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Document:	VMS 5.0 Command Definition Utility Manual 198804
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VMS
•

VMS Command Definition Utility Manual

Order Number AA-LA60A-TE

VMS Command Definition
Utility Manual
Order Number: AA-LA60A-TE

April 1988
This document describes the Command Definition Utility. This utility lets
you modify the DIGIT AL Command Language (DCL) by adding commands
to your process command table or to a specified command table file.

Revision/Update Information:

This document supersedes the VMS
Command Definition Utility Reference
Manual Version 4.0

Software Version:

VMS Version 5.0

digital equipment corporation
maynard, massachusetts

April 1988
The information in this document is subject to change without notice and should
not be construed as a commitment by Digital Equipment Corporation. Digital
Equipment Corporation assumes no responsibility for any errors that may appear
in this document.
The software described in this document is furnished under a license and may be
used or copied only in accordance with the terms of such license.
No responsibility is assumed for the use or reliability of software on equipment
that is not supplied by Digital Equipment Corporation or its affiliated companies.
Copyright © 1988 by Digital Equipment Corporation
All Rights Reserved.
Printed in U.S.A.
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requests the user's critical evaluation to assist in preparing future documentation.
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Contents
PREFACE

vii

NEW AND CHANGED FEATURES

CDU Description
1

CDU-1

1.1
1.2

COMMAND PROCESSING
Command String Components
System and Process Command Tables

CDU-1
CDU-1
CDU-2

USING THE CDU

CDU-2

CHOOSING A TABLE
Modifying Your Process Command Table
Adding a System Command
Creating an Object Module

CDU-3
CDU-3
CDU-3
CDU-4

WRITING A COMMAND DEFINITION FILE
Defining Syntax
Defining Values
Built-In Value Types • CDU-6
User-Defined Keywords • CDU-7
Defining Command Verbs
Disallowing Entity Combinations
Specifying Expression Entities • CDU-1 0
Operators• CDU-13
Identifying Object Modules

CDU-4
CDU-5
CDU-6

CDU-14

5.1
5.2
5.3
5.4

PROCESSING COMMAND DEFINITION FILES
Adding Command Definitions to a Command Table
Deleting Command Definitions
Creating Object Modules
Creating New Command Tables

CDU-14
CDU-15
CDU-15
CDU-16
CDU-16

USING COMMAND LANGUAGE ROUTINES

CDU-17

3.1
3.2

3.3
4
4.1
4.2

4.2.1
4.2.2
4.3

4.4
4.4.1
4.4.2
4.5

CDU Usage Summary

CDU-8
CDU-9

CDU-18

Contents

CDU File Statements

CDU-19
DEFINE SYNTAX
DEFINE TYPE
DEFINE VERB
IDENT
MODULE

CDU-20
CDU-28
CDU-31
CDU-36
CDU-37

CDU Qualifiers

CDU-38
/DELETE
/LISTING
/OBJECT
/OUTPUT
/REPLACE
/TABLE

CDU Examples

CDU-39
CDU-40
CDU-41
CDU-42
CDU-43
CDU-44
CDU-45

INDEX

TABLES
CDU-1
CDU-2

Summary of CDU Operators
CDU-13
How the DEFINE SYNTAX Statement Modifies the Primary DEFINE
Statement
CDU-20

Preface
Intended Audience
This manual is intended for all system users who want to define their own
DCL commands.

Document Structure
This document consists of the following five sections:
•

Description-Provides a full description of the Command Definition
Utility (CDU).

•

Usage Summary-Outlines the following CDU information:
-Invoking the utility
-Exiting from the utility
-Directing output
-Restrictions or privileges required

•

CDU File Statements-Describes the statements used in building
command definition files including statement formats and parameters
together with examples.

•

CDU Qualifiers-Describes qualifiers including format, parameters and
examples.

•

CDU Examples-Provides additional CDU examples.

Associated Documents
For related information about this utility, see the following documents:

•

VMS DCL Dictionary

•

Guide to VMS Programming Resources

vii

Preface

Conventions

Convention

Meaning
In examples, a key name (usually abbreviated)
shown within a box indicates that you press
a key on the keyboard; in text, a key name is
not enclosed in a box. In this example, the key
is the RETURN key. (Note that the RETURN
key is not usually shown in syntax statements
or in all examples; however, assume that you
must press the RETURN key after entering a
command or responding to a prompt.)

viii

CTRL/C

A key combination, shown in uppercase with a
slash separating two key names, indicates that
you hold down the first key while you press the
second key. For example, the key combination
CTRL/C indicates that you hold down the key
labeled CTRL while you press the key labeled C.
In examples, a key combination is enclosed in a
box.

$SHOW TIME
05-JUN-1988 11 :55:22

In examples, system output (what the system
displays) is shown in black. User input (what
you enter) is shown in red.

$ TYPE MYFILE.DAT

In examples, a vertical series of periods, or
ellipsis, means either that not all the data that
the system would display in response to a
command is shown or that not all the data a
user would enter is shown.

input-file, ...

In examples, a horizontal ellipsis indicates
that additional parameters, values, or other
information can be entered, that preceding
items can be repeated one or more times, or
that optional arguments in a statement have
been omitted.

[logical-name]

Brackets indicate that the enclosed item is
optional. (Brackets are not, however, optional
in the syntax of a directory name in a file
specification or in the syntax of a substring
specification in an assignment statement.)

quotation marks
apostrophes

The term quotation marks is used to refer
to double quotation marks ( " ). The term
apostrophe (' ) is used to refer to a single
quotation mark.

New and Changed Features
No enhancements have been made to the Command Definition Utility for
VMS Version 5.0.

CDU Description
The Command Definition Utility (CDU) creates, deletes, or changes command
definitions in a command table. Command tables are data structures created
by the CDU and used the Command Language Interpreter (CLI) to parse and
evaluate DCL commands.
There are two types of command tables: system command tables used to
parse system commands and process command tables used to parse processspecific commands. The CDU creates command tables from command
definition files, from existing command tables, or from a combination of these
sources. The new table can be either executable code or an object module.
The following sections describe:

•

How the DIGITAL Command Language processes commands

•

How to write command definitions

•

How to modify command tables

•

How to process command definitions

•

How to use command language routines in programs

Command Processing
To write command definitions and modify command tables, you must
understand how the DCL command interpreter processes commands. The
process begins when DCL prompts you for a command and you enter an
appropriate command string. Then DCL processes the command string from
left to right using definitions in your process command table. Your process
command table contains a list of valid commands and their attributes.
To parse a command string, DCL calls the CLI$DCL_pARSE routine to
check each entity in the command string. If each entity is valid, DCL sets
up an internal representation of the command string. Then DCL uses the
CLI$DISP ATCH routine to invoke the image or routine that executes the
command. If the command string is not valid, DCL issues an error message.
The image or routine that executes a command must call the CLI$PRESENT
and CLI$GET_VALUE routines to get information about the entities that were
present in the command string. The image or routine uses this information to
determine how to execute the command.

1.1

Command String Components
A command string can contain a verb that specifies the command to be
executed, a parameter that specifies the verb object, and a qualifier that
describes or modifies the action taken by the verb.
The DCL command definitions describe the allowable parameter values
for each command. The command definitions also indicate whether or not
qualifiers can take values and the value types that can be specified. Examples
of qualifier values include file specifications, integer values, keywords, and
character strings. Some commands (SET and SHOW) accept keywords as
CDU-1

CDU Description

parameters. A keyword is a predefined string that can be used as a value for
a parameter, qualifier, or another keyword.
The following example illustrates the components of a DCL command string.
$ DIFFERENCES/MODE=ASCII MYFILE.DAT YOURFILE.DAT

DIFFERENCES is the verb and /MODE is a· qualifier that has as its value the
keyword ASCII. MYFILE.DAT and YOURFILE.DAT are file specifications that
function as the command parameters.
The next example shows a command that uses a keyword as a parameter
value:
$ SHOW DEFAULT

Here, SHOW is the verb and DEFAULT is a keyword used as a parameter.

1.2

System and Process Command Tables
When you log in, the system command table in
SYS$LIBRARY:DCLTABLES.EXE is copied to your process and DCL uses
this process command table to parse command strings. Changing your
process command table does not affect SYS$LIBRARY:DCLTABLES.EXE. To
change the DCL tables, you need the CMKRNL privilege.
The system command table is created from source files called command
definition files. A command definition file contains statements that name and
describe verbs. DIGITAL maintains the command definition files for DCL;
they are not shipped with your system.

Using the CDU
To use the CDU:
•

Determine which table you want to create or modify. In general, you
modify your process command table or the DCL table in SYS$LIBRARY,
or you create an object module for a new table.

•

Choose a name and syntax for the command you define. Use a text editor
to create a command definition file that defines the command(s).

•

Use the DCL command SET COMMAND to add your command
definition to the appropriate command table. You can modify your
process command table or a specified command table file. You can also
create an object module from your command definition file.

•

Write the code for the image or routine that is invoked by the command
you are adding to the command table.

Note that the foreign command facility is an alternate way to define command
verbs. The foreign command allows you to pass information about a
command string to an image. However, if you use the foreign command
facility, your program must parse the command string; DCL does not parse
the command string for you. For information about how to define a foreign
command, see the VMS DCL Dictionary.

CDU-2

CDU Description

Choosing a Table
The type of table you are modifying or creating affects the way that you
write a command definition, process this definition, and write the code that
executes your command.
The most common tables that you modify or create include your process
command table, the DCL table in SYS$LIBRARY and new tables that allow
your programs to process commands.

3.1

Modifying Your Process Command Table
To add a command to your process command table, define the new
command in a command definition file, specifying the name of an image
for the command to invoke. Then use SET COMMAND to add the new
command to your process command table and to copy the new table back
to your process. For example, the following command adds a command in
NEWCOMMAND.CLD to your process command table:
$ SET COMMAND NEWCOMMAND

Now you can enter the new command after the DCL prompt, and DCL will
parse the command and then invoke the image that executes the command.
Note that when you write the source code for the new command, you must
use the command language routines CLI$PRESENT and CLl$GET_VALUE to
obtain information about the command string.
The first example in the Examples section shows how to add a new command
to your process command table and how to write the program that executes
the new command.
To make the command in NEWCOMMAND.CLD available to you each time
you log in, include the SET COMMAND command in your LOGIN.COM file.

3.2

Adding a System Command
To add a command to the DCL command table in SYS$LIBRARY, define
the command in a command definition file, specifying the name of an
image for the command to invoke. Then use SET COMMAND to add
the new definition to the DCL command table and copy the new table back
to SYS$LIBRARY. (You must have the CMKRNL privilege to change the DCL
command table.) For example:
$ SET COMMAND/TABLE=SYS$LIBRARY:DCLTABLES _$ /OUTPUT=SYS$LIBRARY:DCLTABLES NEWCOMMAND

To make the new command available to other users, use the Install Utility.

CDU-3

CDU Description

3.3

Creating an Object Module
To create an object module for a new command table, define the commands
in a command definition file, specifying the name of a routine in a program
that executes the command. Then use the SET COMMAND command
with the /OBJECT qualifier to create an object module from the command
definition file. For example:
$ SET COMMAND/OBJECT NEWCOMMAND

Now link this object module with the program that uses the table. Note
that when you link a command table with your program, the program must
perform the functions of a command interpreter. That is, the program must
obtain the command string and call the parsing routine CLI$DCL _p ARSE to
verify and create an internal representation of it. The program must also call
CLI$DISPATCH to invoke the appropriate routine. Each command routine
must use the DCL interface routines CLI$PRESENT and CLI$GET_VALUE to
get information about the command string that invoked the routine.
The second example in the Examples section shows how to write and process
command definitions for an object module and how to write a program that
parses commands and invokes routines.

Writing a Command Definition File
A command definition file contains information that defines a command and
its parameters, qualifiers and keywords. In addition, the command definition
file provides information about the image or routine that is invoked after the
command string is successfully parsed.
Use a text editor to create a command definition file that contains the
statements you need to describe your new command; you can use clauses
to specify additional information for statements. The default file type for a
command definition file is CLO.
Use exclamation points to delimit comments. An exclamation point causes all
following characters on a line to be treated as comments.
Any statement and its clauses can be coded using several lines. No
continuation character is necessary. (However, you cannot split names across
two lines.) If you place a statement on one line, you can separate clauses in
the statement with either commas or spaces.
You cannot abbreviate statement or clause names in the command definition
language. All names (for example, DEFINE SYNTAX, PARAMETER, and so
forth) must be spelled out completely.
Most statements and clauses accept user-supplied information such as verb
names, qualifier names, image names, and so on. You can specify this
information as a symbol or as a string.
If the statement requires that a term be specified as a string, enclose the
term in quotation marks. A string can contain any alphanumeric or special
characters. To include quotation marks within a string, use two sets of
quotation marks (" "). For example: PARAMETER Pl, LABEL=PORT,
PROMPT=(" )Enter (")(")one(")(") value.(")

Note: To maintain compatibility with earlier releases, the CDU accepts
character strings that are not enclosed in quotation marks. However, it is
recommended that you surround character strings in quotation marks. If
CDU-4

CDU Description

you do not enclose a string in quotation marks, all alphabetic characters
are converted to uppercase characters (capital letters).
If a statement requires that a term be specified as a symbol, do not enclose
the term in quotation marks. A symbol name must start with a letter or a
dollar sign. It may contain between 1 and 31 letters, numbers, dollar signs,
and underscore characters.

The Command Definition Language includes the following statements:
•

DEFINE SYNTAX syntax-name [verb-clause[, ... ]]

•

DEFINE TYPE type-name [type-clause[, ... ]]

•

DEFINE VERB verb-name [verb-clause[, ... ]]

•

IDENT ident-string

•

MODULE module-name

The following subsections provide an overview of each CDU statement. See
the CDU FUes Statements section for more detailed descriptions of each type
of statement.

4.1

Defining Syntax
The DEFINE SYNTAX statement allows a command verb to use alternative
syntax depending on the parameters, qualifiers, and keywords that are present
in the command string. It redefines the syntax for a command verb previously
defined by a DEFINE VERB or DEFINE TYPE statement, or it may be used
to redefine the syntax for a command verb redefined by a previous DEFINE
SYNTAX statement.
To define a syntax change, you must provide two DEFINE statements: a
primary DEFINE statement and a secondary DEFINE statement. The primary
DEFINE statement defines the affected command verb and it must include
a SYNTAX=syntax-name verb clause to point to the secondary DEFINE
statement. The secondary DEFINE statement defines the alternate syntax.
For example, you can write a command definition that uses a different syntax
for a command verb when a particular qualifier is present. When you include
the specified q~alifier in the command string, the syntax defined in the
secondary DEFINE statement applies to the command verb described by the
primary DEFINE statement.
This is the format for the DEFINE SYNTAX statement:
DEFINE SYNTAX syntax-name [verb-clause,[, ... ]]

The syntax-name verb clause is the name of the alternate syntax definition.
The verb clause specifies addjtional information about the syntax. You can
use the same verb clauses in a DEFINE SYNTAX statement as are allowed
in a DEFINE VERB statement, with one exception. You cannot use the
SYNONYM verb clause with DEFINE SYNTAX.
The following example shows how a syntax change is used to specify an
alternate command syntax when the /LINE qualifier is specified.

CDU-5

CDU Description

DEFINE VERB ERASE
IMAGE "DISK1: [MYDIR] ERASE"
QUALIFIER SCREEN
QUALIFIER LINE, SYNTAX=LINE 0
DEFINE SYNTAX LINE fJ
IMAGE "DISK1: [MYDIR]LINE"
QUALIFIER NUMBER, VALUE(REQUIRED)

4.2

The DEFINE VERB statement defines the verb ERASE. This verb accepts
two qualifiers, /SCREEN and /LINE. The qualifier /LINE uses an
alternate syntax, specified with the SYNTAX=LINE clause. If you issue
the command ERASE/LINE, the definitions in the DEFINE SYNTAX
LINE statement override the definitions in the DEFINE VERB ERASE
statement. However, if you issue the command ERASE/SCREEN, or if
you do not specify any qualifiers, the definitions in the DEFINE VERB
ERASE statement apply.

The DEFINE SYNTAX statement defines an alternate syntax called LINE.
If you issue the command ERASE with the /LINE qualifier, the image
DISKl :[MYDIR]LINE.EXE is invoked. The new syntax allows the qualifier
/NUMBER, which requires a value.

Defining Values
To define values for parameters, qualifiers, or keywords, use the VALUE
clause. When you use the VALUE clause, you can further define the value
type with the TYPE clause.
With the TYPE clause, you can specify that a value type must be a builtin type (for example, a file specification) or you can specify that a value
must be a user-defined keyword. Section 4.2.1 lists the built-in value types;
Section 4.2.2 describes how to specify a user-defined keyword.
When you use the VALUE clause and do not define a value type, DCL
processes the value in the following way. If the value is not enclosed in
quotation marks, then DCL converts letters to uppercase and compresses
multiple spaces and tabs to a single space. If the value is enclosed in
quotation marks, then DCL removes the quotation marks, preserves the
case of letters, and does not compress tabs and spaces. To include quotation
marks within a quoted string, use two sets of quotation marks(" ")in the
place you want the quotation marks to appear.
4.2.1

CDU-6

Built-In Value Types
The Command Definition language provides the following built-in value
types:

CDU Description

$ACL

The value must be an access control list.

$DATETIME

The value must be an absolute time or a combination
time. DCL converts truncated time values, combination
time values, and keywords for time values (such as
TODAY) to absolute time format. DCL fills blank date
fields from the current system date and fills omitted time
fields with zeros.

$DELTATIME

The value must be a delta time. DCL fills missing fields
with zeros.

$FILE

The value must be a valid file specification which may
include wildcard characters.

$NUMBER

The value must be an integer represented by either
decimal, octal, or hexadecimal numbers.

$QUOTED_STRING

The value must be a quoted string. Note that DCL does
not remove the quotation marks.

$REST_OF_LINE

DCL treats the rest of the line literally as the specified
value ignoring spaces or punctuation marks. DCL does
not remove quotation marks when processing the string.

The following example shows a parameter that must be specified as a file
specification:
DEFINE VERB PLAY
IMAGE "DISK1: [MYDIR] PLAY"
PARAMETER P1, VALUE(TYPE=$FILE)

4.2.2

User-Defined Keywords
The DEFINE TYPE statement defines keywords that are acceptable for use as
values for various command entities including parameters, qualifiers, or other
keywords.

To indicate that a command entity requires a keyword, use a VALUE clause
of the following form in a definition statement:
DEFINE SYNTAX V ALUE(TYPE=type-name)

The variable type-name points to the DEFINE TYPE statement that specifies
the allowable keywords for the entity.
This is the format for the DEFINE TYPE statement:
DEFINE TYPE type-name [type-clause[, ... ]]

The type-name variable is the name of the keyword list, and the type-clause
variable lists the acceptable keywords. Each type clause begins with the
keyword KEYWORD followed by one or more keywords that can be used
with the parameter, qualifier, or keyword that references the keyword list.
The next example includes two type-clauses in the DEFINE VERB statement:
KEYWORD FAST, DEFAULT
KEYWORD SLOW

The example illustrates the use of a DEFINE TYPE statement in conjunction
with a DEFINE VERB statement:

CDU-7

CDU Description

DEFINE VERB SKIM0
IMAGE "USER: [TOOLS] SKIM"
QUALIFIER SPEED, VALUE(TYPE=SPEED_KEYWORDS)@
DEFINE TYPE SPEED_KEYWORDSC)
KEYWORD FAST, DEFAULT
KEYWORD SLOW

4.3

The DEFINE VERB statement defines a verb, SKIM, which invokes the
image [TOOLS]SKIM.EXE and accepts the qualifier /SPEED.

The VALUE clause indicates that the qualifier /SPEED accepts a list
of keywords as defined by the DEFINE TYPE SPEED_KEYWORDS
statement.

The DEFINE TYPE statement lists the keywords that can be used
with the qualifier /SPEED; you can specify SKIM/SPEED=FAST or
SKIM/SPEED=SLOW. If you specify the qualifier /SPEED without a
value, the default is FAST.

Defining Command Verbs
The DEFINE VERB statement defines a new command verb and specifies its
characteristics. You can define any number of verbs in a single command
definition file.
The format for the DEFINE VERB statement is as follows:
DEFINE VERB verb-name [verb-clause(, ... ]]

The verb name is the name of the command. A verb clause specifies
additional information about the verb. Verb clauses can appear in any
order in the command definition file. Verb clauses are optional.
You can specify the following verb clauses:
DISALLOW

Controls the use of an entity or a combination of entities.

NODISALLOWS

Permits all entities and entity combinations.

IMAGE

Specifies an image to be invoked by the verb.

PARAMETER

Defines a command parameter.

NOP ARA METERS

Disallows parameters.

QUALIFIER

Defines a command qualifier.

NOQUALIFIERS

Disallows qualifiers.

ROUTINE

Specifies a routine to be invoked by the verb.

SYNONYM

Specifies a verb synonym.

The following example illustrates a DEFINE VERB statement:
DEFINE VERB SEARCH 0
IMAGE "SEARCH" @
PARAMETER P1, LABEL=SOURCE, PROMPT="File", VALUE(REQUIRED) C)

CDU-8

The DEFINE VERB statement names the verb "SEARCH."

The IMAGE verb clause identifies the image to be invoked at run time.

CDU Description

4.4

The PARAMETER verb clause defines the first parameter to appear after
the verb in the command string. LABEL, PROMPT, and VALUE are
parameter clauses that further define the parameter. LABEL defines a
name that the image uses to refer to the parameter. PROMPT indicates
the prompt string to be issued if you do not specify the parameter in the
command string. VALUE uses the REQUIRED clause to indicate that the
parameter must be present in the command string.

Disallowing Entity Combinations
When you define a verb, you can use the DISALLOW verb clause to
selectively disallow the use of one or more entities with the verb.
The DISALLOW verb clause has the following format:
DISALLOW expression

The variable expression in the clause specifies the disallowed entities and
you may use any of the various logical operators (exclusive-OR, AND, OR,
and so forth) to define them. When a command string is parsed, each entity
in the expression is tested to determine if the entity is present (true) or absent
(false). If an entity is present by default but is not explicitly present in the
command string, the entity is evaluated as absent (false).
After each entity is evaluated, the logical operations are performed. If the
result is true, the command string is disallowed. If the result is false, the
command string is valid.
For example, a command definition may contain a DEFINE VERB statement
that defines the verb SPORTS with three qualifiers: /TENNIS, /BOWLING,
and /BASEBALL. However, you may want to make the qualifiers mutually
exclusive. The following example shows how to use the DISALLOW verb
clause to put this restriction into the command definition file:
DEFINE VERB SPORTS
IMAGE
QUALIFIER
QUALIFIER
QUALIFIER
DISALLOW

"DISK3: [WILSON] SPORTS"
TENNIS
BOWLING
BASEBALL
ANY2(TENNIS, BOWLING, BASEBALL)

The DISALLOW verb clause indicates that a command string is invalid
if it contains more than one of the qualifiers /TENNIS, /BOWLING, or
/BASEBALL.
Note that when you specify any entity in a DISALLOW expression, the search
context is the entire command string. Therefore, local qualifiers are treated
as if they were global for the purposes of the DISALLOW processing. The
following example shows the global context of the search:
DEFINE VERB TEST
IMAGE
PARAMETER
PARAMETER
QUALIFIER
QUALIFIER
QUALIFIER
DISALLOW
DISALLOW

"DISK3: [WORK] TEST"
Pi
P2
QUALi
QUAL2,POSITION=LOCAL
QUAL3,POSITION=LOCAL
Pi AND QUALi
QUAL2 AND QUAL3

CDU-9

CDU Description

Thus, the following two commands would be disallowed:
TEST P1 P2/QUAL1
TEST P1/QUAL2 P2/QUAL3

The global search context applied to local qualifiers is used only with
DISALLOW processing, not with normal command parsing.
4.4.1

Specifying Expression Entities
When you specify entities in an expression, you need to uniquely identify
the entities that are disallowed. You can specify an entity using one of the
following:

•

A parameter, qualifier, or keyword name or label

•

A keyword path

•

A definition path

Names and Labels

You can refer to a parameter or qualifier using its name or label if the entity
is defined in the current definition. To refer to a keyword, you can use its
name or label if the keyword is in a keyword path that starts from the current
definition, and if the keyword name or label is unique. (See the next section
for more information about keyword paths.)
If the LABEL=label-name keyword is used to assign a label to an entity, use

the label name to refer to the entity. Otherwise use the entity name.
The following example disallows combinations of entities:
DEFINE VERB COLOR
IMAGE "WORK: [JUDY] COLOR"
QUALIFIER RED
QUALIFIER BLUE
QUALIFIER GREEN, VALUE(TYPE=GREEN_AMOUNT)
DISALLOW RED AND ALL
DISALLOW BLUE AND ALL
DEFINE TYPE GREEN_AMOUNT
KEYWORD ALL
KEYWORD HALF

In this example, you can use the qualifier names RED and BLUE in the
DISALLOW verb clause because both names are used in the current
definition. You can use the keyword ALL because it is in a keyword path
which starts within the current definition (the TYPE=GREEN _AMOUNT
qualifier clause starts the path) and the keyword name is unique.
The DISALLOW clauses indicate that the following command strings are not
valid:
$ COLOR/RED/GREEN=ALL
$ COLOR/BLUE/GREEN=ALL

To refer to a parameter or qualifier in another definition, or to refer to a
keyword whose path begins in another DEFINE statement, you must use a
definition path.

CDU-10

CDU Description

Keyword Paths

A keyword path provides a way to uniquely identify a keyword. You can
refer to a keyword using a keyword path if the keyword is in a path that
starts from the current definition, and the keyword name or label is not
unique. You can also use a keyword path if the same keyword can be used
with more than one parameter or qualifier.
A keyword path contains a list of entity names or labels that are separated by
periods. The first name in a keyword path is the name (or label) of the first
entity that references the keyword's value type definition. A keyword path
can contain up to eight names (the first parameter or qualifier definition, plus
seven DEFINE TYPE keyword definitions).
If a keyword is assigned a label name, use the label name in the keyword
path. Otherwise, use the keyword name. You can omit names that are not
needed to resolve a keyword reference from the beginning of a keyword
path. However, you must include enough names to uniquely reference the
keyword.

The following command string illustrates a situation that requires keyword
paths to uniquely identify keywords. In this command string, you can use the
same keywords with more than one qualifier. (In the command definition file
two qualifiers refer to the same DEFINE TYPE statement.)
$ NEWCOMMAND/QUAL1=(START=5,END=10)/QUAL2=(START=2,END=5)

The keyword path QUALl.START identifies the keyword START when it is
used with QUALl; the keyword path QUAL2.START identifies the keyword
START when it is used with QUAL2. The name START is an ambiguous
reference if used alone.
To disallow use of the keyword QUALl.START when a third qualifier
(QUAL3) is present, use the following line in the command definition file:
DISALLOW OUAL 1.ST ART AND OUAL3

Although you cannot use QUALl.START when QUAL3 is present, you can
still use QUAL2.START with QUAL3.
The following example contains a keyword (ALL) that appears in two DEFINE
TYPE statements:
DEFINE VERB COLOR
IMAGE "WORK: [JUDY] COLOR"
QUALIFIER RED, VALUE(TYPE=RED_AMOUNT)
QUALIFIER GREEN, VALUE(TYPE=GREEN_AMOUNT)
DISALLOW RED AND GREEN.ALL
DISALLOW GREEN AND RED.ALL
DEFINE TYPE RED_AMOUNT
KEYWORD ALL
KEYWORD MIXED
DEFINE TYPE GREEN_AMOUNT
KEYWORD ALL
KEYWORD HALF

In this example, you must use the keyword path RED.ALL to refer to the ALL
keyword when it is used in the value type definition RED-AMOUNT; you
must use the keyword path GREEN .ALL to refer to the ALL keyword when it
is used in the value type definition GREEN _AMOUNT.

CDU-11

CDU Description

Definition Paths

A definition path links a syntax definition to an entity that is defined in
another DEFINE statement. For example, a definition path is needed when a
syntax definition provides new disallow clauses for parameters or qualifiers
that are defined in a primary definition.
A definition path has the following format:
<definition-name> entity-spec

The definition name is the name of the DEFINE statement where the entity is
defined or the keyword path begins. The entity specification can be an entity
name, a labet or a keyword path. The angle brackets are required.
For example:
DISALLOW

<SKIP> FIRST

This clause disallows a command string if the entity FIRST (specified in the
DEFINE VERB statement for the command verb SKIP) is present.
The next example uses a keyword path and a definition path:
DISALLOW

<FILE> BILLS.ELECT AND GAS

This clause disallows a command string if the entity described by the keyword
path BILLS.ELECT (which originates in the DEFINE VERB statement for the
command verb FILE) is present.
The CDU does not check a definition path to determine that the path refers
to an entity that is valid in a given context. If you use a definition path
to specify an entity that is not valid in a particular context, results are
unpredictable. For example, if you try to disallow the qualifier NOTES in
the DEFINE SYNTAX statement, the entity NOTES would not be recognized
as valid because the path to BILL_TYPES is not established in the DEFINE
VERB statement for the command verb READ.
DEFINE VERB FILE
QUALIFIER BILLS, SYNTAX=BILL_TYPES
QUALIFIER RECEIPTS
DEFINE VERB READ
QUALIFIER NOTES
DEFINE SYNTAX BILL_TYPES
DISALLOW <FILE>RECEIPTS

Although the DISALLOW clause correctly identifies an entity in the command
definition file, this entity is not valid in the DEFINE SYNTAX statement.
However, the clause DISALLOW <FILE> RECEIPTS is valid in the DEFINE
SYNTAX statement. The DEFINE SYNTAX statement inherits the qualifier
RECEIPTS from the primary DEFINE statement (FILE) because no qualifiers
are specified.
See the description of the DEFINE SYNTAX statement in the CDU Files
Statements section for more information about how entities are inherited by
DEFINE SYNTAX statements.

CDU-12

CDU Description

4.4.2

Operators
A command definition may include one or more expressions of the
relationship between an action verb and one or more objects of the
verb (entities) that may be qualifiers, parameters or keywords in various
combinations. For example, the following expression states that the command
is disallowed if it contains both of the previously defined qualifiers SINCE and
BEFORE:
DISALLOW SINCE AND BEFORE

In the previous example, the logical operator, AND, stipulates that the
command is invalid only when both qualifiers are present. When an
expression contains logical operators, the operators are evaluated after the
related command entities are determined to be present (logical true) or absent
(logical false). If the result of the expression is true (that is, if both qualifiers
are present), the command is disallowed. Conversely, if the result is false
(one or none of the qualifiers is present), the command is accepted.
Table CDU-1 shows the operators you can use in command definition
expressions and the order in which the CDU evaluates these operators. The
highest precedence value is 1. When an expression contains two or more
operators of equal precedence, the CDU evaluates the leftmost operator first.
Table CDU-1

Summary of CDU Operators

Operator

Precedence

Meaning

ANY2

True if any two or more of the entities listed
are present.

NEG

True if the negated form of the entity is
present.

NOT

True if the entity is not present or if an entity
is present by default.

AND

True if both entities are present.

True if either entity is present.

The following example shows how to use the AND operator:
DISALLOW TERMINAL AND PRINTER

This statement disallows the command string if both entities (TERMINAL and
PRINTER) are present.
You can use parentheses to override the order in which operations are
evaluated; operations within parentheses are evaluated first. For example:
DISALLOW FAST AND (SLOW OR STILL)

The parentheses force the OR operator to be evaluated before the AND
operator. Therefore, if the result of SLOW OR STILL is true, and if FAST is
present in the command string, then the string is disallowed.

CDU-13

CDU Description

4. 5

Identifying Object Modules
Use the MODULE and IDENT statements to provide identifying information
if your command definition file is to create an object module. (You can create
an object module from a command definition file with the command SET
COMMAND /OBJECT. The object module contains a command table that you
can link with your program.)
The MODULE statement assigns a symbolic name to the object module
containing the command table. This is the format for the MODULE
statement:
MODULE module-name

The module-name is the symbolic name for the object module.
The IDENT statement provides additional information in a quoted string
format to identify the module. Typically, this might be the date the module
was created or the name of the creator. This is the format for the IDENT
statement:
IDENT ident-string

The ident-string is a quoted string having up to 31 characters.
The following sample command definition file illustrates the use of the
MODULE and IDENT statements:
MODULE TABLE 0
!DENT "Updated 4/15/84"

DEFINE VERB SAVE
C)
ROUTINE SAVE_ROUT
DEFINE VERB GET
C)
ROUTINE GET_ROUT

The MODULE statement assigns the name TABLE to the command
table that the CDU creates when you use the command SET
COMMAND /OBJECT to develop an object module for the new
command.

The IDENT statement provides additional identifying information. In
this example it shows the date when the command definition file was
updated.

The DEFINE VERB statements define command verbs that can be used by
the main program to invoke appropriate routines.

Processing Command Definition Files
A command definition file must be translated into an executable command
table before the commands in the table can be parsed and executed. To
perform this translation, use the DCL command SET COMMAND to invoke
the Command Definition Utility.

CDU-14

CDU Description

The command SET COMMAND has the following modes:
SET COMMAND /DELETE

Deletes command definitions from a command
table

SET COMMAND /OBJECT

Creates an object file from a command definition
file

SET COMMAND /REPLACE

Adds or replaces definitions in a command table
using definitions from a command definition file

The /DELETE, /OBJECT, and /REPLACE qualifiers are mutually exclusive;
you can use only one SET COMMAND mode in a command string. In
addition to the qualifiers that specify modes, SET COMMAND provides the
following qualifiers:
/[NO]LISTING

Controls whether an output listing is created

/[NO]OUTPUT

Controls where the modified command table should be written

/TABLE

Specifies the command table that is to be modified

See the SET COMMAND Qualifiers section for additional information.

5. 1

Adding Command Definitions to a Command Table
Use the /REPLACE qualifier to add or replace verbs in the command table.
By default, SET COMMAND uses the /REPLACE mode to add commands
to your process command table and to return the modified command table to
your process.
The following example shows how to add the new command SKIP to your
process command table:
$ SET COMMAND SKIP

In this example, SET COMMAND adds the definitions from the command
definition file SKIP.CLO to your process command table. The modified table
replaces your original process command table. The /REPLACE qualifier is
present by default, so you do not need to explicitly specify it in the command
string.
To modify a command table other than your process table, use the /TABLE
qualifier and the /OUTPUT qualifier.

5.2

Deleting Command Definitions
Use the /DELETE qualifier to delete a command name from a command
table. By default, commands are deleted from your process command table.
The following example shows how to delete the command SKIP from your
process command table:
$ SET COMMAND/DELETE=SKIP

CDU-15

CDU Description

5.3

Creating Object Modules
Use the /OBJECT qualifier to create an object module from a command
definition file. When you enter the following example command, the
CDU creates an object module containing a command table with the verb
definitions in NEWCOMS.CLD:
$ SET COMMAND/OBJECT NEWCOMS

You can then link NEWCOMS.CLD with a program that parses commands
using the new command table.

5.4

Creating New Command Tables
You cannot use the /OBJECT qualifier to create an object module from a
command definition file that contains the IMAGE clause. However, you can
create an empty command table to which you can add verbs that invoke
images. The following is a step-by-step example of how to do this:

Create an empty command table by developing a command definition
file that contains only a MODULE statement to define the module name
and an IDENT statement. In the following example, the CDU creates
the empty command table, TEST_TABLE, from a command definition file
named TEST_TABLE.CLD:
MODULE TEST_TABLE
IDENT "New command table"

Create an object module (TEST_TABLE.OBJ) from TEST_TABLE.CLO:
$SET COMMAND/OBJECT TEST_TABLE.CLD

Link TEST_TABLE.OBJ to create a shareable image, TEST_TABLE.EXE:
$ LINK/SHARE TEST_TABLE

Create a command definition file that defines verbs that invoke images. In
the following example, the command definition file VERBS.CLD includes
two statements that call existing images:
DEFINE VERB PASS
IMAGE "DISK4: [ROSEN] PASS"
DEFINE VERB THROW
IMAGE "DISK4: [ROSEN] THROW"

Add the new commands in VERBS.CLO to the empty command table
in TEST_TABLE.EXE, and write the modified table back to the file
TEST_TABLE.EXE. The /TABLE and /OUTPUT qualifiers specify the
input and output table files. For example:
$ SET COMMAND/TABLE=TEST_TABLE.EXE/OUTPUT=TEST_TABLE.EXE VERBS

Note that the version number of the output file is one greater than the
version number of the input file. If you do not explicitly specify an
output file using the /OUTPUT qualifier, the CDU replaces your process
command table with the modified command table.
CDU-16

CDU Description

Using Command Language Routines
A program invoked by a command that you have added to your process
(or system) command table needs information about the command string
that invoked it. The program can obtain this information by calling the
appropriate Command Language routine:
CLl$PRESENT

Determines if an entity is present in the command string.

CLl$GET_VALUE

Gets the value of the next entity in the command string.

CLl$DCL_PARSE

Parses a command string.

CLl$DISP A TCH

Invokes the routine which corresponds to the verb most
recently parsed.

When you use the CDU to add a new command, use the CLI$PRESENT and
CLI$GET_VALUE routines from the program invoked by the command to get
information about the command string that called the program.
When you use the CDU to create and link an object module that includes
a command table, use the CLI$DCL_pARSE and CLI$DISPATCH routines
to parse the command string and to execute the command. Then use the
CLI$PRESENT and CLI$GET_VALUE routines within the routines that
execute the command.
The Examples section shows two programs that call these routines. For
more information about the command language routines, see the VMS Utility

Routines Manual.

CDU-17

CDU Usage Summary
The Command Definition Utility (CDU) creates, deletes, or changes
command definitions in a command table. The CDU uses either an existing
command table, a file that contains command definitions, or a combination
of these, to create a new command table. The output table can be part of
an executable image or an object module.
You invoke the CDU with the DCL command SET COMMAND together
with the appropriate qualifiers.

FORMAT

SET COMMAND [filespec[, ... ]]

COMMAND
PARAMETER

filespec[, ... ]
Specifies the name of one or more command definition files (default file type
CLD). If you specify two or more files, separate them with commas.
Wildcard characters are allowed in the file specification.

usage summary
Use the DCL command SET COMMAND to invoke the CDU. SET
COMMAND has the following modes:
SET COMMAND /DELETE

Deletes command definitions from a command
table.

SET COMMAND /OBJECT

Creates an object module from a command
definition file.

SET COMMAND /REPLACE

Adds or replaces definitions in a command table
using definitions from a command definition file.

The /DELETE, /OBJECT, and /REPLACE qualifiers establish the various SET
COMMAND modes and are mutually exclusive; that is, you can use only one
of these qualifiers in a command string.
The DCL prompt reappears on your screen when the CDU finishes processing
the command definition file and/ or table.
By default, SET COMMAND /DELETE and SET COMMAND /REPLACE
modify your process command table and return the modified table to your
process. You can modify a different input command table by using the
/TABLE command qualifier.
Note: To modify the system command table in SYS$LIBRARY:DCLTABLES.EXE
you need CMKRNL privilege.
You can write the command table to an output file by using the /OUTPUT
command qualifier.
SET COMMAND/OBJECT creates an object module with the same name as
the command definition file unless you specify an alternate file name.

CDU-18

CDU File Statements
CDU File Statements

CDU FILE
STATEMENTS

This section provides complete information about the statements that can be
used in a command definition file. The statements are as follows:
DEFINE SYNTAX syntax-name [verb-clause[, ... ]]
DEFINE TYPE type-name [type-clause[, ... ]]
DEFINE VERB verb-name [verb-clause[, ... ]]
IDENT ident-string
MODULE module-name

CDU-19

CDU File Statements
DEFINE SYNTAX

DEFINE SYNTAX
Defines a syntax change that replaces a command's syntax (as defined in
a DEFINE VERB, DEFINE TYPE, or another DEFINE SYNTAX statement).
A syntax change allows a verb to use different syntax depending on the
parameters, qualifiers, and keywords that are present in the command
string.
DEFINE statements that refer to changed syntax are called primary DEFINE
statements; DEFINE SYNTAX statements that define new syntax are called
secondary DEFINE statements.
When a command string is parsed, its components are scanned from left
to right. The string is parsed according to the current definition until the
CDU encounters an entity that specifies a syntax change. The remainder
of the string is parsed using the new definition. DCL does not rescan the
entities that appear before the entity that specified the syntax change.
Table CDU-2 shows how the DEFINE SYNTAX statement modifies
the current command definition if an entity specifies a syntax change.
After parsing the command string, DCL saves the command definition to
determine if any entities in the command string are not allowed. Then,
DCL invokes the image or routine specified by the command definition and
uses the definition to process CLl$PRESENT and CLl$GET_VALUE calls.

Table CDU-2

CDU-20

How the DEFINE SYNTAX Statement Modifies the
Primary DEFINE Statement

DEFINE SYNTAX Specifies

Result

An image

An image overrides the image in the primary
DEFINE statement. DCL invokes the new
image after it parses the command string.

A routine

A routine overrides the routine in the
primary DEFINE statement. DCL invokes the
new routine when CLl$DISPATCH is called.

One or more disallows

One or more disallows are used during
command parsing and they override
disallows in the primary DEFINE statement.
This applies to all entities in the command
that have not been invalidated by the new
syntax definition.

No disallows

Disallows from the primary DEFINE
statement are used during command
parsing.

The NODISALLOWS clause

No disallows are permitted, regardless of
definitions in the primary DEFINE statement.

CDU File Statements
DEFINE SYNTAX

Table CDU-2 (Cont.)

How the DEFINE SYNTAX Statement Modifies
the Primary DEFINE Statement

DEFINE SYNTAX Specifies

Result

One or more parameters

Parameters that were already parsed
are not reparsed according to the new
definitions. However, parameters to the
right of the entity that specified the new
syntax are parsed according to the new
definitions. DCL uses the new parameter
definitions when processing CLl$PRESENT
and CLl$GET_VALUE calls.
Note that in the DEFINE SYNTAX
statement, P 1 refers to the first parameter
in the command string. To define additional
parameters, use the PARAMETER clause
in a secondary DEFINE statement to
first enter the definitons for the original
parameters exactly as they appear in the
primary DEFINE statement. Then, enter the
definitions for the additional parameters.

No parameters

Parameter definitions from the primary
DEFINE statement are used when DCL
parses the remainder of the command
string. DCL also uses these parameter
definitions when processing CLl$PRESENT
and CLl$GET_VALUE calls.

The NOPARAMETERS clause

Parameters previously parsed are not
reparsed to the new definitions. However,
no parameters are allowed when DCL
parses entities to the right of the entity
that specifies the new syntax. DCL uses
the NOP ARA METERS definition when
processing CL1$PRESENT and CLl$GET_
VALUE calls.

One or more qualifiers

The qualifiers previously parsed and the
qualifiers that specify the syntax change
are not affected. Qualifiers that appear
in the command string after the entity
that specifies the new syntax are parsed
according to the new definition. DCL
uses the new qualifier definitions when
processing CLl$PRESENT and CLl$GET_
VALUE calls.
When DCL parses a command string that
contains qualifiers that are ignored because
of a syntax change, DCL issues a warning
message.

CDU-21

CDU File Statements
DEFINE SYNTAX

Table CDU-2 (Cont.)

FORMAT

How the DEFINE SYNTAX Statement Modifies
the Primary DEFINE Statement

DEFINE SYNTAX Specifies

Result

No qualifiers

Qualifier definitions from the primary DEFINE
statement are used when DCL parses the
remainder of the command string. DCL
also uses these qualifier definitions when
processing CLl$PRESENT and CLl$GET_
VALUE calls.

The NOQUALIFIERS clause

Qualifiers previously parsed are ignored.
No qualifiers are allowed when DCL parses
entities to the right of the entity that
specifies the new syntax. DCL uses the
NOQUALIFIERS definition when processing
CLl$PRESENT and CLl$GET_VALUE calls.

DEFINE SYNTAX

syntax-name [verb-clause[, ... 11

syntax-name
The name of the syntax change. The name is required and must immediately
follow the DEFINE SYNTAX statement.

verb-clause[, . . . ]
Optional verb clauses that define attributes of the command string.
DEFINE SYNTAX accepts the following verb clauses:
•

DISALLOW, NODISALLOWS

•

IMAGE

•

PARAMETER, NOP ARAMETERS

•

QUALIFIER, NOQUALIFIERS

•

ROUTINE

The following text describes these clauses. Note that if the syntax list contains
only an IMAGE or ROUTINE clause, it affects only the specified clause in
the primary DEFINE statement. If the list contains any qualifiers or the
NOQUALIFIER keyword, all qualifiers in the primary DEFINE statement are
replaced by the qualifiers in the syntax list. If the syntax list contains neither
qualifiers nor the NOQUALIFIERS keyword, the qualifiers in the primary
DEFINE statement apply. Similarly, if the syntax list contains any parameter,
or the NOP ARAMETER keyword, all parameters in the primary DEFINE
statement are replaced.

DISALLOW expression
NOD/SALLOWS
Disallows a command string if the result of the expression is true. The
NODISALLOWS clause indicates that all entities and entity combinations are
allowed.

CDU-22

CDU File Statements
DEFINE SYNTAX

The variable expression specifies an entity or a combination of entities
connected by operators. Each entity in the expression is tested to see if it is
present (true) or absent (false) in a command string. If an entity is present by
default but not explicitly provided in the command string, the entity is false.
After each entity is evaluated, the operations indicated by the operators are
performed. If the result is true, the command string is disallowed. If the
result is false, the command string is valid.
You can specify entities in an expression using an entity name or label, a
keyword path, or a definition path. See Section 4.4.1 for more information
about entities. You can also specify the operators AND, ANY2, NEG, NOT,
or OR. See Section 4.4.2 for more information about these operators.

IMAGE image-string
Names an image to be invoked by the command. The image-string
parameter is the file specification of the image (a maximum of 63 characters)
DCL invokes when you issue the command. The default device and directory
is SYS$SYSTEM: and the default file type is EXE.
If you do not specify the IMAGE verb clause and you use SET
COMMAND /REPLACE to process the command definition file, the verb
name is used as the image name. At run time, DCL searches for an image
whose file name is the same as the verb name and whose device and directory
names and file type are SYS$SYSTEM: and EXE, respectively.

PARAMETER param-name [,param-clause[, ... 11
NOPARAMETERS
May be used to specify up to eight parameters in the command string. The
NOP ARAMETERS clause indicates that no parameters are allowed.
The param-name is the position of the parameter in the command string.
The name must be in the form Pn, where n is the position of the parameter.
The parameter names must be numbered consecutively from Pl to PS. The
name must immediately follow the PARAMETER clause.
The param-clauses specify additional characteristics for the parameter. You
can use the following parameter clauses:
•

DEFAULT

•

LABEL=label-name

•

PROMPT=prompt-string

•

VALUE[(param-value-clause[, ... ])]

DEFAULT indicates that a user-defined parameter keyword is present by
default. You should use this clause only if you also use the VALUE clause to
indicate that a user-defined keyword must be specified as the parameter value.
See the description of the DEFINE TYPE statement for more information on
defining a keyword that is present by default.

To designate a default parameter that is not a keyword, use the
VALUE(DEFAULT=default-string) clause.
LABEL=label-name defines a label for referring to a parameter at run time.
Specify the label name as a symbol. If you do not specify a label name, the
parameter name (Pl through PS) is used as the label name.

CDU-23

CDU File Statements
DEFINE SYNTAX

PROMPT=prompt-string supplies a prompt string (31 characters maximum)
when a parameter is omitted from the command string. If you do not specify
a prompt string and a required parameter is missing, DCL uses the parameter
name as the prompt string.
When you define more than one parameter but only the first parameter is
required, DCL prompts for the first parameter until the user either types a
value or aborts the command with a CTRL/Z. When the user enters a value
for the first parameter, DCL prompts for the optional parameters. If the user
presses the return key without entering a value for an optional parameter,
DCL executes the command.
VALUE[(param-value-clause[, ... ])] specifies additional characteristics for
the parameter. When you specify parameter value clauses, enclose them in
parentheses and separate items with commas.
VALUE accepts the following parameter value clauses:
CONCA TENA TE

Indicates that a parameter can be concatenated
to another parameter with a plus sign.

DEFAULT=default-string

Specifies a default value to be used in the
absence of an explicit parameter value. The
DEFAULT clause and the REQUIRED clause are
mutually exclusive. Specify the default string
as a character string that does not exceed 95
characters.
Do not use this clause to specify a default
if the value is a keyword; specify keyword
defaults in the DEFINE TYPE statement and by
using the DEFAULT clause.

LIST

Permits you to enter a list of parameters
separated by commas or plus signs.

NOCONCATENATE

Indicates that the parameters cannot be
concatenated.

REQUIRED

Indicates that the parameter is required. All
required parameters must precede optional
ones. If you use the REQUIRED clause, you
should also specify a prompt string.
The REQUIRED clause and the DEFAULT clause
are mutually exclusive.

TYPE=type-name

Gives either a built-in value type or the name
of a DEFINE TYPE statement that defines a
list of keywords that can be specified for the
parameter. Specify the value type name as a
symbol.
See Section 4.2.1 for more information about
built-in value types.

QUALIFIER qual-name [,qual-clause[, ... 11
NOQUALIFIERS
Specifies a qualifier that can be included in the command string. You can use
the QUALIFIER clause up to 255 times in a DEFINE SYNTAX statement. The
NOQUALIFIERS clause indicates that no qualifiers are allowed.

CDU-24

CDU File Statements
DEFINE SYNTAX

The qual-name is the name of the qualifier. Specify the qualifier name as a
symbol. The first four characters of the qualifier name must be unique.
The qual-clause specifies additional qualifier characteristics. You can use the
following qualifier clauses:

•
•
•

BATCH
DEFAULT
LABEL=label-name

•
•
•

PLACEMENT=placement-clause

•

VALUE[(qual-value-clause[, ... ])]

NEGATABLE, NONNEGATABLE
SYNTAX=syntax-name

BATCH indicates that the qualifier is present by default if the command is
used in a batch job.
DEFAULT indicates that the qualifier is present by default in both batch and
interactive jobs.
LABEL=label-name defines a label for requesting information about the
qualifier at run time. Specify the label name as a symbol. If you do not
specify a label name, the qualifier name is used as the label name.
NEGA TABLE and NONNEGA TABLE indicate whether the qualifier can be
negated by adding "NO" to the qualifier name. The default is NEGATABLE;
if you do not specify either NEGATABLE or NONNEGATABLE, "NO'' can be
added to the qualifier name to indicate that the qualifier is not present.
PLACEMENT=placement-clause indicates where the qualifier can appear in
the command string. PLACEMENT accepts the following placement clauses:
GLOBAL

Indicates that the qualifier applies to the entire command and
can be placed after the verb or after a parameter. This is the
default if you do not specify the PLACEMENT clause.

LOCAL

Indicates that the qualifier can appear only after a parameter
value and that it applies only to that parameter.

POSITIONAL

Indicates that the qualifier can appear anywhere in the
command string, but the meaning of the qualifier depends
on its position: if the qualifier is used after a parameter value,
it applies only to that parameter; if it is used after the verb,
the qualifier applies to all parameters.

SYNT AX=syntax-name specifies an alternate syntax definition to be invoked
when the qualifier is present. The syntax name must correspond to the name
used in a DEFINE SYNTAX statement. Specify the syntax name as a symbol.
VALUE[(qual-value-clause[, ... ])] specifies additional characteristics for
the qualifier. When you specify qualifier value clauses, enclose the list
in parentheses and separate items with commas. If you do not specify
any qualifier value clauses, then DCL converts letters in qualifier values to
uppercase.

CDU-25

CDU File Statements
DEFINE SYNTAX

VALUE accepts the following clauses:
DEFAULT=default-string

Specifies a default value to be used if a value
for the qualifier is not explicitly given. The
DEFAULT clause and the REQUIRED clause are
mutually exclusive. Specify the default string
as a character string that does not exceed 95
characters.
Do not use this clause to specify a default
if the value is a keyword; specify keyword
defaults in the DEFINE TYPE statement, and by
using the DEFAULT qualifier clause.

LIST

Indicates that a list of values separated by
commas can be specified for the qualifier. This
list must be enclosed in parentheses, and the
items must be separated by commas. Note
that plus signs cannot be used to separate
items in a list of qualifier values.

REQUIRED

Indicates that the qualifier must have an
explicit value. No prompting is performed for
a required qualifier value. The REQUIRED and
the DEFAULT clauses are mutually exclusive.

TYPE=type-name

ROUTINE routine-name
Names a routine in syntax. Use the ROUTINE clause to create an object
module from the command definition file.
The routine-name provides the name of the routine to be executed when
CLI$DISP ATCH is called. Specify the routine name as a symbol.
If you do not specify a routine, the routine from the primary DEFINE
statement is invoked, if applicable.

CDU-26

CDU File Statements
DEFINE SYNTAX

EXAMPLES
i] DEFINE VERB WRITER
IMAGE "WORK: [JONES] WRITER"
QUALIFIER LINE, SYNTAX=LINE
QUALIFIER SCREEN, SYNTAX=SCREEN
DEFINE SYNTAX LINE
IMAGE "WORK: [JONES] LINE"
QUALIFIER NUM
DEFINE SYNTAX SCREEN
IMAGE "WORK:[JONES]SCREEN"
QUALIFIER AUDIT

This example illustrates a command definition file (WRITER.CLO) containing
DEFINE SYNTAX statements that cause syntax changes depending upon the
qualifiers specified in the command string. The verb WRITER invokes a text
editor (WRITER.EXE). However, you can use the SCREEN and the LINE
qualifiers to invoke alternate text editors.
You can add the command definition to your process command table by
issuing the following command:
$ SET COMMAND WRITER

Then you can use the WRITER command to access different text editors. For
example, assume you specify the following command:
$ WRITER/LINE

Here you invoke the LINE editor instead of the default editor (WRITER).
Syntax redefinition is done from left to right because parsing of the string is
done from left to right. This order means that when you specify two qualifiers
that invoke different syntax lists, the leftmost qualifier takes precedence (since
it is parsed first).
~

DEFINE VERB DISPLAY
PARAMETER Pi, LABEL=ITEM, VALUE(REQUIRED, TYPE=$FILE)
QUALIFIER SAVE, SYNTAX=SAVE
DEFINE SYNTAX SAVE
IMAGE "WORK: [NEWMAN] :SAVE_DISPLAY"
PARAMETER Pi, LABEL=ITEM, VALUE(REQUIRED, TYPE=$FILE)
PARAMETER P2, LABEL=NAME

This example shows a syntax change that defines an additional parameter.
The command definition file defines the verb DISPLAY. If the DISPLAY
command is used without the qualifier /SAVE, then one parameter is
required. This parameter indicates the name of the file to be displayed. If the
DISPLAY command is used with the qualifier /SAVE, then two parameters
are required: the name of the file to be displayed and the name of the file
where the display should be saved. Note that you must repeat the definition
of Pl in the DEFINE SYNTAX statement.

CDU-27

CDU File Statements
DEFINE TYPE

DEFINE TYPE
Describes the keywords referenced by the V ALUE(TYPE=type-name)
clause. You can use the VALUE clause in a DEFINE VERB, DEFINE
SYNTAX, or DEFINE TYPE statement to indicate predefined values
(keywords) for command parameters, qualifiers, or keywords.

FORMAT

DEFINE TYPE

name {type-clause[, ... ]]

name
The name of the DEFINE TYPE statement. This name must match the name
used in the VALUE(TYPE=type-name) clause that references the DEFINE
TYPE statement.

type-clause[, . . . ]
Defines a keyword that can be used as the value of the entity that referenced
the DEFINE TYPE statement. The DEFINE TYPE statement accepts the
following type clause:
KEYWORD keyword-name [,keyword-clause[, ... ]]

This clause specifies a keyword that can be used as the value type of the
entity that references the DEFINE TYPE statement. Repeat the KEYWORD
value type clause for each keyword that can be used. You can specify up to
255 keywords in a DEFINE TYPE statement.
The keyword-name is the name of the keyword. The optional keywordclause specifies additional keyword characteristics.
You can use the following keyword clauses:
•

DEFAULT

•

LABEL=label-name

•

NEGATABLE, NONNEGATABLE

•

SYNTAX=syntax-name

•

VALUE[(key-value-clause[, ... ])]

DEFAULT indicates that the keyword is present by default. For this keyword
to be recognized as present by default, the parameter, qualifier, or keyword
definition that references this DEFINE TYPE statement must also specify the
DEFAULT clause.
LABEL=label-name defines a label for referencing the keyword at run time.
By default, the keyword name is used as the label name.
NEGA TABLE and NONNEGA TABLE indicate whether the keyword
can be negated by adding ,;NO" to the keyword name (the default
is NONNEGATABLE). If you do not specify either NEGATABLE or
NONNEGATABLE, "NO" cannot be used to negate the keyword name.
Note that this differs from qualifiers which, by default, are negatable.
SYNT AX=syntax-name specifies an alternate verb definition to be invoked
when the keyword is present. The syntax name must match the name used
in the corresponding DEFINE SYNTAX statement.
CDU-28

CDU File Statements
DEFINE TYPE

VALUE((key-value-clause[, ... ])] specifies additional characteristics for the
keyword.
VALUE accepts the following value clauses:
DEFAULT=default-string

Specifies a default value to be used if a value
for the keyword is not explicitly given. The
DEFAULT clause and the REQUIRED clause
are mutually exclusive. Specify the default
string as a character string that does not
exceed 95 characters.

Note: Do not use this clause to specify a
default if the value is a keyword; specify
keyword defaults in the DEFINE TYPE
statement, and by using the DEFAULT
clause with the entity that uses the
keyword.
LIST

Indicates that a list of values for the keyword
may be given. This list must be enclosed in
parentheses and separated by commas. Note
that plus signs may not be used to separate
items in a list of keyword values.

REQUIRED

Indicates that the keyword must have an
explicitly specified value. No prompting is
performed for a required keyword value. If
the keyword is specified without a value, an
error is automatically issued by DCL. The
REQUIRED clause and the DEFAULT clause
are mutually exclusive.

TYPE=type-name

Symbolically equates either a built-in value
type or the name of a DEFINE TYPE
statement that defines keywords that can be
specified as the keyword value. The TYPE
clause cannot be specified if the DEFAULT
clause is specified.
See Section 4.2.1 for more information about
built-in value types.

EXAMPLES
iJ

DEFINE VERB DISPLAY
PARAMETER P1, LABEL=OPTION, PROMPT="What"
VALUE(REQUIRED, TYPE=DISPLAY_OPTIONS)
DEFINE TYPE DISPLAY_OPTIONS
KEYWORD ANIMALS, SYNTAX=DISPLAY_ANIMALS
KEYWORD FLOWERS, SYNTAX=DISPLAY_FLOWERS
DEFINE SYNTAX DISPLAY_ANIMALS
IMAGE "USER: [JOHNSON]ANIMALS"
PARAMETER P1, LABEL=OPTION, VALUE(REQUIRED)
QUALIFIER SMALL
QUALIFIER LARGE
QUALIFIER ALL, DEFAULT

CDU-29

CDU File Statements
DEFINE TYPE

DEFINE SYNTAX DISPLAY_FLOWERS
IMAGE "USER: [JOHNSON]FLOWERS"
PARAMETER P1, LABEL=OPTION, VALUE(REQUIRED)
NOQUALIFIERS

This example shows how to define keywords that can be specified as
parameters for the verb DISPLAY. Each keyword uses its own syntax
definition to invoke an image to execute the command.
After you add the command definition to your process command table, you
can issue the following DISPLAY commands:
$ DISPLAY ANIMALS
$ DISPLAY FLOWERS

In addition, the syntax definition DISPLAY_ANIMALS specifies three
qualifiers that can be used only with the command DISPLAY ANIMALS.
No qualifiers are allowed with the command DISPLAY FLOWERS.
~

DEFINE VERB DRAW
QUALIFIER COLOR, TYPE=COLOR_NAMES
DEFINE TYPE COLOR_NAMES
KEYWORD RED
KEYWORD BLUE

This example shows a verb definition that uses a DEFINE TYPE statement
to define keywords that can be used with a qualifier. After you add the
command definition for DRAW to your process command table, you can issue
the following DRAW commands:
$ DRAW/COLOR=RED
$ DRAW/COLOR=BLUE

DEFINE VERB RANDOM
PARAMETER P1, VALUE(TYPE=THINGS), DEFAULT
DEFINE TYPE THINGS
KEYWORD NUMBER, DEFAULT
KEYWORD LETTER

This example defines a verb, RANDOM. RANDOM accepts a parameter,
which must be one of the user-defined keywords NUMBER or LETTER. If
a parameter is not specified with the verb RANDOM, then the default is
NUMBER.
Note that for the keyword NUMBER to be present by default, you must
use the DEFAULT clause in two places. You must specify DEFAULT when
you define the parameter in the DEFINE VERB statement. You must also
specify DEFAULT when defining the NUMBER keyword in the DEFINE
TYPE statement.

CDU-30

CDU File Statements
DEFINE VERB

DEFINE VERB
Defines a new command, its parameters, its qualifiers, and the image or
routine it invokes.

FORMAT

DEFINE VERB

verb-name [verb-clause[, ... ]]

verb-name
The name of the command verb. This parameter is required and must
immediately follow the DEFINE VERB statement. The first four characters of
the verb name must be unique.

verb-clause[, . . . ]
Specifies optional verb clauses that define command string attributes.
The DEFINE VERB statement accepts the following verb clauses:

•

DISALLOW, NODISALLOWS

•

IMAGE

•
•

PARAMETER, NOPARAMETERS

•
•

ROUTINE

QUALIFIER, NOQUALIFIERS

SYNONYM

These clauses are described below.

DISALLOW expression
NOD/SALLOWS
Disallows a command string if the result of the expression is true. The
NODISALLOWS clause indicates that all entities and entity combinations are
allowed.
The variable expression specifies an entity or a combination of entities
connected by operators. Each entity in the expression is tested to see if it is
present (true) or absent (false) in a command string. If an entity is present by
default but not explicitly provided in the command string, the entity is false.
After each entity is evaluated, the operations indicated by the operators are
performed. If the result is true, the command string is disallowed. If the
result is false, the command string is valid.
You can specify entities in an expression using an entity name or label, a
keyword path, or a definition path. See Section 4.4.1 for more information
about entities. You can also specify the operators AND, ANY2, NEG, NOT or
OR. See Section 4.4.2 for more information about these operators.

IMAGE image-string
Names an image to be invoked by the command. The image-string is the file
specification of the image (a maximum of 63 characters) DCL invokes when
you issue the command. The default device and directory is SYS$SYSTEM:
and the default file type is EXE.
CDU-31

CDU File Statements
DEFINE VERB

If you do not specify the IMAGE verb clause and you use SET
COMMAND /REPLACE to process the command definition file, the verb
name is used as the image name. At run time, DCL searches for an image
whose file name is the same as the verb name and whose device and directory
names and file type are SYS$SYSTEM: and EXE, respectively.

PARAMETER param-name [,param-clause[, ... ]]
NOPARAMETERS
May be used to specify up to eight parameters in the command string. The
NOP ARAMETERS clause indicates that no parameters are allowed.
The param-name defines the position of the parameter in the command
string. The position must be in the form Pn, where n is the position of the
parameter. The parameter names must be numbered consecutively from Pl
to PS. The name must immediately follow the PARAMETER clause.
The param-clause specifies additional characteristics for the parameter. You
can use the following parameter clauses:
•

DEFAULT

•

LABEL=label-name

•

PROMPT

•

VALUE[(param-value-clause[, ... ])]

To designate a default parameter that is not a keyword, use the
VALUE(DEFAULT=default-string) clause.
LABEL=label-name symbolically defines a label for referring to a parameter
at run time. If you do not specify a label name, the parameter name (Pl
through PS) is used as the label name.
PROMPT=prompt-string supplies a prompt string (31 characters maximum)
when a parameter is omitted from the command string. If you do not specify
a prompt string and a required parameter is missing, DCL uses the parameter
name as the prompt string.

When you define more than one parameter but only the first parameter is
required, DCL prompts for the first parameter until the user either types a
value or aborts the command with a CTRL/Z. When the user enters a value
for the first parameter, DCL prompt for the optional parameters. If the user
presses the return key without entering a value for an optional parameter,
DCL executes the command.
V ALUE[(param-value-clause[, ... ])] specifies additional parameter
characteristics; multiple parameter characteristics must be enclosed in
parentheses and separated with commas.

CDU-32

CDU File Statements
DEFINE VERB

VALUE accepts the following parameter value clauses:
CONCA TENA TE

Indicates a parameter can be
concatenated.

DEFAULT=default-string

Specifies a default value using a string
(95 characters maximum); the DEFAULT
and REQUIRED value clauses are mutually
exclusive.
Do not use this clause to specify a default
if the value is a keyword. Specify keyword
defaults in the DEFINE TYPE statement,
and by using the DEFAULT parameter
clause.

LIST

Permits you to enter a list of parameters
separated by commas or plus signs.

NOCONCATENATE

Indicates that the parameter cannot be
concatenated.

REQUIRED

Indicates that the parameter is required.
All required parameters must precede
optional ones. If you use the REQUIRED
clause, you should also specify a prompt
string.
The REQUIRED clause and the DEFAULT
clause are mutually exclusive.

TYPE=type-name

Symbolically defines either a built-in value
type or the name of a DEFINE TYPE
statement that lists keywords for the
parameter.
See Section 4.2.1 for more information
about built-in value types.

QUALIFIER qual-name [,qual-clause[, ... ]]
NOQUALIFIERS
Specifies a qualifier that can be included in the command string;
NOQUALIFIERS indicates no qualifiers are allowed. You can use the
QUALIFIER clause up to 255 times in a DEFINE VERB statement.
The qual-name specifies the qualifier name as a symbol (the first four
characters must be unique).
The qual-clause specifies additional qualifier characteristics. You can use the
following qualifier clauses:

•
•

BATCH

•

LABEL=label-name

•

NEGATABLE, NONNEGATABLE

•

PLACEMENT=placement-clause

•
•

SYNTAX=syntax-name

DEFAULT

VALUE[(qual-value-clause[, ... ])]

CDU-33

CDU File Statements
DEFINE VERB

BATCH indicates that the qualifier is present by default in a batch job.
DEFAULT indicates that the qualifier is present by default.
LABEL=label-name symbolically defines a label for requesting information
about the qualifier at run time (the default is the qualifier name).
NEGA TABLE and NONNEGA TABLE indicate whether the qualifier can be
negated by adding "NO" to the qualifier name (the default is NEGATABLE).
PLACEMENT=placement-keyword indicates where you can position
the qualifier in the command string. PLACEMENT accepts the following
placement keywprds:
GLOBAL

This is the default if you do not specify the PLACEMENT clause.
It indicates that the qualifier can be placed after the verb or after
a parameter.

LOCAL

Indicates that the qualifier can appear only after a parameter and
applies only to that parameter.

POSITIONAL

Indicates that the qualifier can appear anywhere in the command
string, but its function varies according to its position: if it is
positioned as a qualifier to the verb, it qualifies all parameters;
if it is positioned as a parameter qualifier, it qualifies only the
parameter.

SYNT AX=syntax-name symbolically specifies an alternate syntax definition
to be invoked when the qualifier is present; syntax-name must correspond to
the name used in related DEFINE SYNTAX statement. This alternate syntax
is useful for commands that invoke different images depending upon the
particular qualifiers that are present.
VALUE[(qual-value-clause[, ... ])] used to specify additional qualifier
characteristics; must be in entered in parentheses and separated with commas.
If you do not specify any qualifier value clauses, DCCL converts letters in a
qualifier value to uppercase.
VALUE accepts the following clauses:
DEFAULT=default-string

Specifies a default value using a character
string limited to 95 characters; the DEFAULT
clause and the REQUIRED clause are mutually
exclusive.
Do not use this clause to specify a default
if the value is a keyword; specify keyword
defaults in the DEFINE TYPE statement and by
using the DEFAULT qualifier clause.

CDU-34

LIST

Indicates a list of qualifier values; list must
be enclosed in parentheses and separated by
commas. Note that plus signs cannot be used
to separate items in a list of qualifier values.

REQUIRED

Indicates that the qualifier must have an
explicitly specified value. No prompting is
performed for a required qualifier value. The
REQUIRED clause and the DEFAULT clause are
mutually exclusive.

CDU File Statements
DEFINE VERB

TYPE=type-name

Symbolically identifies either a built-in value
type or a DEFINE TYPE statement that lists
qualifier keywords.
See Section 4.2.1 for more information about
built-in value types.

ROUTINE routine-name
Symbol that specifies a routine the command calls to create an object module
from the command definition file.
The routine-name provides the name of a routine that is executed when
CLI$DISPATCH is called.
If you do not specify a routine, no default is provided.

SYNONYM synonym-name
Symbol that defines a synonym for the verb name.

EXAMPLES

DEFINE VERB ERASE
PARAMETER, Pl VALUE(DEFAULT=DISK3: [JONES] STATS.DAT)

This definition tells the command language interpreter that ERASE is a valid
verb and that it takes a parameter. If you do not enter a parameter value, the
default is DISK3:[JONES]STATS.DAT.
Because no image name is specified, the verb ERASE invokes the image
SYS$SYSTEM:ERASE.EXE.
DEFINE VERB SCATTER
IMAGE "WRKD$: [MORRISON] SCATTER"
PARAMETER Pl, LABEL=INFILE, PROMPT="Input_file?", VALUE(REQUIRED)
PARAMETER P2, LABEL=OUTFILE, PROMPT="Output_file?", VALUE(REQUIRED)
QUALIFIER SLOW, DEFAULT
QUALIFIER FAST
DISALLOW SLOW AND FAST

This example shows a command definition file which defines a new
command called SCATTER that invokes the image WRKD$:[MORRISON]
SCATTER.EXE. It has two required parameters, an input file and an output
file. It has two mutually exclusive qualifiers, /SLOW and /FAST (the default
is /SLOW).

CDU-35

CDU File Statements
IDENT

IDENT
Provides identifying information for an object module created from a
command definition file.

FORMAT

I DENT

ident-string

ident-string
A string (31 characters maximum) containing identifying information.

EXAMPLE
MODULE COMMAND_TABLE
!DENT "V04-001"
DEFINE VERB SPIN

This command definition file uses the IDENT statement to identify the object
module file.

CDU-36

CDU File Statements
MODULE

MODULE
Symbolically locates a command table object module.

FORMAT

MODULE

module-name

module-name
The module-name refers to the address where the linker locates a command
table module linked with your program.
By default, the CDU uses the object file name specified with the /OBJECT
command qualifier. If no object file is explicitly specified, then the CDU uses
the name of the first command definition file as the module name.

EXAMPLE
$ CREATE TEST.CLO
MODULE TEST_TABLE
DEFINE VERB SEND
ROUTINE SEND_ROUT
PARAMETER P1

DEFINE VERB SEARCH
ROUTINE SEARCH_ROUT
PARAMETER P1

-z

$SET COMMAND/OBJECT=TEST.OBJ TEST
$LINK PROG,TEST
$ RUN PROG

TEST.CLO defines two commands (SEND and SEARCH) that call routines in
PROG.EXE, a program that uses DCL to parse command strings and execute
routines.
The SET COMMAND command creates a command table object module that
is linked with the program object module (PROG.OBJ) to produce an image
(PROG.EXE) that includes the code for the program and for the command
table. TEST_TABLE refers to the address of the command table in the image.
When you run PROG.EXE, it calls DCL parsing routines to parse the
command string using the command table at module TEST_TABLE.

CDU-37

CDU Qualifiers
CDU Qualifiers

CDU
QUALIFIERS

The following pages describe t~e qualifiers that can be used with the DCL
command SET COMMAND. The qualifiers are as follows:

•
•
•
•
•
•

/DELETE
/LISTING
/OBJECT
/OUTPUT
/REPLACE
/TABLE

The /DELETE, /OBJECT, and /REPLACE qualifiers indicate SET
COMMAND modes; these qualifiers are mutually exclusive.

CDU-38

CDU Qualifiers
/DELETE

/DELETE
Used to delete verb names or synonym names from the command table.
If a verb name has synonyms, this qualifier deletes the specified verb or
synonym name. If any synonyms remain, or if you delete synonyms and
the original verb name remains, the remaining names still reference the
verb definition.
You can use the /DELETE qualifier to delete a verb in either your process
command table or in a command table file specified with the /TABLE
qualifier. If you do not use the /TABLE qualifier to specify an alternate
command table, the default is to delete verbs from your process command
table. If you do not use the /OUTPUT qualifier to specify an output file,
the default is to return the modified command table to your process.
You cannot use the /LISTING, /OBJECT, or /REPLACE qualifiers with
/DELETE.

FORMAT

SET COMMAND/DELETE=

(verb[, ... ])

verb
A verb or verb synonym to be deleted from the specified command table. If
you specify two or more names, separate them with commas and enclose the
list in parentheses.

EXAMPLES

$ SET COMMAND/DELETE=DO

In this example, SET COMMAND deletes the verb DO from your process
command table.
~

$ SET COMMAND/DELETE=(PUSH,SHOVE)/TABLE=TEST_TABLE/OUTPUT=NEW_TABLE

The commands PUSH and SHOVE are deleted from the command table
TEST_TABLE.EXE. The /OUTPUT qualifier writes the modified table to the
file NEW_TABLE.EXE. If you do not include the /OUTPUT qualifier, the
CDU uses the modified table to overwrite your process command table.

CDU-39

CDU Qualifiers
/LISTING

/LISTING
Controls whether an output listing is created and optionally provides an
output file specification for the listing file. A listing file contains a listing of
the command definitions along with any error messages. The listing file is
similar to a compiler listing.
If you specify the /LISTING qualifier and omit the file specification, output
is written to the default device and directory; the listing file has the same
name as the first command definition file and a file type of LIS.
You can use the /LISTING qualifier only in /OBJECT or /REPLACE mode;
you cannot create a listing in /DELETE mode. In /OBJECT and /REPLACE
modes, the default is /NOLISTING.

FORMAT

SET COMMAND/LISTING [=listing-filespec]
[filespec[, . . . 11
SET COMMAND/NOLISTING
listing-filespec
The file specification for the listing file. The default file name is the name of
the first command definition file. The default file type is LIS.

filespec
The name of the command definition file to be processed (wildcard characters
are allowed). The default file type is CLD.

EXAMPLES

$ SET COMMAND/LISTING TEST

In this example, the command definition file TEST.CLD is processed by the
CDU, and the new verbs are added to your process command table. (By
default, SET COMMAND uses /REPLACE mode.) The modified table is
returned to your process, and a listing file named TEST.LIS is created.
~

$ SET COMMAND/LISTING=A TEST

The command definition file TEST.CLD is processed by the CDU, and the
verb definitions are added to your process command table. The modified
table is returned to your process, and a listing file named A.LIS is created.
~

$ SET COMMAND/LISTING/OBJECT GAMES

SET COMMAND is used to create an object module (GAMES.OBJ) that
contains the command definitions in GAMES.CLD. The output object module
can then be linked with a program. A listing file named GAMES.LIS is
created.

CDU-40

CDU Qualifiers
/OBJECT

/OBJECT
Creates an object module from a command definition file and optionally
provides an object file specification. You cannot use the /OBJECT qualifier
to create an object module from a command definition that contains the
IMAGE clause.
An object module containing a command table can be linked with the
object modules from your program. This enables the program to use its
own command table for parsing command strings and executing routines.
You can specify only one command definition file when you use SET
COMMAND/OBJECT.
If you specify the /OBJECT qualifier and omit the file specification, output
is written to the default device and directory; the object file has the same
name as the input file and a file type of OBJ.
You cannot use the /DELETE, /OUTPUT, /REPLACE, or /TABLE qualifiers
with /OBJECT.

FORMAT

SET COMMAND/OBJECT [=object-filespec]
filespec
object-filespec
The file specification for the object file. If no file name is specified, defaults to
the name of the first input (command definition) file; the default file type is
OBJ.

filespec
The command definition file to be processed (wildcard characters are
allowed). The default file type is CLO.

EXAMPLES

$ SET COMMAND/OBJECT TEST

In this example, the command definition file TEST.CLO is processed and a
new command table is created. This table is written as an object module to a
file named TEST.OBJ. (If not explicitly given, the name of the object module
defaults to the name of the command definition file with a file type of OBJ.)
~

$ SET COMMAND/OBJECT=A TEST

In this example, the command definition file TEST .CLO file is processed and
the command table is written as an object module to a file named A.OBJ.

CDU-41

CDU Qualifiers
/OUTPUT

/OUTPUT
Controls where the modified command table should be placed. If you
provide an output file specification, the modified command table is written
to the specified file. If you do not provide an output file specification,
the modified command table is placed in your process. The /NOOUTPUT
qualifier indicates that no output is to be generated.
You can use the /OUTPUT qualifier only in /DELETE or /REPLACE mode;
the default is /OUTPUT with no file specification. You cannot use the
/OUTPUT qualifier in /OBJECT mode.

FORMAT

SET COMMAND/OUTPUT [=output-filespec}
[filespec[, . . . ]]
SET COMMAND/NOOUTPUT
output-filespec
The specification of the output file that contains the edited command table
(default file type EXE).
You can specify an output file only when you use the /TABLE=filespec
qualifier to describe an input table.

filespec
The name of the command definition file to be processed (default file type
CLD). Wildcard characters are allowed.

EXAMPLES

D $ SET COMMAND/OUTPUT TEST
The file TEST.CLO is processed and the definitions are added to your process
command table. The modified table is returned to your process. (The result is
the same as if you had issued the command SET COMMAND TEST.)
~

$ SET COMMAND/TABLE=A/OUTPUT=A TEST

The definitions from TEST.CLO are added to command table A.EXE. The
CDU writes the modified table to the new A.EXE which has a version number
one greater than the input table file.
If you use the /TABLE qualifier and do not provide an output file
specification, the modified command table replaces your process command
table.
~

$ SET COMMAND/NOOUTPUT TEST

The definitions from TEST.CLO are added to your process command table,
and the modified table is not written anywhere. You can use this command
string to test whether a command definition file is written correctly.

CDU-42

CDU Qualifiers
/REPLACE

/REPLACE
Used to add or replace verbs in the command table.
You can use the /REPLACE qualifier to either modify the process command
table or, with the /TABLE qualifier, to modify a command table file.
You cannot use the /REPLACE qualifier with the /OBJECT or the
/DELETE qualifiers. If you do not explicitly specify /DELETE, /OBJECT, or
/REPLACE, the default is /REPLACE.

FORMAT

SET COMMAND/REPLACE [filespec [, ... ]]
file spec
The file to be processed (default file type CLO). Wildcard characters are
allowed.

EXAMPLES

$ SET COMMAND SCROLL

This command adds the command definitions from the file SCROLL.CLO to
your process command table. The /REPLACE, /TABLE, and /OUTPUT
qualifiers are present by default. The /REPLACE qualifier indicates
/REPLACE mode; the /TABLE qualifier indicates that your process command
table is to be modified; the /OUTPUT qualifier indicates that the modified
command table is to be written to your process.

$ SET COMMAND/TABLE/OUTPUT SCROLL

This command adds the command definitions from the file SCROLL.CLO to
your process command table, and returns the modified table to your process.
(The /TABLE and /OUTPUT qualifiers, with no specified files, default to your
process command table.) This command is the same as the command SET
COMMAND SCROLL.
~

$ SET COMMAND/TABLE=COMMAND_TABLE/OUTPUT=NEW_TABLE TEST

CDU adds command definitions from TEST.CLO to the command table in the
file COMMAND_TABLE.EXE, and the modified command table is written to
NEW_TABLE.EXE.
If you use the /TABLE qualifier to provide an input command table, be sure
to provide an output file specification. Otherwise, the CDU uses the modified
command table to replace your process command table.
~

$ SET COMMAND/TABLE=TEST_TABLE MYCOMS

In this example, the definitions from MYCOMS.CLD are added to the
command table in TEST_TABLE.EXE. The modified command table is written
to your process and replaces your process command table. You should
replace your process command table only if the new command table contains
all the commands you need to perform your work. DCL commands copied to
your process command table when you logged are overwritten.
CDU-43

CDU Qualifiers
/TABLE

/TABLE
Specifies the command table to be modified (default file type EXE). If you
specify the /TABLE qualifier and omit the file specification, the current
process command table is modified.
May be used with /DELETE or /REPLACE but not with /OBJECT; the
default is /TABLE with no input file specification.
If you include a file specification, the specified command table is modified.
If you use the /TABLE qualifier without the /OUTPUT qualifier, the
modified command table replaces your process command table.

FORMAT

SET COMMAND/TABLE [=input-filespec]
[filespec {, . . . ]]
SET COMMAND/NOTABLE
input-filespec
The input file which contains the command table to be edited (default file
type EXE).

file spec
The command definition file to be processed (default file type CLD). Wildcard
characters are allowed.

EXAMPLES

$ SET COMMAND/TABLE TEST

The commands from TEST.CLO are added to your process command table,
and the results are returned to your process. The /TABLE qualifier with no
file specification indicates that your process command table is to be modified.
This command is the same as the command SET COMMAND TEST.
~

$ SET COMMAND/TABLE=A/OUTPUT=B TEST

CDU adds the command definitions from TEST.CLO to the command table in
A.EXE and writes the modified command table to B.EXE.
If you use the /TABLE qualifier to provide an input command table, be sure
to provide an output file specification. Otherwise, the modified command
table replaces your process command table.
~

$ SET COMMAND/TABLE=A

In this example, the command table in A.EXE is written to your process
and replaces your process command table. You should replace your process
command table only if the new command table contains all the commands
you need to perform your work; the DCL commands copied to your process
command table when you logged are overwritten.

CDU-44

CDU Examples
CDU Examples

CDU
EXAMPLES

Adding a Command to Your Process Command Table

This example shows how to add a command to your process command table,
and how to use command language routines in the image invoked by the new
command.
The following command definition file defines a new verb called SAMPLE.
DEFINE VERB SAMPLE
IMAGE "USERDISK: [MYDIR] SAMPLE"
PARAMETER P1,LABEL=FILESPEC
QUALIFIER EDIT

To process this command definition file, use the DCL command SET
COMMAND:
$ SET COMMAND SAMPLE

This command string invokes the CDU to process the command definition
file (SAMPLE.CLD) and to add the verb SAMPLE to your process command
table. The modified table is returned to your process.
The following program illustrates a program called SAMPLE.BAS. It uses the
CLI$PRESENT and CLI$GET_VALUE command language routines to obtain
information about a command string parsed by DCL.
1

EXTERNAL INTEGER FUNCTION CLI$PRESENT,CLI$GET_VALUE

IF CLI$PRESENT('EDIT') AND 1%
THEN
PRINT '/EDIT IS PRESENT' ,A$

IF CLI$PRESENT('FILESPEC') AND 1%
THEN
CALL CLI$GET_VALUE('FILESPEC' ,A$)
PRINT 'FILESPEC =',A$

END

This source program must be compiled and linked before it can be invoked by
a command verb. When you compile and link the source program the output
file (SAMPLE.EXE) contains an executable image.
You can now use the SAMPLE command to invoke the image SAMPLE.EXE,
as follows:
$ SAMPLE

DCL processes this command in the same way it processes the DIGITALsupplied DCL commands; that is, DCL checks the syntax and then invokes
SAMPLE.EXE to execute the command.
You can include in the command string any parameters and qualifiers defined
for the SAMPLE command verb. For example, you can enter the following
command string:
$ SAMPLE MYFILE

In this case, you receive the following display on your screen:
FILESPEC = MYFILE

You can also include the /EDIT qualifier in the command string. For example:
$

SAMPLE MYFILE/EDIT

CDU-45

CDU Examples
CDU Examples

In this case, you receive the following display on your screen:
/EDIT IS PRESENT
FILESPEC = MYFILE

If you include a qualifier that is not accepted by the command verb, you
receive a DCL error message. For example:
$ SAMPLE MYFILE/UPDATE
%DCL-W-IVQUAL. unrecognized qualifier - check validity. spelling. and placement
\UPDATE\

If you include two or more parameters in the command string for a verb that
was defined to accept only one parameter, you receive an error message. For
example:
$ SAMPLE MYFILE INFILE
%DCL-W-MAXPARM. too many parameters - reenter command with fewer parameters
\INFILE\

Creating an Object Module Table for Your Program

This example shows how to create an object module table for your program.
It also shows how to use command language routines to parse a command

string and to invoke the correct program routine.
When you write a command definition file to create an object module table,
specify routines (not images) for each command verb. Your program calls
these routines when it processes command strings.
The following example illustrates a command definition file called TEST.CLO
that defines three verbs: SEND, SEARCH, and EXIT. Each verb invokes a
routine in the program USEREXAMP.BAS.
MODULE TEST_TABLE
DEFINE VERB SEND
ROUTINE SEND_COMMAND
PARAMETER P1, LABEL = FILESPEC
QUALIFIER EDIT
DEFINE VERB SEARCH
ROUTINE SEARCH_COMMAND
PARAMETER P1, LABEL= SEARCH_STRING
DEFINE VERB EXIT
ROUTINE EXIT_COMMAND

Process TEST.CLO by using SET COMMAND with the /OBJECT qualifier to
create object module TEST.OBJ:
$ SET COMMAND/OBJECT TEST

You can then link TEST.OBJ with an object module that was created from
your source program.
The following BASIC program, entitled USEREXAMP.BAS, invokes the
routines listed in the command table in TEST.OBJ. It uses the command
language routines CLI$DCL _p ARSE and CLI$DISP ATCH to parse command
strings and to invoke the routine associated with the command. The program
also uses CL1$PRESENT and CLl$GET_VALUE to obtain information about
command strings.

CDU-46

CDU Examples
CDU Examples

10 SUB SEND_COMMAND
EXTERNAL INTEGER FUNCTION CLI$PRESENT,CLI$GET_VALUE
PRINT 'SEND COMMAND'
PRINT
I I

IF CLI$PRESENT ('EDIT') AND 1%
THEN
PRINT '/EDIT IS PRESENT'

IF CLI$PRESENT ('FILESPEC') AND 1%
THEN
CALL CLI$GET_VALUE ('FILESPEC',A$)
PRINT 'FILESPEC = ,A$
I

90 SUBEND
100 SUB SEARCH_COMMAND
EXTERNAL INTEGER FUNCTION CLI$PRESENT,CLI$GET_VALUE
PRINT 'SEARCH COMMAND'
PRINT
I I

110 IF CLI$PRESENT('SEARCH_STRING') AND 1%
THEN
CALL CLI$GET_VALUE('SEARCH_STRING',A$)
PRINT 'SEARCH_STRING = ',A$
190 SUBEND
200 SUB EXIT_COMMAND
CALL SYS$EXIT(1% BY VALUE)
290 SUBEND
1

EXTERNAL INTEGER FUNCTION CLI$DCL_PARSE,CLI$DISPATCH
EXTERNAL INTEGER FUNCTION SEND_COMMAND,SEARCH_COMMAND,EXIT_COMMAND
EXTERNAL INTEGER TEST_TABLE,LIB$GET_INPUT

IF NOT CLI$DCL_PARSE(,TEST_TABLE,LIB$GET_INPUT,LIB$GET_INPUT, 'TEST>') AND 1%
THEN
GOTO 2

PRINT
CALL CLI$DISPATCH
PRINT I'
GOTO 2
END
I I

This source program must be compiled before it can be linked with an object
module created from the SET COMMAND/OBJECT command. To compile
this program, invoke the VAX BASIC compiler:
$ BASIC USEREXAMP

You now have a USEREXAMP.OBJ file in addition to the original
USEREXAMP.BAS source file. Link USEREXAMP.OBJ with TEST.OBJ by
issuing the following command:
$LINK USEREXAMP,TEST

You now have a file containing an executable image (USEREXAMP.EXE). To
execute the image, issue the following command:
$ RUN USEREXAMP

CDU-47

CDU Examples
CDU Examples

USEREXAMP .EXE displays the following prompt on your screen:
TEST>

You can now enter any of the commands you defined in TEST.CLD. For
example:
TEST> SEND

The program calls CLI$ DCL _p ARSE to parse the command string SEND.
SEND is a valid command, so CLI$DISP ATCH transfers control to the
SEND_COMMAND routine . This routine displays the following text:
SEND COMMAND
TEST>

You can also include a parameter with the SEND command. For example:
TEST> SEND MESSAGE.TXT

DCL invokes the SEND_COMMAND routine which displays the following
text:
SEND COMMAND
FILESPEC = MESSAGE.TXT
TEST>

You can also enter the /EDIT qualifier with ~END. For example:
TEST> SEND/EDIT MESSAGE.TXT
SEND COMMAND
/EDIT is present
FILESPEC = MESSAGE.TXT
TEST>

You can enter other commands that your program accepts. For example:
TEST> SEARCH

The SEARCH command string invokes a different routine from the one
defined by SEND. In this case, the screen displays the following text:
SEARCH COMMAND
TEST>

Unlike the SEND command, the SEARCH command accepts no qualifiers. If
you attempt to include a qualifier (such as /EDIT) in the SEARCH command
string, CLI$DCL _PARSE signals the following error:
%CLI-W-NOQUAL, qualifier not allowed on this command

To exit from the USEREXAMP program and return to the DCL command
level, issue the EXIT command:
TEST> EXIT

CDU-48

Index
Command table (cont'd.)

B
BATCH clause
for QUALIFIER clause•CDU-25, CDU-33
Built-in value type• CDU-6, CDU-24

c
CDU (Command Definition Utility)• CDU-1
exiting • CDU-18
invoking• CDU-18
Character string
See String
Clauses
summary of• CDU-19 to CDU-22
CLl$DCL_PARSE•CDU-17,CDU-46
CLl$DISPA TCH. CDU-17 CDU-46
CLl$GET_VALUE•CDU-17,CDU-45,CDU-46
CLl$PRESENT•CDU-17,CDU-45,CDU-46
Command definition file• CDU-4
changing syntax• CDU-5 to CDU-6
creating • CDU-4 to CDU-14
defining verbs • CDU-8 to CDU-9
for sample program• CDU-45, CDU-46
processing • CDU-14 to CDU-16
statements in• CDU-19 to CDU-37
Command Definition Language statements • CDU-5
Command Definition Utility
See CDU
Command language interpreter• CDU-1
Command language routines• CDU-1
types of• CDU-17
use of• CDU-45, CDU-46
Command processing
See DCL
Command string• CDU-1 to CDU-2
Command table
adding commands to• CDU-15, CDU-43
creating a new table• CDU-16
creating an object module for• CDU-4
deleting commands from• CDU-15, CDU-39
input table• CDU-44
listing file for• CDU-40
I

object module for• CDU-16, CDU-4 1
output file • CDU-42
process table• CDU-2
system table• CDU-2
Command verb
See DEFINE VERB statement
CONCA TENA TE clause
for VALUE clause• CDU-24, CDU-33

D
DCL
command language routines• CDU-17
command processing• CDU-1 to CDU-2
DEFAULT clause
for DEFINE TYPE statement• CDU-28
for PARAMETER clause•CDU-23, CDU-32
for QUALIFIER clause• CDU-25, CDU-34
for VALUE clause• CDU-24, CDU-26,
CDU-29,CDU-33,CDU-34
DEFINE SYNTAX statement
example• CDU-5, CDU-27
format• CDU-5
table of syntax changes• CDU-20 to CDU-22
with DISALLOW and NODISALLOWS clauses•
CDU-22
with IMAGE clause• CDU-23
with PARAMETER and NOPARAMETER clauses
•CDU-23
with PARAMETER clause• CDU-21
with QUALIFIER and NOQUALIFIERS clauses•
CDU-24
with ROUTINE clause• CDU-26'
with SYNTAX keyword• CDU-28
DEFINE TYPE statement
acceptable keyword clauses• CDU-28
acceptable type-clause• CDU-28
defining qualifier keywords• CDU-30
format• CDU-7
keywords referenced by VALUE• CDU-28
with DEFAULT clause• CDU-28
with DEFINE VERB statement• CDU-7
with LABEL clause• CDU-28
with NEGA TABLE and NONNEGATABLE clauses
•CDU-28

lndex-1

Index

DEFINE TYPE statement (cont'd.)
with SYNTAX clause• CDU-28
with VALUE clause• CDU-7
DEFINE VERB statement
example• CDU-7, CDU-8
format• CDU-8
with DEFAULT clause• CDU-30
with DEFINE SYNTAX statement• CDU-6
with DISALLOW and NODISALLOWS clauses•
CDU-31
with IMAGE clause• CDU-31
with PARAMETER and NOPARAMETERS
clauses • CDU-32
with QUALIFIER and NOQUALIFIERS clauses•
CDU-33
with ROUTINE clause• CDU-35
with SYNONYM clause• CDU-35
Definition path• CDU-12
/DELETE qualifier• CDU-39
Digital Command Language
See DCL
DISALLOW clause• CDU-9 to CDU-13
definition path • CDU-12
for DEFINE SYNTAX statement • CDU-22
for DEFINE VERB statement• CDU-31
keyword path • CDU-11
operators for• CDU-13

F
File type
default for command definition file• CDU-4
Format
for DEFINE SYNTAX statement• CDU-5
for DEFINE TYPE statement• CDU-7
for DEFINE VERB statement• CDU-8
for definition path • CDU-12
for DISALLOW verb clause• CDU-9
for IDENT statement• CDU-14
for MODULE statement• CDU-14
for SET COMMAND command• CDU-18

G
GLOBAL clause
for PLACEMENT clause• CDU-25, CDU-34

lndex-2

I
IDENT statement• CDU-14, CDU-36
IMAGE clause
for DEFINE SYNTAX statement• CDU-23
for DEFINE VERB statement• CDU-31

K
Key value clause• CDU-28
Keyword• CDU-2
See also DEFINE TYPE statement
how to define• CDU-7 to CDU-8, CDU-30
Keyword path • CDU-11

L
LABEL clause
for DEFINE TYPE statement• CDU-28
for PARAMETER clause• CDU-23, CDU-32
for QUALIFIER clause• CDU-25, CDU-34
LIST clause
for VALUE clause• CDU-34
with keywords• CDU-29
with parameters• CDU-24
with qualifiers• CDU-26
/LISTING qualifier• CDU-40
LOCAL clause
for PLACEMENT clause• CDU-:-25, CDU-34

M
MODULE statement• CDU-14, CDU-37

N
NEGA TABLE clause
for DEFINE TYPE statement• CDU-28
for QUALIFIER clause• CDU-25, CDU-34
NOCONCA TENA TE clause
for VALUE clause• CDU-24, CDU-33
NODISALLOW clause

Index

NODISALLOW clause (cont'd.)

Qualifier (cont'd.)

for DEFINE SYNTAX statement• CDU-22
for DEFINE VERB statement• CDU-3 1
NONNEGATABLE clause
for DEFINE TYPE statement• CDU-28
for QUALIFIER clause• CDU-25, CDU-34
NOP ARA METERS clause
for DEFINE SYNTAX statement• CDU-23
for DEFINE VERB statement• CDU-32
NOQUALIFIERS clause
for DEFINE SYNTAX statement• CDU-24
for DEFINE VERB statement• CDU-33

how to define• CDU-24, CDU-33
QUALIFIER clause
for DEFINE SYNTAX statement• CDU-24
for DEFINE VERB statement• CDU-33

0
Object module
for command table• CDU-4, CDU-16, CDU-41
how to create • CDU-46
statements for• CDU-14
/OBJECT qualifier• CDU-41
Operators
for DISALLOW clause• CDU-13
/OUTPUT qualifier• CDU-42

p
Parameter
how to define•CDU-23, CDU-32
PARAMETER clause
for DEFINE SYNTAX statement• CDU-23
for DEFINE VERB statement• CDU-32
PLACEMENT clause
for QUALIFIER clause• CDU-25, CDU-34
POSITIONAL clause
for PLACEMENT clause• CDU-25, CDU-34
Process command table• CDU-2
adding commands to• CDU-3, CDU-45
deleting commands from• CDU-39
PROMPT clause
for PARAMETER clause•CDU-23, CDU-32

Q
Qualifier
for SET COMMAND command•
CDU-38to CDU-44

R
/REPLACE qualifier• CDU-43
REQUIRED clause
specifying keyword in a VALUE clause•
CDU-29
specifying parameter in a VALUE clause •
CDU-24
specifying qualifier in a VALUE clause• CDU-26
ROUTINE clause
for DEFINE SYNTAX statement• CDU-26
for DEFINE VERB statement• CDU-35

s
Sample program
invoked by user-defined command• CDU-45
to parse and execute commands• CDU-46
SET COMMAND command
delete mode•CDU-15, CDU-39
input for• CDU-44
object mode • CDU-16, CDU-4 1
output from • CDU-42
processing modes• CDU-14
qualifiers for• CDU-38 to CDU-44
replace mode• CDU-15, CDU-43
Statement
for command definition file• CDU-19 to CDU-37
String • CDU-4
Symbol• CDU-4
SYNONYM clause
for DEFINE VERB statement• CDU-35
Syntax
See also DEFINE SYNTAX statement
how to change • CDU-5 to CDU-6
SYNTAX clause
for DEFINE TYPE statement• CDU-28
for QUALIFIER clause• CDU-25, CDU-34
Syntax-name verb clause• CDU-5
System command table• CDU-2
adding commands to• CDU-3

lndex-3

Index

T
Table
See Command table
/TABLE qualifier• CDU-44
Type
See Built-in value type
TYPE clause
definition of value types• CDU-6
for VALUE clause• CDU-24, CDU-26,
CDU-33,CDU-34
with VALUE clause• CDU-29

v
Value
See also Built-in value type
how to define • CDU-6 to CDU-8
VALUE clause
for defining parameters, qualifiers, keywords•
CDU-6
for PARAMETER clause•CDU-24, CDU-32
for QUALIFIER clause• CDU-25, CDU-34
Verb
See also DEFINE VERB statement
how to define • CDU-8 to CDU-9

lndex-4

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VMS Command Definition
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