The majority of code in os-prober is Copyright 2004-2011 by Joshua Kwan, Joey Hess, Christian Perrier, Colin Watson and Otavio Salvador. This is licensed $under the terms of the GNU GPL, either version 2 or, at your option, any later version. Some portions of os-prober by other contributors has an unclear license of "GNU GPL", with the version not specified. On Debian systems, a copy of the GNU General Public License is available in /usr/share/common-licenses/GPL-2.