Description:
VX/CLD is a Command Line Definition (CLD) compiler that allows VMS/OpenVMS command parsing to function identically on Linux. 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 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
Seamless Migration of VMS Command Syntax
VX/CLD ensures that legacy VMS CLD-based applications can:
✅ Run on Linux 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.
