The many varieties of proprietary Unix in the 1980s and 1990s — almost all derived from AT&T Unix under licence and all called "Unix", but increasingly mutually incompatible. SeeUNIX wars.
Most Linux distributions are descended from other distributions, most being traceable back to Debian, Red Hat or Softlanding Linux System (see image right). Since most of the content of a distribution is free and open source software, ideas and software interchange freely as is useful to the individual distribution. Merges (e.g., United Linux or Mandriva) are rare.
Symbolics Lisp Machine operating system, later called Symbolics Genera. Forked from the MIT Lisp Machine operating system, which was licensed by MIT to Symbolics in 1980.[1] This fork later motivated Richard Stallman to start the GNU Project.[2]
1985
POSTGRES (later PostgreSQL), after Ingres branched off as a proprietary project.
NeoOffice, a fork of OpenOffice.org, with an incompatible license (GPL rather than LGPL), due to disagreements about licensing and about the best method to port OpenOffice.org to Mac OS X.
WineX (later Cedega), was a proprietary fork of Wine.
XOrg, from XFree86, in order to adopt a more open development model and due to concerns over the latter's change to a license many distributors found unacceptable.
2005
Audacious, from Beep Media Player to continue work on the old version of that project.
Joomla, from Mambo due to concerns over project structure.
Claws Mail, from Sylpheed, due to perceived slowness in accepting enhancements.
2006
Adempiere, a community maintained fork of Compiere 2.5.3b, due to disagreement with commercial and technical direction of Compiere Inc.
Cdrkit, from Cdrtools due to perceived licensing issues.[4][5][6]
LedgerSMB, from SQL-Ledger, due to disagreements over handling of security issues.
Xonotic, from Nexuiz, after that project was taken proprietary.
Mageia, from Mandriva Linux, due to financial uncertainty and the layoff by Edge-IT, a Mandriva subsidiary employing many of the corporate staff working on the Mandriva distribution
Jenkins, from Hudson (2011), due to Oracle Corporation's perceived neglect of the project's infrastructure and disagreements over use of the name on non-Oracle-maintained infrastructure.