Introduction to DCL Programming

This document provides an introductory presentation to programming in Digital Command Language (DCL). It covers fundamental DCL concepts, command structures, and programming elements.

The presentation begins by outlining DCL basics, including commands, verbs (both internal and external), and how to use symbols to define or customize "foreign" commands. It then details command qualifiers, explaining their role in specifying additional information or alternate behaviors, differentiating between non-positional and positional qualifiers, and listing common qualifiers.

Further, the document delves into DCL statement elements, focusing on assignment statements for strings, numerics, bit manipulation, and booleans. It differentiates between local and global symbol assignments and the handling of quoted versus unquoted strings. Control flow mechanisms are explained, covering conditional expressions (IF-THEN, IF-THEN-ENDIF, IF-THEN-ELSE-ENDIF) including nesting and best practices for compatibility. It also introduces GOTO statements and internal subroutines using GOSUB/RETURN, and briefly mentions SUBROUTINE/ENDSUBROUTINE for more structured subroutines.

A significant portion is dedicated to common DCL lexical functions, such as F$CVTIME for date and time operations, F$GETDVI for device information, F$GETQUI for queue details, F$GETJPI for process information, and F$GETSYI for system information. The presentation also explains how to pass parameters to DCL procedures (P1 through P8) and the functionality of logical names, including their creation, deletion, scope (process, job, group, system), access modes, and "rooted" logicals.

Finally, the document illustrates practical applications by demonstrating how to create recurring batch jobs that can re-submit themselves, adjusting their behavior based on daily, weekly, monthly, or yearly schedules using lexical functions like F$GETQUI and F$CVTIME to select specific tasks by date. The presentation concludes by inviting questions and mentioning a follow-up "Intermediate DCL Programming" session.