Editing UNIX System V (section)

== Market position ==

=== Availability during the 1990s on x86 platforms ===
[[File:OpenSolaris 2009.06 screenshot.png|thumb|A [[GNOME]]-based [[OpenSolaris]] desktop, OpenSolaris was one of the SVR4 varieties available for x86 platforms]]
In the 1980s and 1990s, a variety of SVR4 versions of Unix were available commercially for the x86 PC platform. However, the market for commercial Unix on PCs declined after [[Linux]] and BSD became widely available. In late 1994, [[Eric S. Raymond]] discontinued his ''PC-clone UNIX Software Buyer's Guide'' on [[USENET]], stating, "The reason I am dropping this is that I run Linux now, and I no longer find the SVr4 market interesting or significant."<ref>{{cite web|url=http://www.catb.org/~esr/faqs/clone-unix-guide.txt|title=PC-clone UNIX Software Buyer's Guide|author=Eric S. Raymond|date=16 November 1994|access-date=3 February 2014}}</ref>

In 1998, a [[Halloween Documents|confidential memo]] at Microsoft stated, "Linux is on track to eventually own the x86 UNIX market", and further predicted, "I believe that Linux&nbsp;– moreso than [[Windows NT|NT]]&nbsp;– will be the biggest threat to SCO in the near future."<ref>{{cite web|url=http://www.catb.org/~esr/halloween/halloween1.html|title=Open Source Software: A (New?) Development Methodology|author=Vinod Valloppillil|date=11 August 1998|access-date=3 February 2014}}</ref>

An ''[[InfoWorld]]'' article from 2001 characterized SCO UnixWare as having a "bleak outlook" due to being "trounced" in the market by Linux and Solaris, and IDC predicted that SCO would "continue to see a shrinking share of the market".<ref name="2001_vital_signs">{{cite news|url=http://www.computerworld.com/article/2584450/operating-systems/vital-signs-for-unix.html|title=Vital Signs for Unix|author=Tom Yager|newspaper=[[Computerworld]]|date=19 November 2001|access-date=5 June 2015}}</ref>

=== Project Monterey ===
[[Project Monterey]] was started in 1998 to combine major features of existing commercial Unix platforms, as a joint project of [[Compaq]], IBM, Intel, SCO, and [[Sequent Computer Systems]]. The target platform was meant to be Intel's new [[IA-64]] architecture and [[Itanium]] line of processors. However, the project was abruptly canceled in 2001 after little progress.<ref>Raymond, Eric S. ''The Art of Unix Programming.'' 2003. p. 43</ref>

=== System V and the Unix market ===
By 2001, several major Unix variants such as SCO UnixWare, Compaq [[Tru64 UNIX]], and SGI IRIX were all in decline.<ref name="2001_vital_signs"/> The three major Unix versions doing well in the market were IBM AIX, Hewlett-Packard's HP-UX, and Sun's Solaris.<ref name="2001_vital_signs"/>

In 2006, when SGI declared bankruptcy, analysts questioned whether Linux would replace proprietary Unix altogether. In a 2006 article written for ''[[Computerworld]]'' by Mark Hall, the economics of Linux were cited as a major factor driving the migration from Unix to Linux:<ref name="2006_end_of_unix">{{citation|url=http://www.computerworld.com/article/2555262/operating-systems/the-end-of-unix-.html|title=The End of Unix?|author=Mark Hall|date=15 May 2006|access-date=5 June 2015}}</ref>

{{quote|Linux's success in high-end, [[scientific computing|scientific]] and [[high-performance technical computing|technical computing]], like Unix's before it, preceded its success in your [[data center]]. Once Linux proved itself by executing the most complex calculations possible, IT managers quickly grasped that it could easily [[web server|serve Web pages]] and run [[payroll]]. Naturally, it helps to be lucky: Free, downloadable Linux's star began to rise during one of the longest downturns in IT history. With companies doing more with less, one thing they could dump was Unix.}}

The article also cites trends in high-performance computing applications as evidence of a dramatic shift from Unix to Linux:<ref name="2006_end_of_unix"/>

{{quote|A look at the [[TOP500|Top500]] list of [[supercomputer]]s tells the tale best. In 1998, Unix machines from Sun and SGI combined for 46% of the 500 fastest computers in the world. Linux accounted for one (0.2%). In 2005, Sun had 0.8%&nbsp;— or four systems&nbsp;— and SGI had 3.6%, while 72% of the Top500 ran Linux.}}

In a November 2015 survey of the top 500 supercomputers, Unix was used by only 1.2% (all running IBM AIX), while Linux was used by 98.8%; the same survey in November 2017 reports 100% of them using Linux.<ref name="top500_stats">{{cite web|url=http://www.top500.org/statistics/list/|title=TOP500 Supercomputer Sites - List Statistics|access-date=28 January 2016}}</ref>

System V derivatives continued to be deployed on some proprietary server platforms. The principal variants of System V that remain in commercial use are AIX (IBM), Solaris (Oracle), and HP-UX (HP). According to a study done by [[International Data Corporation|IDC]], in 2012 the worldwide Unix market was divided between IBM (56%), Oracle (19.2%), and HP (18.6%). No other commercial Unix vendor had more than 2% of the market.{{r|lastdays}} Industry analysts generally characterize proprietary Unix as having entered a period of slow but permanent decline.<ref>{{cite web|url=http://www.computerworld.com/article/2486806/linux/as-unix-fades-away-from-data-centers--it-s-unclear-what-s-next.html|title=As Unix fades away from data centers, it's unclear what's next|author=Patrick Thibodeau|date=12 December 2013|access-date=6 June 2015|archive-url=https://web.archive.org/web/20150520013205/http://www.computerworld.com/article/2486806/linux/as-unix-fades-away-from-data-centers--it-s-unclear-what-s-next.html|archive-date=2015-05-20}}</ref>

=== OpenSolaris and illumos distributions===
[[File:OpenIndiana Hipster 2021.10 MATE desktop environment screenshot.png|thumb|The [[MATE (desktop environment)|MATE]] desktop on [[OpenIndiana]], an SVR4 derivative]]
OpenSolaris and its derivatives are the only SVR4 descendants that are [[open-source software]]. 
Core system software continues to be developed as [[illumos]], which is used in [[Illumos#Distributions|illumos distributions]] such as [[SmartOS]], [[OpenIndiana]] and others.

=== System V compatibility ===
The System V interprocess communication mechanisms are available in Unix-like operating systems not derived from System V; in particular, in Linux<ref name="kerrisk"/><ref>{{man|7|svipc|Linux}}</ref> (a reimplementation of Unix) as well as the BSD derivative [[FreeBSD]].<ref>{{man|2|msgsnd|FreeBSD}}</ref> POSIX 2008 specifies a replacement for these interfaces.<ref name="kerrisk"/>

FreeBSD maintains a binary compatibility layer for the [[COFF]] format, which allows FreeBSD to execute binaries compiled for some SVR3.2 derivatives such as SCO UNIX and Interactive UNIX.<ref>Lehey, Greg. ''The Complete FreeBSD: Documentation from the Source.'' 2003. pp. 164-165</ref> Modern System V, Linux, and BSD platforms use the [[Executable and Linkable Format|ELF]] file format for natively compiled binaries.