writes "Alcatel-Lucent has authorized The University of California, Berkeley to `release all Plan 9 software previously governed by the Lucent Public License, Version 1.02 under the GNU General Public License, Version 2.' Plan 9 was developed primarily for research purposes as the successor to Unix by the Computing Sciences Research Center at Bell Labs between the mid-1980s and 2002. Plan 9 has subsequently emerged as Inferno, a commercially supported derivative, and ports to various platforms including a recent port to the Raspberry Pi. In Plan 9, all system interfaces, including those required for networking and the user interface, are represented through the file system rather than specialized interfaces. The system provides a generic protocol, 9P, to perform all communication with the system, among processes and with network resources. Applications compose resources using union file systems to form isolated namespaces."