1STANDARDS(7) Linux Programmer's Manual STANDARDS(7)
2
6 standards - C and UNIX Standards
7
9 The CONFORMING TO section that appears in many manual pages identifies
10 various standards to which the documented interface conforms. The fol‐
11 lowing list briefly describes these standards.
12 V7 Version 7 (also known as Seventh Edition) UNIX, released by
14 AT&T/Bell Labs in 1979. After this point, UNIX systems diverged
15 into two main dialects: BSD and System V.
16 4.2BSD This is an implementation standard defined by the 4.2 release of
18 the Berkeley Software Distribution, released by the University
19 of California at Berkeley. This was the first Berkeley release
20 that contained a TCP/IP stack and the sockets API. 4.2BSD was
21 released in 1983.
22 Earlier major BSD releases included 3BSD (1980), 4BSD (1980),
24 and 4.1BSD (1981).
25 4.3BSD The successor to 4.2BSD, released in 1986.
27 4.4BSD The successor to 4.3BSD, released in 1993. This was the last
29 major Berkeley release.
30 System V
32 This is an implementation standard defined by AT&T's milestone
33 1983 release of its commercial System V (five) release. The
34 previous major AT&T release was System III, released in 1981.
35 System V release 2 (SVr2)
37 This was the next System V release, made in 1985. The SVr2 was
38 formally described in the System V Interface Definition version
39 1 (SVID 1) published in 1985.
40 System V release 3 (SVr3)
42 This was the successor to SVr2, released in 1986. This release
43 was formally described in the System V Interface Definition ver‐
44 sion 2 (SVID 2).
45 System V release 4 (SVr4)
47 This was the successor to SVr3, released in 1989. This version
48 of System V is described in the "Programmer's Reference Manual:
49 Operating System API (Intel processors)" (Prentice-Hall 1992,
50 ISBN 0-13-951294-2) This release was formally described in the
51 System V Interface Definition version 3 (SVID 3), and is consid‐
52 ered the definitive System V release.
53 SVID 4 System V Interface Definition version 4, issued in 1995. Avail‐
55 able online at ⟨http://www.sco.com/developers/devspecs/⟩.
56 C89 This was the first C language standard, ratified by ANSI (Ameri‐
58 can National Standards Institute) in 1989 (X3.159-1989). Some‐
59 times this is known as ANSI C, but since C99 is also an ANSI
60 standard, this term is ambiguous. This standard was also rati‐
61 fied by ISO (International Standards Organization) in 1990
62 (ISO/IEC 9899:1990), and is thus occasionally referred to as ISO
63 C90.
64 C99 This revision of the C language standard was ratified by ISO in
66 1999 (ISO/IEC 9899:1999). Available online at
67 ⟨http://www.open-std.org/jtc1/sc22/wg14/www/standards⟩.
68 C11 This revision of the C language standard was ratified by ISO in
70 2011 (ISO/IEC 9899:2011).
71 POSIX.1-1990
73 "Portable Operating System Interface for Computing Environ‐
74 ments". IEEE 1003.1-1990 part 1, ratified by ISO in 1990
75 (ISO/IEC 9945-1:1990). The term "POSIX" was coined by Richard
76 Stallman.
77 POSIX.2
79 IEEE Std 1003.2-1992, describing commands and utilities, rati‐
80 fied by ISO in 1993 (ISO/IEC 9945-2:1993).
81 POSIX.1b (formerly known as POSIX.4)
83 IEEE Std 1003.1b-1993, describing real-time facilities for por‐
84 table operating systems, ratified by ISO in 1996 (ISO/IEC
85 9945-1:1996).
86 POSIX.1c
88 IEEE Std 1003.1c-1995, which describes the POSIX threads inter‐
89 faces.
90 POSIX.1d
92 IEEE Std 1003.1c-1999, which describes additional real-time
93 extensions.
94 POSIX.1g
96 IEEE Std 1003.1g-2000, which describes networking APIs (includ‐
97 ing sockets).
98 POSIX.1j
100 IEEE Std 1003.1j-2000, which describes advanced real-time exten‐
101 sions.
102 POSIX.1-1996
104 A 1996 revision of POSIX.1 which incorporated POSIX.1b and
105 POSIX.1c.
106 XPG3 Released in 1989, this was the first significant release of the
108 X/Open Portability Guide, produced by the X/Open Company, a mul‐
109 tivendor consortium. This multivolume guide was based on the
110 POSIX standards.
111 XPG4 A revision of the X/Open Portability Guide, released in 1992.
113 XPG4v2 A 1994 revision of XPG4. This is also referred to as Spec 1170,
115 where 1170 referred to the number of interfaces defined by this
116 standard.
117 SUS (SUSv1)
119 Single UNIX Specification. This was a repackaging of XPG4v2 and
120 other X/Open standards (X/Open Curses Issue 4 version 2, X/Open
121 Networking Service (XNS) Issue 4). Systems conforming to this
122 standard can be branded UNIX 95.
123 SUSv2 Single UNIX Specification version 2. Sometimes also referred to
125 as XPG5. This standard appeared in 1997. Systems conforming to
126 this standard can be branded UNIX 98. See also
127 ⟨http://www.UNIX-systems.org/version2/⟩.)
128 POSIX.1-2001, SUSv3
130 This was a 2001 revision and consolidation of the POSIX.1,
131 POSIX.2, and SUS standards into a single document, conducted
132 under the auspices of the Austin Group ⟨http://www.opengroup.org
133 /austin/⟩. The standard is available online at
134 ⟨http://www.unix-systems.org/version3/⟩, and the interfaces that
135 it describes are also available in the Linux manual pages pack‐
136 age under sections 1p and 3p (e.g., "man 3p open").
137 The standard defines two levels of conformance: POSIX confor‐
139 mance, which is a baseline set of interfaces required of a con‐
140 forming system; and XSI Conformance, which additionally mandates
141 a set of interfaces (the "XSI extension") which are only
142 optional for POSIX conformance. XSI-conformant systems can be
143 branded UNIX 03. (XSI conformance constitutes the Single UNIX
144 Specification version 3 (SUSv3).)
145 The POSIX.1-2001 document is broken into four parts:
147 XBD: Definitions, terms and concepts, header file specifica‐
149 tions.
150 XSH: Specifications of functions (i.e., system calls and library
152 functions in actual implementations).
153 XCU: Specifications of commands and utilities (i.e., the area
155 formerly described by POSIX.2).
156 XRAT: Informative text on the other parts of the standard.
158 POSIX.1-2001 is aligned with C99, so that all of the library
160 functions standardized in C99 are also standardized in
161 POSIX.1-2001.
162 Two Technical Corrigenda (minor fixes and improvements) of the
164 original 2001 standard have occurred: TC1 in 2003 (also known as
165 POSIX.1-2003), and TC2 in 2004 (also known as POSIX.1-2004).
166 POSIX.1-2008, SUSv4
168 Work on the next revision of POSIX.1/SUS was completed and rati‐
169 fied in 2008.
170 The changes in this revision are not as large as those that
172 occurred for POSIX.1-2001/SUSv3, but a number of new interfaces
173 are added and various details of existing specifications are
174 modified. Many of the interfaces that were optional in
175 POSIX.1-2001 become mandatory in the 2008 revision of the stan‐
176 dard. A few interfaces that are present in POSIX.1-2001 are
177 marked as obsolete in POSIX.1-2008, or removed from the standard
178 altogether.
179 The revised standard is broken into the same four parts as
181 POSIX.1-2001, and again there are two levels of conformance: the
182 baseline POSIX Conformance, and XSI Conformance, which mandates
183 an additional set of interfaces beyond those in the base speci‐
184 fication.
185 In general, where the CONFORMING TO section of a manual page
187 lists POSIX.1-2001, it can be assumed that the interface also
188 conforms to POSIX.1-2008, unless otherwise noted.
189 Technical Corrigendum 1 (minor fixes and improvements) of this
191 standard was released in 2013 (also known as POSIX.1-2013).
192 Technical Corrigendum 2 of this standard was released in 2016
194 (also known as POSIX.1-2016).
195 Further information can be found on the Austin Group web site,
197 ⟨http://www.opengroup.org/austin/⟩.
198
200 getconf(1), confstr(3), pathconf(3), sysconf(3), attributes(7), fea‐
201 ture_test_macros(7), libc(7), posixoptions(7)
202
204 This page is part of release 5.04 of the Linux man-pages project. A
205 description of the project, information about reporting bugs, and the
206 latest version of this page, can be found at
207 https://www.kernel.org/doc/man-pages/.
208Linux 2017-11-26 STANDARDS(7)