1 .\" Copyright (c) 2006, Michael Kerrisk <mtk.manpages@gmail.com>
3 .\" SPDX-License-Identifier: GPL-2.0-or-later
5 .TH STANDARDS 7 2020-11-01 "Linux man-pages (unreleased)" "Linux Programmer's Manual"
7 standards \- C and UNIX Standards
9 The STANDARDS section that appears in many manual pages identifies
10 various standards to which the documented interface conforms.
11 The following list briefly describes these standards.
14 Version 7 (also known as Seventh Edition) UNIX,
15 released by AT&T/Bell Labs in 1979.
16 After this point, UNIX systems diverged into two main dialects:
20 This is an implementation standard defined by the 4.2 release
22 .IR "Berkeley Software Distribution",
23 released by the University of California at Berkeley.
24 This was the first Berkeley release that contained a TCP/IP
25 stack and the sockets API.
26 4.2BSD was released in 1983.
28 Earlier major BSD releases included
38 The successor to 4.2BSD, released in 1986.
41 The successor to 4.3BSD, released in 1993.
42 This was the last major Berkeley release.
45 This is an implementation standard defined by AT&T's milestone 1983
46 release of its commercial System V (five) release.
47 The previous major AT&T release was
51 .B System V release 2 (SVr2)
52 This was the next System V release, made in 1985.
53 The SVr2 was formally described in the
54 .I "System V Interface Definition version 1"
58 .B System V release 3 (SVr3)
59 This was the successor to SVr2, released in 1986.
60 This release was formally described in the
61 .I "System V Interface Definition version 2"
64 .B System V release 4 (SVr4)
65 This was the successor to SVr3, released in 1989.
66 This version of System V is described in the "Programmer's Reference
67 Manual: Operating System API (Intel processors)" (Prentice-Hall
68 1992, ISBN 0-13-951294-2)
69 This release was formally described in the
70 .I "System V Interface Definition version 3"
72 and is considered the definitive System V release.
75 System V Interface Definition version 4, issued in 1995.
77 .UR http://www.sco.com\:/developers\:/devspecs/
81 This was the first C language standard, ratified by ANSI
82 (American National Standards Institute) in 1989
84 Sometimes this is known as
86 but since C99 is also an
87 ANSI standard, this term is ambiguous.
88 This standard was also ratified by
89 ISO (International Standards Organization) in 1990
90 .RI ( "ISO/IEC 9899:1990" ),
91 and is thus occasionally referred to as
95 This revision of the C language standard was ratified by ISO in 1999
96 .RI ( "ISO/IEC 9899:1999" ).
98 .UR http://www.open\-std.org\:/jtc1\:/sc22\:/wg14\:/www\:/standards
102 This revision of the C language standard was ratified by ISO in 2011
103 .RI ( "ISO/IEC 9899:2011" ).
106 The Large File Summit specification, completed in 1996.
107 This specification defined mechanisms that allowed 32-bit systems
108 to support the use of large files (i.e., 64-bit file offsets).
110 .UR https://www.opengroup.org\:/platform\:/lfs.html
114 This was the first POSIX standard,
115 ratified by IEEE as IEEE Std 1003.1-1988,
116 and subsequently adopted (with minor revisions) as an ISO standard in 1990.
117 The term "POSIX" was coined by Richard Stallman.
120 "Portable Operating System Interface for Computing Environments".
121 IEEE 1003.1-1990 part 1, ratified by ISO in 1990
122 .RI ( "ISO/IEC 9945-1:1990" ).
125 IEEE Std 1003.2-1992,
126 describing commands and utilities, ratified by ISO in 1993
127 .RI ( "ISO/IEC 9945-2:1993" ).
129 .BR POSIX.1b " (formerly known as \fIPOSIX.4\fP)"
130 IEEE Std 1003.1b-1993,
131 describing real-time facilities
132 for portable operating systems, ratified by ISO in 1996
133 .RI ( "ISO/IEC 9945-1:1996" ).
135 .B POSIX.1c " (formerly known as \fIPOSIX.4a\fP)"
136 IEEE Std 1003.1c-1995, which describes the POSIX threads interfaces.
139 IEEE Std 1003.1d-1999, which describes additional real-time extensions.
142 IEEE Std 1003.1g-2000, which describes networking APIs (including sockets).
145 IEEE Std 1003.1j-2000, which describes advanced real-time extensions.
148 A 1996 revision of POSIX.1 which incorporated POSIX.1b and POSIX.1c.
151 Released in 1989, this was the first release of the X/Open
152 Portability Guide to be based on a POSIX standard (POSIX.1-1988).
153 This multivolume guide was developed by the X/Open Group,
154 a multivendor consortium.
157 A revision of the X/Open Portability Guide, released in 1992.
158 This revision incorporated POSIX.2.
161 A 1994 revision of XPG4.
162 This is also referred to as
164 where 1170 referred to the number of interfaces
165 defined by this standard.
168 Single UNIX Specification.
169 This was a repackaging of XPG4v2 and other X/Open standards
170 (X/Open Curses Issue 4 version 2,
171 X/Open Networking Service (XNS) Issue 4).
172 Systems conforming to this standard can be branded
176 Single UNIX Specification version 2.
177 Sometimes also referred to (incorrectly) as
179 This standard appeared in 1997.
180 Systems conforming to this standard can be branded
183 .UR http://www.unix.org\:/version2/
186 .B POSIX.1-2001, SUSv3
187 This was a 2001 revision and consolidation of the
188 POSIX.1, POSIX.2, and SUS standards into a single document,
189 conducted under the auspices of the Austin Group
190 .UR http://www.opengroup.org\:/austin/
192 The standard is available online at
193 .UR http://www.unix.org\:/version3/
196 The standard defines two levels of conformance:
197 .IR "POSIX conformance" ,
198 which is a baseline set of interfaces required of a conforming system;
200 .IR "XSI Conformance",
201 which additionally mandates a set of interfaces
202 (the "XSI extension") which are only optional for POSIX conformance.
203 XSI-conformant systems can be branded
206 The POSIX.1-2001 document is broken into four parts:
209 Definitions, terms, and concepts, header file specifications.
212 Specifications of functions (i.e., system calls and library
213 functions in actual implementations).
216 Specifications of commands and utilities
217 (i.e., the area formerly described by POSIX.2).
220 Informative text on the other parts of the standard.
222 POSIX.1-2001 is aligned with C99, so that all of the
223 library functions standardized in C99 are also
224 standardized in POSIX.1-2001.
226 The Single UNIX Specification version 3 (SUSv3) comprises the
227 Base Specifications containing XBD, XSH, XCU, and XRAT as above,
228 plus X/Open Curses Issue 4 version 2 as an extra volume that is
231 Two Technical Corrigenda (minor fixes and improvements)
232 of the original 2001 standard have occurred:
236 .B POSIX.1-2008, SUSv4
237 Work on the next revision of POSIX.1/SUS was completed and
239 The standard is available online at
240 .UR http://www.unix.org\:/version4/
243 The changes in this revision are not as large as those
244 that occurred for POSIX.1-2001/SUSv3,
245 but a number of new interfaces are added
246 and various details of existing specifications are modified.
247 Many of the interfaces that were optional in
248 POSIX.1-2001 become mandatory in the 2008 revision of the standard.
249 A few interfaces that are present in POSIX.1-2001 are marked
250 as obsolete in POSIX.1-2008, or removed from the standard altogether.
252 The revised standard is structured in the same way as its predecessor.
253 The Single UNIX Specification version 4 (SUSv4) comprises the
254 Base Specifications containing XBD, XSH, XCU, and XRAT,
255 plus X/Open Curses Issue 7 as an extra volume that is
258 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 STANDARDS 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.
272 Technical Corrigendum 2 of this standard was released in 2016.
274 Further information can be found on the Austin Group web site,
275 .UR http://www.opengroup.org\:/austin/
278 .B SUSv4 2016 edition
279 This is equivalent to POSIX.1-2008, with the addition of
280 Technical Corrigenda 1 and 2 and the XCurses specification.
283 This revision of POSIX is technically identical to POSIX.1-2008 with
284 Technical Corrigenda 1 and 2 applied.
286 .B SUSv4 2018 edition
287 This is equivalent to POSIX.1-2017, with the addition of
288 the XCurses specification.
290 The interfaces documented in POSIX.1/SUS are available as
291 manual pages under sections 0p (header files), 1p (commands),
293 thus one can write "man 3p open".
300 .BR feature_test_macros (7),
302 .BR posixoptions (7),
303 .BR system_data_types (7)