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1 .\" Copyright (c) 2006, Michael Kerrisk <mtk.manpages@gmail.com>
2 .\"
3 .\" SPDX-License-Identifier: GPL-2.0-or-later
4 .\"
5 .TH standards 7 (date) "Linux man-pages (unreleased)"
6 .SH NAME
7 standards \- C and UNIX Standards
8 .SH DESCRIPTION
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.
12 .TP
13 .B V7
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:
17 BSD and System V.
18 .TP
19 .B 4.2BSD
20 This is an implementation standard defined by the 4.2 release
21 of the
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.
27 .IP
28 Earlier major BSD releases included
29 .I 3BSD
30 (1980),
31 .I 4BSD
32 (1980),
33 and
34 .I 4.1BSD
35 (1981).
36 .TP
37 .B 4.3BSD
38 The successor to 4.2BSD, released in 1986.
39 .TP
40 .B 4.4BSD
41 The successor to 4.3BSD, released in 1993.
42 This was the last major Berkeley release.
43 .TP
44 .B System V
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
48 .IR "System III" ,
49 released in 1981.
50 .TP
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"
55 .RI ( "SVID 1" )
56 published in 1985.
57 .TP
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"
62 .RI ( "SVID 2" ).
63 .TP
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"
71 .RI ( "SVID 3" ),
72 and is considered the definitive System V release.
73 .TP
74 .B SVID 4
75 System V Interface Definition version 4, issued in 1995.
76 Available online at
77 .UR http://www.sco.com\:/developers\:/devspecs/
78 .UE .
79 .TP
80 .B C89
81 This was the first C language standard, ratified by ANSI
82 (American National Standards Institute) in 1989
83 .RI ( X3.159-1989 ).
84 Sometimes this is known as
85 .IR "ANSI C" ,
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
92 .IR "ISO C90" .
93 .TP
94 .B C99
95 This revision of the C language standard was ratified by ISO in 1999
96 .RI ( "ISO/IEC 9899:1999" ).
97 Available online at
98 .UR http://www.open\-std.org\:/jtc1\:/sc22\:/wg14\:/www\:/standards
99 .UE .
100 .TP
101 .B C11
102 This revision of the C language standard was ratified by ISO in 2011
103 .RI ( "ISO/IEC 9899:2011" ).
104 .TP
105 .B LFS
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).
109 See
110 .UR https://www.opengroup.org\:/platform\:/lfs.html
111 .UE .
112 .TP
113 .B POSIX.1-1988
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.
118 .TP
119 .B POSIX.1-1990
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" ).
123 .TP
124 .B POSIX.2
125 IEEE Std 1003.2-1992,
126 describing commands and utilities, ratified by ISO in 1993
127 .RI ( "ISO/IEC 9945-2:1993" ).
128 .TP
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" ).
134 .TP
135 .BR POSIX.1c " (formerly known as \fIPOSIX.4a\fP)"
136 IEEE Std 1003.1c-1995, which describes the POSIX threads interfaces.
137 .TP
138 .B POSIX.1d
139 IEEE Std 1003.1d-1999, which describes additional real-time extensions.
140 .TP
141 .B POSIX.1g
142 IEEE Std 1003.1g-2000, which describes networking APIs (including sockets).
143 .TP
144 .B POSIX.1j
145 IEEE Std 1003.1j-2000, which describes advanced real-time extensions.
146 .TP
147 .B POSIX.1-1996
148 A 1996 revision of POSIX.1 which incorporated POSIX.1b and POSIX.1c.
149 .TP
150 .B XPG3
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.
155 .TP
156 .B XPG4
157 A revision of the X/Open Portability Guide, released in 1992.
158 This revision incorporated POSIX.2.
159 .TP
160 .B XPG4v2
161 A 1994 revision of XPG4.
162 This is also referred to as
163 .IR "Spec 1170" ,
164 where 1170 referred to the number of interfaces
165 defined by this standard.
166 .TP
167 .B "SUS (SUSv1)"
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
173 .IR "UNIX 95" .
174 .TP
175 .B SUSv2
176 Single UNIX Specification version 2.
177 Sometimes also referred to (incorrectly) as
178 .IR XPG5 .
179 This standard appeared in 1997.
180 Systems conforming to this standard can be branded
181 .IR "UNIX 98" .
182 See also
183 .UR http://www.unix.org\:/version2/
184 .UE .)
185 .TP
186 .B POSIX.1-2001
187 .TQ
188 .B SUSv3
189 This was a 2001 revision and consolidation of the
190 POSIX.1, POSIX.2, and SUS standards into a single document,
191 conducted under the auspices of the Austin Group
192 .UR http://www.opengroup.org\:/austin/
193 .UE .
194 The standard is available online at
195 .UR http://www.unix.org\:/version3/
196 .UE .
197 .IP
198 The standard defines two levels of conformance:
199 .IR "POSIX conformance" ,
200 which is a baseline set of interfaces required of a conforming system;
201 and
202 .IR "XSI Conformance",
203 which additionally mandates a set of interfaces
204 (the "XSI extension") which are only optional for POSIX conformance.
205 XSI-conformant systems can be branded
206 .IR "UNIX 03" .
207 .IP
208 The POSIX.1-2001 document is broken into four parts:
209 .IP
210 .BR XBD :
211 Definitions, terms, and concepts, header file specifications.
212 .IP
213 .BR XSH :
214 Specifications of functions (i.e., system calls and library
215 functions in actual implementations).
216 .IP
217 .BR XCU :
218 Specifications of commands and utilities
219 (i.e., the area formerly described by POSIX.2).
220 .IP
221 .BR XRAT :
222 Informative text on the other parts of the standard.
223 .IP
224 POSIX.1-2001 is aligned with C99, so that all of the
225 library functions standardized in C99 are also
226 standardized in POSIX.1-2001.
227 .IP
228 The Single UNIX Specification version 3 (SUSv3) comprises the
229 Base Specifications containing XBD, XSH, XCU, and XRAT as above,
230 plus X/Open Curses Issue 4 version 2 as an extra volume that is
231 not in POSIX.1-2001.
232 .IP
233 Two Technical Corrigenda (minor fixes and improvements)
234 of the original 2001 standard have occurred:
235 TC1 in 2003
236 and TC2 in 2004.
237 .TP
238 .B POSIX.1-2008
239 .TQ
240 .B SUSv4
241 Work on the next revision of POSIX.1/SUS was completed and
242 ratified in 2008.
243 The standard is available online at
244 .UR http://www.unix.org\:/version4/
245 .UE .
246 .IP
247 The changes in this revision are not as large as those
248 that occurred for POSIX.1-2001/SUSv3,
249 but a number of new interfaces are added
250 and various details of existing specifications are modified.
251 Many of the interfaces that were optional in
252 POSIX.1-2001 become mandatory in the 2008 revision of the standard.
253 A few interfaces that are present in POSIX.1-2001 are marked
254 as obsolete in POSIX.1-2008, or removed from the standard altogether.
255 .IP
256 The revised standard is structured in the same way as its predecessor.
257 The Single UNIX Specification version 4 (SUSv4) comprises the
258 Base Specifications containing XBD, XSH, XCU, and XRAT,
259 plus X/Open Curses Issue 7 as an extra volume that is
260 not in POSIX.1-2008.
261 .IP
262 Again there are two levels of conformance: the baseline
263 .IR "POSIX Conformance" ,
264 and
265 .IR "XSI Conformance" ,
266 which mandates an additional set of interfaces
267 beyond those in the base specification.
268 .IP
269 In general, where the STANDARDS section of a manual page
270 lists POSIX.1-2001, it can be assumed that the interface also
271 conforms to POSIX.1-2008, unless otherwise noted.
272 .IP
273 Technical Corrigendum 1 (minor fixes and improvements)
274 of this standard was released in 2013.
275 .IP
276 Technical Corrigendum 2 of this standard was released in 2016.
277 .IP
278 Further information can be found on the Austin Group web site,
279 .UR http://www.opengroup.org\:/austin/
280 .UE .
281 .TP
282 .B SUSv4 2016 edition
283 This is equivalent to POSIX.1-2008, with the addition of
284 Technical Corrigenda 1 and 2 and the XCurses specification.
285 .TP
286 .B POSIX.1-2017
287 This revision of POSIX is technically identical to POSIX.1-2008 with
288 Technical Corrigenda 1 and 2 applied.
289 .TP
290 .B SUSv4 2018 edition
291 This is equivalent to POSIX.1-2017, with the addition of
292 the XCurses specification.
293 .P
294 The interfaces documented in POSIX.1/SUS are available as
295 manual pages under sections 0p (header files), 1p (commands),
296 and 3p (functions);
297 thus one can write "man 3p open".
298 .SH SEE ALSO
299 .BR getconf (1),
300 .BR confstr (3),
301 .BR pathconf (3),
302 .BR sysconf (3),
303 .BR attributes (7),
304 .BR feature_test_macros (7),
305 .BR libc (7),
306 .BR posixoptions (7),
307 .BR system_data_types (7)