ULTRIX Reference Pages Section 2: System Calls

This document is the ULTRIX Reference Pages, Section 2: System Calls, specifically for ULTRIX Version 4.0 or higher, published in June 1990.

Its primary purpose is to define and describe the system calls (entries into the ULTRIX kernel) available to all programmers for both RISC and VAX computing platforms.

The document is structured into several sections, with a strong focus on the "System Calls" section (Section 2). Key information provided for each system call entry typically includes:

• Name: The name of the system call and a brief description.
• Syntax: The C language function prototype and required include files.
• Description: A detailed explanation of the call's functionality, its arguments, and any specific behaviors.
• Return Value: What the call returns on successful completion and upon failure (often -1, with the errno variable indicating the specific error).
• Diagnostics: A comprehensive list of possible error codes (from <errno.h>) and their meanings when the system call fails.
• Environment: Notes on how the system call's behavior might differ when programs are compiled under POSIX or System V environments.
• See Also: References to related manual pages and documents.

The introductory intro(2) page for this section is particularly important, as it defines common terms and concepts used throughout, such as:

• File access permissions.
• Process management (Process IDs, process groups, user/group IDs).
• Interprocess communication mechanisms (message queues, semaphores, shared memory, including their associated data structures and permissions).
• Networking concepts (sockets and address families).
• Special system processes.

Some system call entries include suffixes like 2yp (Yellow Pages) or 2nfs (Network File System) to denote service-specific functionalities. This manual serves as a fundamental guide for developers programming at the kernel interface level on ULTRIX systems.