Base Definitions (XBD)
XBD is part of the Base Specifications, Issue 7. XBD provides common
definitions for the Base Specifications of the Single UNIX Specification;
therefore, readers should be familiar with it before using the other parts
of the Single UNIX Specification. The presence of this volume reduces
duplication in the other related parts of the Single UNIX Specification
and ensures consistent use of terminology.
This volume is structured as follows:
Chapter 1 is an introduction which includes the scope of the Base
Specifications, and the scope of the changes made in this version.
Normative references, terminology, and portability codes used
throughout the Base Specifications are included in this chapter.
Chapter 2 defines the conformance requirements, both for implementation
and application conformance. For implementation conformance, this includes
documentation requirements, conformance definitions for the core POSIX
subset, conformance definitions for systems conforming to the Single
UNIX Specification (denoted as XSI conformance), and option groups.
Chapter 3 contains the general terms and definitions that apply
throughout the Base Specifications.
Chapter 4 describes general concepts that apply throughout the Base
Chapter 5 describes the notation used to specify file input and output
formats in XBD and XCU.
Chapter 6 describes the portable character set and the process of
character set definition.
Chapter 7 describes the syntax for defining internationalization
locales as well as the POSIX locale provided on all systems.
Chapter 8 describes the use of environment variables for
internationalization and other purposes.
Chapter 9 describes the syntax of pattern matching using regular
expressions employed by many utilities and matched by the
functions. Both Basic Regular Expressions (BREs) and Extended Regular
Expressions (EREs) are described in this chapter.
Chapter 10 describes files and devices found on all systems and their
semantics. For example, the device
is an infinite data source and data sink.
Chapter 11 describes the asynchronous terminal interface for many of
the functions in XSH and the
utility in XCU.
Chapter 12 describes the policies for command line argument construction
and parsing. It contains the utility argument syntax used throughout
XCU, and also utility syntax guidelines for naming of utilities and the
specification of their options, option-arguments, and operands.
Chapter 13 defines the contents of headers which declare the functions
and global variables, and define types, constants, macros, and data
structures that are needed by programs using the services provided by
the system interfaces defined in XSH. These are in the form of reference
pages and are organized alphabetically.