OpenVMS Command Definition, Librarian, and Message Utilities Manual

This manual describes three core OpenVMS utilities: the Command Definition Utility (CDU), the Librarian Utility, and the Message Utility.

1. Command Definition Utility (CDU): This utility is used to create, delete, or modify command definitions within OpenVMS DCL (Digital Command Language) command tables. It allows users to define new DCL commands, their parameters, qualifiers, and keywords by creating command definition files (.CLD) using statements like DEFINE SYNTAX, DEFINE TYPE, and DEFINE VERB. CDU can modify a user's process command table, add commands to the system command table, or create object modules for custom command tables. It also involves using DCL's command language routines (e.g., CLI$DCL_PARSE, CLI$DISPATCH) for parsing and executing these commands. The primary DCL command for interacting with CDU is SET COMMAND.

2. Librarian Utility (LIBRARIAN): This utility manages various types of OpenVMS libraries, including object, macro, help, text, and shareable image libraries. It enables users to create new libraries, insert and extract modules, delete modules, compress library space, and generate cross-reference listings. Libraries have a specific structure, including a header and module name tables, with considerations for character case. The main command for this utility is LIBRARY.

3. Message Utility (MESSAGE): This utility allows users to define and supplement OpenVMS system messages with their own custom messages. Messages are structured with a facility name, severity level (Success, Informational, Warning, Error, Fatal), an identifier, and the message text itself. Users write message source files (.MSG) using directives like .FACILITY, .SEVERITY, and Message Definition, which are then compiled into object modules. The utility also supports message pointers, enabling flexible management of message text without requiring relinking. The MESSAGE DCL command is used for compilation, and SET MESSAGE can be used to manage how messages are displayed and loaded.