VX/CLD - OpenVMS CLD Compiler

Description:

VX/CLD is a Command Line Definition (CLD) compiler that allows VMS/OpenVMS command parsing to function identically on Linux and Windows. It ensures that applications using CLD to define commands, parameters, and qualifiers continue working without modification.

By integrating with VX/DCL, VX/CLD allows users to extend, modify, or restrict VMS-style commands, ensuring complete compatibility with existing OpenVMS command-line applications.

Extending and Customizing DCL Syntax

Why Use VX/CLD?

• Migrate CLD-based applications to Linux/Windows while preserving command parsing logic.

• Extend the VMS DCL command set, adding custom verbs, qualifiers, and parameters.

• Restrict or modify existing commands, ensuring greater control over application behavior.

• Enable automated command parsing, launching applications seamlessly from VX/DCL.

VX/CLD ensures that applications using VMS-style command definitions function identically in non-VMS environments.

How VX/CLD Works

VX/CLD compiles a CLD file into an executable command parser, allowing commands to be interpreted and executed under VX/DCL.

Example CLD Definition

Below is an example CLD definition that defines a custom “TYPE” command:

DEFINE VERB TYPE
  ROUTINE DO_TYPE
  IMAGE "TYPE"
  PARAMETER P1
    LABEL=INPUT
    PROMPT="File"
    VALUE(REQUIRED, LIST, TYPE=$INFILE)
  QUALIFIER BACKUP
  QUALIFIER BEFORE, VALUE(DEFAULT="TODAY", TYPE=$DATETIME)
  QUALIFIER CONFIRM
  QUALIFIER CREATED
  QUALIFIER EXCLUDE, VALUE(REQUIRED, LIST)
  QUALIFIER EXPIRED
  QUALIFIER HEADER
  QUALIFIER MODIFIED
  QUALIFIER ON, VALUE(DEFAULT="TODAY", TYPE=$DATETIME)
  QUALIFIER OUTPUT,
	DEFAULT, VALUE(DEFAULT="SYS$OUTPUT", TYPE=$FILE)
  QUALIFIER PAGE
  QUALIFIER SINCE, VALUE(DEFAULT="TODAY", TYPE=$DATETIME)
  QUALIFIER BY_OWNER, VALUE(TYPE=$UIC)
  QUALIFIER TAIL, VALUE(DEFAULT="22", TYPE=$NUMBER)
  DISALLOW (OUTPUT) AND (PAGE)

VX/CLD File Processing Overview

Input File	VX/CLD Output Files	Description
Filename.cld	Filename.exe	Compiled command syntax parser for execution.
	Filename.def	Generated command definitions in structured format.

Seamless Migration of VMS Command Syntax

VX/CLD ensures that legacy VMS CLD-based applications can:

✅ Run on Linux/Windows without modification

✅ Maintain existing command structures and qualifiers

✅ Extend or modify command parsing logic as needed

VX/CLD is a critical component for VMS migrations, ensuring DCL-based command-line applications continue to function as expected.