1STANDARDS(7) Linux Programmer's Manual STANDARDS(7)
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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).
65 POSIX.1-1990
67 "Portable Operating System Interface for Computing Environ‐
68 ments". IEEE 1003.1-1990 part 1, ratified by ISO in 1990
69 (ISO/IEC 9945-1:1990). Further information can be found in Don‐
70 ald Lewine's "POSIX Programmer's Guide" (O'Reilly & Associates,
71 Inc., 1991, ISBN 0-937175-73-0). The term "POSIX" was coined by
72 Richard Stallman.
73 POSIX.2
75 IEEE Std 1003.2-1992, describing commands and utilities, rati‐
76 fied by ISO in 1993 (ISO/IEC 9945-2:1993).
77 POSIX.1b (formerly known as POSIX.4)
79 IEEE Std 1003.1b-1993 describing real-time facilities for porta‐
80 ble operating systems, ratified by ISO in 1996 (ISO/IEC
81 9945-1:1996). For further information, see "POSIX.4: Program‐
82 ming for the real world" by Bill O. Gallmeister (O'Reilly & As‐
83 sociates, Inc. ISBN 1-56592-074-0).
84 POSIX.1c
86 IEEE Std 1003.1c-1995 describing the POSIX threads interfaces.
87 POSIX.1d
89 IEEE Std 1003.1c-1999 describing additional real-time exten‐
90 sions.
91 POSIX.1g
93 IEEE Std 1003.1g-2000 describing networking APIs (including
94 sockets).
95 POSIX.1j
97 IEEE Std 1003.1j-2000 describing advanced real-time extensions.
98 POSIX.1-1996
100 A 1996 revision of POSIX.1 which incorporated POSIX.1b and
101 POSIX.1c.
102 XPG3 Released in 1989, this was the first significant release of the
104 X/Open Portability Guide, produced by the X/Open Company, a
105 multi-vendor consortium. This multi-volume guide was based on
106 the POSIX standards.
107 XPG4 A revision of the X/Open Portability Guide, released in 1992.
109 XPG4v2 A 1994 revision of XPG4. This is also referred to as Spec 1170,
111 where 1170 referred to the number of interfaces defined by this
112 standard.
113 SUS (SUSv1)
115 Single UNIX Specification. This was a repackaging of XPG4v2 and
116 other X/Open standards (X/Open Curses Issue 4 version 2, X/Open
117 Networking Service (XNS) Issue 4). Systems conforming to this
118 standard can be branded UNIX 95.
119 SUSv2 Single UNIX Specification version 2. Sometimes also referred to
121 as XPG5. This standard appeared in 1997. Systems conforming to
122 this standard can be branded UNIX 98. See also http://www.UNIX-
123 systems.org/version2/ .)
124 POSIX.1-2001, SUSv3
126 This was a 2001 revision and consolidation of the POSIX.1,
127 POSIX.2, and SUS standards into a single document, conducted
128 under the auspices of the Austin group (http://www.open‐
129 group.org/austin/ .) The standard is available online at
130 http://www.unix-systems.org/version3/ , and the interfaces that
131 it describes are also available in the Linux manual pages pack‐
132 age under sections 1p and 3p (e.g., "man 3p open").
133 The standard defines two levels of conformance: POSIX confor‐
135 mance, which is a baseline set of interfaces required of a con‐
136 forming system; and XSI Conformance, which additionally mandates
137 a set of interfaces (the "XSI extension") which are only
138 optional for POSIX conformance. XSI-conformant systems can be
139 branded UNIX 03. (XSI conformance constitutes the Single UNIX
140 Specification version 3 (SUSv3).)
141 The POSIX.1-2001 document is broken into four parts:
143 XBD: Definitions, terms and concepts, header file specifica‐
145 tions.
146 XSH: Specifications of functions (i.e., system calls and library
148 functions in actual implementations).
149 XCU: Specifications of commands and utilities (i.e., the area
151 formerly described by POSIX.2).
152 XRAT: Informative text on the other parts of the standard.
154 POSIX.1-2001 is aligned with C99, so that all of the library
156 functions standardised in C99 are also standardised in
157 POSIX.1-1001.
158 Two Technical Corrigenda (minor fixes and improvements) of the
160 original 2001 standard have occurred: TC1 in 2003 (referred to
161 as POSIX.1-2003), and TC2 in 2004 (referred to as POSIX.1-2004).
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164 feature_test_macros(7)
165Linux 2006-08-03 STANDARDS(7)