changing, or deleting a file in one location, and having the same file added to, changed, or deleted at another location. This article covers three utilties, cp, tar, and rsync, that can aid with synchronization of UNIX files. While cp and tar commands have limited synchronization abilities, rsync provides you with the full range of options; however, all three have their place.

Of particular interest is a script that provides an encrypted wrapper around rsync, which I use to provide a nice secure rsync-able backup. Read: Synchronizing UNIX files