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| .TH STANDARDS 7 2020-11-01 "Linux" "Linux Programmer's Manual" |
| .SH NAME |
| standards \- C and UNIX Standards |
| .SH DESCRIPTION |
| The CONFORMING TO section that appears in many manual pages identifies |
| various standards to which the documented interface conforms. |
| The following list briefly describes these standards. |
| .TP |
| .B V7 |
| Version 7 (also known as Seventh Edition) UNIX, |
| released by AT&T/Bell Labs in 1979. |
| After this point, UNIX systems diverged into two main dialects: |
| BSD and System V. |
| .TP |
| .B 4.2BSD |
| This is an implementation standard defined by the 4.2 release |
| of the |
| .IR "Berkeley Software Distribution", |
| released by the University of California at Berkeley. |
| This was the first Berkeley release that contained a TCP/IP |
| stack and the sockets API. |
| 4.2BSD was released in 1983. |
| .IP |
| Earlier major BSD releases included |
| .IR 3BSD |
| (1980), |
| .I 4BSD |
| (1980), |
| and |
| .I 4.1BSD |
| (1981). |
| .TP |
| .B 4.3BSD |
| The successor to 4.2BSD, released in 1986. |
| .TP |
| .B 4.4BSD |
| The successor to 4.3BSD, released in 1993. |
| This was the last major Berkeley release. |
| .TP |
| .B System V |
| This is an implementation standard defined by AT&T's milestone 1983 |
| release of its commercial System V (five) release. |
| The previous major AT&T release was |
| .IR "System III" , |
| released in 1981. |
| .TP |
| .B System V release 2 (SVr2) |
| This was the next System V release, made in 1985. |
| The SVr2 was formally described in the |
| .I "System V Interface Definition version 1" |
| .RI ( "SVID 1" ) |
| published in 1985. |
| .TP |
| .B System V release 3 (SVr3) |
| This was the successor to SVr2, released in 1986. |
| This release was formally described in the |
| .I "System V Interface Definition version 2" |
| .RI ( "SVID 2" ). |
| .TP |
| .B System V release 4 (SVr4) |
| This was the successor to SVr3, released in 1989. |
| This version of System V is described in the "Programmer's Reference |
| Manual: Operating System API (Intel processors)" (Prentice-Hall |
| 1992, ISBN 0-13-951294-2) |
| This release was formally described in the |
| .I "System V Interface Definition version 3" |
| .RI ( "SVID 3" ), |
| and is considered the definitive System V release. |
| .TP |
| .B SVID 4 |
| System V Interface Definition version 4, issued in 1995. |
| Available online at |
| .UR http://www.sco.com\:/developers\:/devspecs/ |
| .UE . |
| .TP |
| .B C89 |
| This was the first C language standard, ratified by ANSI |
| (American National Standards Institute) in 1989 |
| .RI ( X3.159-1989 ). |
| Sometimes this is known as |
| .IR "ANSI C" , |
| but since C99 is also an |
| ANSI standard, this term is ambiguous. |
| This standard was also ratified by |
| ISO (International Standards Organization) in 1990 |
| .RI ( "ISO/IEC 9899:1990" ), |
| and is thus occasionally referred to as |
| .IR "ISO C90" . |
| .TP |
| .B C99 |
| This revision of the C language standard was ratified by ISO in 1999 |
| .RI ( "ISO/IEC 9899:1999" ). |
| Available online at |
| .UR http://www.open\-std.org\:/jtc1\:/sc22\:/wg14\:/www\:/standards |
| .UE . |
| .TP |
| .B C11 |
| This revision of the C language standard was ratified by ISO in 2011 |
| .RI ( "ISO/IEC 9899:2011" ). |
| .IP |
| .B LFS |
| The Large File Summit specification, completed in 1996. |
| This specification defined mechanisms that allowed 32-bit systems |
| to support the use of large files (i.e., 64-bit file offsets). |
| See |
| .UR https://www.opengroup.org\:/platform\:/lfs.html |
| .UE . |
| .TP |
| .B POSIX.1-1988 |
| This was the first POSIX standard, |
| ratified by IEEE as IEEE Std 1003.1-1988, |
| and subsequently adopted (with minor revisions) as an ISO standard in 1990. |
| The term "POSIX" was coined by Richard Stallman. |
| .TP |
| .B POSIX.1-1990 |
| "Portable Operating System Interface for Computing Environments". |
| IEEE 1003.1-1990 part 1, ratified by ISO in 1990 |
| .RI ( "ISO/IEC 9945-1:1990" ). |
| .TP |
| .B POSIX.2 |
| IEEE Std 1003.2-1992, |
| describing commands and utilities, ratified by ISO in 1993 |
| .RI ( "ISO/IEC 9945-2:1993" ). |
| .TP |
| .BR POSIX.1b " (formerly known as \fIPOSIX.4\fP)" |
| IEEE Std 1003.1b-1993, |
| describing real-time facilities |
| for portable operating systems, ratified by ISO in 1996 |
| .RI ( "ISO/IEC 9945-1:1996" ). |
| .TP |
| .B POSIX.1c " (formerly known as \fIPOSIX.4a\fP)" |
| IEEE Std 1003.1c-1995, which describes the POSIX threads interfaces. |
| .TP |
| .BR POSIX.1d |
| IEEE Std 1003.1c-1999, which describes additional real-time extensions. |
| .TP |
| .B POSIX.1g |
| IEEE Std 1003.1g-2000, which describes networking APIs (including sockets). |
| .TP |
| .B POSIX.1j |
| IEEE Std 1003.1j-2000, which describes advanced real-time extensions. |
| .TP |
| .B POSIX.1-1996 |
| A 1996 revision of POSIX.1 which incorporated POSIX.1b and POSIX.1c. |
| .TP |
| .B XPG3 |
| Released in 1989, this was the first release of the X/Open |
| Portability Guide to be based on a POSIX standard (POSIX.1-1988). |
| This multivolume guide was developed by the X/Open Group, |
| a multivendor consortium. |
| .TP |
| .B XPG4 |
| A revision of the X/Open Portability Guide, released in 1992. |
| This revision incorporated POSIX.2. |
| .TP |
| .B XPG4v2 |
| A 1994 revision of XPG4. |
| This is also referred to as |
| .IR "Spec 1170" , |
| where 1170 referred to the number of interfaces |
| defined by this standard. |
| .TP |
| .B "SUS (SUSv1)" |
| Single UNIX Specification. |
| This was a repackaging of XPG4v2 and other X/Open standards |
| (X/Open Curses Issue 4 version 2, |
| X/Open Networking Service (XNS) Issue 4). |
| Systems conforming to this standard can be branded |
| .IR "UNIX 95" . |
| .TP |
| .B SUSv2 |
| Single UNIX Specification version 2. |
| Sometimes also referred to (incorrectly) as |
| .IR XPG5 . |
| This standard appeared in 1997. |
| Systems conforming to this standard can be branded |
| .IR "UNIX 98" . |
| See also |
| .UR http://www.unix.org\:/version2/ |
| .UE .) |
| .TP |
| .B POSIX.1-2001, SUSv3 |
| This was a 2001 revision and consolidation of the |
| POSIX.1, POSIX.2, and SUS standards into a single document, |
| conducted under the auspices of the Austin Group |
| .UR http://www.opengroup.org\:/austin/ |
| .UE . |
| The standard is available online at |
| .UR http://www.unix.org\:/version3/ |
| .UE . |
| .IP |
| The standard defines two levels of conformance: |
| .IR "POSIX conformance" , |
| which is a baseline set of interfaces required of a conforming system; |
| and |
| .IR "XSI Conformance", |
| which additionally mandates a set of interfaces |
| (the "XSI extension") which are only optional for POSIX conformance. |
| XSI-conformant systems can be branded |
| .IR "UNIX 03" . |
| .IP |
| The POSIX.1-2001 document is broken into four parts: |
| .IP |
| .BR XBD : |
| Definitions, terms, and concepts, header file specifications. |
| .IP |
| .BR XSH : |
| Specifications of functions (i.e., system calls and library |
| functions in actual implementations). |
| .IP |
| .BR XCU : |
| Specifications of commands and utilities |
| (i.e., the area formerly described by POSIX.2). |
| .IP |
| .BR XRAT : |
| Informative text on the other parts of the standard. |
| .IP |
| POSIX.1-2001 is aligned with C99, so that all of the |
| library functions standardized in C99 are also |
| standardized in POSIX.1-2001. |
| .IP |
| The Single UNIX Specification version 3 (SUSv3) comprises the |
| Base Specifications containing XBD, XSH, XCU, and XRAT as above, |
| plus X/Open Curses Issue 4 version 2 as an extra volume that is |
| not in POSIX.1-2001. |
| .IP |
| Two Technical Corrigenda (minor fixes and improvements) |
| of the original 2001 standard have occurred: |
| TC1 in 2003 |
| and TC2 in 2004. |
| .TP |
| .B POSIX.1-2008, SUSv4 |
| Work on the next revision of POSIX.1/SUS was completed and |
| ratified in 2008. |
| The standard is available online at |
| .UR http://www.unix.org\:/version4/ |
| .UE . |
| .IP |
| The changes in this revision are not as large as those |
| that occurred for POSIX.1-2001/SUSv3, |
| but a number of new interfaces are added |
| and various details of existing specifications are modified. |
| Many of the interfaces that were optional in |
| POSIX.1-2001 become mandatory in the 2008 revision of the standard. |
| A few interfaces that are present in POSIX.1-2001 are marked |
| as obsolete in POSIX.1-2008, or removed from the standard altogether. |
| .IP |
| The revised standard is structured in the same way as its predecessor. |
| The Single UNIX Specification version 4 (SUSv4) comprises the |
| Base Specifications containing XBD, XSH, XCU, and XRAT, |
| plus X/Open Curses Issue 7 as an extra volume that is |
| not in POSIX.1-2008. |
| .IP |
| Again there are two levels of conformance: the baseline |
| .IR "POSIX Conformance" , |
| and |
| .IR "XSI Conformance" , |
| which mandates an additional set of interfaces |
| beyond those in the base specification. |
| .IP |
| In general, where the CONFORMING TO section of a manual page |
| lists POSIX.1-2001, it can be assumed that the interface also |
| conforms to POSIX.1-2008, unless otherwise noted. |
| .IP |
| Technical Corrigendum 1 (minor fixes and improvements) |
| of this standard was released in 2013. |
| .IP |
| Technical Corrigendum 2 of this standard was released in 2016. |
| .IP |
| Further information can be found on the Austin Group web site, |
| .UR http://www.opengroup.org\:/austin/ |
| .UE . |
| .TP |
| .B SUSv4 2016 edition |
| This is equivalent to POSIX.1-2008, with the addition of |
| Technical Corrigenda 1 and 2 and the XCurses specification. |
| .TP |
| .B POSIX.1-2017 |
| This revision of POSIX is technically identical to POSIX.1-2008 with |
| Technical Corrigenda 1 and 2 applied. |
| .TP |
| .B SUSv4 2018 edition |
| This is equivalent to POSIX.1-2017, with the addition of |
| the XCurses specification. |
| .PP |
| The interfaces documented in POSIX.1/SUS are available as |
| manual pages under sections 0p (header files), 1p (commands), |
| and 3p (functions); |
| thus one can write "man 3p open". |
| .SH SEE ALSO |
| .BR getconf (1), |
| .BR confstr (3), |
| .BR pathconf (3), |
| .BR sysconf (3), |
| .BR attributes (7), |
| .BR feature_test_macros (7), |
| .BR libc (7), |
| .BR posixoptions (7), |
| .BR system_data_types (7) |