ULTRIX POSIX Conformance Document

This document, the ULTRIX POSIX Conformance Document (Order Number: AA-LY25C-TE), published in June 1990 by Digital Equipment Corporation, provides a detailed explanation of how the ULTRIX Operating System, Version 4.0 (or higher), conforms to the IEEE Std 1003.1-1988 (POSIX.1) and ISO DIS 9945-1 (1989) standards.

Its primary purpose is to clarify and specify the implementation-defined characteristics of ULTRIX 4.0 as they relate to POSIX.1, ensuring that the system meets the requirements for a "conforming implementation." It also highlights that ULTRIX 4.0 adheres to the Federal Information Processing Standard (FIPS 151-1).

The document is intended for users and evaluators who are assessing operating systems for POSIX conformance, as well as those interested in understanding how ULTRIX 4.0 implements various POSIX features. Familiarity with the IEEE Std 1003.1-1988 or ISO DIS 9945-1 standard is assumed.

Key areas covered in the document include:

• Definitions and General Requirements: Explains ULTRIX-specific terms, error numbers, data types, and numerical/symbolic limits.
• Process Primitives: Details ULTRIX's implementation of process creation, execution, termination, signal handling, and timer operations.
• Process Environment: Describes user and system identification, environment variables, terminal identification, and configurable system variables.
• Files and Directories: Outlines ULTRIX's approach to directory entries, file creation, removal, characteristics, and accessibility.
• Input and Output Primitives: Explains read/write operations and file control.
• Device- and Class-Specific Functions: Focuses on the general terminal interface characteristics and control functions.
• Language-Specific Services for the C Programming Language: Discusses ULTRIX's conformance to C language binding, extensions to time functions, and locale settings.
• System Databases: Provides information on group and user database access.
• Data Interchange Format: Describes the tar and cpio file formats on ULTRIX systems.
• POSIX FIPS Additional Requirements: Lists specific federal requirements met by ULTRIX 4.0.