standards - C and UNIX Standards
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. 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. 4.2BSD This is an implementation standard defined by the 4.2 release of the 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. Earlier major BSD releases included 3BSD (1980), 4BSD (1980), and 4.1BSD (1981). 4.3BSD The successor to 4.2BSD, released in 1986. 4.4BSD The successor to 4.3BSD, released in 1993. This was the last major Berkeley release. 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 System III, released in 1981. System V release 2 (SVr2) This was the next System V release, made in 1985. The SVr2 was formally described in the System V Interface Definition version 1 (SVID 1) published in 1985. System V release 3 (SVr3) This was the successor to SVr2, released in 1986. This release was formally described in the System V Interface Definition version 2 (SVID 2). 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 System V Interface Definition version 3 (SVID 3), and is considered the definitive System V release. SVID 4 System V Interface Definition version 4, issued in 1995. Available online at http://www.sco.com/developers/devspecs/. C89 This was the first C language standard, ratified by ANSI (American National Standards Institute) in 1989 (X3.159-1989). Sometimes this is known as 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 (ISO/IEC 9899:1990), and is thus occasionally referred to as ISO C90. C99 This revision of the C language standard was ratified by ISO in 1999 (ISO/IEC 9899:1999). Available online at http://www.open- std.org/jtc1/sc22/wg14/www/standards. C11 This revision of the C language standard was ratified by ISO in 2011 (ISO/IEC 9899:2011). POSIX.1-1990 "Portable Operating System Interface for Computing Environments". IEEE 1003.1-1990 part 1, ratified by ISO in 1990 (ISO/IEC 9945-1:1990). The term "POSIX" was coined by Richard Stallman. POSIX.2 IEEE Std 1003.2-1992, describing commands and utilities, ratified by ISO in 1993 (ISO/IEC 9945-2:1993). POSIX.1b (formerly known as POSIX.4) IEEE Std 1003.1b-1993, describing real-time facilities for portable operating systems, ratified by ISO in 1996 (ISO/IEC 9945-1:1996). POSIX.1c IEEE Std 1003.1c-1995, which describes the POSIX threads interfaces. POSIX.1d IEEE Std 1003.1c-1999, which describes additional real-time extensions. POSIX.1g IEEE Std 1003.1g-2000, which describes networking APIs (including sockets). POSIX.1j IEEE Std 1003.1j-2000, which describes advanced real-time extensions. POSIX.1-1996 A 1996 revision of POSIX.1 which incorporated POSIX.1b and POSIX.1c. XPG3 Released in 1989, this was the first significant release of the X/Open Portability Guide, produced by the X/Open Company, a multivendor consortium. This multivolume guide was based on the POSIX standards. XPG4 A revision of the X/Open Portability Guide, released in 1992. XPG4v2 A 1994 revision of XPG4. This is also referred to as Spec 1170, where 1170 referred to the number of interfaces defined by this standard. 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 UNIX 95. SUSv2 Single UNIX Specification version 2. Sometimes also referred to as XPG5. This standard appeared in 1997. Systems conforming to this standard can be branded UNIX 98. See also http://www.UNIX-systems.org/version2/.) 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 http://www.opengroup.org /austin/. The standard is available online at http://www.unix-systems.org/version3/, and the interfaces that it describes are also available in the Linux manual pages package under sections 1p and 3p (e.g., "man 3p open"). The standard defines two levels of conformance: POSIX conformance, which is a baseline set of interfaces required of a conforming system; and 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 UNIX 03. (XSI conformance constitutes the Single UNIX Specification version 3 (SUSv3).) The POSIX.1-2001 document is broken into four parts: XBD: Definitions, terms and concepts, header file specifications. XSH: Specifications of functions (i.e., system calls and library functions in actual implementations). XCU: Specifications of commands and utilities (i.e., the area formerly described by POSIX.2). XRAT: Informative text on the other parts of the standard. POSIX.1-2001 is aligned with C99, so that all of the library functions standardized in C99 are also standardized in POSIX.1-2001. Two Technical Corrigenda (minor fixes and improvements) of the original 2001 standard have occurred: TC1 in 2003 (also known as POSIX.1-2003), and TC2 in 2004 (also known as POSIX.1-2004). POSIX.1-2008, SUSv4 Work on the next revision of POSIX.1/SUS was completed and ratified in 2008. 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. The revised standard is broken into the same four parts as POSIX.1-2001, and again there are two levels of conformance: the baseline POSIX Conformance, and XSI Conformance, which mandates an additional set of interfaces beyond those in the base specification. 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. Technical Corrigendum 1 (minor fixes and improvements) of this standard was released in 2013 (also known as POSIX.1-2013). Technical Corrigendum 2 of this standard was released in 2016 (also known as POSIX.1-2016). Further information can be found on the Austin Group web site, http://www.opengroup.org/austin/.
attributes(7), feature_test_macros(7), libc(7), posixoptions(7)
This page is part of release 4.09 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.
Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.
Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.
Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.
The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.
Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.
Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.
Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.