dar is a shell command, that makes backup of a directory tree and files. It is released under the GNU General Public License (GPL in the following) and actually has been tested under Linux, Windows and Solaris. Since version 2.0.0 an Application Interface (API) is available to open the way to external independent Graphical User Interfaces (GUIs). An extension of this API (in its version 2) is in the air, for release 2.1.0, and would overcome some limitation of API version 1. This API relies on the libdar library which is the core part of DAR programs and, as such, is released under the GPL. In consequences, to use it, your program must be released under the GPL, no commercial use will be tolerated.