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24 .TH STANDARDS 7 2017-11-26 "Linux" "Linux Programmer's Manual"
26 standards \- C and UNIX Standards
28 The CONFORMING TO section that appears in many manual pages identifies
29 various standards to which the documented interface conforms.
30 The following list briefly describes these standards.
33 Version 7 (also known as Seventh Edition) UNIX,
34 released by AT&T/Bell Labs in 1979.
35 After this point, UNIX systems diverged into two main dialects:
39 This is an implementation standard defined by the 4.2 release
41 .IR "Berkeley Software Distribution",
42 released by the University of California at Berkeley.
43 This was the first Berkeley release that contained a TCP/IP
44 stack and the sockets API.
45 4.2BSD was released in 1983.
47 Earlier major BSD releases included
57 The successor to 4.2BSD, released in 1986.
60 The successor to 4.3BSD, released in 1993.
61 This was the last major Berkeley release.
64 This is an implementation standard defined by AT&T's milestone 1983
65 release of its commercial System V (five) release.
66 The previous major AT&T release was
70 .B System V release 2 (SVr2)
71 This was the next System V release, made in 1985.
72 The SVr2 was formally described in the
73 .I "System V Interface Definition version 1"
77 .B System V release 3 (SVr3)
78 This was the successor to SVr2, released in 1986.
79 This release was formally described in the
80 .I "System V Interface Definition version 2"
83 .B System V release 4 (SVr4)
84 This was the successor to SVr3, released in 1989.
85 This version of System V is described in the "Programmer's Reference
86 Manual: Operating System API (Intel processors)" (Prentice-Hall
87 1992, ISBN 0-13-951294-2)
88 This release was formally described in the
89 .I "System V Interface Definition version 3"
91 and is considered the definitive System V release.
94 System V Interface Definition version 4, issued in 1995.
96 .UR http://www.sco.com\:/developers\:/devspecs/
100 This was the first C language standard, ratified by ANSI
101 (American National Standards Institute) in 1989
103 Sometimes this is known as
105 but since C99 is also an
106 ANSI standard, this term is ambiguous.
107 This standard was also ratified by
108 ISO (International Standards Organization) in 1990
109 .RI ( "ISO/IEC 9899:1990" ),
110 and is thus occasionally referred to as
114 This revision of the C language standard was ratified by ISO in 1999
115 .RI ( "ISO/IEC 9899:1999" ).
117 .UR http://www.open\-std.org\:/jtc1\:/sc22\:/wg14\:/www\:/standards
121 This revision of the C language standard was ratified by ISO in 2011
122 .RI ( "ISO/IEC 9899:2011" ).
125 "Portable Operating System Interface for Computing Environments".
126 IEEE 1003.1-1990 part 1, ratified by ISO in 1990
127 .RI ( "ISO/IEC 9945-1:1990" ).
128 The term "POSIX" was coined by Richard Stallman.
131 IEEE Std 1003.2-1992,
132 describing commands and utilities, ratified by ISO in 1993
133 .RI ( "ISO/IEC 9945-2:1993" ).
135 .BR POSIX.1b " (formerly known as \fIPOSIX.4\fP)"
136 IEEE Std 1003.1b-1993,
137 describing real-time facilities
138 for portable operating systems, ratified by ISO in 1996
139 .RI ( "ISO/IEC 9945-1:1996" ).
142 IEEE Std 1003.1c-1995, which describes the POSIX threads interfaces.
145 IEEE Std 1003.1c-1999, which describes additional real-time extensions.
148 IEEE Std 1003.1g-2000, which describes networking APIs (including sockets).
151 IEEE Std 1003.1j-2000, which describes advanced real-time extensions.
154 A 1996 revision of POSIX.1 which incorporated POSIX.1b and POSIX.1c.
157 Released in 1989, this was the first significant release of the
158 .IR "X/Open Portability Guide" ,
160 X/Open Company, a multivendor consortium.
161 This multivolume guide was based on the POSIX standards.
164 A revision of the X/Open Portability Guide, released in 1992.
167 A 1994 revision of XPG4.
168 This is also referred to as
170 where 1170 referred to the number of interfaces
171 defined by this standard.
174 Single UNIX Specification.
175 This was a repackaging of XPG4v2 and other X/Open standards
176 (X/Open Curses Issue 4 version 2,
177 X/Open Networking Service (XNS) Issue 4).
178 Systems conforming to this standard can be branded
182 Single UNIX Specification version 2.
183 Sometimes also referred to as
185 This standard appeared in 1997.
186 Systems conforming to this standard can be branded
189 .UR http://www.UNIX\-systems.org\:/version2/
192 .B POSIX.1-2001, SUSv3
193 This was a 2001 revision and consolidation of the
194 POSIX.1, POSIX.2, and SUS standards into a single document,
195 conducted under the auspices of the Austin Group
196 .UR http://www.opengroup.org\:/austin/
198 The standard is available online at
199 .UR http://www.unix\-systems.org\:/version3/
201 and the interfaces that it describes are also available in the Linux
202 manual pages package under sections 1p and 3p (e.g., "man 3p open").
204 The standard defines two levels of conformance:
205 .IR "POSIX conformance" ,
206 which is a baseline set of interfaces required of a conforming system;
208 .IR "XSI Conformance",
209 which additionally mandates a set of interfaces
210 (the "XSI extension") which are only optional for POSIX conformance.
211 XSI-conformant systems can be branded
213 (XSI conformance constitutes the
214 .I "Single UNIX Specification version 3"
217 The POSIX.1-2001 document is broken into four parts:
220 Definitions, terms and concepts, header file specifications.
223 Specifications of functions (i.e., system calls and library
224 functions in actual implementations).
227 Specifications of commands and utilities
228 (i.e., the area formerly described by POSIX.2).
231 Informative text on the other parts of the standard.
233 POSIX.1-2001 is aligned with C99, so that all of the
234 library functions standardized in C99 are also
235 standardized in POSIX.1-2001.
237 Two Technical Corrigenda (minor fixes and improvements)
238 of the original 2001 standard have occurred:
239 TC1 in 2003 (also known as
241 and TC2 in 2004 (also known as
244 .B POSIX.1-2008, SUSv4
245 Work on the next revision of POSIX.1/SUS was completed and
248 The changes in this revision are not as large as those
249 that occurred for POSIX.1-2001/SUSv3,
250 but a number of new interfaces are added
251 and various details of existing specifications are modified.
252 Many of the interfaces that were optional in
253 POSIX.1-2001 become mandatory in the 2008 revision of the standard.
254 A few interfaces that are present in POSIX.1-2001 are marked
255 as obsolete in POSIX.1-2008, or removed from the standard altogether.
257 The revised standard is broken into the same four parts as POSIX.1-2001,
258 and again there are two levels of conformance: the baseline
259 .IR "POSIX Conformance" ,
261 .IR "XSI Conformance" ,
262 which mandates an additional set of interfaces
263 beyond those in the base specification.
265 In general, where the CONFORMING TO section of a manual page
266 lists POSIX.1-2001, it can be assumed that the interface also
267 conforms to POSIX.1-2008, unless otherwise noted.
269 Technical Corrigendum 1 (minor fixes and improvements)
270 of this standard was released in 2013
274 Technical Corrigendum 2 of this standard was released in 2016
278 Further information can be found on the Austin Group web site,
279 .UR http://www.opengroup.org\:/austin/
287 .BR feature_test_macros (7),