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, the ancestral UNIX from Bell Labs.
14 4.2BSD This is an implementation standard defined by the 4.2 release of
16 the Berkeley Software Distribution, released by the University
17 of California at Berkeley. This was the first Berkeley release
18 that contained a TCP/IP stack and the sockets API. 4.2BSD was
19 released in 1983.
20 Earlier major BSD releases included 3BSD (1980), 4BSD (1980),
22 and 4.1BSD (1981).
23 4.3BSD The successor to 4.2BSD, released in 1986.
25 4.4BSD The successor to 4.3BSD, released in 1993. This was the last
27 major Berkeley release.
28 System V
30 This is an implementation standard defined by AT&T's milestone
31 1983 release of its commercial System V (five) release. The
32 previous major AT&T release was System III, released in 1981.
33 System V release 2 (SVr2)
35 This was the next System V release, made in 1985. The SVr2 was
36 formally described in the System V Interface Definition version
37 1 (SVID 1) published in 1985.
38 System V release 3 (SVr3)
40 This was the successor to SVr2, released in 1986. This release
41 was formally described in the System V Interface Definition ver‐
42 sion 2 (SVID 2).
43 System V release 4 (SVr4)
45 This was the successor to SVr3, released in 1989. This version
46 of System V is described in the "Programmer's Reference Manual:
47 Operating System API (Intel processors)" (Prentice-Hall 1992,
48 ISBN 0-13-951294-2) This release was formally described in the
49 System V Interface Definition version 3 (SVID 3), and is consid‐
50 ered the definitive System V release.
51 SVID 4 System V Interface Definition version 4, issued in 1995. Avail‐
53 able online at http://www.sco.com/developers/devspecs/ .
54 C89 This was the first C language standard, ratified by ANSI (Ameri‐
56 can National Standards Institute) in 1989 (X3.159-1989). Some‐
57 times this is known as ANSI C, but since C99 is also an ANSI
58 standard, this term is ambiguous. This standard was also rati‐
59 fied by ISO (International Standards Organization) in 1990
60 (ISO/IEC 9899:1990), and is thus occasionally referred to as ISO
61 C90.
62 C99 This revision of the C language standard was ratified by ISO in
64 1999 (ISO/IEC 9899:1999). Available online at http://www.open-
65 std.org/jtc1/sc22/wg14/www/standards.
66 POSIX.1-1990
68 "Portable Operating System Interface for Computing Environ‐
69 ments". IEEE 1003.1-1990 part 1, ratified by ISO in 1990
70 (ISO/IEC 9945-1:1990). The term "POSIX" was coined by Richard
71 Stallman.
72 POSIX.2
74 IEEE Std 1003.2-1992, describing commands and utilities, rati‐
75 fied by ISO in 1993 (ISO/IEC 9945-2:1993).
76 POSIX.1b (formerly known as POSIX.4)
78 IEEE Std 1003.1b-1993 describing real-time facilities for porta‐
79 ble operating systems, ratified by ISO in 1996 (ISO/IEC
80 9945-1:1996).
81 POSIX.1c
83 IEEE Std 1003.1c-1995 describing the POSIX threads interfaces.
84 POSIX.1d
86 IEEE Std 1003.1c-1999 describing additional real-time exten‐
87 sions.
88 POSIX.1g
90 IEEE Std 1003.1g-2000 describing networking APIs (including
91 sockets).
92 POSIX.1j
94 IEEE Std 1003.1j-2000 describing advanced real-time extensions.
95 POSIX.1-1996
97 A 1996 revision of POSIX.1 which incorporated POSIX.1b and
98 POSIX.1c.
99 XPG3 Released in 1989, this was the first significant release of the
101 X/Open Portability Guide, produced by the X/Open Company, a mul‐
102 tivendor consortium. This multivolume guide was based on the
103 POSIX standards.
104 XPG4 A revision of the X/Open Portability Guide, released in 1992.
106 XPG4v2 A 1994 revision of XPG4. This is also referred to as Spec 1170,
108 where 1170 referred to the number of interfaces defined by this
109 standard.
110 SUS (SUSv1)
112 Single UNIX Specification. This was a repackaging of XPG4v2 and
113 other X/Open standards (X/Open Curses Issue 4 version 2, X/Open
114 Networking Service (XNS) Issue 4). Systems conforming to this
115 standard can be branded UNIX 95.
116 SUSv2 Single UNIX Specification version 2. Sometimes also referred to
118 as XPG5. This standard appeared in 1997. Systems conforming to
119 this standard can be branded UNIX 98. See also http://www.UNIX-
120 systems.org/version2/ .)
121 POSIX.1-2001, SUSv3
123 This was a 2001 revision and consolidation of the POSIX.1,
124 POSIX.2, and SUS standards into a single document, conducted
125 under the auspices of the Austin group (http://www.open‐
126 group.org/austin/ .) The standard is available online at
127 http://www.unix-systems.org/version3/ , and the interfaces that
128 it describes are also available in the Linux manual pages pack‐
129 age under sections 1p and 3p (e.g., "man 3p open").
130 The standard defines two levels of conformance: POSIX confor‐
132 mance, which is a baseline set of interfaces required of a con‐
133 forming system; and XSI Conformance, which additionally mandates
134 a set of interfaces (the "XSI extension") which are only
135 optional for POSIX conformance. XSI-conformant systems can be
136 branded UNIX 03. (XSI conformance constitutes the Single UNIX
137 Specification version 3 (SUSv3).)
138 The POSIX.1-2001 document is broken into four parts:
140 XBD: Definitions, terms and concepts, header file specifica‐
142 tions.
143 XSH: Specifications of functions (i.e., system calls and library
145 functions in actual implementations).
146 XCU: Specifications of commands and utilities (i.e., the area
148 formerly described by POSIX.2).
149 XRAT: Informative text on the other parts of the standard.
151 POSIX.1-2001 is aligned with C99, so that all of the library
153 functions standardized in C99 are also standardized in
154 POSIX.1-2001.
155 Two Technical Corrigenda (minor fixes and improvements) of the
157 original 2001 standard have occurred: TC1 in 2003 (referred to
158 as POSIX.1-2003), and TC2 in 2004 (referred to as POSIX.1-2004).
159 POSIX.1-2008, SUSv4
161 Work on the next revision of POSIX.1/SUS was completed and rati‐
162 fied in 2008.
163 The changes in this revision are not as large as those that
165 occurred for POSIX.1-2001/SUSv3, but a number of new interfaces
166 are added and various details of existing specifications are
167 modified. Many of the interfaces that were optional in
168 POSIX.1-2001 become mandatory in the 2008 revision of the stan‐
169 dard. A few interfaces that are present in POSIX.1-2001 are
170 marked as obsolete in POSIX.1-2008, or removed from the standard
171 altogether.
172 The revised standard is broken into the same four parts as
174 POSIX.1-2001, and again there are two levels of conformance: the
175 baseline POSIX Conformance, and XSI Conformance, which mandates
176 an additional set of interfaces beyond those in the base speci‐
177 fication.
178 In general, where the CONFORMING TO section of a manual page
180 lists POSIX.1-2001, it can be assumed that the interface also
181 conforms to POSIX.1-2008, unless otherwise noted.
182 Further information can be found on the Austin group web site,
184 http://www.opengroup.org/austin/ .
185
187 feature_test_macros(7), libc(7), posixoptions(7)
188
190 This page is part of release 3.25 of the Linux man-pages project. A
191 description of the project, and information about reporting bugs, can
192 be found at http://www.kernel.org/doc/man-pages/.
193Linux 2009-06-01 STANDARDS(7)