Editing POSIX (section)

==POSIX-oriented operating systems==
Depending upon the degree of compliance with the standards, one can classify operating systems as fully or partly POSIX compatible.

===POSIX-certified===
Current versions of the following operating systems have been certified to conform to one or more of the various POSIX standards. This means that they passed the automated conformance tests<ref name="achieve_status">{{cite web|url=https://posix.opengroup.org/certification_guide.html#Howto|title=POSIX Certified by IEEE and The Open Group - Program Guide|at=Section 2, How to Achieve Certification|access-date=26 September 2024}}</ref> and their certification has not expired and the operating system has not been discontinued.<ref name="renew_certification">{{cite web |url=https://posix.opengroup.org/certification_guide.html#Renewals|title=POSIX Certified by IEEE and The Open Group - Program Guide|at=Section 4, Renewals and Certified Product Updates|access-date=26 September 2024}}</ref><ref>{{cite web|url=https://www.opengroup.org/openbrand/register/company.htm|title=Certified Products by Company|author=<!--Not stated-->|date=n.d.|publisher=The Open Group |access-date=22 January 2022}}</ref>
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*[[IBM AIX|AIX]]<ref name="ibm">{{cite web |url=https://www.opengroup.org/openbrand/register/ibm.htm |title=IBM |publisher=The Open Group |access-date=23 January 2022}}</ref>
*[[HP-UX]]<ref name="hp">{{cite web |url=https://www.opengroup.org/openbrand/register/hp.htm |title=Hewlett-Packard  |publisher=The Open Group |access-date=26 January 2014}}</ref>
*[[Integrity (operating system)|INTEGRITY]]<ref name="posix-register">{{Cite web|url=https://posix.opengroup.org/register.html|title=POSIX Certification Register|website=[[The Open Group]]|access-date=22 August 2024}}</ref>
*[[macOS]] (since [[Mac OS X Leopard]]<ref>{{cite web|title=macOS version 10.5 Leopard on Intel-based Mac computers |url=https://www.opengroup.org/openbrand/register/brand3555.htm|work=Register of Open Branded Products|publisher=The Open Group |access-date=20 May 2015}}</ref> to [[macOS Sequoia]]<ref>{{cite web|url=https://www.opengroup.org/openbrand/register/brand3715.htm|title=macOS version 10.15 Sequoia on Intel-based Mac computers|publisher=The Open Group|access-date=25 April 2025}}</ref><ref>{{cite web|url=https://www.opengroup.org/openbrand/register/brand3710.htm|title=macOS version 10.15 Sequoia on Apple Silicon-based Mac computers|publisher=The Open Group|access-date=25 April 2025}}</ref>)
*[[OpenServer]]<ref>{{cite web|url=https://www.opengroup.org/openbrand/register/brand2574.htm|title=SCO OpenServer Release 5  |date=3 May 1995|publisher=The Open Group|access-date=24 December 2021}}</ref>
*[[UnixWare]]<ref>{{cite web|url=https://www.opengroup.org/openbrand/register/brand2713.htm |title=UnixWare ® 7.1.3 and later  |date=16 May 2003|publisher=The Open Group|access-date=24 December 2021}}</ref>
*[[VxWorks]]<ref name="posix-register"/>
*[[z/OS]]<ref name="ibm"/>
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===Formerly POSIX-certified===
Some versions of the following operating systems had been certified to conform to one or more of the various POSIX standards. This means that they passed the automated conformance tests. The certification has expired and some of the operating systems have been discontinued.<ref name="renew_certification" />
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*[[EulerOS]] (exp. 2022)<ref>{{cite web |url=https://www.opengroup.org/openbrand/register/huawei.htm|title=Huawei Technology Co., Ltd|publisher=The Open Group|access-date=26 May 2017}}</ref>
*[[Inspur K-UX]] (exp. 2019)<ref>{{cite web|url=https://www.opengroup.org/openbrand/register/inspur.htm|title=Inspur Co., Ltd |publisher=The Open Group|access-date=26 May 2017}}</ref>
*[[IRIX]] (defunct 2006)<ref>{{cite web |url=https://www.opengroup.org/openbrand/register/sgi.htm|title=Silicon Graphics, Inc. |publisher=The Open Group|access-date=26 January 2014}}</ref>
*[[OS/390]] (defunct 2004)<ref>{{cite web|archive-url=https://web.archive.org/web/20030802103246/http://www.opengroup.org/openbrand/register/|url=http://www.opengroup.org/openbrand/register/|title=The Open Brand - Register of Certified Products|date=23 July 2003|archive-date=2 August 2003|access-date=23 January 2022|website=Open Group}}</ref>
*[[QNX|QNX Neutrino]]<ref>{{cite press release|url=http://www.qnx.com/news/pr_2862_1.html|title=QNX Achieves New POSIX Certification|date=8 April 2008|access-date=16 January 2016 | publisher=QNX}}</ref>
*[[Solaris (operating system)|Solaris]] (exp. 2019)<ref>{{cite web|url=https://www.opengroup.org/openbrand/register/sun.htm|title=Oracle Corporation|publisher=The Open Group|access-date=26 January 2014|archive-url=https://web.archive.org/web/20170712134003/https://www.opengroup.org/openbrand/register/sun.htm|archive-date=12 July 2017}}</ref>
*[[Tru64 UNIX|Tru64]] (defunct 2010)<ref>{{cite web|url=https://www.opengroup.org/openbrand/register/hp.htm|title=Hewlett-Packard  |publisher=The Open Group|access-date=26 January 2014|archive-url=https://web.archive.org/web/20140709114759/https://www.opengroup.org/openbrand/register/hp.htm|archive-date=9 July 2014}}</ref>
*[[LiteOS]] (defunct 2020)<ref>{{cite web |title=Huawei LiteOS / LiteOS |url=https://gitee.com/LiteOS/LiteOS |website=Gitee |publisher=Huawei |access-date=23 May 2024}}</ref>
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===Mostly POSIX-compliant===
The following are not certified as POSIX compliant yet comply in large part:
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*[[Android (operating system)|Android]] (Available through Android NDK){{citation needed|date=December 2014}}
*[[Darwin (operating system)|Darwin]] (core of [[macOS]] and [[iOS]])
*[[DragonFly BSD]]
*[[FreeBSD]]<ref name="FreeBSD">{{cite web|url=http://people.freebsd.org/~schweikh/posix-utilities.html|title=FreeBSD POSIX 2001 Utility Compliance|first=Jens|last=Schweikhardt|publisher=FreeBSD}}</ref>
*[[Haiku (operating system)|Haiku]]
*[[illumos]]
*[[Linux]] (most distributions)
*[[LynxOS]]
*[[Minix]] (now [[Minix 3]])
*[[HP Multi-Programming Executive|MPE/iX]]<ref>{{Cite magazine|magazine=Computerworld|url=https://books.google.com/books?id=-6GcSQAVaHgC&q=posix&pg=PA24|title = HP 3000 sales catch market by surprise|author=Mark Halper|volume = 28|issue=4|publisher=IDG Enterprise|date= 7 November 1994}}</ref>
*[[NetBSD]]
*[[Nucleus RTOS]]
*[[NuttX]]
*[[OpenBSD]]
*[[OpenSolaris]]<ref>{{Cite book|title=OpenSolaris Bible|url=https://books.google.com/books?id=y8qaxiZNvqAC|publisher=John Wiley & Sons|date=21 March 2011|isbn=9781118080313|language=en|first1=Nicholas A.|last1=Solter|first2=Jerry|last2=Jelinek|first3=David|last3=Miner}}</ref>
*[[PikeOS]] RTOS for embedded systems with optional PSE51 and PSE52 partitions; see [[Logical partition|partition (mainframe)]]
*[[PX5 RTOS]]<ref>{{cite web|url=https://www.embedded.com/rtos-with-standard-posix-pthreads-api-a-complement-to-embedded-linux/|title=RTOS with standard POSIX pthreads API: a complement to embedded Linux|website=Embedded.com|author-first1=Bill|author-last1=Lamie|author-first2=Rafael|author-last2=Taubinger|date=15 June 2023|access-date=13 September 2023}}</ref>
*[[Redox (operating system)|Redox]]
*[[RTEMS]] – POSIX API support designed to IEEE Std. 1003.13-2003 PSE52
*[[SerenityOS]]
*[[Stratus OpenVOS]]<ref>{{cite web|url=https://stratadoc.stratus.com/vos/19.3.0/r217m-03/wwhelp/wwhimpl/js/html/wwhelp.htm?context=r217m-03&file=ch1r217m-03.html|title=OpenVOS POSIX.1: Conformance Guide|publisher=Status Technologies|access-date=26 November 2021}}</ref>
*[[SkyOS]] (discontinued)
*[[Syllable Desktop|Syllable]] (discontinued)
*[[ULTRIX]]<ref>{{cite manual|url=http://bitsavers.org/pdf/dec/vax/ultrix-32/4.0_Jun90/AA-LY25C-TE_POSIX_Conformance_Document_Jun1990.pdf|title=ULTRIX POSIX Conformance Document|date=June 1990|publisher=Digital|access-date=13 December 2021}}</ref>
*[[VSTa]]
*[[VMware ESXi]]
*[[Xenix]]
*[[Zephyr_(operating_system)|Zephyr]]<ref>{{cite web|url=https://docs.zephyrproject.org/latest/services/portability/posix.html|title=POSIX Support|publisher=Zephyr documentation|access-date=7 March 2023}}</ref>

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====POSIX for Microsoft Windows====
*[[Cygwin]] provides a largely POSIX-compliant development and run-time environment for [[Microsoft Windows]].
*[[MinGW]], a [[fork (software development)|fork]] of Cygwin, provides a less POSIX-compliant development environment and supports compatible [[C (programming language)|C]]-programmed applications via [[Msvcrt]], Microsoft's old Visual C [[runtime library]].
*libunistd, a largely POSIX-compliant development library originally created to build the Linux-based C/[[C++]] source code of [[CinePaint]] as is in [[Microsoft Visual Studio]]. A lightweight implementation that has POSIX-compatible header files that map POSIX APIs to call their Windows API counterparts.<ref>{{cite web|url = https://github.com/robinrowe/libunistd|title=libunistd| last=Rowe|first=Robin|date=8 September 2022|website=Github|publisher=|access-date=18 February 2023|quote=If you want to build single codebase C++ code to run on Windows, Linux and MacOS, you need this for Windows}}</ref>
*[[Microsoft POSIX subsystem]], an optional Windows subsystem included in Windows NT-based operating systems up to Windows 2000. It supported POSIX.1 as it stood in the 1990 revision, without [[pthreads|threads]] or [[Berkeley socket|sockets]].
*[[Interix]], originally OpenNT by Softway Systems, Inc., is an upgrade and replacement for [[Microsoft POSIX subsystem]] that was purchased by [[Microsoft]] in 1999. It was initially marketed as a stand-alone add-on product and then later included as a component in [[Windows Services for UNIX]] (SFU) and finally incorporated as a component in [[Windows Server 2003 R2]] and later Windows OS releases under the name "Subsystem for UNIX-based Applications" (SUA); later made deprecated in 2012 (Windows 8)<ref>{{cite web|url=https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2012-R2-and-2012/hh831568(v=ws.11)|title=Features Removed or Deprecated in Windows Server 2012|date=31 August 2016|website=[[Microsoft Docs]]}}</ref> and dropped in 2013 (2012 R2, 8.1). It enables full POSIX compliance for certain [[Microsoft Windows]] products.{{Citation needed|date=March 2011}}
*[[Windows Subsystem for Linux]], also known as WSL, is a compatibility layer for running Linux binary executables natively on Windows 10 and 11 using a Linux image such as Ubuntu, Debian, or OpenSUSE among others, acting as an upgrade and replacement for Windows Services for UNIX. It was released in beta in April 2016. The first distribution available was Ubuntu.
*[[UWIN]] from AT&T Research implements a POSIX layer on top of the Win32 APIs.
*[[MKS Toolkit]], originally created for MS-DOS, is a software package produced and maintained by [[MKS Inc.]] that provides a [[Unix-like]] environment for scripting, connectivity and porting [[Unix]] and [[Linux]] software to both 32- and 64-bit [[Microsoft Windows]] systems. A subset of it was included in the first release of [[Windows Services for UNIX]] (SFU) in 1998.<ref>{{cite web|url=http://www.microsoft.com/ntserver/nts/exec/overview/sfu.asp|title=Windows NT Services for UNIX Add-On Pack|website=[[Microsoft]]|archive-url=https://web.archive.org/web/19990508011234/http://www.microsoft.com/ntserver/nts/exec/overview/sfu.asp|archive-date=8 May 1999}}</ref><ref>{{cite press release|url=http://mks.com/press/981109a.htm|title=MKS Solves Enterprise Interoperability Challenges|archive-url=https://web.archive.org/web/19990428003638/http://mks.com/press/981109a.htm|archive-date=28 April 1999}}</ref>
*[[Microsoft Windows library files#Runtime libraries|Windows C Runtime Library]] and [[Winsock|Windows Sockets API]] implement commonly used POSIX API functions for file, time, environment, and socket access,<ref>{{cite web |url=https://docs.microsoft.com/en-us/previous-versions/ms235384(v=vs.100) |title=Deprecated CRT Functions |date=15 October 2009 |access-date=23 July 2022 |website=[[Microsoft Docs]]}}</ref> although the support remains largely incomplete and not fully interoperable with POSIX-compliant implementations.<ref>{{cite web |url=https://docs.microsoft.com/en-us/windows/win32/winsock/porting-socket-applications-to-winsock?redirectedfrom=MSDN |title=Porting Socket Applications to Winsock |date=7 January 2021 |access-date=23 July 2022 |website=[[Microsoft Docs]]}}</ref><ref>{{cite web|url=https://tangentsoft.net/wskfaq/articles/bsd-compatibility.html|title=Winsock Programmer's FAQ Articles: BSD Sockets Compatibility|date=31 August 2015 |access-date=8 October 2015 |publisher=Warren Young}}</ref>{{discuss|BSD sockets as "POSIX"}}

====POSIX for OS/2====
Mostly POSIX compliant environments for [[OS/2]]:
* [[EMX (programming environment)|emx+gcc]] – largely POSIX compliant

====POSIX for DOS====
Partially POSIX compliant environments for [[DOS]] include:
* [[EMX (programming environment)|emx+gcc]] – largely POSIX compliant
* [[DJGPP]] – partially POSIX compliant
* [[DR-DOS]] multitasking core via {{mono|[[EMM386]] /MULTI}} – a POSIX threads frontend API extension is available
{{Anchor|Compliant via compatibility feature}}

====Compliant via compatibility layer====
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The following are not officially certified as POSIX compatible, but they conform in large part to the standards by implementing POSIX support via some sort of compatibility feature (usually translation libraries, or a layer atop the kernel). Without these features, they are usually non-compliant.

*[[AmigaOS]] (through the ixemul library or [[vbcc]]_PosixLib<ref>{{Cite web|url=http://aminet.net/package/dev/c/vbcc_PosixLib|title=Aminet - dev/C/Vbcc_PosixLib.lha}}</ref>)
*[[eCos]]&nbsp;– POSIX is part of the standard distribution, and used by many applications. 'external links' section below has more information.
*[[IBM i]] (through the [[IBM i#PASE|PASE]] compatibility layer)<ref>{{cite web|title=Programming IBM PASE for i|url=https://www.ibm.com/docs/de/ssw_ibm_i_73/rzalf/rzalfpdf.pdf|website=ibm.com|publisher=IBM|date=2013|access-date=25 November 2021}}</ref>
*[[MorphOS]] (through the built-in ixemul library)
*[[OpenVMS]] (through optional POSIX package)<ref>{{cite web|url=https://peren.com/fips151-2_peren_vpl.htm|title=FIPS 151-2 Conformance Validated Products List|publisher=Perennial Test Lab|access-date=14 August 2022}}</ref>
*[[Plan 9 from Bell Labs]] APE - ANSI/POSIX Environment<ref name="APE">{{cite web|url=http://plan9.bell-labs.com/sys/doc/ape.html |title=APE — ANSI/POSIX Environment|publisher=Bell Labs|work=Plan 9 documents|archive-url=https://web.archive.org/web/20170601064807/http://plan9.bell-labs.com/sys/doc/ape.html|archive-date=1 June 2017}}</ref>
*[[RIOT (operating system)|RIOT]] (through optional POSIX module)
*[[Symbian|Symbian OS]] with [[PIPS]] (PIPS Is POSIX on Symbian)
*[[VAXELN]] (partial support of 1003.1 and 1003.4 through the VAXELN POSIX runtime library)<ref>{{cite manual|url=http://www.bitsavers.org/pdf/dec/vax/realtime/EK-RPTSS-TM-004_Real-Time_Products_Technical_Summary_Dec92.pdf|title=Realtime Products Technical Summary, Fifth Edition|publisher=[[Digital Equipment Corporation]]|date=December 1992|access-date=8 December 2021}}</ref>
*[[Architecture of Windows NT|Windows NT kernel]] when using Microsoft [[Windows Services for UNIX|SFU]] 3.5 or [[Subsystem for UNIX-based Applications|SUA]]
**[[Windows 2000|Windows 2000 Server or Professional with Service Pack 3 or later]]. To be POSIX compliant, one must activate optional features of Windows NT and Windows 2000 Server.<ref name="MS">{{cite web|url=http://www.microsoft.com/technet/archive/ntwrkstn/reskit/poscomp.mspx|title=Chapter 29 - POSIX Compatibility|work=MS Windows NT Workstation Resource Kit|publisher=Microsoft|archive-url=https://web.archive.org/web/20080115185233/http://www.microsoft.com/technet/archive/ntwrkstn/reskit/poscomp.mspx|archive-date=15 January 2008}}</ref>
**[[Windows XP|Windows XP Professional with Service Pack 1 or later]]
**[[Windows Server 2003]]
**[[Windows Server 2008]] and Ultimate and Enterprise versions of [[Windows Vista]]
**[[Windows Server 2008 R2]] and Ultimate and Enterprise versions of [[Windows 7]]
**albeit deprecated, still available for [[Windows Server 2012]] and Enterprise version of [[Windows 8]]