POSIX.1 FAQ
`12/11/23, 12:19 AM
`The Wayback Machine - https://web.archive.org/web/20050403095528/http://www.opengroup.org:80/austin/p…
`
`POSIX® 1003.1 Frequently Asked Questions (FAQ
`Version 1.10)
`
`Last Updated : November 25 2004: freq.ques,v 1.11
`
`This is the Frequently Asked Questions file for the POSIX 1003.1 standard (IEEE Std 1003.1). Its maintainer is
`Andrew Josey (ajosey at The Open Group ). Suggestions and contributions are always welcome.
`
`This document can be found on the world wide web at http://www.opengroup.org/austin/papers/posix_faq.html.
`
`This article includes answers to the following.
`
`Q0. What is POSIX? What is POSIX.1?
`Q1. What is the Portable Application Standards Committee (PASC)?
`Q2. What is the Austin Group?
`Q3. What is the latest version of POSIX.1?
`Q4. Where can I download the 1003.1 standard from?
`Q5. What are the restrictions on the 1003.1 standard drafts and the full standard?
`Q6. Is the standard available in Man Pages format?
`Q7. How do I become a participant in the development of the POSIX.1 standard?
`Q8. What happened to the existing POSIX 1003.1-1990 and POSIX 1003.2-1992 standards when this revision
`completed?
`Q9. What is the history of IEEE POSIX 1003.1 System Application Interface (C API) ?
`Q10. What is the IEEE POSIX 1003.2 Shell and Utilities?
`Q11. What are the IEEE POSIX Standards for Real-time?
`Q12. How does the 1003.1 standard compare to the Linux Standard Base?
`Q13. What options are there in the POSIX.1 standard?
`Q14. What are the core technical changes in the latest POSIX.1 standard over 1003.1-1990 and 1003.2-1992?
`Q15. Does removal of obsolescent utility syntax mean that implementations supporting usages of head -5 file,
`tail -5 file, tail -l file are no longer allowed?
`Q16. What about POSIX Certification?
`Q17. How do I report a bug in the POSIX.1 standard?
`Q18. How do I add a question to this FAQ?
`
`Q0. What is POSIX? What is POSIX.1?
`
`POSIX is a registered trademark of the IEEE.
`
`POSIX is an acronym for Portable Operating System Interface.
`
`Although originated to refer to the original IEEE Std 1003.1-1988, the name POSIX more correctly refers to a
`family of related standards: IEEE Std 1003.n (where n is a number) and the parts of ISO/IEC 9945. The term
`POSIX was originally used as a synonym for IEEE Std 1003.1-1988. A preferred term for that standard,
`POSIX.1, emerged. This maintained the advantages of readability of the symbol ``POSIX'' without being
`ambiguous with the POSIX family of standards.
`
`For a full listing of the project numbers see PASC Standing Document SD11.
`
`The name POSIX was suggested by Richard Stallman. It is expected to be pronounced pahz-icks, as in positive,
`not poh-six, or other variations. The pronunciation has been published in an attempt to promulgate a
`https://web.archive.org/web/20050403095528/https://www.opengroup.org/austin/papers/posix_faq.html
`
`1/6
`
`Dropbox Exhibit 1014 - Page 1
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`POSIX.1 FAQ
`12/11/23, 12:19 AM
`standardized way of referring to a standard operating system interface.
`
`The latest version of the POSIX.1 standard is IEEE Std 1003.1, 2004 Edition, developed by the Austin Group
`(see later). For further information on the background, audience and purpose of POSIX.1 see the following
`document:
`
`URL:http://www.opengroup.org/austin/papers/backgrounder.html.
`
`Q1. What is the Portable Application Standards Committee (PASC)?
`
`The IEEE Computer Society's Portable Application Standards Committee (PASC) is the group that has and
`continues to develop the POSIX family of standards. Historically, the major work has been undertaken within
`Project 1003 (POSIX) with the best known standard being IEEE Std 1003.1 (also known as POSIX 1003.1,
`colloquially termed "dot 1"). The goal of the PASC standards has been to promote application portability at the
`source code level.
`
`Q2. What is the Austin Group?
`
`The Austin Common Standards Revision Group (CSRG) is a joint technical working group established to
`develop and maintain the latest version of the 1003.1 standard --- which combined and revised ISO/IEC 9945-
`1,1996 edition, ISO/IEC 9945-2, 1993 Edition, IEEE Std 1003.1,1996 edition, IEEE Std 1003.2, 1992 edition
`and the appropriate parts of the Single UNIX Specification.
`
`See http://www.opengroup.org/austin/ for more information.
`
`Q3. What is the latest version of POSIX.1?
`
`The 2004 edition of the 1003.1 standard was published on April 30th 2004, and updates the 2001 edition of the
`standard to include Technical Corrigendum 1 (TC1) and Technical Corrigendum 2 (TC2). The 2004 Edition is
`formally known as:
`
`IEEE Std 1003.1, 2004 Edition
`The Open Group Technical Standard Base Specifications, Issue 6
`
`Includes IEEE Std 1003.1-2001, IEEE Std 1003.1-2001/Cor 1-2002 and IEEE Std 1003.1-2001/Cor
`2-2004
`
`and its worth noting that within the text the standard is still referred to as IEEE Std 1003.1-2001.
`
`POSIX.1 is also an international standard, and ISO/IEC publication occurred on August 18 2003, denoted as
`ISO/IEC 9945:2003. It comprises four parts:
`
`Part 1: Base Definitions
`Part 2: System Interfaces
`Part 3: Shell and Utilities
`Part 4: Rationale
`
`Technical Corrigendum 2 has been approved by ISO and will be published as ISO/IEC 9945:2003/Cor 1:2004.
`
`Q4. Where can I download the 1003.1 standard from?
`
`The html version of the latest version of the standard (which incorporates technical corrigendum 1) is freely
`available to read and download from: URL:http://www.unix-systems.org/version3/, you need to register for a
`copy.
`
`https://web.archive.org/web/20050403095528/https://www.opengroup.org/austin/papers/posix_faq.html
`
`2/6
`
`Dropbox Exhibit 1014 - Page 2
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`POSIX.1 FAQ
`12/11/23, 12:19 AM
`A summary of the changes in Technical Corrigendum 1 is available from:
`URL:http://www.opengroup.org/austin/docs/austin_155.txt.
`
`A summary of the changes in Technical Corrigendum 2 is available from:
`URL:http://www.opengroup.org/austin/docs/austin_206.txt.
`
`The pdf text of just the Technical Corrigendum 1 (changes to the 2001 edition of the standard) is available from:
`URL: http://www.opengroup.org/pubs/catalog/u057.htm .
`
`The pdf text of just the Technical Corrigendum 2 (changes to the 2001/2003 edition of the standard) is available
`from: URL: http://www.opengroup.org/pubs/catalog/u059.htm .
`
`PDF copies of the final standard can also be obtained either from The IEEE (search on 1003.1-2001) , The Open
`Group (Look for documents T041,C046,C047,C048,C049) or ISO (look for ISO/IEC 9945 parts 1 thru 4). It is
`freely available in pdf format to members of The Open Group from The Open Group publications catalog. If you
`wish to signup up your organization to become a member of The Open Group and are an active participant you
`can sign up for no fee at http://www.opengroup.org/austin/ogmembers/ (note this is for companies and
`organizations only). If you want to join as an individual please contact Andrew Josey directly, he can then add
`you as an individual affiliate member.
`
`Ongoing draft specifications for the technical corrigenda are available online from the Austin Group web site at
`http://www.opengroup.org/austin/ . You need to be a member of the Austin Group. Information on how to join
`the group is on the web site.
`
`URL: http://www.opengroup.org/austin/. (Austin Group Home Page)
`
`Interpretations of the standard can be found at URL: http://www.opengroup.org/austin/interps/
`
`Q5. What are the restrictions on the 1003.1 standard drafts and the full standard?
`
`See the copyright notice on the documents and the notice at http://www.opengroup.org/austin/login.html .
`Downloading the draft is taken as agreement to abide by the stated terms and conditions. In brief you need to be
`a participant in the Austin Group in order to download the drafts.
`
`URL: http://www.opengroup.org/austin/login.html (Copyright Notice)
`
`Note also that the IEEE and The Open Group have granted permission to several open source projects to
`incorporate materials from the standard. All queries regarding permission to reproduce sections of the standard
`should be sent to austin-group-permissions at Open Group . Permission needs to be granted by both copyright
`holders, The IEEE and The Open Group.
`
`The IEEE and The Open Group position on implementations of the standard is as follows: "it is fair use of the
`standard for implementors to use the names, labels etc contained within the specification. The intent of
`publication of the standard is to encourage implementations of the standard. Your attention is drawn to the
`disclaimer regarding verification of patents when implementing the standard."
`
`Q6. Is the standard available in Man Pages format?
`
`A personal use copy of the standard in html man page format can be downloaded from
`http://www.unix.org/single_unix_specification.
`
`A set of nroff manual pages are maintained by Professor Andries Brouwer, who oversees the Linux Manual
`Pages Project, with the permission of IEEE and The Open Group. These can be obtained from
`ftp://ftp.win.tue.nl/pub/linux-local/manpages
`
`Q7. How do I become a participant in the POSIX.1 Working Group?
`
`https://web.archive.org/web/20050403095528/https://www.opengroup.org/austin/papers/posix_faq.html
`
`3/6
`
`Dropbox Exhibit 1014 - Page 3
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`POSIX.1 FAQ
`12/11/23, 12:19 AM
`To participate you need to join the Austin Group. See http://www.opengroup.org/austin/lists.html for more
`information.
`
`URL: http://www.opengroup.org/austin/lists.html. (How to Join the Austin Group)
`
`Q8. What happened to the existing POSIX 1003.1-1990 and POSIX 1003.2-1992 standards when this
`revision completed?
`
`Since the material contained in the existing POSIX 1003.1 and POSIX 1003.2 standards is merged into the
`revision, POSIX 1003.1-1990 and its amendments, and POSIX 1003.2-1992 and its amendments were
`administratively withdrawn by the IEEE.
`
`Q9. What is the history of the IEEE POSIX 1003.1 System Application Interface (C API) ?
`
`Historically, POSIX 1003.1 has been the base standard upon which the POSIX family of standards has been
`built. In keeping with its original focus on the UNIX system, it is aimed at interactive timesharing computing
`environments.
`
`The first edition of IEEE Std 1003.1 was published in 1988. Subsequent editions were published in 1990, 1996
`and 2001. The 1990 edition was a revision to the 1988 edition and became the stable base standard onto which
`further amendments were added. The 1990 edition was also approved as an international standard, ISO/IEC
`9945-1:1990.
`
`The 1996 edition added the IEEE Std 1003.1b-1993, IEEE Std 1003.1c-1995, and 1003.1i-1995 amendments to
`the base standard, keeping the stable core text unchanged. The 1996 edition of IEEE Std 1003.1 was also
`approved as an international standard, ISO/IEC 9945-1:1996.
`
`In 1998 the first real-time profile standard, IEEE Std 1003.13-1998 was published, enabling POSIX to address
`embedded real-time applications and smaller footprint devices.
`
`In 1999 the decision was taken to commence the first major revision to the core base standard in ten years,
`including a merger with the 1003.2 standards for Shell and Utilities which had been a separate standard up to this
`point . It was agreed that this work be undertaken by the Austin Group. As part of this decision the PASC
`decided to cease rolling amendments to the base standard after completion of IEEE Stds 1003.1a, 1003.1d,
`1003.1g, 1003.1j, 1003.1q, and 1003.2b. These projects were rolled into the 2001 edition of IEEE Std 1003.1. It
`was decided to convert other projects in progress to standalone documents.
`
`Q10. What is IEEE POSIX 1003.2 Shell and Utilities?
`
`This standard defines a standard source level interface to the shell and utility functionality required by
`application programs, including shell scripts. This standard has been incorporated into the latest revision of
`POSIX 1003.1 and thus a POSIX.2 standard no longer exists.
`
`Q11. What are the IEEE POSIX Standards for Real-time?
`
`The PASC Real-time System Services Working Group (SSWG-RT) has developed a series of standards that
`amend IEEE Std 1003.1-1990 and a profile standard (IEEE Std 1003.13-1998).
`
`The Real-time amendments to IEEE Std 1003.1-1990 are as follows:
`
`IEEE Std 1003.1b-1993 Realtime Extension
`IEEE Std 1003.1c-1995 Threads
`IEEE Std 1003.1d-1999 Additional Realtime Extensions
`IEEE Std 1003.1j-2000 Advanced Realtime Extensions
`IEEE Std 1003.1q-2000 Tracing
`
`https://web.archive.org/web/20050403095528/https://www.opengroup.org/austin/papers/posix_faq.html
`
`4/6
`
`Dropbox Exhibit 1014 - Page 4
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`POSIX.1 FAQ
`12/11/23, 12:19 AM
`These have all been folded in as options within the revision project undertaken by the Austin Group in producing
`IEEE Std 1003.1-2001.
`
`The Real-time profile is known as IEEE Std 1003.13-1998. At the time of writing there is a revision to IEEE Std
`1003.13-1998 in progress to align it with IEEE Std 1003.1-2001, this project current known as IEEE P1003.13-
`200x.
`
`Q12. How does the POSIX.1 standard compare to the Linux Standard Base?
`
`The POSIX.1 standard specifies application programming interfaces (APIs) at the source level, and is about
`source code portability. Its neither a code implementation nor an operating system, but a stable definition of a
`programming interface that those systems supporting the specification guarantee to provide to the application
`programmer. Efforts such as the Linux Standard Base, and similarly the iBCS2 for x86 implementations of
`System V, are primarily about binary portability and define a specific binary implementation of an interface to
`operating system services. In general they build upon the foundations of the POSIX standard.
`
`Two white papers with further information on this topic are available at:
`http://www.opengroup.org/platform/single_unix_specification/doc.tpl?gdid=6075,
`http://www.opengroup.org/platform/single_unix_specification/doc.tpl?gdid=5992.
`
`Q13. What options are there in the POSIX.1 standard?
`
`For a good description of the modular options in the POSIX.1 standard see URL:
`http://people.redhat.com/~drepper/posix-option-groups.html
`
`Q14. What are the core technical changes in the latest POSIX.1 standard over 1003.1-1990 and 1003.2-
`1992?
`
`The main changes are as follows: alignment with ISO/IEC 9899:1999 (ISO C), support for IPv6, integration of
`recent POSIX realtime amendments ( 1003.1d, 1003.1j, 1003.1q), amendments to the core POSIX functionality
`from the 1003.2b and 1003.1a amendments, application of technical corrigendum from The Open Group and
`IEEE interpretations, revision of options , removal of obsolescent and legacy interfaces.
`
`Q15. Does removal of obsolescent utility syntax mean that implementations supporting usages of head -5
`file, tail -5 file, tail -l file are no longer allowed?
`
`No, in general the intent of removing the obsolescent forms of the utility synopses was not to disallow them to
`be supported by implementations but to downgrade the status of their use in applications from conforming
`application using an obsolescent feature to non-conforming application. In general it is allowed for utilities to
`have extensions that violate the utility syntax guidelines so long as the forms defined in the standard that are
`required to follow the utility syntax guidelines do so. The cases cited fit the case. The Austin Group has more
`general cases under review at the present time.
`
`Q16. What about POSIX Certification?
`
`In November 2003, The IEEE and The Open Group launched a new program extending POSIX(R) Certification
`for the 2003 Edition of IEEE Std 1003.1.
`
`For the full announcement see: http://www.opengroup.org/press/03nov03.htm.
`
`For a summary of web references for the new program see:
`http://www.opengroup.org/certification/idx/posix.html.
`
`The program includes a product standard for each type of product that can be certified within the POSIX
`Certification Program. In this initial iteration of the certification program these are as follows:
`
`https://web.archive.org/web/20050403095528/https://www.opengroup.org/austin/papers/posix_faq.html
`
`5/6
`
`Dropbox Exhibit 1014 - Page 5
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`

`

`POSIX.1 FAQ
`12/11/23, 12:19 AM
`1003.1-2003 Base Product Standard: This is a profile product standard that comprises the mandatory
`functionality from IEEE Std 1003.1, 2003 Edition. It is comprised of two component product standards.
`1003.1-2003 System Interfaces Product Standard: This is a component product standard for the mandatory
`system interfaces and headers related functionality from IEEE Std 1003.1.
`1003.1-2003 Shell and Utilities Product Standard: This is a component product standard for the mandatory
`shell and utilities related functionality from IEEE Std 1003.1.
`
`A product can be certified against one or more product standards and the program allows for two levels of
`certification: Platform Specific Certification, which applies to a single defined hardware and software
`environment, and Product Family Certification, which applies to all members of a binary-compatible family.
`
`The POSIX trademark can be optionally licensed for use in association with certified products meeting the
`10003.1-2003 Base Product Standard. The POSIX certification system is a web-based workflow system
`designed to lead applicants through the process to submit a product for certification. The two POSIX
`Conformance test suites, VSX-PCTS2003 and VSC-PCTS2003, are freely available to organizations that register
`to apply for certification.
`
`More information about the program, including all supporting documentation is found at
`http://posixcertified.ieee.org/.
`
`Two FAQs can be found at http://posixcertified.ieee.org/pcfaqs.html and
`http://get.posixcertified.ieee.org/docs/posixfaq.html.
`
`Q17. How do I report a bug in the POSIX.1 standard?
`
`To report a bug in the POSIX.1 standard please complete the defect report form at
`http://www.opengroup.org/austin/defectform.html.
`
`Q18. How do I add a question to this FAQ?
`
`Send the question (preferably with a proposed answer) to Andrew Josey.
`
`https://web.archive.org/web/20050403095528/https://www.opengroup.org/austin/papers/posix_faq.html
`
`6/6
`
`Dropbox Exhibit 1014 - Page 6
`Dropbox, Inc. v. Entangled Media, LLC
`IPR2024-00285 - U.S. Patent No. 8,484,260
`
`