Editing Fork (software development) (section)

==Forking of free and open-source software==
Free and [[open-source software]] may be legally forked without prior approval of those currently developing, managing, or distributing the software per both [[The Free Software Definition]] and [[The Open Source Definition]]:<ref name=wheeler/>
{{quotation|The freedom to distribute copies of your modified versions to others (freedom 3). By doing this, you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.|[[The Free Software Definition]]<ref>{{cite web
 |url         = https://www.gnu.org/philosophy/free-sw.html
 |title       = The Free Software Definition
 |first       = Richard
 |last        = Stallman
 |publisher   = Free Software Foundation
 |access-date  = 2013-10-15
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20131014132149/http://www.gnu.org/philosophy/free-sw.html
 |archive-date = 14 October 2013
}}</ref>}}
{{quotation|3. Derived Works: The license must allow modifications and derived works, and must allow them to be distributed under the same terms as the license of the original software.|[[The Open Source Definition]]<ref>{{cite web|url=http://opensource.org/docs/osd|title=The Open Source Definition|date=7 July 2006 |publisher=The Open Source Initiative|access-date=15 October 2013|url-status=live|archive-url=https://web.archive.org/web/20131015144021/http://opensource.org/docs/osd|archive-date=15 October 2013}}</ref>}}

In free software, forks often result from a schism over different goals or personality clashes. In a fork, both parties assume nearly identical code bases, but typically only the larger group, or whoever controls the web site, will retain the full original name and the associated user community. Thus, there is a reputation penalty associated with forking.<ref name=wheeler/> The relationship between the different teams can be cordial or very bitter. On the other hand, a ''friendly fork'' or a ''soft fork'' is a fork that does not intend to compete, but wants to eventually merge with the original.

[[Eric S. Raymond]], in his essay ''[[Homesteading the Noosphere]]'',<ref>{{cite web |last=Raymond |first=Eric S. |author-link=Eric S. Raymond |date=15 August 2002 |title=Promiscuous Theory, Puritan Practice |url=http://www.catb.org/~esr/writings/cathedral-bazaar/homesteading/ar01s03.html |url-status=live |archive-url=https://web.archive.org/web/20061006010031/http://www.catb.org/~esr/writings/cathedral-bazaar/homesteading/ar01s03.html |archive-date=6 October 2006 |website=catb.org}}</ref> stated that "The most important characteristic of a fork is that it spawns competing projects that cannot later exchange code, splitting the potential developer community". He notes in the [[Jargon File]]:<ref>[http://catb.org/jargon/html/F/forked.html Forked] {{webarchive|url=https://web.archive.org/web/20111108171515/http://catb.org/jargon/html/F/forked.html |date=8 November 2011 }} ([[Jargon File]]), first added to [http://magic-cookie.co.uk/jargon/jarg422/ v4.2.2] {{webarchive|url=https://web.archive.org/web/20120114192615/http://magic-cookie.co.uk/jargon/jarg422/ |date=14 January 2012 }}, 20 August 2000)</ref>

{{quotation|Forking is considered a Bad Thing—not merely because it implies a lot of wasted effort in the future, but because forks tend to be accompanied by a great deal of strife and acrimony between the successor groups over issues of legitimacy, succession, and design direction. There is serious social pressure against forking. As a result, major forks (such as the [[GNU Emacs|Gnu-Emacs]]/[[XEmacs]] split, the fissioning of the [[386BSD]] group into three daughter projects, and the short-lived GCC/EGCS split) are rare enough that they are remembered individually in hacker folklore.}}

David A. Wheeler notes<ref name=wheeler>[http://www.dwheeler.com/oss_fs_why.html#forking Why Open Source Software / Free Software (OSS/FS, FLOSS, or FOSS)? Look at the Numbers!: Forking] {{webarchive|url=https://web.archive.org/web/20060405112628/http://www.dwheeler.com/oss_fs_why.html |date=5 April 2006 }} (David A. Wheeler)</ref> four possible outcomes of a fork, with examples:

# The death of the fork. This is by far the most common case. It is easy to declare a fork, but considerable effort to continue independent development and support.
# A re-merging of the fork (''e.g.'', [[egcs]] becoming "blessed" as the new version of [[GNU Compiler Collection]].)
# The death of the original (''e.g.'' the [[X.Org Server]] succeeding and [[XFree86]] dying.)
# Successful branching, typically with differentiation (''e.g.'', [[OpenBSD]] and [[NetBSD]].)

[[Distributed revision control]] (DVCS) tools have popularised a less emotive use of the term "fork", blurring the distinction with "branch".<ref>''e.g.'' {{cite web|url=https://lwn.net/Articles/628527/|title=An "open governance" fork of Node.js|first=Nathan|last=Willis|work=LWN.net|date=15 January 2015|access-date=15 January 2015|quote=Forks are a natural part of the open development model—so much so that GitHub famously plasters a "fork your own copy" button on almost every page.|url-status=live|archive-url=https://web.archive.org/web/20150421055059/http://lwn.net/Articles/628527/|archive-date=21 April 2015}} See also {{cite thesis|type=PhD|page=57|first=Linus|last=Nyman|title=Understanding Code Forking in Open Source Software|publisher=Hanken School of Economics|year=2015|quote=Where practitioners have previously had rather narrow definitions of a fork, [...] the term now appears to be used much more broadly. Actions that would traditionally have been called a branch, a new distribution, code fragmentation, a pseudo-fork, etc. may all now be called forks by some developers. This appears to be in no insignificant part due to the broad definition and use of the term fork by GitHub.|hdl=10138/153135}}</ref> With a DVCS such as [[Mercurial]] or [[Git]], the normal way to contribute to a project, is to first create a personal branch of the repository, independent of the main repository, and later seek to have your changes integrated with it. Sites such as [[GitHub]], [[Bitbucket]] and [[Launchpad (website)|Launchpad]] provide free DVCS hosting expressly supporting independent branches, such that the technical, social and financial barriers to forking a source code repository are massively reduced, and GitHub uses "fork" as its term for this method of contribution to a project.

Forks often restart version numbering from numbers typically used for initial versions of programs like 0.0.1, 0.1, or 1.0 even if the original software was at another version such as 3.0, 4.0, or 5.0. An exception is sometimes made when the forked software is designed to be a drop-in replacement for the original project, ''e.g.'' [[MariaDB]] for [[MySQL]]<ref>[http://programmers.stackexchange.com/questions/31551/forked-a-project-where-do-my-version-numbers-start Forked a project, where do my version numbers start?] {{webarchive|url=https://web.archive.org/web/20110826152252/http://programmers.stackexchange.com/questions/31551/forked-a-project-where-do-my-version-numbers-start |date=26 August 2011 }}</ref> or [[LibreOffice]] for [[OpenOffice.org]].

The [[BSD licenses]] permit forks to become proprietary software, and [[copyleft]] proponents say that commercial incentives thus make proprietisation almost inevitable. (Copyleft licenses can, however, be circumvented via dual-licensing with a proprietary grant in the form of a [[Contributor License Agreement]].) Examples include [[macOS]] (based on the proprietary [[NeXTSTEP]] and the open source [[FreeBSD]]), [[Cedega (software)|Cedega]] and [[CrossOver]] (proprietary forks of [[Wine (software)|Wine]], though CrossOver tracks Wine and contributes considerably), EnterpriseDB (a fork of [[PostgreSQL]], adding Oracle compatibility features<ref>[http://www.enterprisedb.com EnterpriseDB] {{webarchive|url=https://web.archive.org/web/20061113052033/http://www.enterprisedb.com/ |date=13 November 2006 }}</ref>), Supported PostgreSQL with their proprietary ESM storage system,<ref>[http://www.fastware.com.au/docs/FujitsuSupportedPostreSQLWhitePaperV1_02.pdf Fujitsu Supported PostgreSQL] {{webarchive|url=https://web.archive.org/web/20060820144738/http://fastware.com.au/docs/FujitsuSupportedPostreSQLWhitePaperV1_02.pdf |date=20 August 2006 }}</ref> and Netezza's<ref>[http://www.netezza.com/media/2004/Weblog.htm Netezza] {{webarchive|url=https://web.archive.org/web/20061113210650/http://www.netezza.com/media/2004/Weblog.htm |date=13 November 2006 }}</ref> proprietary highly scalable derivative of PostgreSQL. Some of these vendors contribute back changes to the community project, while some keep their changes as their own competitive advantages.