Document revision date: 19 July 1999

Chapter 16
16	Advanced Programming with DCL
16.1	Performing Command Procedure Input
16.1.1	Restrictions to Including Data in Command Procedures
16.1.2	Other Methods of Inputting Data
16.2	Using Parameters to Pass Data
16.2.1	Specifying Parameters as Integers
16.2.2	Specifying Parameters as Character Strings
16.2.3	Specifying Parameters as Symbols
16.2.4	Specifying Parameters as Null Values
16.3	Using Parameters to Pass Data to Batch Jobs
16.4	Using Parameters to Pass Data to Nested Command Procedures
16.5	Prompting for Data
16.6	Using the SYS$INPUT Logical Name to Obtain Data
16.6.1	Redefining SYS$INPUT as Your Terminal
16.6.2	Defining SYS$INPUT as a Separate File
16.7	Performing Command Procedure Output
16.7.1	Writing Data to Terminals
16.7.2	Redirecting Output from Commands and Images
16.7.3	Returning Data from Command Procedures
16.7.4	Redirecting Error Messages
16.7.4.1	Redefining SYS$ERROR
16.7.4.2	Suppressing System Error Messages
16.8	Reading and Writing Files (File I/O)
16.9	Using the OPEN Command
16.10	Writing to Files
16.10.1	Creating Files with Unique File Names
16.11	Using the WRITE Command
16.11.1	Specifying Data
16.11.2	Using the /SYMBOL Qualifier
16.11.3	Using the /UPDATE Qualifier
16.12	Using the READ Command
16.12.1	Using the /END_OF_FILE Qualifier
16.12.2	Using the /INDEX and /KEY Qualifiers
16.12.3	Using the /DELETE Qualifier
16.13	Using the Close Command
16.14	Modifying Files
16.14.1	Updating Records
16.14.2	Creating New Output Files
16.14.3	Appending Records to Files
16.15	Handling File I/O Errors
16.15.1	Default Error Actions
16.16	Techniques for Controlling Execution Flow
16.16.1	Using the IF Command
16.16.2	Using the THEN Command
16.16.3	Using the ELSE Command
16.16.4	Using Command Blocks
16.16.5	Using the GOTO Command
16.16.5.1	Avoiding Reexecution
16.16.6	Using the GOSUB and RETURN Commands
16.17	Creating New Command Levels
16.17.1	Using the CALL Command
16.17.1.1	CALL Command Defaults
16.17.1.2	Beginning and Ending Subroutines
16.18	Writing Case Statements
16.18.1	Listing the Labels
16.18.2	Writing the Case Statement
16.18.3	Writing the Command Blocks
16.19	Writing Loops
16.20	Using the PIPE Command
16.20.1	Using the PIPE Command for Conditional Command Execution
16.20.2	Using the PIPE Command for Pipeline Execution
16.20.3	Using the PIPE Command for Subshell Execution
16.20.4	Using the PIPE Command for Background Execution
16.20.5	Using the PIPE Command for Input/Output Redirection
16.20.6	Interrupting a PIPE Command
16.20.7	Improving Subprocess Performance
Chapter 17
17	Lexical Functions: Obtaining and Manipulating Information
17.1	About Lexical Functions
17.1.1	Information Manipulation
17.2	Obtaining Information About Your Process
17.2.1	Changing Verification Settings
17.2.2	Changing Default File Protection
17.3	Obtaining Information About the System
17.3.1	Determining Your OpenVMS Cluster Node Name
17.3.2	Obtaining Queue Information
17.3.3	Obtaining Process Information
17.3.4	F$CONTEXT Lexical Function
17.4	Obtaining Information About Files and Devices
17.4.1	Searching for Devices
17.4.2	Searching for a File in a Directory
17.4.3	Deleting Old Versions of Files
17.5	Translating Logical Names
17.6	Manipulating Strings
17.6.1	Determining Presence of Strings or Characters
17.6.2	Extracting Parts of Strings
17.6.3	Formatting Output Strings
17.7	Manipulating Data Types
17.7.1	Converting Data Types
17.7.2	Evaluating Expressions
17.7.3	Determining Whether a Symbol Exists

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