Digital Command Language (DCL) is the command language used by the OpenVMS operating system. It is a powerful scripting language that allows users to automate tasks, manage system resources, and perform complex operations. This module will introduce you to the basics of DCL scripting, including its syntax, structure, and common use cases.

1. DCL Syntax and Structure
2. Creating and Running DCL Scripts
3. Basic Commands and Operations
4. Practical Examples

DCL scripts are composed of a series of commands that are executed sequentially. Each command in a DCL script typically follows a specific syntax:

• command: The action to be performed (e.g., SHOW, SET, COPY).
• parameters: Additional information required by the command (e.g., filenames, directories).
• qualifiers: Optional settings that modify the behavior of the command (e.g., /LOG, /CONFIRM).

To create a DCL script, you need to write your commands in a text file with a .COM extension. You can use any text editor available on OpenVMS to create this file.

1. Create the Script File:

   • Use a text editor to create a file named example.com.
   • Write your DCL commands in this file.

2. Save the Script File:

   • Save the file with the .COM extension.

3. Run the Script:

   • Use the @ command followed by the script filename to execute the script.

   $ @example.com
   

Here are some basic DCL commands that you will frequently use in your scripts:

• SET DEFAULT: Changes the current default directory.

  $ SET DEFAULT [directory]
  

• SHOW TIME: Displays the current system time.

  $ SHOW TIME
  

• COPY: Copies files from one location to another.

  $ COPY source destination [/qualifiers]
  

• DELETE: Deletes files.

  $ DELETE filename
  

• TYPE: Displays the contents of a file.

  $ TYPE filename
  

This script creates a backup of a file and logs the operation.

This script lists the contents of a directory and saves the output to a file.

1. Create a DCL script named greet.com that:

   • Sets the default directory to your login directory.
   • Displays a greeting message.
   • Shows the current system time.
   • Exits the script.

2. Run the script and verify the output.

To run the script:

In this section, you have learned the basics of DCL scripting, including the syntax and structure of DCL commands, how to create and run DCL scripts, and some basic commands and operations. You also practiced creating a simple DCL script. In the next section, we will delve deeper into variables and data types in DCL scripting.