Advanced Programming in the UNIX® Environment

ptg10805159

2

UNIX Standardiza tion and

Implementa tions

2.1 Introduction

Much work has gone into standardizing the UNIX programming environment and the

Cprogramming language. Although applications have always been quite portable

across different versions of the UNIX operating system, the proliferation of versions and

differences during the 1980s led many large users, such as the U.S. government, to call

for standardization.

In this chapter we first look at the various standardization efforts that have been

under way over the past two and a half decades.We then discuss the effects of these

UNIX programming standards on the operating system implementations that are

described in this book. An important part of all the standardization efforts is the

specification of various limits that each implementation must define, so we look at these

limits and the various ways to determine their values.

2.2 UNIX Standardization

2.2.1 ISO C

In late 1989, ANSI StandardX3.159-1989 for the C programming language was

approved. This standardwas also adopted as International StandardISO/IEC

9899:1990. ANSI is the American National Standards Institute, the U.S. member in the

International Organization for Standardization(ISO).IEC stands for the International

Electrotechnical Commission.

25