MakeDirDiff is a simple command line tool for finding differences between two directories and storing all new/updates files in a new directory. MakeDirDiff compares two directories and creates the third directory with the first directory structure, but with new or updated files only. It can update the second directory content with the current content of the first directory. On the next run MakeDirDiff will find and place only new/changed files appeared in the first directory into the third directory. I found this extremely useful for creating incremental backups and updating big web-sites. It is a simple java application, designed as an Apache Ant task. MakeDirDiff can be (a) run from the command line, (b) run as a single Ant task, (c) used as a part of other Ant tasks or (d) integrated into other applications like a library as well. Original source is http://code.google.com/p/makedirdiff/ Author is Igor Kanshyn. It is free software.