If you're not careful, mv can overwrite existing files. Move files wisely with mv --backup=existing -v. To save typing, set VERSION_CONTROL to existing.
Martin Streicher is the founder of Locomotive, an expert Rails consultancy. Formerly, he was Editor-in-Chief of Linux Magazine from 2002 to 2007. You can contact him at martin.streicher@linux-mag.com and follow him on Twitter.