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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><meta name="generator" content="HTML Tidy, see www.w3.org"><link type="text/css" rel="stylesheet" href="style.css"><!-- Copyright 2001 The Open Group, All Rights Reserved --><title>The Base Specifications Issue 6</title></head><body bgcolor="white"><center><font size="2">The Open Group Base Specifications Issue 6<br>IEEE Std 1003.1, 2003 Edition<br><a href="../copyr.html">Copyright</a> © 2001-2003 The IEEE and The Open Group</font> <hr size="2" noshade></center><basefont size="3"> <p>This standard has been jointly developed by the IEEE and The Open Group. It is simultaneously an IEEE Standard, an ISO/IECStandard, and an Open Group Technical Standard.</p><h5>The Austin Group</h5><p>This standard was developed, and is maintained, by a joint working group of members of the IEEE Portable Applications StandardsCommittee, members of The Open Group, and members of ISO/IEC Joint Technical Committee 1. This joint working group is known as theAustin Group.<a href="#tag_foot_1"><sup><small>1</small></sup></a> The Austin Group arose out of discussions amongst the partieswhich started in early 1998, leading to an initial meeting and formation of the group in September 1998. The purpose of the AustinGroup has been to revise, combine, and update the following standards: ISO/IEC 9945-1, ISO/IEC 9945-2, IEEE Std 1003.1, IEEE Std1003.2, and the Base Specifications of The Open Group Single UNIX Specification.</p><p>After two initial meetings, an agreement was signed in July 1999 between The Open Group and the Institute of Electrical andElectronics Engineers (IEEE), Inc., to formalize the project with the first draft of the revised specifications being madeavailable at the same time. Under this agreement, The Open Group and IEEE agreed to share joint copyright of the resulting work.The Open Group has provided the chair and secretariat for the Austin Group.</p><p>The base document for the revision was The Open Group's Base volumes of its Single UNIX Specification, Version 2. These wereselected since they were a superset of the existing POSIX.1 and POSIX.2 specifications and had some organizational aspects thatwould benefit the audience for the new revision.</p><p>The approach to specification development has been one of ``write once, adopt everywhere'', with the deliverables being a set ofspecifications that carry the IEEE POSIX designation, The Open Group's Technical Standard designation, and an ISO/IEC designation.This set of specifications forms the core of the Single UNIX Specification, Version 3.</p><p>This unique development has combined both the industry-led efforts and the formal standardization activities into a singleinitiative, and included a wide spectrum of participants. The Austin Group continues as the maintenance body for this document.</p><p>Anyone wishing to participate in the Austin Group should contact the chair with their request. There are no fees forparticipation or membership. You may participate as an observer or as a contributor. You do not have to attend face-to-facemeetings to participate; electronic participation is most welcome. For more information on the Austin Group and how to participate,see <a href="http://www.opengroup.org/austin">http://www.opengroup.org/austin</a>.</p><h5>Background</h5><p>The developers of this standard represent a cross section of hardware manufacturers, vendors of operating systems and othersoftware development tools, software designers, consultants, academics, authors, applications programmers, and others.</p><p>Conceptually, this standard describes a set of fundamental services needed for the efficient construction of applicationprograms. Access to these services has been provided by defining an interface, using the C programming language, a commandinterpreter, and common utility programs that establish standard semantics and syntax. Since this interface enables applicationwriters to write portable applications-it was developed with that goal in mind-it has been designated POSIX,<a href="#tag_foot_2"><sup><small>2</small></sup></a> an acronym for Portable Operating System Interface.</p><p>Although originated to refer to the original IEEE Std 1003.1-1988, the name POSIX more correctly refers to a<i>family</i> of related standards: IEEE Std 1003.<i>n</i> and the parts of ISO/IEC 9945. In earlier editions of theIEEE standard, the term POSIX was used as a synonym for IEEE Std 1003.1-1988. A preferred term, POSIX.1, emerged. Thismaintained the advantages of readability of the symbol ``POSIX'' without being ambiguous with the POSIX family of standards.</p><h5>Audience</h5><p>The intended audience for this standard is all persons concerned with an industry-wide standard operating system based on theUNIX system. This includes at least four groups of people:</p><ol><li><p>Persons buying hardware and software systems</p></li><li><p>Persons managing companies that are deciding on future corporate computing directions</p></li><li><p>Persons implementing operating systems, and especially</p></li><li><p>Persons developing applications where portability is an objective</p></li></ol><h5>Purpose</h5><p>Several principles guided the development of this standard:</p><ul><li><p>Application-Oriented</p><p>The basic goal was to promote portability of application programs across UNIX system environments by developing a clear,consistent, and unambiguous standard for the interface specification of a portable operating system based on the UNIX systemdocumentation. This standard codifies the common, existing definition of the UNIX system.</p></li><li><p>Interface, Not Implementation</p><p>This standard defines an interface, not an implementation. No distinction is made between library functions and system calls;both are referred to as functions. No details of the implementation of any function are given (although historical practice issometimes indicated in the RATIONALE section). Symbolic names are given for constants (such as signals and error numbers) ratherthan numbers.<br></p></li><li><p>Source, Not Object, Portability</p><p>This standard has been written so that a program written and translated for execution on one conforming implementation may alsobe translated for execution on another conforming implementation. This standard does not guarantee that executable (object orbinary) code will execute under a different conforming implementation than that for which it was translated, even if the underlyinghardware is identical.</p></li><li><p>The C Language</p><p>The system interfaces and header definitions are written in terms of the standard C language as specified in the ISO Cstandard.</p></li><li><p>No Superuser, No System Administration</p><p>There was no intention to specify all aspects of an operating system. System administration facilities and functions areexcluded from this standard, and functions usable only by the superuser have not been included. Still, an implementation of thestandard interface may also implement features not in this standard. This standard is also not concerned with hardware constraintsor system maintenance.</p></li><li><p>Minimal Interface, Minimally Defined</p><p>In keeping with the historical design principles of the UNIX system, the mandatory core facilities of this standard have beenkept as minimal as possible. Additional capabilities have been added as optional extensions.</p></li><li><p>Broadly Implementable</p><p>The developers of this standard endeavored to make all specified functions implementable across a wide range of existing andpotential systems, including:</p><ol><li><p>All of the current major systems that are ultimately derived from the original UNIX system code (Version 7 or later)</p></li><li><p>Compatible systems that are not derived from the original UNIX system code</p></li><li><p>Emulations hosted on entirely different operating systems</p></li><li><p>Networked systems</p></li><li><p>Distributed systems</p></li><li><p>Systems running on a broad range of hardware</p></li></ol><p>No direct references to this goal appear in this standard, but some results of it are mentioned in the Rationale (Informative)volume.</p></li><li><p>Minimal Changes to Historical Implementations</p><p>When the original version of IEEE Std 1003.1 was published, there were no known historical implementations that didnot have to change. However, there was a broad consensus on a set of functions, types, definitions, and concepts that formed aninterface that was common to most historical implementations.</p><p>The adoption of the 1988 and 1990 IEEE system interface standards, the 1992 IEEE shell and utilities standard, the various OpenGroup (formerly X/Open) specifications, and the subsequent revisions and addenda to all of them have consolidated this consensus,and this revision reflects the significantly increased level of consensus arrived at since the original versions. The earlierstandards and their modifications specified a number of areas where consensus had not been reached before, and these are nowreflected in this revision. The authors of the original versions tried, as much as possible, to follow the principles below whencreating new specifications:</p><ol><li><p>By standardizing an interface like one in an historical implementation; for example, directories</p></li><li><p>By specifying an interface that is readily implementable in terms of, and backwards-compatible with, historical implementations,such as the extended <a href="../utilities/tar.html"><i>tar</i></a> format defined in the <a href="../utilities/pax.html"><i>pax</i></a> utility</p></li><li><p>By specifying an interface that, when added to an historical implementation, will not conflict with it; for example, the <ahref="../functions/sigaction.html"><i>sigaction</i>()</a> function</p></li></ol><p>This revision tries to minimize the number of changes required to implementations which conform to the earlier versions of theapproved standards to bring them into conformance with the current standard. Specifically, the scope of this work excluded doingany ``new'' work, but rather collecting into a single document what had been spread across a number of documents, and presenting itin what had been proven in practice to be a more effective way. Some changes to prior conforming implementations were unavoidable,primarily as a consequence of resolving conflicts found in prior revisions, or which became apparent when bringing the variouspieces together.</p><p>However, since it references the 1999 version of the ISO C standard, and no longer supports ``Common Usage C'', there are anumber of unavoidable changes. Applications portability is similarly affected.</p><p>This standard is specifically not a codification of a particular vendor's product.</p><p>It should be noted that implementations will have different kinds of extensions. Some will reflect ``historical usage'' and willbe preserved for execution of pre-existing applications. These functions should be considered ``obsolescent'' and the standardfunctions used for new applications. Some extensions will represent functions beyond the scope of this standard. These need to beused with careful management to be able to adapt to future extensions of this standard and/or port to implementations that providethese services in a different manner.</p></li><li><p>Minimal Changes to Existing Application Code</p><p>A goal of this standard was to minimize additional work for the developers of applications. However, because every knownhistorical implementation will have to change at least slightly to conform, some applications will have to change.</p></li></ul><hr><h4>Footnotes</h4><dl compact><dt><a name="tag_foot_1">1.</a></dt><dd>The Austin Group is named after the location of the inaugural meeting held at the IBM facility in Austin, Texas in September1998.</dd><dt><a name="tag_foot_2">2.</a></dt><dd>The name POSIX was suggested by Richard Stallman. It is expected to be pronounced <i>pahz-icks</i>, as in <i>positive</i>, not<i>poh-six</i>, or other variations. The pronunciation has been published in an attempt to promulgate a standardized way ofreferring to a standard operating system interface.</dd></dl><p> </p><p> </p><hr size="2" noshade><center><font size="2"><!--footer start-->UNIX ® is a registered Trademark of The Open Group.<br>POSIX ® is a registered Trademark of The IEEE.<br>[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href="../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>]</font></center><!--footer end--><hr size="2" noshade></body></html>⌨️ 快捷键说明
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