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Document:	VMS 5.0 DCL Concepts Manual 198804
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VMS

VMS DCL Concepts Manual

Order Number AA-LA10A-TE

VMS DCL Concepts

Manual
Order Number: AA-LA 1OA- TE

April 1988
This manual describes the VMS DIGITAL Command Language (DCL).

Revision/Update Information:

This manual supersedes the VAX/VMS
DCL Concepts Manual, Version 4.4.

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.
The postpaid READER'S COMMENTS form on the last page of this document
requests the user's critical evaluation to assist in preparing future documentation.
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PostScript is a trademark of Adobe Systems, Inc.

Contents
PREFACE

xiii

CHAPTER 1 THE DCL COMMAND LINE

1-1

1.1
1.1.1
1.1.2
1.1.3
1.1.4
1.1.5
1.1.6

ENTERING COMMANDS
The Parts of a Command Line
Command Prompting
Continuing Commands on More Than One Line
Entering Comments
Abbreviating Command Names
Abbreviations in Command Procedure Files

1-1
1-3
1-4
1-4
1-5
1-5
1-6

1.2
1.2.1

ENTERING PARAMETERS
Specifying a File

1-6
1-6

1.3
1.3.1
1.3.2
1.3.3
1.3.4
1.3.5
1.3.6

ENTERING QUALIFIERS
Types of Qualifiers
Qualifier Defaults
Qualifiers That Accept Values
Qualifiers That Create Output Files
Abbreviating Qualifiers and Keywords
Commonly Used Qualifiers

1-7
1-7
1-7
1-9
1-10
1-12
1-12

1.4
1.4.1
1.4.2
1.4.3

ENTERING DATES AND TIMES
Absolute Time
Delta Time
Combination Time

1-13
1-14
1-15
1-16

CHAPTER 2 EDITING THE DCL COMMAND LINE

2-1

2.1

EXECUTING A DCL COMMAND

2-1

2.2

INTERRUPTING AND CANCELING A DCL COMMAND

2-1

2.3

EDITING COMMANDS

2-4
v

Contents

2.3.1
2.3.2
2.3.3

Deleting Characters
Deleting Lines
More Editing Commands

2:....5
2-5
2-5

2.4

RECALLING COMMANDS

2-6

2.5

TERMINAL FUNCTION KEYS

2-7

2.6

DEFINING TERMINAL KEYS

2-9

CHAPTER 3 FILE SPECIFICATIONS
3.1

FORMAT FOR FILE SPECIFICATIONS

3-1

3.2
3.2.1
3.2.2

NETWORK NODES
Network File Specifications
Access Control Strings

3-2
3-3
3-3

3.3
3.3.1
3.3.2
3.3.3
3.3.4

DEVICES
Device Names
Logical Device Names
Generic Device Names
Cluster Device Names

3-4
3-4
3-6
3-6
3-6

3.4
3.4.1
3.4.2

DIRECTORIES
Directory Structure
Directory Names

3-7
3-7
3-9

3.4.2.1
3.4.2.2

3-1

Named Format • 3-9
UIC Format • 3-9

3.4.3

Searching the Directory Hierarchy

3.4.3.1
3.4.3.2

The Ellipsis ( ... ) Wildcard • 3-1 0
The Hyphen (- ) Wildcard • 3-12

3-10

3.4.4

DCL Commands to Use With Directories

3-12

3.5
3.5.1
3.5.2
3.5.3
3.5.4
3.5.5

FILES
File Names
File Types
Version Numbers
Null File Names and Types
Alternate File Names for Magnetic Tapes

3-13
3-13
3-14
3-15
3-16
3-16

Contents

3.5.6

Specifying a List of Files

3-16

3.6
3.6.1
3.6.1.1
3.6.1.2
3.6.2
3.6.2.1
3.6.2.2

USING WILDCARDS
Input File Specifications
The Asterisk ( *) Wildcard • 3-18
The Percent ( % ) Wildcard • 3-19
Output File Specifications
Output File Names • 3-19
Output Directory Specifications • 3-20

3-17
3-17

3.7

DEFAULT VALUES

3-22

CHAPTER 4 LOGICAL NAMES

4-1

3-19

4-2
4-3

4.1
4.1.1
4. 1.1.1
4.1.1.2
4.1.2

CREATING, DISPLAYING, AND DELETING LOGICAL NAMES
Displaying Logical Names
The SHOW TRANSLATION Command • 4-3
The SHOW LOGICAL Command • 4-3
Deleting Logical Names

4-4

4.2
4.2.1
4.2.2
4.2.3
4.2.4

LOGICAL NAME TABLES
The Process Table
The Job Table
The Group Table
The System Table

4-4
4-5
4-6
4-6
4-7

4.3
4.3.1
4.3.2

LOGICAL NAME DIRECTORY TABLES
The Process Directory Table
The System Directory Table

4-8
4-8
4-9

4.4
4.4.1
4.4.2
4.4.2.1
4.4.2.2
4.4.3

4-11
4-12
4-12

4.4.4

LOGICAL NAME TRANSLATION
Iterative Translation
Modifying Logical Name Translation
Concealing the True Identity of a Logical Name• 4-13
Preventing Iterative Translation • 4-13
How the System Applies Defaults During Logical Name
Translation
Including a Logical Name in an Input File List

4.5

LOGICAL NAME ACCESS MODES

4-14

4-13
4-13

vii

Contents

4.6
4.6.1
4.6.2
4.6.3
4.6.4

4-15
4-15
4-16
4-16
4-16

4.6.5
4.6.6

CREATING YOUR OWN LOGICAL NAME TABLES
Shareable Tables
Choosing a Table for a Logical Name
Deleting Tables
Quotas for Tables
The /QUOTA Qualifier• 4-17
Job Table Quota • 4-17
Access Modes
Protection

4.7
4.7.1
4.7.2

SEARCH LISTS
Using Search Lists
Search Order for Multiple Search Lists

4-18
4-20
4-21

4.8

LOGICAL NODE NAMES

4-21

4.9
4.9.1
4.9.2
4.9.3
4.9.4

LOGICAL NAMES FOR PROCESS-PERMANENT FILES
Redefining SYS$1NPUT
Redefining SYS$0UTPUT
Redefining SYS$ERROR
Redefining SYS$COMMAND

4-23
4-24
4-24
4-25
4-26

4.6.4.1
4.6.4.2

CHAPTER 5 SYMBOLS

viii

4-17
4-18

5-1

5.1

SYMBOL TYPES

5-1

5.2
5.2.1
5.2.2
5.2.3
5.2.4
5.2.5

CREATING SYMBOLS
Local Symbols
Global Symbols
Symbol Search Order
DCL Commands to Use with Symbols
Abbreviating Symbol Names

5-2
5-3
5-3
5-3
5-4
5-4

5.3
5.3.1
5.3.2
5.3.3
5.3.4
5.3.5

VALUES USED IN SYMBOLS
Character Strings
Numbers
Lexical Functions
Another Symbol
Combination of Values

5-5
5-5
5-5
5-6
5-7
5-7

Contents

5.4

FOREIGN COMMANDS

CHAPTER 6 MORE ON EXPRESSIONS

5-8

6-1

6.1
6.1.1
6.1.2
6.1.3

CHARACTER STRING EXPRESSIONS
String Operations
String Comparisons
Replacing Substrings

6-1
6-2
6-2
6-3

6.2
6.2.1
6.2.2
6.2.3
6.2.4

NUMERIC EXPRESSIONS
Numeric Operations
Numeric Comparisons
Logical Operations
Numeric Overlays

6-6
6-7
6-7
6-8
6-9

6.3

ORDER OF OPERATIONS

6-10

6.4
6.4.1
6.4.2
6.4.3

VALUE TYPE CONVERSION
String to Integer Conversion
Integer to String Conversion
How DCL Evaluates an Expression

6-11
6-12
6-12
6-12

CHAPTER 7 SYMBOL SUBSTITUTION

7-1

7.1

AUTOMATIC SYMBOL SUBSTITUTION

7-1

7.2
7.2.1

SUBSTITUTION OPERATORS
The Apostrophe ( ' )

7-2
7-2

7.2.1.1
7.2.1.2

Concatenation of Symbol Names • 7-2
Substitution Within Character Strings • 7-3

7.2.2

The Ampersand ( & )

7-3

7.3

THE THREE PHASES OF COMMAND PROCESSING

7-4

7.4
7.4.1
7.4.2
7.4.3

REPETITIVE AND ITERATIVE SUBSTITUTION
First Phase
Second Phase
Third Phase

7-5
7-5
7-6
7-6
ix

Contents

7.5

UNDEFINED SYMBOLS

CHAPTER 8 PROTECTION

7-7

8-1

8.1
8.1.1
8.1.2
8.1.3
8.1.4
8.1.5
8.1.6

WHAT IS UIC-BASED PROTECTION?
User Identification Code (UIC)
UIC Translation and Storage
How the System Determines Access
The Protection Code
How the System Interprets a Protection Code
How Privileges Affect Protection

8-1
8-1
8-2
8-3
8-5
8-5
8-6

8.2
8.2.1
8.2.2
8.2.3
8.2.4
8.2.5
8.2.6
8.2.7

ESTABLISHING AND CHANGING UIC-BASED PROTECTION
Devices
Queues
Volumes
Directories
Files
Global Sections
Logical Name Tables

8-6
8-6
8-7
8-7
8-8
8-9
8-10
8-10

APPENDIX A VMS PROCESS PRIVILEGES AND RESOURCE
QUOTAS

A-1

APPENDIX B DEC MULTINATIONAL CHARACTER SET

B-1

APPENDIX C DCL CHARACTER SET

C-1

INDEX

FIGURES
3-1
6-1
8-1

How Directories Are Structured on a Disk
Replacing Character Strings in Assignment Statements
Illustrating User Categories with a UIC of [100, 100] __

3-8
6-6
8-4

Contents

DEC Multinational Character Set and Hexadecimal
Values

B-1

1-1

Built-in Commands

1-2

Commonly Used Qualifiers

1-12

2-1

Interrupting Built-in Commands

2-2

Interrupting Nonprivileged Command Images

2-2

2-3

Interrupting Privileged Command Images

2-3

2-4

Line Editing Keys

2-5

Terminal Function Keys

2-7

3-1

Examples of Device Codes

3-5

3-2

DCL Commands to Use With Directories

3-12

3-3

Default File Types

3-14

3-4

File Specification Defaults

3-22

4-1

Default Process Logical Names

4-5

4-2

Default Job Logical Names

4-6

4-3

Default System Logical Names

4-7

4-4

Default Process Directory Logical Names

4-9

4-5

Default System Directory Logical Names

4-10

4-6

Equivalence Names for Process-Permanent Files

4-23

5-1

DCL Commands to Use with Symbols

5-4

6-1

Order of Operations

6-10

6-2

Determining the Value of an Expression

6-13

A-1

Process Privileges

A-1

A-2

Resource Quotas

A-3

C-1

DCL Character Set

C-1

B-1

TABLES

Preface
The VMS DCL Concepts Manual provides an overview of the DIGITAL
Command Language. Read it to learn the syntax for using DCL commands. It
also covers symbols and logical names, two structures that let you tailor DCL
to suit your needs. Before using this manual you should read the Introduction
to VMS.

Intended Audience
This manual is intended for anyone who uses the VMS operating system.

Document Structure
The VMS DCL Concepts Manual is organized into the following eight chapters.
•

Chapter 1, The DCL Command Line
Describes the syntax rules for entering DCL commands. It explains how
to enter parameters, qualifiers, and comments, as well as date and time
values.

•

Chapter 2, Editing the DCL Command Line
Describes how to execute, recall, and cancel DCL commands. It explains
how to edit the command line.

•

Chapter 3, File Specifications
Describes the syntax rules for entering node, device, directory, and file
specifications. It tells you how the system interprets the components of a
file specification, including the default value that is assumed if you omit
anything. It also shows you how to use wildcard characters to indicate
groups of files.

•

Chapter 4, Logical Names
Explains how to use logical names to refer to devices, directories, and
files.

•

Chapter 5, Symbols
Shows you how to create and use symbols. Symbols have a variety
of uses such as providing customized abbreviations for commands and
passing variables in command procedures.

•

Chapter 6, More on Expressions
Describes the rules for creating character string and numeric expressions.
It discusses how DCL interprets the different operations and comparisons

you can perform.
•

Chapter 7, Symbol Substitution
Explains how the DCL command interpreter replaces symbol names with
their current values when it processes a command.

xiii

Preface

•

Chapter 8, UIC-Based Protection
Explains how to protect devices, directories, and files with user
identification codes (UICs).

Associated Documents
Overview of VMS Documentation-describes the new organization of the
document set.

Introduction to VMS-provides an introduction to the VMS operating
system and the DIGITAL Command Language. This manual is especially
recommended for novice users.
VMS DCL Dictionary-contains a detailed description of each DCL command
and lexical function.
Guide to Using VMS Command Procedures- explains how to write command
procedures with DCL commands and lexical functions.

VMS System Messages and Recovery Procedures Reference Manual-explains
error and warning messages you might receive.

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.)

xiv

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.

Preface

Convention

Meaning

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.

The DCL Command Line

DIGITAL Command Language (DCL) is the language you use to communicate
with the VMS operating system. DCL commands let you do the following
tasks:
•

Get information about the system

•

Work with files

•

Work with disks, magnetic tapes, and other devices

•

Modify your work environment

•

Develop and execute programs

•

Provide security and ensure that resources are used efficiently

This chapter explains the format for entering DCL commands. It describes the
parts of a command line and the rules for the following:

1 .1

•

Entering commands

•

Entering parameters

•

Entering qualifiers

•

Entering date and time values

Entering Commands
You can use DCL in the following two modes:
•

Interactive. In interactive mode, you enter commands from your terminal.
A command has to finish executing before you can enter another one.

•

Noninteractive. In noninteractive mode, the system creates another
process to execute commands on your behalf. Batch jobs and network
processes use DCL in noninteractive mode. For example, when you
submit a command procedure as a batch job, a separate process is created
to execute the command procedure. You can continue to use your
terminal interactively while the batch job runs.

DCL commands consist of words from the English language (generally verbs)
that describe what you want the system to do. When you type a command
and press the RETURN key, it is read and translated by the DCL command
interpreter. The way the command interpreter responds to a command is
determined by the type of command entered. The three types of commands
are as follows:
•

Built-in commands. These commands are built into the command
interpreter. DCL executes a built-in command directly. The DCL built-in
commands are listed in Table 1-1.

1-1

The DCL Command Line
1 .1 Entering Commands

•

Commands that call command images. DCL calls another program to
execute the command. A program that is called to execute a command is
referred to as a command image. Parameter and qualifier information are
passed to the program. Most commands not listed in Table 1-1 are in
this category.
A command image can be VMS- or user-supplied. All VMS-supplied
DCL commands are described in the VMS DCL Dictionary.

•

Commands that call interactive programs. DCL calls the program
associated with the command. You then work interactively with the
program until you exit from it and return to DCL command level. For
example, the MAIL command calls an interactive program.

Table 1-1
= == ·= ·==

ALLOCATE

ASSIGN

ATTACH

CALL

CANCEL

CONNECT

CONTINUE

CREATE/NAME_TABLE

DEALLOCATE

DEASSIGN

DEBUG

DECK

DEFINE

DEFINE/KEY

DELETE/KEY

DELETE/SYMBOL

DEPOSIT

DISCONNECT

ENDSUBROUTINE

EOD

EXAMINE

EXIT

GOSUB

GOTO

INQUIRE

OPEN

READ

RECALL

RETURN

SET CONTROL

SET DEFAULT

SET KEY

SET ON

SET OUTPUT_RA TE

SET PROMPT

SET PROTECTION
/DEFAULT

SET UIC

SET VERIFY

SHOW DEFAULT

SHOW KEY

SHOW QUOTA

SHOW PROTECTION

SHOW STATUS

SHOW SYMBOL

SHOW TIME

SHOW TRANSLATION

SPAWN

STOP

SUBROUTINE

WAIT

WRITE

1-2

Built-in Commands

The DCL Command Line
1 .1 Entering Commands

1 .1 .1

The Parts of a Command Line
The DCL command line can contain the following components:
$

The dollar sign ($) is the DCL prompt. When you work
interactively, DCL displays the prompt when it is ready to accept a
command. When you write a command procedure, you must type
the dollar sign ($) at the beginning of each line.

Label

Identifies a line in a command procedure. Use labels only within
command procedures.

Command

Specifies the name of the command.

Parameter

Specifies what the command acts upon. Examples of parameters
are file specifications, queue names, and logical names.

Qualifier

Modifies the action taken by the command. Some qualifiers can
modify parameters. Some can accept values.

Value

Modifies a qualifier. A value can be a filename, a character string,
a number, or a DCL keyword. A keyword is a word that has
special meaning in DCL. For example, GROUP, WORLD, and
OWNER are DCL keywords. A DCL keyword may also have a
value.

The way in which the parts of a command line are put together is referred to
as the command line syntax. DCL command line syntax follows the general
format shown below (items in square brackets [] are optional).
[$] [label:]

command [/qualifier[=value] ... ] [parameter[/qualifier ... ])

Observe the following rules when entering DCL commands:
•

You can use any combination of uppercase and lowercase letters. The
DCL command interpreter translates lowercase letters to uppercase.

•

A DCL command line can contain up to 1024 characters after symbols
and lexical functions have been expanded. There can be 256 characters
on a line. For information on extending a command over multiple lines,
see Section 1.1.3.

•

A command line can contain a maximum of 128 elements (for example, a
file specification or qualifier). Each element can have up to 255 characters.

•

At least one blank space must separate the command name from the
first parameter, and at least one blank must separate each additional
parameter from the previous parameter. Multiple spaces and tabs are
permitted in all cases where a single blank is required. The command
interpreter compresses multiple blank spaces or tabs to a single blank
space.

•

Each qualifier must be preceded with a slash ( / ). The slash can be
preceded or followed by any number of spaces or tabs.

•

A label must be terminated with a colon. The colon can be preceded or
followed by any number of spaces or tabs. A label name can have up to
255 characters, but it cannot include blank spaces.

1-3

The DCL Command Line
1 .1 Entering Commands

The following is an example of a DCL command line:
$ PRINT/COPIES=10 FDOD.LST

where:

1.1.2

•

$ is the DCL prompt

•

PRINT is a command

•

/COPIES is a qualifier that modifies the command

•

10 is a value that modifies the /COPIES qualifier

•

FOOD.LSI is a parameter (in this case the parameter is a file specification)

Command Prompting
If you enter a command that requires parameters and you do not specify the
parameters, the DCL command interpreter asks you for them. For example:
$ PRINT/COPIES=15

File:

The PRINT command expects a file specification. If you do not enter one, the
system asks you for it. A line beginning with an underscore (-) means that
the system is waiting for your response.
On any prompt, you can enter one or more of the remaining parameters and
any additional qualifiers. When you are asked for an optional parameter, you
can press RETURN to omit it.
If you press CTRL/Z after a command prompt, DCL ignores the command
and redisplays the DCL prompt.

1.1.3

Continuing Commands on More Than One Line
If you want to type a lengthy command line that includes many qualifiers,
you can extend it over multiple lines to make it more readable.

Extend a command line by typing a hyphen(-), pressing RETURN, and typing
the rest of the command on the next line. The DCL command interpreter
responds with an underscore followed by a dollar sign ( _$ ). This indicates
that DCL is still accepting the command. For example:
$ TYPE _$

TAXES.MEM

Follow these rules for continuing a command line:

1-4

•

Enter the hyphen as the last element on the line or the last element
before a comment. A hyphen not used at the end of a line is treated like
any other character and is valid in file specifications.

•

There is no restriction on the number of continued lines you can use to
enter a command, as long as you do not exceed the 1024-character limit.

•

The RETURN after a hyphen is not treated as a delimiter. You must
supply any required spaces.

The DCL Command Line
1 .1 Entering Commands

Command line continuation is also used in command procedures when you
want to make a procedure more readable. In command procedures, do not
begin continuation lines with dollar signs. For example:
$

PRINT LAB.DAT /AFTER=17:00 /COPIES=20 /NAME= 11 COMGUIDE 11

For more information on command procedures, see the Guide to Using VMS
Command Procedures.

1.1.4

Entering Comments
Indicate a comment by preceding it with an exclamation point(!). DCL
considers everything to the right of an exclamation point to be a comment. It
ignores this information when processing the command line. Comments are
valid in the following positions:
•

As the first item in a command line. In this case, the entire line is
considered a comment and is not processed.

•

After the last character in a command line or after a hyphen continuation
character.

Some examples follow:
$ !THIS ENTIRE LINE IS A COMMENT
$ PRINT LAB.DAT- ! PRINT COMMAND COMMENT
_$

1.1.5

/COPIES=3

3 COPIES, PLEASE

Abbreviating Command Names
When the DCL command interpreter examines a command line, it looks only
at the first four characters of a command. All command names are unique
within four characters. This means that you can abbreviate any command by
typing only the first four characters.
You can abbreviate a command name to fewer than four characters as long as
the abbreviated name remains unique among all DCL command names. For
example, the HELP command is currently the only command that begins with
the letter "H." Therefore, the HELP command can be truncated to just one
character. The DEALLOCATE and DEASSIGN commands, however, have
the same first three characters, so these commands need at least the first four
characters to be unique.
The following commands are exceptions to the minimum truncation rule
because they can be truncated to their first character, even though other
commands begin with the same character:
CONTINUE
DEPOSIT
EXAMINE
RUN
You can also abbreviate qualifiers and keywords. For more information, see
Section 1.3.5.

1-5

The DCL Command Line
1 .1 Entering Commands

1.1.6

Abbreviations in Command Procedure Files
You should not abbreviate commands, qualifiers, or keywords in command
procedures for the following reasons:

1 .2

•

Your command procedures will be difficult to read.

•

The abbreviations may not be valid after new DCL commands are added.

Entering Parameters
The parameter section of the command descriptions in the VMS DCL
Dictionary shows the parameters that are accepted by each command. The
following rules apply:
•

Square brackets [] indicate optional items. For example:
SHOW QUEUE [queue-name]

The square brackets mean that entering a queue name is optional.
Anything not enclosed in square brackets is required. For example:
SET HOST node-name

You must enter a node name with the SET HOST command.
•

Required parameters must be placed to the left of optional parameters.

•

An input file parameter must precede an output file parameter.

•

A parameter may be one item or a series of items. If you enter a series
of items, separate them with commas (,) or plus signs (+). Any number
of spaces or tab characters can precede or follow a comma or a plus sign.
For example:
PRINT file-spec[, ... ]

This shows that you can optionally enter a list of files as the parameter.

Note: Some commands regard the plus sign as a concatenator, not as a
separator. The parameter descriptions in the VMS DCL Dictionary
state how each command interprets commas and plus signs.

1.2.1

Specifying a File
File specifications are the most common type of parameter. DCL commands
can accept input file specifications (files that are acted upon by a command)
and output file specifications (files that are created by a command). For
complete details on file specifications, see Chapter 3.
The command descriptions in the VMS DCL Dictionary describe how each
command interprets file specifications. Command descriptions provide
information about defaults for file specifications that are entered as
parameters. They also indicate whether you can use wildcards.

1-6

The DCL Command Line
1 .3 Entering Qualifiers

1 .3

Entering Qualifiers
The qualifier section of the command descriptions in the VMS DCL Dictionary
shows the qualifiers that are accepted by each command. It also indicates
whether or not a qualifier accepts a value. Although typing any qualifier is
optional, certain defaults are automatically applied. You need to be aware
of the defaults that apply for each qualifier. The following sections describe
types of qualifiers and qualifier defaults.

1.3.1

Types of Qualifiers
The three types of qualifiers are as follows:
•

Command qualifiers modify commands. You can place a command
qualifier anywhere in the command line. For example:
$ PRINT/HOLD FARM.DAT
$ PRINT FARM.DAT/HOLD

The /HOLD qualifier is a command qualifier. Therefore, the two PRINT
commands shown in this example are equivalent. The file FARM.DAT is
placed in a hold state.
•

Positional qualifiers can modify commands or parameters. They have
different effects depending on where they are placed in the command
line. If you place a positional qualifier after the command, it affects the
entire command line. If you place a positional qualifier after a parameter,
it affects only that parameter. For example:
$ PRINT/COPIES=2 FARM.DAT.GROTON.DAT
$ PRINT FARM.DAT/COPIES=2,GROTON.DAT

The first PRINT command prints two copies of each of the files
FARM.DAT and GROTON.DAT. The second PRINT command prints
two copies of FARM.DAT, but only one copy of GROTON.DAT. You can
use positional qualifiers after more than one parameter in the command
line.
•

1.3.2

Parameter qualifiers can be used only after a certain type of parameter.
For example, the BACKUP command accepts several parameter qualifiers
that apply only to input and output file specifications.

Qualifier Defaults
A qualifier default is defined as what happens when you omit the qualifier
from the command line. Qualifiers can be either present or absent by default.
The following paragraphs explain the syntax used in the VMS DCL Dictionary
to display qualifiers and defaults.
Qualifiers can take one of the following formats:
•

Qualifiers with positive and negative forms. These qualifiers have a value
of true or false. You indicate a true value by naming the qualifier. You
indicate a false value by inserting the prefix NO.

1-7

The DCL Command Line
1.3 Entering Qualifiers

For example, the /LOG qualifier can be expressed positively or negatively.
If you omit the qualifier, the default action is /NOLOG. The following

shows how the /LOG qualifier is listed in a command description.
/LOG
/NOLOG (default)
•

Qualifiers that require values. If you use a qualifier that requires a value,
you must specify a value. If you omit the qualifier, then the default value
is applied.
For example, if you use the /COPIES qualifier, you must provide
a numeric value. If you omit the /COPIES qualifier, the default is
/COPIES=l. The following shows how the /COPIES qualifier is listed in
a command description.
/COPIES=n
Qualifiers can also accept other types of values. For more information,
see Section 1.3.3.

•

Qualifiers that affect command execution only if explicitly present. There
is no corresponding default.
For example, the /ABORT qualifier does not affect the command if it is
not specified. The following shows how the /ABORT qualifier is listed in
a command description.
/ABORT

•

Qualifiers that override other qualifiers. Sometimes a command has a
qualifier that is automatically applied as a default. Other qualifiers are
available to override the default qualifier.
For example, there are four access modes within the VMS operating
system. They are user mode (least privileged), supervisor mode, executive
mode, and kernel mode (most privileged). By default, all DCL commands
run in supervisor mode. The DEFINE command lets you determine which
mode it will run in. It has a /SUPERVISOR_MODE qualifier that applies
supervisor mode as the default. However, you can override this default
with either the /USER_MODE or EXECUTIVE_MODE qualifiers.
The following example shows how these qualifiers are listed in a
command description:
/EXECUTIVE_MODE
/SUPERVISOR_MODE (default)
/USER_MODE

The command line is processed from left to right. If two or more
contradictory qualifiers are present, then the right-most qualifier overrides
the others. For example:
$ PRINT MYFILE/COPIES=3/BURST/COPIES=2/NOBURST

For this PRINT command, only the /COPIES=2 and the /NOBURST
qualifiers are accepted.
Some commands contain conflicting qualifiers that cannot be specified in
the same command line. If you use incompatible qualifiers, the command
interpreter usually displays an error message. The command descriptions in
the VMS DCL Dictionary indicate which qualifiers cannot be used together.

1-8

The DCL Command Line
1 .3 Entering Qualifiers

1.3.3

Qualifiers That Accept Values
Qualifiers can accept the following types of values:
•

Keywords

•

File specifications

•

Character strings

•

Numeric values

When you enter a value for a qualifier, separate the qualifier and the value
with either an equal sign ( =) or a colon (: ). For example, the following
expressions are equivalent:
/COPIES=3

/COPIES:3

/OUTPUT=DBA 1 :NEW.DAT

/OUTPUT:DBA 1 :NEW .DAT

/OVERRIDE=EXPIRA TION

/OVERRIDE:EXPIRATION

Some qualifier keyword values require additional data. In these cases,
separate the keyword from its data with a colon or an equal sign. For
example, the following expressions are equivalent:
/PROTECTION:GROUP:RW
/PROTECTION=GROUP=RW
/PROTECTION=GROUP:RW
/PROTECTION:GROUP=RW
The command descriptions in the VMS DCL Dictionary use the following
notation to indicate that a qualifier can accept a value or a list of values:
/qualifier=(value[, ... ])

The qualifier requires a value or list
of values. If you specify a single
value, you can omit the parentheses.
However, if you specify a list of
values, you must separate the values
with commas and enclose them in
parentheses. For example:

$ SET COMMAND/DELETE=TYPE
$ SET COMMAND/DELETE=(PRINT,COPY)
/qualifier[=(value[, ... ])]

The square brackets indicate that the
value or list of values is optional. If you
specify a single value, you can omit the
parentheses. However, if you specify
a list of values, you must separate the
values with commas and enclose them
in parentheses. For example:

$ RUNOFF/MESSAGES
$ RUNOFF/MESSAGES=(OUTPUT,USER)

To specify multiple keywords that require values, enclose the list in
parentheses and separate the keyword and value with either an equal sign
( =) or a colon ( : ). For example:
/BLOCKS=(START:O ,END: 10)
/PROTECTION=(OWNER=RWD,GROUP=RW)

1-9

The DCL Command Line
1 .3 Entering Qualifiers

If a qualifier accepts a keyword value, you can abbreviate the keyword as

described in Section 1.3.5.

1.3.4

Qualifiers That Create Output Files
With some qualifiers you can specify the output file. For example, the /LIST
and /OBJECT qualifiers let you specify the names of the files that result from
running a language compiler. You can also use the /EXECUTABLE qualifier
for the linker for the same purpose.
The default output file specification created by these qualifiers depends on the
placement of the qualifier in the command. The following rules apply:
•

If the qualifier is present by default, the output file specification defaults

to the current default device and directory and the name of the first
input file. The qualifier provides a default file type. Following are some
examples:
Command

Output File

LINK A,B

A.EXE

LINK [TEST]A,[ ]B

A.EXE

In these examples, the qualifier /EXECUTABLE is present by default. The
first input file name is A. The /EXECUTABLE qualifier provides a default
file type of EXE. Therefore, the output file is named A.EXE and is written
to the current default device and directory.
•

If the qualifier is used after the command name and does not include

an output file specification, the output file specification defaults to the
current default device and directory and the name of the first input file.
The qualifier provides a default file type. Following is an example:

•

Command

Output File

LINK/EXE CUT ABLE A,B

A.EXE

If the qualifier is used after an input file specification and does not include

an output file specification, the output file specification defaults to the
device, directory, and file name of the immediately preceding input file.
The qualifier provides a default file type. Following are some examples:
Command

Output Files

MACRO A+C/LIST

A.OBJ and C.LIS

LINK A+[TEST]D/EXECUT ABLE

[TEST]D.EXE

In the first example, the plus sign ( +) concatenates the files A.MAR and
C.MAR (MAR is the file type for a MACRO file). The /OBJECT qualifier
is present by default, so MACRO creates an object file with the same
name as the first input file. The /LIST qualifier is placed after C.MAR. It
affects only that file and causes the listing to be named C.LIS.

1-10

The DCL Command Line
1 .3 Entering Qualifiers

In the second example, the LINK command links two object files together.
Because the /EXECUTABLE qualifier is specified after the second input
file, the resulting output file is named [TEST]D.EXE. This overrides the
default output file naming convention.
•

If the qualifier specifies a file specification for the output file, then any
fields entered in the file specification are used to name the output file.
Missing device and directory fields are filled in by the current defaults.
Following are some examples:
Command

Output Files

LINK A+B/EXECUT ABLE=C

C.EXE

MACRO/LIST=FRED B+C

FRED.LIS and B.OBJ. Both files contain B
and C concatenated.

In the first example, A and B are linked together. The /EXECUTABLE
qualifier is used to override the default and name the output file C.EXE.
In the second example, the /LIST qualifier is used to name the listing file
FRED.LIS. The /OBJECT qualifier is present by default so the object file
B.OBJ is also produced.
•

If the current default device or directory is different from that specified in
the command parameter, the current default is used for the output file.
If the current default device or directory is different from that specified
for a command parameter, and if the output qualifier does not include a
specification, the output file resulting from the qualifier takes its device
and directory from the command parameter. In the following examples
the current default device and directory is DIS Kl :[JONES]:
Command

Output Files

MACRO DISK2:[SMITH]A
/LIST=CAT

DISK 1:[JONES]A.OBJ and
DISK1 :[JONES]CAT.LIS

MACRO [.PROGRAMS]A/LIST

DISK 1:[JONES]A.OBJ and
DISK 1:[JONES.PROGRAMS]A.LIS

In the first example A.MAR is located in DISK2:[SMITH]. Because a file
specification is included with the /LIST qualifier, the LIS file is placed in
th~ current default device and directory, DISKl:[JONES].
In the second example, A.MAR is located in DISKl:[JONES.PROGRAMS].
Because a file specification is not included with the /LIST qualifier, the
LIS file is placed in the directory specified by the command parameter.
In all cases, the version number of the output file is always one greater than
any existing file with the same file name and file type.

1-11

The DCL Command Line
1 .3 Entering Qualifiers

1.3.5

Abbreviating Qualifiers and Keywords
When the DCL command interpreter examines a command line, it looks at
only the first four characters of a qualifier name. This means that you can
abbreviate any qualifier by typing only the first four characters. All qualifier
names are unique within four characters. You can abbreviate a qualifier to
less than four characters, as long as the abbreviation remains unique. Follow
these rules:
•

Disregard the slash character(/) in counting characters.

•

Count the underscore. For example, /BY_OWNER can be shortened to
/BY_O.

•

Many qualifiers permit a negative form. In applying the minimum fourcharacter truncation rule, count the NO prefix as the first one of the
four characters. For example, /NOLIST is the negative form of the
/LIST qualifier. In this case, the minimum truncation that guarantees
uniqueness is /NOUS.

The command interpreter looks at keywords in their entirety. You can
abbreviate keywords to the fewest number of characters that provide a unique
abbreviation within a set of possible keywords.

1.3.6

Commonly Used Qualifiers
Table 1-2 lists qualifiers that are used with many DCL commands.
Table 1-2 Commonly Used Qualifiers
Qualifier

What It Does

/BACKUP

Indicates that the command should operate on
files or directories backed up before or after the
specified date. For example:

$ DELETE/BACKUP/BEFORE=15-APR *.*;*
/BEFORE[=time]

Indicates that the command should operate on files
or directories dated before the specified time. For
example:

$ DELETE/BEFORE=YESTERDAY *.*;*
/BY_OWNER[=uic]

Indicates that the command should operate on files
or directories belonging to the specified owner.
For example:
$ DELETE/BY_OWNER=[BAND,ROHBA]

/CONFIRM

Requests your permission before performing the
indicated operation. For example:

$ DELETE/CONFIRM *.*;*

1-12

*.*;*

The DCL Command Line
1 .3 Entering Qualifiers

Table 1-2 {Cont.)

Commonly Used Qualifiers

Qualifier

What It Does

/CREA TED

Indicates that the command should operate on files
or directories created before or after the specified
date. For example:

$ DELETE/CREATED/SINCE=YESTERDAY *.*;*
/EXCLUDE

Indicates that the command should not operate on
the specified files. For example:

$ PRINT/EXCLUDE=TAX.DAT *.DAT
/FULL

Requests detailed information. For example:
$ DIR/FULL

/LOG

Displays each file specification affected by the
command. For example:

$ DELETE/LOG*.*;*
/MODIFIED

Indicates that the command should operate on files
or directories modified before or after the specified
date. For example:

$ DELETE/MODIFIED/SINCE=YESTERDAY *.*;*
/NOOUTPUT

Suppresses command output. However any value
that results from the operation is still returned. For
example:
$ DIR/NOOUTPUT

/OUTPUT[=file-spec]

Redirects the command output to a file. Default file
names and types vary with different commands.
For example:

$ SHOW QUEUE/OUTPUT=MYJOBS.DAT
/PROTECTION=(code)

Specifies the UIC-based protection to be applied.
For example:

$ CREATE/DIRECTORY/PROTECTION=(S:RWED,O:RWED,G:R)
/SINCE[=time]

Indicates that the command should operate on files
or directories dated after the specified time. For
example:

$ DELETE/SINCE=YESTERDAY *.*;*

1 .4

Entering Dates and Times
Certain commands and qualifiers accept date and time values. You can
specify these values in one of the three following formats:
•

Absolute time

•

Delta time

•

Combination time
1-13

The DCL Command Line
1 .4 Entering Dates and Times

The command descriptions in the VMS DCL Dictionary indicate the time
formats accepted by commands and qualifiers.

1.4.1

Absolute Time
Absolute time is a specific date or time of day. The format for an absolute
time is as follows:
[dd-mmm-yyyy[:]][hh:mm:ss.cc]

The fields are as follows:
Field

Meaning

Day of the month; an integer in the range of 1-31

mmm

Month; specified as JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG,
SEP, OCT, NOV, or DEC

yyyy

Year; an integer

Hour of the day; an integer in the range of 0-23

Minute of the hour; an integer in the range of 0-59

Seconds; an integer in the range of 0-59

Hundredths of a second; an integer in the range of 0-99

You can specify an absolute time value using either the date or the time, or
both. Follow these rules:
•

If you specify both the date_ and the time, type a colon between them.

•

If you specify the date, include the hyphen ( - ).

•

You can truncate either the date or the time on the right.

•

You can omit any of the fields within the date or time, as long as you
type the punctuation marks that separate the fields.

•

When fields are omitted, the system supplies default values. If you omit
a date field, the default is the corresponding field for the current date. If
you omit a time field, the default value is zero.

•

If you specify a past time in a command that expects the current or a

future time, the current time is used.
•

1-14

You can use one of the following keywords to specify an absolute time.
Keyword

Meaning

TODAY

The current day, month, and year at 00:00:00.0 o'clock

TOMORROW

24 hours after 00:00:00.0 o'clock today

YESTERDAY

24 hours before 00:00:00.0 o'clock today

The DCL Command Line
1 .4 Entering Dates and Times

Some examples of valid absolute time specifications follow:
Time Specification

1.4.2

Result

31-DEC-1988:12

12:00 noon on December 31, 1988

3:00 P.M., today

15-::30

12:30 AM, on the 15th day of the current month

31-DEC

Midnight (00:00 o'clock) at the beginning of the
31st of December, this year

15-

The 15th day of the current month and year, at
midnight

18:30

6:30 P.M., today

00:00:00.2

Two-hundredths of a second after midnight, today

Delta Time
Delta time is an offset from the current date and time to a time in the future.
The format for a delta time is as follows:
[dddd-][hh:mm:ss.cc]

The fields are as follows:
Field

Meaning

dddd

Number of days; an integer in the range of 0-9999

Number of hours; an integer in the range of 0-23

Number of minutes; an integer in the range of 0-59

Number of seconds; an integer in the range of 0-59

Number of hundredths of seconds; an integer in the range of 0-99

Follow these rules for entering a delta time:
•

If you specify both the number of days and the time, type a hyphen
between them.

•

If you specify the number of days, include the hyphen ( - ).

•

You can truncate the time on the right.

•

You can omit any of the fields within the time, as long as you type the
punctuation marks that separate the fields.
·

•

When a field is omitted, the system supplies default values. If you omit a
time field, the default is zero.

1-15

The DCL Command Line
1 .4 Entering Dates and Times

Some examples of valid.delta time specifications follow:

1.4.3

Time Specification

Result

3 days from now (72 hours)

3 hours from now

:30

30 minutes from now

3-:30

3 days and 30 minutes from now

15:30

15 hours and 30 minutes from now

Combination Time
To combine absolute and delta time, specify an absolute time plus ( +) or
minus ( - ) a' delta time. The format is as follows:
"[absolute time][+delta time]"
or
[absolute time)[-delta time]

The fields are as follows:
Field

Meaning

absolute time

Use the syntax for entering an absolute time
value:
[dd-mmm-yyyy[:]][hh:mm:ss:cc]

delta time

Use the syntax for entering a delta time value:
[dddd-][hh:mm:ss:cc]

The rules for entering an absolute or a delta time value still apply. In
addition, do the following:

1-16

•

Precede the delta time value by a plus or minus sign. (Note that the
minus sign is the same keyboard key as the hyphen.)

•

Whenever a plus sign precedes the delta time value, enclose the entire
time specification in quotation marks.

•

You can omit the absolute time value. If you do, the delta time is offset
from the current date and time.

•

Specify date and time information as completely as possible.

The DCL Command Line
1 .4 Entering Dates and Times

Some examples of valid combination time specifications follow:
Time Specification

Result

"+5"

Current time plus 5 hours. The absolute time
portion is omitted, so it defaults to the current
date and time.

-1

Current time minus 1 hour. The minus sign ( - )
indicates a negative offset. (The 1 is interpreted
as an hour, not a day, because it is not followed
by a dash.)

"+:5"

Current time plus 5 minutes. The absolute time
portion is omitted, so it defaults to the current
date and time.

-:5

Current time minus 5 minutes. The absolute
time specification is omitted, so it defaults to the
current date and time.

-1-00

Current time minus 1 day. The minus sign (-)
indicates a negative offset. The dash ( - ) separates
the day from the time field.

"31-DEC:+:5"

12:05 AM on December 31 of the current year.
The absolute time specification (before the colon)
defaults to midnight on December 31 of the current
year. The plus sign ( +) indicates a positive offset.

31-DEC:-OO: 10

11 :50 PM on December 30 of the current year.
The absolute time specification (before the colon)
defaults to midnight on December 3 1 of the current
year. The minus sign (-) after DEC: indicates a
negative offset. The dash ( - ) indicates that the
value for the day is missing.

Note: If a description of a qualifier states that the value can be expressed as an
absolute time, a delta time, or a combination of the two, you must specify
a delta time as if it were a part of a combination time. For example, to
specify a delta time value of five minutes from the current time, use "+:5"
(not ":5").

1-17

Editing the DCL Command Line

At the DCL command level, you can use many individual keys and key
combinations to change what you type, recall commands, or display
information. DCL also provides you with the option of defining keys so
that you can enter commands with fewer keystrokes. This chapter describes
how to use the keyboard in DCL.

2.1

Executing a DCL Command
The RETURN key is recognized as a line terminator. Once you type a
command at the DCL prompt, press RETURN to terminate the line and send
it to the DCL command interpreter for execution. CTRL/Z and certain escape
sequences are also recognized as line terminators.

2.2

Interrupting and Canceling a DCL Command
After you enter a DCL command, you can temporarily interrupt its execution,
run other commands, and then return to executing the command that was
interrupted. To interrupt the execution of a command, use CTRL/T, CTRL/Y,
or CTRL/C. These keys behave in different ways depending upon the type of
DCL command that is currently executing.
As mentioned in Chapter 1, there are built-in commands and command
images. A built-in command is a part of the command interpreter. A
command image is a program that is called by the command interpreter.
A command image can be privileged or nonprivileged. Privileged command
images are those installed as such by VMS, you, or the system manager. They
may vary from system to system. Whether a command image is privileged
or nonprivileged affects the way it reacts to interruptions. Typically, you will
not know if a command is privileged or not until you interrupt it and try to
execute certain commands. For more information on privileged command
images, see the VMS Install Utility Manual.
The following tables list the results of CTRL/T, CTRL/Y, and CTRL/C on
the different types of DCL commands.

2-1

Editing the DCL Command Line
2.2 Interrupting and Canceling a DCL Command

Table 2-1
Key
Combination
CTRL/T

Interrupting Built-in Commands
Result
Interrupts the command, displays a line of information (node
name, process name, current time, image name, elapsed CPU
time, page faults, direct and buffered 1/0 operations, and pages
in physical memory) and then resumes command execution. Use
CTRL/T at the DCL prompt whenever you want to display any of
this information.
SET CONTROL=T must be set, either by you or by the system
manager. CTRL/T will not echo information if the system is
temporarily hung or if your terminal is set to NOBROADCAST.

CTRL/Y

No effect.

CTRL/C

Cancels command execution.

Table 2-2
Key
Combination

Result

CTRL/T

Same as for built-in commands.

CTRL/Y

Interrupts the command. The interrupted command is
temporarily suspended and control returns to the command
interpreter. You see the DCL prompt. After interrupting a
non privileged command image with CTRL/Y, you can do the
following:

CTRL/C

2-2

Interrupting Nonprivileged Command Images

•

Type CONTINUE to resume execution of the interrupted
command.

•

Enter another command. Entering any number of built-in
commands does not affect the interrupted one. (All the DCL
built-in commands are listed in Chapter 1.) Entering any
other type of command effectively cancels the interrupted
one.

•

Type STOP to terminate immediately the interrupted
command. STOP suppresses any cleanup activities such
as the display of error messages.

CTRL/C works like CTRL/Y unless the program you are executing
has enabled CTRL/C as the cancel key (which is a common
practice).

Editing the DCL Command Line
2.2 Interrupting and Canceling a DCL Command

Table 2-3

Interrupting Privileged Command Images

Key
Combination

Result

CTRL/T

Same as for built-in commands.

CTRL/Y

Interrupts the command. The interrupted command is
temporarily suspended and control returns to the command
interpreter. You see the DCL prompt. After interrupting
a privileged command image with CTRL/Y, you can do the
following:

CTRL/C

•

Type CONTINUE to resume execution of the interrupted
command.

•

Enter another command. Entering SPAWN, ATTACH, or
CONTINUE followed by any other command does not affect
the interrupted one. Entering any other command effectively
cancels the interrupted one.

•

Type STOP to terminate immediately the interrupted
command. STOP suppresses any cleanup activities such
as the display of error messages.

CTRL/C works like CTRL/Y unless the program you are executing
has enabled CTRL/C as the cancel key (which is a common
practice).

After interrupting a command image you can use the SPAWN command (a
built-in DCL command). The SP AWN command creates a subprocess. Within
that subprocess you can execute another command image without losing the
context of the interrupted one. Log out of a subprocess and type CONTINUE
to return to what you were doing.
For example, you can interrupt the EDT editor with the SPAWN command to
create a subprocess, read your mail, return to your main process, and continue
your editing session, as follows:
$EDT WORKFILE.TXT

lcTRL/YI

$ SPAWN
%DCL-S-SPAWNED, process MOOLA_1 spawned
%DCL-S-ATTACHED, terminal now attached to process MOOLA_1
$ MAIL
MAIL>

MAIL> EXIT
$ LOGOUT
Process MOOLA_1 logged out at 31-DEC-1988 17:03:04.03
%DCL-S-RETURNED, control returned to process MOOLA
$ CONTINUE

After you type the CONTINUE command, you can press CTRL/W to refresh
the screen.
2-3

Editing the DCL Command Line
2.3 Editing Commands

2.3

Editing Commands
There are many types of terminals, each with its own operating
characteristics. In general, they all have standard function and line editing
keys. This section describes the line editing keys that let you edit the DCL
command line.
To use the line editing keys, line editing must be enabled on your terminal.
To see whether or not line editing is enabled, type the SHOW TERMINAL
command. The current characteristics of the terminal are displayed. The
current status of line editing is displayed in the first column under "Terminal
Characteristics." For example:
$SHOW TERMINAL
Terminal: _VTA130:
Device_Type: VT200_Series Owner: ROHBA
LAT Server/Port: L121/Port_3
Physical terminal: _LTA130:
Width: 80
Parity: None
Input:
9600
LFfill: 0
24
Output: 9600
CRfill: 0
Page:
Terminal Characteristics:
Interactive
Echo
Type_ahead
No Escape
No Hostsync
TTsync
Lowercase
Tab
No Eightbit
Wrap
Scope
No Remote
Broadcast
No Readsync
No Form
Fulldup
No Modem
No Local_echo
No Autobaud
Hangup
Set_speed
No Brdcstmbx
No DMA
No Altypeahd
No Dialup
No Line Editing
Insert editing
No Fallback
No Syspassword
No Secure server
Disconnect
No Pasthru
Numeric Keypad
No SIXEL Graphics No Soft Characters No Printer Port
Advanced_ video
ANSI_CRT
No Regis
No Block_mode
No Edit_mode
DEC_CRT
No DEC_CRT2

If you find that line editing is not enabled, type the SET TERMINAL/LINE_

EDIT command to enable it.
You can edit a command line in either overstrike or insert mode. In overstrike
mode, the character you type overwrites the character indicated by the cursor.
In insert mode, the character you type is inserted to the left of the cursor.
The SET TERMINAL command establishes the default editing mode. You can
use the SET TERMINAL/INSERT command or the
SET TERMINAL/OVERSTRIKE command. Press CTRL/ A to change editing
modes (CTRL/ A acts as a toggle).
You can use the SET TERMINAL/WRAP command so that whenever you
enter more characters than will fit on one line of the terminal screen, the text
wraps to the next line. Keep in mind that you can edit only the line where
your cursor appears. When text wraps, you cannot use the up arrow key to
move the cursor up to edit the previous line. However, you can move the
cursor up to the previous line by using the DELETE key to delete all the
characters in the current line.
By default, changes made with the SET TERMINAL command apply only
to the current session. You can include SET TERMINAL commands in your
LOGIN.COM file to set the terminal to operate the way you want. For more
information on the SET TERMINAL command, see the VMS DCL Dictionary.
For more information on LOGIN.COM, see the Introduction to VMS.

2-4

Editing the DCL Command Line
2.3 Editing Commands

2.3.1

Deleting Characters
The DELETE key backspaces over·the most recently entered character and
deletes it. On a hardcopy terminal, the deleted letters are displayed between
backslash characters so you can see what is being deleted. On a video display
terminal, pressing the DELETE key erases the character from the screen and
moves the cursor backwards. Note that the key that performs the delete
function is marked RUBOUT on some terminals and is marked <Xl on
LK201 keyboards.
Note: Do not use the BACKSPACE key to delete characters when you are
entering DCL commands; the BACKSPACE key does not delete characters.

2.3.2

Deleting Lines
When line editing is enabled, you can use CTRL/U to delete characters from
the beginning of the line to the current cursor position.
When line editing is not enabled, you can use CTRL/U to cancel an entire
line. When you cancel a line with CTRL/U, the system ignores the line and
redisplays the DCL prompt.

2.3.3

More Editing Commands
Use the keys listed in Table 2-4 to edit the DCL command line. For some of
these keys to work, line editing must be enabled.
Table 2-4

Line Editing Keys

Key

Function

DELETE

Deletes the last character entered at the terminal. (On
some terminals, the DELETE key is labeled RUBOUT.)
The DELETE key also works when line editing is
disabled.

CTRL/A and
F14 1

Switches between overstrike mode and insert mode.
The default mode (as set with the SET TERMINAL
/LINE_EDIT command) is reset at the beginning of each
line.

CTRL/D and
Left arrow

Moves the cursor one character to the left.

CTRL/E

Moves the cursor to the end of the line.

CTRL/F and
Right arrow

Moves the cursor one character to the right.

CTRL/H and
BACKSPACE and
F12 1

Moves the cursor to the beginning of the line.

This key is available only on an LK201 keyboard.

2-5

Editing the DCL Command Line
2.3 Editing Commands

Table 2-4 (Cont.)

Line Editing Keys

Key

Function

CTRL/I and
TAB

Moves the cursor to the next tab stop on the terminal.
The system provides tab stops at every eighth character
position on a line. Tab settings are hardware terminal
characteristics that, in general, you can modify. The
TAB key also works when line editing is disabled.

CTRL/J and
LINEFEED and
F13 1

Deletes the word to the left of the cursor.

CTRL/U

Deletes characters from the beginning of the line to the
cursor. (This overrides the standard CTRL/U function,
which deletes the current line.)

CTRL/V

Turns off some of the line editing function keys. For
example, if you press CTRL/V followed by CTRL/D, a
CTRL/D is generated instead of the cursor moving left
one character. CTRL/D is a line terminator at the DCL
level.
When combined with CTRL/V, characters that are not
line terminators have no effect. Examples are CTRL/H
and CTRL/J. However, certain control keys, such as
CTRL/U, retain their line editing function in spite of
CTRL/V.

F7,F8,F9,F11

Reserved to DIGIT AL

1 This key is available only on an LK201

2.4

keyboard.

Recalling Commands
At the DCL command level you can recall previously typed command lines
by using one of the following:
•

CTRL/B

•

Up and down arrow keys

•

RECALL command

All of the above let you display the commands that are stored in the recall
buffer. The recall buffer holds up to 20 previously entered commands. Once
a command is displayed, you can reexecute it or edit it.
Pressing CTRL/B displays the previous command line. Pressing CTRL/B
again displays the line before the previous line, and so on to the last saved
command line.
Pressing the up and down arrow keys recalls the previous and successive
command respectively. You can press the arrow keys repeatedly to move
through the commands.

2-6

Editing the DCL Command Line
2.4 Recalling Commands

The RECALL/ ALL command displays a list of previously entered commands.
You can then request a command by its number. For example:
$ RECALL 3

After you press RETURN, the third command from the list is displayed at the
DCL prompt. (The RECALL command itself is not placed in the buffer.)
You can also follow RECALL with the first character(s) of the command line
you want to display. RECALL scans the previous command lines (beginning
with the most recent one) and returns the first one that begins with the
character(s) you typed. For example:
$ RECALL D
$DIR

At the DCL command level, you can always use CTRL/B and the up and
down arrow keys for command recall. If you are in a utility or an application
program that uses VMS screen management software, you can also use these
keys to perform command recall. Line editing must be enabled. In this case,
you can recall up to the last 20 command lines. Examples of utilities that
have this feature are MAIL, DEBUG, SHOW CLUSTER, the System Dump
Analyzer (SDA), and the VAXTPU editor.

2.5

Terminal Function Keys
The terminal has standard function keys that let you perform terminal
functions. Table 2-5 lists the standard terminal function keys and describes
their use.
Table 2-5

Terminal Function Keys

Key

Function

CTRL/B and
Up arrow

Displays the last command line entered. If pressed
again, displays the previous command in the recall
buffer. The recall buffer stores the 20 most recently
entered commands.

CTRL/C and
F6 1

During command entry, cancels command processing.
CTRL/C is displayed as "Cancel".
Certain applications enable CTRL/C as the cancel key.
For these applications, CTRL/C cancels the operation
in progress. If CTRL/C is not enabled, the action is
changed to an interrupt (CTRL/Y).

CTRL/K

Advances the current line to the next vertical tab stop.

CTRL/L

Causes the terminal to go to the beginning of the next
page. This use of this key is ignored when line editing is
enabled.

CTRL/O

Alternately suspends and continues display of output to
the terminal. CTRL/O is displayed as "Output off" and
"Output on".

CTRL/Q

Restarts terminal output that was suspended by CTRL/S.

1 This key is available only on an LK201

keyboard.

2-7

Editing the DCL Command Line
2.5 Terminal Function Keys

Table 2-5 (Cont.)

Terminal Function Keys

Key

Function

CTRL/R

Retypes the current input line and leaves the cursor
positioned at the end of the line.

CTRL/S

Suspends terminal output until CTRL/Q is pressed.

CTRL/T

Momentarily interrupts terminal output to display a line
of statistical information about the current process.
SET CONTROL=T must be specified in the systemwide login command file, or by you (in LOGIN.COM or
interactively). The display includes your node and user
name, the time, the name of the image you are running;
and information about system resources used during
your current terminal session.
You can also use the CTRL/T key to determine if the
system is operating. (CTRL/T does not echo information
if the system is temporarily hung or if your terminal is
set to NOBROADCAST .)

CTRL/U

Cancels the current input line.

CTRL/X

Cancels the current line and deletes data in the typeahead buffer.

CTRL/Y

Interrupts command processing. CTRL/Y is displayed as
"Interrupt". You can disable CTRL/Y with the command
SET NOCONTROL=Y.
Under most conditions, CTRL/Y returns you to the DCL
prompt. The program running is still active. You can
enter any of the commands discussed in Section 2.2
and then continue the program with the CONTINUE
command.

CTRL/Z and
F10 1

Signals the end of the file for data entered from the
terminal. CTRL/Z is displayed as "Exit".

Down arrow

Displays the next line in the recall buffer.

RETURN

Sends the current line to the system for processing. (On
some terminals, the RETURN key is labeled CR.)
Before a terminal session, initiates a login sequence.

1 This key is available only on an LK201

2-8

keyboard.

Editing the DCL Command Line
2.6 Defining Terminal Keys

2.6

Defining Terminal Keys
Key definitions let you customize your keyboard so you can enter DCL
commands with fewer keystrokes. A key definition is a string of characters
that you assign to a particular terminal key. When a key is defined, you can
press it instead of typing the characters. A key definition usually contains all
or part of a command line. When you press a defined key, the command is
either executed or displayed on your terminal.
Some definable keys are enabled for definition all the time (like keys PFl
through PF4 and keys F17 through F20 on VT200 series terminals). Other
keys, including KPO through KP9, PERIOD, COMMA, and MINUS, need
to be enabled for definition purposes. Enter either the SET TERMINAL
/APPLICATION command or the SET TERMINAL/NONUMERIC command
before using these keys. For a list of keys that you can define and for more
information on how to create definitions, see the description of the DEFINE
/KEY command in the VMS DCL Dictionary.

2-9

File Specifications

This chapter provides the rules for using VMS file specifications and device
names with DCL commands. It contains information about the following:

3.1

•

Specifying the parts of a file specification; including' the node, device,
directory, file name, and file type

•

Using wildcards in file specifications to indicate groups of files

Format for File Specifications
To uniquely identify a file that you want to access, use a file specification.
A file specification provides the system with all the information it needs to
identify a file. A full file specification has the following format:
node:: device:[ directory ]filename. type ;version

The fields are as follows:
node

A network node name; applicable only to systems that support
DECnet-VAX.

device

The name of the physical device on which the file is stored or
is to be written.

directory

The system uses the directory name established at login or
by the SET DEFAULT command.

file name

No defaults are applied to the first file name in an input
file specification. Most commands apply default output file
names based on the file name of an input file.

file type

Various commands apply defaults for file types, based
on the standard file type conventions summarized in
Table 3-3.

file version

For input files, the system assumes the highest version
number.
For output files, if no file with the specified file name and
file type exists in the current directory, the file is created
with a version number of 1. However, if one or more
versions do exist, the next highest version number is used.

3-22

Logical Names

A logical name usually represents a file specification, a device name, or
another logical name. Use logical names as a shorthand way of specifying
files or directories that you refer to frequently. For example, you might assign
a logical name to your default disk and directory. You can also use logical
names to do the following:
•

Keep your programs and command procedures independent of physical
file specifications

•

Refer to physical devices

For example, you can assign logical names to tape drives, terminals, and
line printers. Also, the system manager assigns logical names to public disk
volumes. That way you do not have to be concerned with the physical
location of those volumes.
Logical names can be defined by you or by the system. Logical names and
their definitions are kept in tables called logical name tables. The system
provides the following logical name tables:
•

Your process table

•

The job table for your process

•

Your group table

•

The system table

When you enter a logical name as part of a command line, the system
translates the logical name. It does t.his by referring to the logical name tables
in a certain order. Information about existing logical name tables and the
search order are stored in logical name directory tables.
With DCL you can create your own logical names and logical name tables.
You can also apply special attributes to logical names and define the order in
which logical name tables are searched.
The following sections describe logical name tables, logical name directory
tables, and logical names provided by the system. Included are all the
commands and qualifiers provided by DCL that you need to work with
logical names.

4-1

Logical Names
4.1 Creating, Displaying, and Deleting Logical Names

4.1

Creating, Displaying, and Deleting Logical Names
You can create your own logical names with either the ASSIGN command
or the DEFINE command. This chapter uses the DEFINE command to create
logical names. (Note that the syntax for the ASSIGN command differs from
the syntax for the DEFINE command. For information on using ASSIGN, see
the VMS DCL Dictionary.)
The syntax for defining a logical name is as follows:
DEFINE logical-name equivalence-name[, ... ]

where:

•

logical-name is the name you create

•

equivalence-name is the definition

For example:
$ DEFINE CAT WORK1: [SIAMESE]

Now you can use CAT to refer to the directory WORKl :[SIAMESE].
Observe the following rules when creating a logical name with the DEFINE
command:
•

A logical name can be used to form all or part of a file specification.

•

A logical name and its equivalence name can each have a maximum of
255 characters. A logical name can contain alphanumeric characters, as
well as the underscore (- ), dollar sign ( $ ), and hyphen ( - ).

•

The equivalence name must include the punctuation marks (colons,
brackets, periods) that would be required if it were part of a file
specification. For example, a device name is terminated by a colon,
a directory specification is enclosed in square brackets, a file type is
preceded by a period.

•

You can optionally terminate a logical name with a colon. If you do this,
the ASSIGN command removes the colon before placing the logical name
in a logical name table. The DEFINE command does not remove the
colon before placing the name in a logical name table.
In general, you should not specify a colon at the end of a logical name
when you are creating it. However, if you do specify a colon at the end
of a logical name, and if you want to save the colon as part of the logical
name, use the DEFINE command. (Note that when you delete a logical
name ending with a colon, you need to specify two colons.)

When you use a logical name as part of a file specification, the logical
name must be the leftmost component of the file specification and must
be terminated by a colon ( : ). When you use a logical name to represent a
complete file specification, the terminating colon is not needed.

4-2

Logical Names
4.1 Creating, Displaying, and Deleting Logical Names

The following examples illustrate the correct use of the colon with logical
names:

Logical Name

Used in a File
Specification

DEFINE BOSS DISK$DOC:

DIR BOSS:[RALPH]

DEFINE BOSS DISK$DOC:[RALPH]PLANT.DAT

EDIT BOSS

By default, the DEFINE command places logical names in your process
logical name table. To specify a different table, use the /TABLE qualifier. For
example:
$ DEFINE/TABLE=LNM$JOB CAT WORK1: [SIAMESE]

Now the logical name CAT exists in your job logical name table. You can also
use the /JOB qualifier to place a logical name in the job table. For example:
$ DEFINE/JOB CAT WORK1: [SIAMESE]

For more information on logical name tables, see Section 4.2.

4.1.1

Displaying Logical Names
Display the definition of a logical name with either the SHOW
TRANSLATION command or the SHOW LOGICAL command.

4.1.1.1

The SHOW TRANSLATION Command
When you enter the SHOW TRANSLATION command, it searches the logical
name tables in a certain order for the specified logical name. It displays
the first definition it finds as well as the table in which it was found. For
example:
$ SHOW TRANSLATION CAT
"CAT" = "WORK1: [SIAMESE]" (LNM$PROCESS_TABLE)

This shows that the logical name CAT stands for WORKl :[SIAMESE]. It
also shows that the name CAT exists in the process logical name table
(LNM$PROCESS_TABLE).

4.1.1.2

The SHOW LOGICAL Command
When you enter the SHOW LOGICAL command, it searches all the logical
name tables for the specified logical name. It displays all the definitions it
finds as well as the tables in which they were found. For example:
$ SHOW LOGICAL CAT
"CAT"= "WORK1: [SIAMESE]" (LNM$PROCESS_TABLE)
"CAT" = "WORK1: [SIAMESE]" (LNM$JOB_80F874CO)

The system found the logical name CAT in both the process and job logical
name tables.
Sometimes the definition of a logical name may include another logical name.
The SHOW LOGICAL command keeps searching the logical name tables until
all levels of logical names in a definition have been found. This is referred to
as iterative translation.

4-3

Logical Names
4.1 Creating, Displaying, and Deleting Logical Names

When iterative translation is performed, the SHOW LOGICAL command
displays multiple lines. Each line has a number that shows the level of
translation. For example:
$ SHOW LOGICAL MYDISK
"MYDISK" = "WORK4" (LNM$PROCESS_TABLE)
1 "WORK4" = "$255$DUA17:" (LNM$SYSTEM_TABLE)

Level numbers are zero based; that is, 0 is the first level, 1 is the second,
and so on. In this example, two translations were performed. The number 1
indicates the second level of translation.
Unless you have redefined the search order, you can display the contents
of the process, job, group, and system logical name tables by entering the
SHOW LOGICAL command without qualifiers or parameters. For example:
$ SHOW LOGICAL

This command displays the logical names and their definitions in all four
tables.
To display all the entries in a particular logical name table, use the /TABLE
qualifier. For example:
$ SHOW LOGICAL/TABLE=LNM$GROUP

This command displays all the logical names in the group table. You can also
use the /GROUP qualifier to display the logical names in the group table.
For example:
$ SHOW LOGICAL/GROUP

The /SYSTEM, /JOB, and /PROCESS qualifiers display the logical names in
the system, job, and process tables.

4.1.2

Deleting Logical Names
To delete a logical name, use the DEASSIGN command. For example:
$ DEFINE TEST [JONES]

$ DEASSIGN TEST

4.2

Logical Name Tables
The system stores logical names in logical name tables. Some logical name
tables are available only to your process. Other tables are shareable, they are
available to other users on the system. Within each table, the system defines
some logical names for you. Each table and its system-defined logical names
are described in the following sections.

4-4

Logical Names
4.2 Logical Name Tables

4.2.1

The Process Table
Your process logical name table contains logical names that are available only
to your process. Its name is LNM$PROCESS_TABLE. However, you should
use the logical name LNM$PROCESS to refer to it. To display the names in
your process table, use the following command:
$ SHOW LOGICAL/PROCESS

By default, the DEFINE and DEASSIGN commands place names in and delete
names from your process table.
There is a process logical name table for every process on the system. When
you log in, the VMS operating system creates logical names for your process,
and places them in your process table. These names are listed in Table 4-1.
Table 4-1

Default Process Logical Names

Logical Name

Description

SYS$COMMAND

The initial file from which DCL reads input. (A file from
which DCL reads input is called an input stream.) The
command interpreter uses SYS$COMMAND to "remember"
the original input stream.

SYS$DISK

Default device established at login or changed by the SET
DEFAULT command.

SYS$ERROR

The default device or file to which DCL writes error
messages generated by warnings, errors, and severe
errors.

SYS$1NPUT

The default file from which DCL reads input.

SYS$NET

The source process that invokes a target process in
DECnet-VAX task-to-task communication. When opened
by the target process, SYS$NET represents the logical
link over which that process can exchange data with its
partner. SYS$NET is defined only during task-to-task
communication.

SYS$0UTPUT

The default file to which DCL writes output. (A file to
which DCL writes output is called an output stream.)

Default device name for terminals.

Note that SYS$INPUT, SYS$0UTPUT, SYS$ERROR, and SYS$COMMAND
define files that remain open for the life of the process. They are referred to
as process permanent files. For more information on process permanent files,
see Section 4.9.
Each user on the system is represented by a job tree. A job tree is a hierarchy
of all your processes and subprocesses, with your main process at the top.
Process logical names are recognized by the process they were created in
and by any subsequent subprocess. However, process logical names are not
recognized by any parent process.

4-5

Logical Names
4.2 Logical Name Tables

4.2.2

The Job Table
Your job logical name table contains logical names that are available to all
processes in your job tree. These logical names are available to you no matter
what process or subprocess you are currently in. The name for your job table
is LNM$JOB_xxx where xxx is the Job Information Block address (defined
by the system) for your job tree. However, you should use the logical name
LNM$JOB to refer to your job table.
When you log in, the VMS operating system creates certain logical names
and places them in the job logical name table. These names are listed in
Table 4-2. In addition, the logical names that are created for mounted disks
and tapes and temporary mailboxes are also placed in the job logical name
table.
Table 4-2

Default Job Logical Names

Logical Name

Description

SYS$LOGIN

Your default device and directory when you log in.

SYS$LOGIN_DEVICE

Your default device when you log in.

SYS$REM_ID

For jobs initiated through a DECnet network connection,
the identification of the process on the remote node
from which the job was originated. On VMS operating
systems, if proxy logins are enabled, this identification
is the process' user name, or, if proxy logins are not
enabled, this is the process identification number (PIO).
For more information about proxy logins, see the Guide
to VMS System Security. Other operating systems may
send other data (terminal numbers, for example) as the
remote process identification.

SYS$REM_NODE

For jobs initiated through a DECnet network connection,
the name of the remote node from which the job was
originated.

SYS$SCRATCH

Default device and directory to which temporary files are
written.

There is one job table for each job tree in the system. All job tables are
shareable. They are located on the system so that all users may access them.
However, to access a job logical name table other than your own, you must
redefine LNM$JOB in your process directory logical name table. For more
information, see Section 4.3.

4.2.3

The Group Table
The group logical name table contains logical names that are available to
all users with the same UIC group number. Its name is LNM$GROUP_xxx
where xxx represents your UIC group number. However, you should use the
logical name LNM$GROUP to refer to your group table. To create or delete
a name in your group table, you need GRPNAM, GRPPRV, or SYSPRV
privilege. There is a group logical name table for every group on the system.

4-6

Logical Names
4.2 Logical Name Tables

4.2.4

The System Table
The system logical name table contains logical names that are available to
all users on the system. Its name is LNM$SYSTEM_TABLE. However, you
should use the logical name LNM$SYSTEM to refer to it. To create or delete
a name in the system table, you must have one of the following:
•

A UIC group number between zero and 10

•

SYSNAM privilege

•

SYSPRV privilege

There is only one system logical name table for the system. It contains the
names shown in Table 4-3.
Table 4-3

Default System Logical Names

Logical Name

Description

DBG$1NPUT

Default input stream for the VMS Debugger; equated to
SYS$1NPUT.

DBG$0UTPUT

Default output stream for the VMS Debugger; equated
to SYS$0UTPUT.

SYS$COMMON

Device and directory name for the common part of
SYS$SYSROOT. (Note that for private system disks, this
is identical to SYS$SPECIFIC.)

SYS$ERRORLOG

Device and directory name of error log data files.

SYS$EXAMPLES

Device and directory name of system examples.

SYS$HELP

Device and directory name of system help files.

SYS$1NSTRUCTION

Device and directory name of system instruction data
files.

SYS$LIBRARY

Device and directory name of system libraries.

SYS$MAINTENANCE

Device and directory name of system maintenance files.

SYS$MANAGER

Device and directory name of system manager files.

SYS$MESSAGE

Device and directory name of system message files.

SYS$NODE

Network node name for the local system if DECnet-VAX
is active on the system.

SYS$SHARE

Device and directory name of system shareable images.

SYS$SPECIFIC

Device and directory name for node-specific part of
SYS$SYSROOT.

SYS$SYSDEVICE

VMS system disk containing system directories.

SYS$SYSROOT

Device and root directory for system directories. (For a
common system disk, this logical name will be defined
as a search list that consists of the node-specific device
and directory, and the common device and directory.
For a noncommon system disk, this logical name will
only consist of the node-specific device and directory.)

4-7

Logical Names
4.2 Logical Name Tables

Table 4-3 (Cont.)

4.3

Default System Logical Names

Logical Name

Description

SYS$SYSTEM

Device and directory of operating system programs and
procedures.

SYS$TEST

Device and directory name of User Environment Test
Package (UETP) files.

SYS$UPDATE

Device and directory name of system update files.

Logical Name Directory Tables
The system provides the following two directory tables to catalog your logical
name tables:
•

LNM$PROCESS_DIRECTORY catalogs your process tables

•

LNM$SYSTEM_DIRECTORY catalogs your shareable tables

Both of these directories contain logical names that translate iteratively to
table names. The name of a logical name table must be recorded in one of
these directory tables in order for the system to find it.
You can see the relationship of directory tables to logical name tables with
the SHOW LOGICAL/STRUCTURE command. For example:
$ SHOW LOGICAL/STRUCTURE
(LNM$PROCESS_DIRECTORY)
(LNM$PROCESS_TABLE)
(LNM$SYSTEM_DIRECTORY)
(LNM$GROUP_000360)
(LNM$JOB_806E98EO)
(LNM$SYSTEM_TABLE)

4.3.1

The Process Directory Table
Each process on the system has its own process directory logical name table.
When you log in, the VMS operating system places certain logical names in
your process directory table. These names are listed in Table 4-4.

4-8

Logical Names
4.3 Logical Name Directory Tables

Table 4-4

4.3.2

Default Process Directory Logical Names

Logical Name

Description

LNM$GROUP

A logical name that is defined as
LNM$GROUP_xxx, where xxx represents
your group number. LNM$GROUP_xxx is
the logical name table used by your UIC
group. (The table LNM$GROUP_xxx is
cataloged in the system directory table.)
Therefore, LNM$GROUP is a logical name
that translates iteratively to the name of
your group logical name table.

LNM$JOB

A logical name that is defined as
LNM$JOB_xxx, where xxx represents a
number unique to your job tree. LNM$JOB_
xxx is the logical name table used by your
job. (The table LNM$JOB_xxx is cataloged
in the system directory table.) Therefore,
LNM$JOB is a logical name that translates
iteratively to the name of your job logical
name table.

LNM$PROCESS

A logical name that is defined as
LNM$PROCESS_TABLE. Therefore,
LNM$PROCESS is a logical name that
translates iteratively to the name of your
process logical name table.

LNM$PROCESS_DIRECTORY

The name of your process directory logical
name table.

LNM$PROCESS_TABLE

The name of your process logical name
table.

The System Directory Table
There is one system directory logical name table. The VMS operating system
places certain logical names in the system directory table. These names are
listed in Table 4-5.

4-9

Logical Names
4.3 Logical Name Directory Tables

Table 4-5

4-10

Default System Directory Logical Names

Logical Name

Description

LNM$DCL_LOGICAL

A logical name that is defined as
LNM$FILE_DEV. This logical name
iteratively translates into the list of logical
name tables searched and displayed by the
SHOW LOGICAL and SHOW TRANSLATION
commands and the F$TRNLNM lexical
function. By default, these commands
search and display the process, job, group,
and system logical name tables, in that
order.

LNM$DIRECTORIES

A logical name that is defined as
LNM$PROCESS_DIRECTORY and
LNM$SYSTEM _DIRECTORY.

LNM$FILE_DEV

A logical name that is defined as the
list of logical name tables searched
by the system when processing a file
specification. By default, it is defined as
LNM$PROCESS, LNM$JOB, LNM$GROUP,
and LNM$SYSTEM. This means that the
process, job, group, and system logical
name tables are searched, in that order.

LNM$GROUP_xxx

The name of a group logical name table.
The characters xxx represent a particular
group number. There is an LNM$GROUP_
xxx logical name table for each group in the
system.

LNM$JOB_xxx

The name of a job logical name table. The
characters xxx represent a number unique
to this job tree. There is an LNM$JQB_
xxx logical name table for each job in the
system.

LNM$PERMANENT_MAILBOX

A logical name that is defined as
LNM$SYSTEM. (Logical names associated
with permanent mailboxes are entered in the
logical name table to which the logical name
LNM$PERMANENT_MAILBOX iteratively
translates.)

Logical Names
4.3 Logical Name Directory Tables

Table 4-5 (Cont.)

4.4

Default System Directory Logical Names

·Logical Name

Description

LNM$SYSTEM

A logical name that is defined as
LNM$SYSTEM_TABLE. Therefore,
LNM$SYSTEM is a logical name that
translates iteratively to the name of the
system logical name table.

LNN$SYSTEM_DIRECTORY

The name of the system directory logical
name table.

LNM$SYSTEM _TABLE

The name of the system logical name table.

LNM$TEMPORARY_MAILBOX

A logical name that is defined as LNM$JOB.
(Logical names associated with temporary
mailboxes are entered in the logical
name table to which the logical name
LNM$TEMPORARY_MAILBOX iteratively
translates.)

Logical Name Translation
When the system reads a file specification or device name in a DCL command
line, it examines it to see if the leftmost component is a logical name. If the
leftmost component ends with a colon, space, comma, or an end-of-line, the
system attempts to translate it as a logical name. If the leftmost component
ends with any other character, the system does not attempt to translate it as a
logical name.
In the following example, the system checks to see if ALPHA is a logical
name because ALPHA is the leftmost component of the file specification:
$ TYPE ALPHA

In the next example, the system checks to see if DISK is a logical name
because it is the leftmost component and it ends with a colon (it does not
check ALPHA):
$ TYPE DISK:ALPHA

In the third example, the system does not try to translate [MALCOLM]ALPHA
because the leftmost component ends with a square bracket (]):
$ TYPE [MALCOLM]ALPHA

By default, when the system translates logical names in file specifications, it
searches the process, job, group, and system tables, in that order, and uses
the first match it finds. The two ways to change this search order are as
follows:
•

Redefine the logical name LNM$FILE_DEV within the system directory
table

•

Create a private definition of LNM$FILE_DEV within the process
directory table

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Logical Names
4.4 Logical Name Translation

The system searches the specified tables. For example:
$ DEFINE/TABLE=LNM$PROCESS_DIRECTORY _$ LNM$FILE_DEV LNM$PROCESS,LNM$SYSTEM

In this example, LNM$FILE_DEV is defined so that LNM$JOB and
LNM$GROUP are omitted. When a logical name is used in a file
specification, the process and system tables are searched but not the job
and group tables.

4.4.1

Iterative Translation
Logical name translation can be iterative. This means that after the system
translates a logical name, it repeats the process for any logical names it finds
contained within the first logical name. For example:
$DEFINE DISK DBA1:
$DEFINE REPORT DISK: [PAT.STUFF]MAC.SUB

In this example, the first DEFINE command equates the logical name DISK
to the device name DBA1. The second DEFINE command equates the logical
name REPORT to the file specification DISK:[PAT.STUFF]MAC.SUB. When
the system translates the logical name REPORT, it finds the equivalence name
DISK:[PAT.STUFF]MAC.SUB. It then checks to see if the leftmost component
in this file specification ends in a colon, a space, a comma, or an end-of-line.
It finds a colon after DISK. The system translates that logical name also. The
final translation of the file specification is as follows:
DBA1: [PAT.STUFF]MAC.SUB

The system limits the number of levels to which it performs logical name
translation. The number of levels varies among system facilities, but it is at
least nine. If you define more than the system-determined number of levels,
or if you create a circular definition, an error occurs when the logical name is
used.

4.4.2

Modifying Logical Name Translation
When you create a logical name, you can specify translation attributes
that modify the interpretation of an equivalence name. Use the
/TRANSLATION-ATTRIBUTES qualifier after the DEFINE command. This
is a positional qualifier. Depending on where you place it on a command line,
it can apply translation attributes to all equivalence names or only to certain
ones.
The following sections describe the two translation attributes that are
available: CONCEALED and TERMINAL.

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Logical Names
4.4 Logical Name Translation

4.4.2.1

Concealing the True Identity of a Logical Name
The CONCEALED attribute causes the logical name of a device, rather
than the physical name, to be displayed in system messages. The following
example shows how to create a concealed device name:
$ DEFINE/TRANSLATION_ATTRIBUTES=CONCEALED DISK DMA3:
$ SHOW DEFAULT
DISK: [ALICE.RATS]
$ SHOW LOGICAL DISK
"DISK" = "DMA3" (LNM$PROCESS_TABLE)

The logical name DISK represents the physical device DMA3. Thus, the
SHOW DEFAULT command displays the logical name DISK rather than the
actual physical device name, DMA3. The SHOW LOGICAL command reveals
the translation of DISK.
You can only use the CONCEALED attribute with logical names that
represent physical devices. Using concealed devices lets you write programs,
write command procedures, and perform other operations without being
concerned about which physical device actually holds the disk or tape. It also
lets you use names that are more meaningful than the physical device names.

4.4.2.2

4.4.3

Preventing Iterative Translation
The TERMINAL attribute prevents iterative translation of a logical name.
That is, the equivalence name is not examined to see if it is also a logical
name. The translation is "terminal" (final, or completed) after the first
translation.

How the System Applies Defaults During Logical Name Translation
When the system translates a logical name, it fills in any missing fields in a
file specification. It fills them in with the current default device, directory, and
version number. When you use a logical name to specify the input file for a
command, the command uses the logical name to assign a file specification to
the output file as well.
If the equivalence name contains a file name and file type, the output file
is given the same file name and file type. If the equivalence name does not

contain a file type, a default file type is supplied. The file type supplied
depends on the command you are using.

4.4.4

Including a Logical Name in an Input File List
When you use logical names in a list of input files, the equivalence name of
each logical name provides a temporary default. For example:
$ SET DEFAULT DBA2: [CASEY]
$DEFINE MAL DBA1: [MALCOLM]
$ DEFINE HIG [HIGGINS]
$ PRINT ALPHA,MAL:BETA,HIG:GAMMA

The PRINT command looks for the following files:
DBA2:[CASEY]ALPHA. LIS
DBAl :[MALCOLM]BETA.LIS

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Logical Names
4.4 Logical Name Translation

DBAl :[HIGGINS]GAMMA.LIS
Because a device name was not specified for the logical name HIG, the device
name for MAL defines DBAl as the temporary default device. For more
information on temporary defaults, see Section 3.5.6.

4.5

Logical Name Access Modes
The four access modes in the VMS operating system are as follows:
•

User-mode (the outermost and least privileged mode)

•

Supervisor-mode

•

Executive-mode

•

Kernel-mode (the innermost and most privileged mode)

When you create a logical name with DCL commands, it has an access mode
of user, supervisor, or executive. By default, logical names are created in
supervisor mode. There are qualifiers that let you specify user mode or
executive mode. For example:
$ DEFINE TEST USE1:
$ DEFINE/EXECUTIVE_MODE TEST USE1:

The first command places the logical name TEST in the process logical name
table in supervisor mode. The second command places the logical name
TEST in the process logical name table in executive mode. (You must have
SYSNAM privilege to create an executive mode logical name. If you do
not have SYSNAM privilege, the name is created in supervisor mode, even
though you specified executive mode.) After you enter these commands, two
logical names called TEST exist in the process table.
To see the access mode for a logical name, use the SHOW LOGICAL/FULL
command. For example:
$ SHOW LOGICAL/FULL MAX
"MAX" [super] = "USE1: [JONES]" (LNM$PROCESS_TABLE)

This shows that the logical name MAX was created in supervisor mode.
Logical names created in user mode are temporary. They are deleted when
the current image (or the next image, if none is currently active) terminates.
During VMS operations when the integrity of the system could be
compromised by incorrect logical names (such as in the activation of
privileged images), only executive-mode and kernel-mode logical names
are used; supervisor-mode and user-mode names are ignored. DIGITAL
therefore recommends that logical names for important system components
(public disks and directories, for example) be defined in executive mode, using
the DCL command DEFINE/SYSTEM/EXECUTIVE. (Only the operating
system and privileged programs can create logical names in kernel-mode.)

4-14

Logical Names
4.6 Creating Your Own Logical Name Tables

4.6

Creating Your Own Logical Name Tables
Use the CREATE/NAME_TABLE command to create a new logical name
table. The CREATE/NAME_TABLE command creates a logical name table
and enters its name in one of the directory logical name tables. (Table names,
or logical names that translate iteratively to table names, must always be
entered in one of the directory logical name tables.)
You can create logical name tables that are process-private (the default) or
shareable. Process-private tables are listed in LNM$PROCESS_DIRECTORY.
Shareable tables are listed in LNM$SYSTEM_DIRECTORY.
A name in a directory table can contain 1 to 31 characters. Only
alphanumeric characters, the dollar sign ( $ ), and the underscore (-) are
valid. For example:
$ CREATE/NAME_TABLE NEWTAB

This command creates a logical name table called NEWTAB. By default,
NEWTAB is entered in LNM$PROCESS_DIRECTORY (the directory table for
logical names that are process-private). Use either of the following commands
to verify that the table was created:
SHOW LOGICAL/TABLE=LNM$PROCESS_DIRECTORY
SHOW LOGICAL/STRUCTURE

4.6.1

Shareable Tables
To create a shareable logical name table, use the /PARENT_TABLE qualifier
and specify the name of a shareable table. For example:
·
$ CREATE/NAME_TABLE/PARENT_TABLE=LNM$SYSTEM_DIRECTORY NEWTAB

The following privilege and access requirements apply to the use of shareable
logical name tables:

•

To create a shareable logical name table, you must have SYSPRV privilege
and ENABLE ( E) access to the parent table. 1

•

To delete a shareable logical name table, you must have SYSPRV
privilege or DELETE ( D) access to the table.

•

To place a name in or delete a name from a shareable logical name table,
you must have WRITE ( W) access to the table.

•

To read (translate) a name in a shareable logical name table, you must
have READ ( R) access to the table.

For more information on ENABLE access and logical name tables, see Section 8.2.7.

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Logical Names
4.6 Creating Your Own Logical Name Tables

4.6.2

Choosing a Table for a Logical Name
To place a logical name in a particular table, use the DEFINE/TABLE
command. For example:
$ DEFINE/TABLE=NEWTAB TESTDIR [JONES.TESTFILES]

The logical name TESTDIR is placed in NEWTAB (a user-defined table).
However, the next time you refer to TESTDIR in a file specification, the
system looks for it in the process, job, group, and system tables only. It does
not look in the NEWTAB table. You need to include NEWTAB in the list of
tables that the system searches. The two ways to do this are as follows:
•

Redefine LNM$FILE_DEV within the system directory table

•

Create a private definition of LNM$FILE_DEV within the process
directory table

For example:
$ DEFINE/TABLE=LNM$PROCESS_DIRECTORY LNM$FILE_DEV _$

NEWTAB, LNM$PROCESS, LNM$JOB, LNM$GROUP, LNM$SYSTEM

A process-private version of LNM$FILE_DEV is defined to include NEWTAB.
During logical name translation, NEWTAB is searched first for the following
reasons:
•

The process-private version of LNM$FILE_DEV is used before the default
system version.

•

Within LNM$FILE_DEV, NEWTAB is listed before the process, job,
group, and system tables.

Note that you create LNM$FILE_DEV in the process directory table. You
cannot change or add things to LNM$SYSTEM_DIRECTORY unless you
have SYSNAM or SYSPRV privilege.

4.6.3

Deleting Tables
To delete a logical name table, delete it from the directory table where it is
cataloged. For example:
$ DEASSIGN/TABLE=LNM$PROCESS_DIRECTORY NEWTAB

The table NEWTAB is deleted from the process directory table.

4.6.4

Quotas for Tables
Quotas are used to limit the amount of system resources that a given logical
name table can consume. The process, group, and system logical name tables
have an infinite quota. By default, when you create a logical name table it too
has an unlimited quota.

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Logical Names
4.6 Creating Your Own Logical Name Tables

4.6.4.1

The /QUOTA Qualifier
You can specify a quota to limit the size, in bytes, of a logical name table that
you create. For example:
$ CREATE/NAME_TABLE/QUOTA=500 ABC

This creates a logical name table, ABC, and gives it a quota of 500 bytes.
Before a logical name is created, the size of its data structure is checked
against the quota remaining fot the table. If there is insufficient quota
available for the new entry, the system displays an error message.
Once you set the quota for a table, you cannot change it. If the table runs out
of room, use the DEASSIGN command to delete old logical names. This frees
space for your new logical names.

4.6.4.2

Job Table Quota
The job logical name table is a shareable table. The quota for a job logical
name table is established when the table is created. The quota is determined
by whichever of the following applies:

•

The JTQUOTA value established for the user in the system user
authorization file, SYSUAF.DAT (if the first image activated by the
process was the VMS system image LOGINOUT).

•

The PQL$_JTQUOTA quota list value specified in the call to the Create
Process ($CREPRC) system service.

•

The /JOB_TABLE_QUOTA qualifier value on the RUN command used
to create the detached process.

•

The SYSGEN parameter PQL _DJTQUOTA (if none of the preceding
conditions applies). The standard default value for this parameter is 1024
bytes; however, the system manager can change it. The SYSGEN utility
can be used to display and set the _values of the parameters
PQL_DJTQUOTA (default job logical name table quota) and
PQL _MJTQUOTA (minimum job logical name table quota).

A quota value of 0 for a job logical name table specifies that the quota is, for
all practical purposes, unlimited.

4.6.5

Access Modes
When you create a logical name table, it has an access mode. A logical name
table can have an access mode of user, supervisor, or executive. By default,
logical name tables are created in supervisor mode. You can specify user
mode with the /USER_MODE qualifier. If you have SYSNAM privilege,
you can specify executive mode with the /EXECUTIVE_MODE qualifier. For
more information on access modes, see Section 4.5.

4-17

Logical Names
4.6 Creating Your Own Logical Name Tables

4.6.6

Protection
There are two ways to define the protection of a logical name table:

4. 7

•

Use the /PROTECTION qualifier with the CREATE/NAME_TABLE
command. This command lets you set UIC-based protection for a
shareable logical name table. For more information, see Chapter 8.

•

You can apply access control list (ACL) protection with the ACL Editor
or with the SET ACL/OBJECT_TYPE=LOGICAL_NAME_TABLE
command. ACLs for system logical name tables are saved, but ACLS
for process logical name tables are not. You must reestablish ACLs on
process logical name tables every time the system is booted. For more
information, see the SET/ ACL command in the VMS DCL Dictionary.

Search Lists
A search list is a logical name that has more than one equivalence name. You
can use a search list in any place you can use a logical name. For example:
$DEFINE FIFI [JONES.MEMOS], [JONES.WORKFILES]
$ SHOW LOGICAL FIFI
"FIFI"= "[JONES.MEMOS]" (LNM$PROCESS_TABLE)
= "[JONES.WORKFILES]"

The logical name FIFI is a search list because it has two equivalence names.
When you use a logical name that is a search list, the system translates the
logical name a number of times. It uses each equivalence name listed in the
definition. For example:
$DIRECTORY FIFI:POEM.DAT
Directory DISK1: [JONES.MEMOS]
POEM.DAT;2

POEM.DAT;1

Total of 2 files.
Directory DISK1: [JONES.WORKFILES]
POEM.DAT;1
Total of 1 file.
Grand total of 2 directories, 3 files.

The DIRECTORY command searches the equivalence names
[JONES.MEMOS] and [JONES.WORKFILES], in the order they were listed
when FIFI was defined. It finds a file named POEM.DAT in each directory. If
POEM.DAT exists in only one of the directories, only one directory listing is
displayed. If POEM.DAT does not exist in either directory, an error message
is displayed indicating that the file was not found.
A search list is not a wildcard. It is a list of places to look. Once a file is
found, the search is ended. For example, the following command finds the
most recent version of POEM.DAT in the search list defined by FIFI:

4-18

Logical Names
4. 7 Search Lists

$TYPE FIFI:POEM.DAT
DISK1: [JONES.MEMOS]POEM.DAT;2
When in disgrace with fortune and men's eyes
I all alone beweep my outcaste state,

However, you can use a search list with a command that accepts wildcards.
When you use wildcards, the system forms file specifications using each
equivalence name in the search list. The command operates on each file
specification that identifies an existing file.
For example, if you specify the TYPE command with a wildcard character in
the version field, it finds all versions of POEM.DAT in the search list defined
by FIFI.
$TYPE POEM:FILE.DAT;*
DISK1: [JONES.MEMOS]POEM.DAT;2
When in disgrace with fortune and men's eyes
I all alone beweep my outcaste state,
And trouble deaf heaven with
DISK1:[JONES.MEMOS]POEM.DAT;1
When in disgrace with fortune and men's eyes
I all alone beweep my outcaste state,
DISK1: [JONES.WORKFILES]POEM.DAT;1
Let me not to the marriage of true minds
admit after-dinner mints

When you use a search list with a command that does not accept wildcards in
a file specification, the system forms a file specification using each equivalence
name in the search list, until a file specification for an existing file is found.
The command performs its function only on the first existing file that is
identified by the search list. For example:
$DEFINE SISTER DISK1: [MUFFIN] ,WORK2: [FRED]
$EDIT SISTER:AVERAGE.TXT

First, the system forms the file specification DISKl :[MUFFIN]AVERAGE. TXT
and searches for that file. If the file is found, it is opened so that you can
edit it. No other files are subsequently opened. If the first file is not found,
the system searches for the file WORK2:[FRED]AVERAGE.TXT. If the file is
found, it is opened. If the file is not found, an error message is displayed.
The system displays an error message only after it has used all equivalence
names in a search list. Then the system reports an error only on the last file
it attempted to find.

Note: The RUN command is an exception. When the RUN command is followed
by a search list, the system forms file specifications as described above.
However, it then looks for each file specification in the known file list.
The known file list is a list of all images that are installed on the system.
In other words, the system checks to see if any of the files in the list are
installed images. It runs the first file in the search list that is an installed
image. Then the RUN command terminates.

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Logical Names
4. 7 Search Lists

If none of the file specifications are installed images, the system repeats
the process of forming file specifications. This time it looks for each file
specification on the disk. It runs the first file it finds there. An error
message is displayed if none of the specified files are found in either the
known file list or on the disk.

4.7.1

Using Search Lists
When you use a search list in a file specification, the search list is translated
as follows:
•

If the search list contains only a device, then the original default directory
is used

•

If the search list contains both a device and a directory, then these are
used to construct a complete file specification

For example:
$DEFINE FIFI DISK1: [FRED] ,DISK2: [GLADYS] ,DISK3: [MEATBALL.SUB]
$ DIRECTORY FIFI:MEMO.LIS

This command displays the following files:
DIS Kl :[FRED]MEMO.LIS
DISK2:[GLADYS]MEMO.LIS
DISK3:[MEATBALL.SUB]MEMO.LIS
When you specify a search list as the first part of the parameter for the SET
DEFAULT command, the system assigns the search list name, untranslated, to
SYS$DISK. (SYS$DISK is a logical name that translates to your default disk.)
For example:
$ SHOW DEFAULT
DISK2: [MEATBALL.SUB]
$DEFINE FIFI DISK1: [FRED], DISK2: [GLADYS], DISK3:
$ SET DEFAULT FIFI
$ SHOW DEFAULT
FIFI: [MEATBALL.SUB]
DISK1 : [FRED]
DISK2: [GLADYS]
DISK3: [MEATBALL.SUB]

At the beginning of this example, the default disk and directory are
DISK2:[MEATBALL.SUB]. Next, a search list is defined. The SET DEFAULT
command uses the search list as its parameter. When you enter the SHOW
DEFAULT command a second time, the default directory has not changed.
However, the search list FIFI is displayed as the default device along with its
equivalence names. The SHOW DEFAULT command displays the search list
in the order in which the search list is evaluated by the system.

Note: When you specify a search list as the first part of a parameter for the
SET DEFAULT command, each equivalence name in the search list must
contain a device name.

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Logical Names
4. 7 Search Lists

4.7.2

Search Order for Multiple Search Lists
It is possible to have a file specification that contains more than one search

list. When this occurs, each item in the file name search list is used, while the
first device name is held constant. After all the items in the file name search
list have been used with the first device name, they are used with the second
device name. This continues until each device has been used.
The following example shows a file specification that has a search list in the
file name and in the device name:
$DEFINE FILE CHAP1.RNO, CHAP2.RNO
$DEFINE DISK WORK1: [ROSE], WORK2: [THORN]
$ SET DEFAULT DISK
$ DIRECTORY FILE
Directory WORK1: [ROSE]
CHAP1.RN0;2

CHAP2.RN0;1

Total of 2 files.
Directory WORK2: [THORN]
CHAP1.RN0;1

CHAP2.RN0;1

Total of 2 files.
Grand total of 2 directories, 4 files.

The directory listing for each file name is given first for WORKl:[ROSE], and
second for WORK2:[THORN].
You can also have iterative (nested) search lists, when one name in a search
list translates to another search list. If this occurs, the system uses each name
in a sublist before continuing on to the next upper level name. For example:
$ DEFINE NESTED FRED.DAT, NEW_LIST, RICKY.DAT
$DEFINE NEW_LIST ETHEL.DAT, LUCY.DAT

The search order for the search list NESTED would be as follows:
FRED.DAT
ETHEL.DAT
LUCY.DAT
RICKY.DAT

4.8

Logical Node Names
A logical node name is a special type of logical name that can be used in
place of a network node name, or in place of a node name and an access
control string. For example:
$ DEFINE BOS II BOSTON II II ADAMS JOHN" II : : II

The logical name BOS is equated to a node name, BOSTON, and an access
control string where:
•

ADAMS is the user name

•

JOHN is the password

4-21

Logical Names
4.8 Logical Node Names

Use the logical name BOS to avoid typing (and displaying) your user name
and password on the terminal screen.

Note: You should not place a DEFINE command that includes a password in a
file (LOGIN.COM, for example). If others read the file, they will see the
password.
Observe the following rules for using logical node names:
•

A logical node name can contain 1 to 15 characters. Its equivalence name
must end with a double colon ( :: ). If the equivalence name does not end
in a double colon, the logical name is not interpreted as a logical node
name. Enclose the equivalence name in quotation marks. Use double
quotation marks in the places where you want quotation marks to appear
in an access control string.

•

A logical node name is translated at the local node. After the logical node
name is translated, the rest of the file specification is parsed to determine
whether the syntax is valid. However, logical names used as device
names are not translated at the local node. Therefore, a file specification
can contain a logical node name that is translated at your local node. It
can also contain a logical device name that is translated at the remote
node. For example:
$ DEFINE NYC NEWYRK::
$ TYPE NYC: :DOC: [PERKINS]TERM_PAPER.DAT

The logical node name NYC is translated at the local node but the device
name (DOC:) is translated at the remote node (NEWYRK). Use a double
colon in the DEFINE command to define a logical node name. You must
also use a double colon in the TYPE command because NYC is in the
node position of the file specification.
•

You can specify an access control string with a logical node name when
you perform network file operations. This access control string overrides
an access control string that is provided in the equivalence name for the
logical node name. For example:
$ DEFINE BOS "BOSTON" "ADAMS JOHN'"':: II
$TYPE BOS"REVERE PAUL": :RIDE.DAT

In this example, the access control string "REVERE PAUL" overrides the
access control string provided in the equivalence name.
•

Logical node names are translated iteratively. After a logical node name
is translated, the new node name becomes a candidate for logical node
name translation. (Iterative translation is described in Section 4.4. l.)

•

When a logical node name is translated iteratively, the access control
information in the logical node name that is first translated overrides
subsequent access control information. For example:
$ DEFINE TORONTO "TRNTD" "TEST RESULTS"": : "
$ DEFINE TEST1 "TORONTO" "TEST 1001"": : DBA1: II
$ TYPE TEST1:PROC.DAT

4-22

Logical Names
4.8 Logical Node Names

In the previous example, the logical name TESTl translates to
TORONTO"TEST lOOl"::DBAl:. TORONTO is a logical node name, so
iterative translation occurs. However, the access control string provided
by the DEFINE TESTl logical name assignment overrides the access
control string provided in the DEFINE TORONTO logical node name
assignment. Therefore, the TYPE command displays the following file:
TRNTO"TEST 1001": :DBA1:PROC.DAT

•

Logical node names that begin with an underscore character are not
translated even though the underscore character is not considered part of
the node name.

Logical Names for Process-Permanent Files
Process-permanent files are files that can remain open for the life of your
process. By default, DCL creates the following process-permanent files for
you when you log in:
•

SYS$INPUT-default input device or file

•

SYS$0UTPUT-default output device or file

•

SYS$ERROR-default device or file to which the system writes messages

•

SYS$COMMAND-the value of SYS$INPUT when you log in

Table 4-6 shows what these logical names are equated to by default.
Table 4-6

Equivalence Names for Process-Permanent Files

Logical
Name

Interactive
Mode

Batch
Mode

Command
Procedure

SYS$COMMAND

Terminal 1

Disk 2

Terminal

SYS$1NPUT

Terminal

Disk

SYS$ERROR

Terminal

Log file

SYS$0UTPUT

Terminal

Log file

Disk
3

Terminal
Terminal

1 Device name of your terminal
2 Device name of the initial default device

3 Batch job log file

You can use the logical names for process permanent files as file
specifications. The following example shows a FORTRAN command that
could be executed in a batch job:
$ FORTRAN/OBJECT=WEATHER SYS$INPUT:

When this command is executed, the compiler reads the input file from the
data lines following the FORTRAN command in the batch job command
procedure.

4-23

Logical Names
4.9 Logical Names for Process-Permanent Files

The /OBJECT=WEATHER qualifier provides the compiler with a default file
name for the output files: it creates WEATHER.OBJ and WEATHER.LIS. To
request that the listing file be written to the batch job log file, you could
specify the following:
$ FORTRAN/OBJECT=WEATHER/LIST=SYS$0UTPUT

SYS$INPUT:

The compiler creates the file WEATHER.OBJ and prints the listing in the
batch job log file.

Redefining SYS$1NPUT
You can redefine SYS$INPUT so that a command procedure reads input from
the terminal or another file. For example, to edit a file from a command
procedure, include the following lines in the command procedure:
$
$

DEFINE/USER_MODE SYS$INPUT SYS$COMMAND
EDIT MYFILE.DAT

SYS$INPUT is redefined as SYS$COMMAND so that the editor obtains input
from the terminal, rather than from the command procedure file (the default).
SYS$COMMAND refers to the terminal, the initial input stream when you
logged in. The /USER_MODE qualifier tells the command procedure that
SYS$INPUT is redefined only for the duration of the next image. In this
case, the next image is the editor. When the editor is finished, SYS$1NPUT
resumes its default value. In a command procedure, the default value of
SYS$INPUT is the command procedure file.
Note that if you redefine SYS$INPUT, DCL ignores your definition. DCL
always obtains input from the default input stream. However, images, such
as command procedures, can use your definition for SYS$INPUT.

Redefining SYS$0UTPUT
You can redefine SYS$0UTPUT to redirect output from your default device
to another file. When you redefine SYS$0UTPUT, the system opens a file
with the name you specify in the logical name assignment. When you define
SYS$0UTPUT, all subsequent output is directed to the new file.
When you redefine SYS$0UTPUT to redirect output from DCL commands
that are executed within the command interpreter, the following conditions
must be met:
•

Create the new logical name definition in supervisor mode and place it in
the process logical name table

•

Specify only one equivalence name

•

Do not specify any attributes for the new logical name

The following example shows a valid definition for SYS$0UTPUT:
$DEFINE SYS$0UTPUT MYFILE.LIS

After you enter this command, DCL output is written to MYFILE.LIS, not to
the terminal.

4-24

Logical Names
4.9 Logical Names for Process-Permanent Files

When you log in, the system creates two logical names called SYS$0UTPUT.
One name is created in executive mode; the other name is created in
supervisor mode. You can supersede the supervisor mode logical name
by redefining SYS$0UTPUT. If you deassign the supervisor mode name,
the system redefines SYS$0UTPUT in supervisor mode, using the executive
mode equivalence name. You cannot deassign the executive mode name. For
example:
$DEFINE SYS$0UTPUT TEMP.DAT
$ SHOW LOGICAL SYS$0UTPUT
$ SHOW TIME
$ DEASSIGN SYS$0UTPUT
$TYPE TEMP.DAT
"SYS$0UTPUT" = "DISK1:" (LNM$PROCESS_TABLE)
27-JAN-1988 13:26:53

First, SYS$0UTPUT is redefined (in supervisor mode) to the file TEMP.DAT.
When SYS$0UTPUT is redefined, output from DCL and from images is
directed to the file TEMP.DAT. Therefore, the output from the SHOW
LOGICAL command (an image) and from the SHOW TIME command (a
command that is executed within DCL) is sent to TEMP.DAT. When you
deassign SYS$0UTPUT, the system closes the file TEMP.DAT and redefines
SYS$0UTPUT (in supervisor mode) to your terminal. Therefore, when you
enter the TYPE command, the output is displayed on your terminal.
When you redefine SYS$0UTPUT to a file, the logical name contains only
the device portion of the file specification, even though the output is directed
to the file you specify. In this example, when SYS$0UTPUT was redefined,
the equivalence name contained the device name DIS Kl:, not the full file
specification.

If the system cannot open the file you specify when you redefine
SYS$0UTPUT, an error message is displayed.
After you redefine SYS$0UTPUT, most commands direct output to the
existing version of the file. However, certain commands create a new version
of the file before they write output.
Note that you can redefine SYS$0UTPUT in user mode to redirect output
from images.

Redefining SYS$ERROR
You can redefine SYS$ERROR to direct error messages to a specified file.
However, if you redefine SYS$ERROR so it is different from SYS$0UTPUT
(or if you redefine SYS$0UTPUT without also redefining SYS$ERROR), DCL
commands send informational, warning, error, and severe error messages to
both SYS$ERROR and SYS$0UTPUT. Therefore, you receive these messages
twice-once in the file indicated by the definition of SYS$ERROR, and once
in the file indicated by SYS$0UTPUT. Success messages are sent only to the
file indicated by SYS$0UTPUT.

If you redefine SYS$ERROR and then run an image that references
SYS$ERROR, the image sends error messages only to the file indicated
by SYS$ERROR-even if SYS$ERROR is different from SYS$0UTPUT. Only
DCL commands and images using standard VMS error display mechanisms
send error messages to both SYS$ERROR and SYS$0UTPUT when these files
are different.

4-25

Logical Names
4.9 Logical Names for Process-Permanent Files

Redefining SYS$COMMAND
Although you can redefine SYS$COMMAND, DCL ignores your definition.
DCL always uses the default definition for your initial input stream.
However, if you execute an image that references SYS$COMMAND, the
image can use your new definition.

4-26

Symbols

A symbol is a name that represents a numeric, character, or logical value.
When you use a symbol in a DCL command line, DCL replaces the symbol
with its value. Use a symbol in the following ways:
•

As a synonym for a DCL command line. Defining a symbol as a
command line lets you execute the command by typing only the symbol
name. For example, you can create a symbol for a lengthy command line
that you type frequently.

•

As a variable in a command procedure.

•

To refer to data records in command procedures with commands such as
READ, WRITE, and INQUIRE.

•

To pass a parameter to a command procedure.

•

To define a foreign command. Defining a symbol as a foreign command
lets you execute a non-DCL image by typing only the symbol name.

This chapter describes the rules for creating symbols.

5.1

Symbol Types
Symbols can be either of the following:
•

Local-A local symbol is available to the command level that defined it,
any command procedure executed from that command level, and lower
command levels.

•

Global-A global symbol can be accessed from any command level,
regardless of the level at which it was defined.

Local symbols take precedence over global symbols of the same name.
Symbols take precedence over identical command names. For example, if
you define a symbol with the same name as a DCL command, your definition
overrides the command name.
Symbols are stored in the following symbol tables:
•

Local symbol table-DCL maintains a local symbol table for your main
process and for every command level that you create when you execute a
command procedure, use the CALL command, or submit a batch job. A
local table is deleted when its associated command level terminates.
In addition to the local symbols you create, a local symbol table contains
eight symbols that are maintained by DCL. These symbols, named Pl,
P2, and so on through P8, are used for passing parameters to a command
procedure. Parameters passed to a command procedure are regarded as
character strings. Otherwise Pl through P8 are defined as null character
strings (" "). They are stored in the local symbol table.

5-1

Symbols
5.1 Symbol Types

•

Global symbol table-DCL maintains only one global symbol table for
the duration of a process. In addition to the global symbols you create,
the global symbol table contains the following reserved global symbols:
$ST A TUS

The condition code returned by the most recently executed
command. ·$STATUS conforms to the format of a VMS
message code.

$SEVERITY

The severity level of the condition code returned by the most
recently executed command. $SEVERITY, which is equal to
the three low-order bits of $ST A TUS, can have the following
values:
Warning
0

$REST ART

5.2

Success

Error

Information

Severe (fatal) error

Has the value TRUE if a batch job was restarted after it was
interrupted by a system crash. Otherwise, $RESTART has the
value FALSE.

Creating Symbols
There are several ways to create a symbol. They are as follows:
•

You can define a symbol with an assignment statement.

•

You can use the READ and INQUIRE commands. These commands are
usually included in command procedures.

This chapter shows how to create symbols with assignment statements.
For more information on READ and INQUIRE, see the Guide to Using VMS
Command Procedures or the VMS DCL Dictionary.
An assignment statement has the following format:
symbol-name =[=] value

The left side of the assignment statement defines the symbol name. The
right side of the assignment statement contains a value. A symbol can
represent a number, a character string, a lexical function, another symbol, or
a combination of these values. Use an equal sign to define a local symbol. A
double equal sign defines a global symbol.
Observe the following rules when creating a symbol:

5-2

•

A symbol name can contain 1 to 255 alphanumeric characters, as well as
the underscore (-) and dollar sign ( $ ) characters. The system translates
lowercase letters to uppercase.

•

Begin a symbol name with a letter, an underscore ( _ ), or a dollar sign
( $ ).

Symbols
5.2 Creating Symbols

5.2.1

Local Symbols
To create a local symbol with a numeric value, use an equal sign. For
example:
$ TEST = 15

There are two ways to create a local symbol with a character string value.
You can use an equal sign and quotes. For example:
$ SD = "set default"

When you enclose a character string in quotes, lowercase letters are not
converted to uppercase; spaces and tab characters are retained.
You can also use a colon and an equal sign. For example:
$ SD := set default

In this case, character values are converted to uppercase, leading and trailing
spaces and tabs are removed; multiple spaces and tabs are compressed to a
single space.
A local symbol exists as long as the command level at which it is defined
remains active, unless the symbol is specifically deleted.

5.2.2

Global Symbols
To create a global symbol with a numeric value, use two equal signs. For
example:
$ RESULT == 50

There are two ways to create a global symbol with a character string value.
You can use two equal signs and quotes (== ""), or a colon and two equal
signs (:==). The same rules apply as described in Section 5.2.1.
A global symbol exists for the duration of the process, unless the symbol is
specifically deleted.

5.2.3

Symbol Search Order
When the command interpreter determines the value of a symbol, it searches
symbol tables in the following order:
1

The local symbol table for the current command level

Local symbol tables for each previous command level, searching
backwards from the current level

The global symbol table

5-3

Symbols
5.2 Creating Symbols

5.2.4

DCL Commands to Use with Symbols
Use the following DCL commands to create, display, and delete symbols.
Table 5-1

5.2.5

DCL Commands to Use with Symbols

Command

Function

DELETE/SYMBOL

Deletes a symbol. By default, the DELETE/SYMBOL
command searches for symbols only in the local
symbol table. To delete a global symbol, use the
/GLOBAL qualifier.

INQUIRE

Reads a value from SYS$COMMAND and assigns it
to a symbol.

READ

Reads a record from a file and assigns its contents to
a symbol.

SET SYMBOL/SCOPE

You can mask global or local symbols at the specified
command level.

SHOW SYMBOL

Displays the value of the specified symbol. By
default, the SHOW SYMBOL command searches the
local symbol tables and then the global symbol table
to locate a specified symbol name.

Abbreviating Symbol Names
You can use abbreviated forms of symbols if you define them with the
asterisk. The following example shows how to create a local symbol that can
be abbreviated:
$ M*AIL = "MAIL"

The VMS Mail Utility is executed whenever the following versions of the
symbolic name are used:
$ M
$ MA

$ MAI
$ MAIL

Generally, you can use abbreviated symbol definitions in any situation that
allows a symbol to be used. However, there are some restrictions:
•

You cannot abbreviate symbols that involve substring replacement.

•

When you define a symbol that includes an asterisk, existing symbols
may be deleted. If an existing symbol exactly matches the new symbol at
or past the asterisk, the new symbol replaces the existing symbol.

•

If you define a symbol with an asterisk, you cannot define another symbol

whose name partly matches the existing symbol at or past the asterisk.

5-4

Symbols
5.3 Values Used in Symbols

5.3

Values Used in Symbols
A symbol can be defined as a character string, a number, a lexical function,
another symbol, or a combination of these values. The following sections
describe these values.

5.3.1

Character Strings
A character string can contain any characters that can be printed. You can
define a character string by enclosing it in quotes. In this way, alphabetic
case and spaces are preserved when the symbol assignment is made. Note
the following:
•

To include quotation marks within a string, type two consecutive
quotation marks. For example:
$ PUP = "Type 1111 YES 1111 to proceed"

•

To continue a character string over two lines, use a plus sign (for string
concatenation) and a hyphen (for continuation). For example:
$ HEAD = "MONTHLY REPORT --" + _$ II DECEMBER 1988"

You can also define a character string with a colon and one or two equal signs
(:=or :==). In this way, all alphabetic characters are converted to uppercase,
and spaces are compressed. To continue a character string over two lines in
this format, use a single hyphen.
You can also concatenate several symbols to create a long character string. Do
not place quotation marks around symbols when you use them in expressions.
For example:
$ DOG1 = "Ralph,

$ DOG2 = "ruthless pup"
$ DOG3 = DOG1 + DOG2
$ SHOW SYMBOL DOG3
DOG3 = "Ralph, ruthless pup"

5.3.2

Numbers
A number can have the following values:
•

Decimal-the ASCII characters 0 through 9

•

Hexadecimal-the ASCII characters 0 through 9 and A through F

•

Octal-the ASCII characters 0 through 7

You can specify a number as follows:
•

Positive number-Specify a positive number by typing the appropriate
digits. For example:
$ COUNT = 13

•

Negative number-Precede a negative number with a minus sign. For
example:
$ COUNT = -13

5-5

Symbols
5.3 Values Used in Symbols

•

Radix-Specify a number in a radix other than decimal by preceding the
number with a %X for hexadecimal numbers and %0 for octal numbers.
There cannot be any blanks between a radix operator and a value. For
example:
$ COUNT = %XO
$ SHOW SYMBOL COUNT
COUNT = 13
Hex = 00000000

Octal = 00000000015

To specify a negative number in a radix, precede the percent sign (%)
with a minus sign (-). For example:
$ NEG = -%XO
$ SHOW SYMBOL NEG
NEG = -13
Hex = FFFFFFF3

Octal = 37777777763

When you specify a value in either hexadecimal or octal, the command
interpreter converts the value to a decimal integer.

5.3.3

Lexical Functions
Lexical functions return information about a requested item. Type the name
of the lexical function (which always begins with F$) and its argument list.
Use the following syntax:
F$function-name(args[, ... ])

Use lexical functions the same way you would use character strings, integers,
and symbols. The following example uses the F$LENGTH function.
F$LENGTH returns an integer that specifies the length of the string. The
returned value is assigned to the symbol LEN.
$LEN= F$LENGTH("Th~ cat jumped over the moon.")
$ SHOW SYMBOL LEN
LEN = 29
Hex = 00000010 Octal = 000035

Observe the following rules:
•

Do not enclose lexical functions in quotation marks.

•

Enclose the argument list in parentheses.

•

If an argument contains a character string, enclose the character string in
quotation marks.

•

If an argument contains an integer, a symbol, or another lexical function,
do not enclose these values in quotation marks.

For a complete description of each lexical function, its required arguments,
and its return values, see the VMS DCL Dictionary.

5-6

Symbols
5.3 Values Used in Symbols

5.3.4

Another Symbol
After a symbol is defined, it can be used as a value for another symbol. It can
be interpreted as a character string or a number, depending on the context in
which it is used. For example, suppose a symbol, COUNT, is assigned the
integer value 3:
$ COUNT = 3

Then the value of COUNT can be used in other assignment statements as
shown in the following examples.
$ TOTAL = COUNT + 1

The value of COUNT is added to 1. The result, 4, is equated to the symbol
TOTAL.
$ SHOW SYMBOL TOTAL
TOTAL = 4
Hex = 00000004

Octal = 00000000004

You can include the symbol COUNT in a string assignment statement. For
example:
$BARK := P'COUNT'

COUNT is converted to a string value and appended to the character P. BARK
now has the value P3.
To include a symbol in a string assignment, follow these rules:
•

Use either a colon and an equal sign (:=) or a colon and two equal signs
(:==).

•

Enclose the symbol in apostrophes. Otherwise DCL will not recognize it
as a symbol.

If you define a null character string value for a symbol, that symbol has a
value of 0 when it is used in an arithmetic context. For example:
$ A = 1111
$ B = 2

$ C=A+ B
$ SHOW SYMBOL C
C = 2 Hex = 00000002

5.3.5

Octal = 00000000002

Combination of Values
A symbol can be defined as a combination of values, called an expression.
Within an expression each value is regarded as an operand. An operand
is connected to another operand by an operator. Operators specify the
operations to be performed. For more information on how DCL handles
expressions and operators, see Chapter 6.

5-7

Symbols
5.4 Foreign Commands

5.4

Foreign Commands
You may have a non-DCL image that you run frequently. Rather than typing
the entire file specification of the image every time you want to run it, you
can equate it to a symbol. This way you can run the image by typing the
symbol. A symbol that runs an image is referred to as a foreign command.
A foreign command is an image that is not recognized by the command
interpreter as a DCL command.
Use either of the following formats to define a foreign command:
$ symbol-name :=[=] $image-file-spec
$ symbol-name =[=] "$image-file-spec"

where:

•

symbol-name is the name you want to use to run the image.

•

$image-file-spec is the file specification of the image. The dollar sign ( $)
preceding image-file-spec is required. The default device and directory
name is SYS$SYSTEM, the default file type is EXE, and the default file
version number is the highest version.

The following example defines the symbol PROCESS as a foreign command
(note that the file specification begins with a $):
$PROCESS := $DB1: [SARAH.PROG]CREPROCES

The request to run the image is implied in the symbol definition. In a
command line, PROCESS could be followed by a parameter. In the following
example, the file specification RAT.DAT is a parameter that is passed to the
image defined by PROCESS:
$PROCESS RAT.DAT

The command interpreter looks for symbols enclosed by apostrophes and
translates them. Thus, if you use symbols or lexical functions preceded by
apostrophes to specify parameters, symbol substitution occurs. Otherwise
the command interpreter does not parse the line. The image must obtain the
parameter and perform any parsing or evaluation of the command line.
You can use an abbreviated form of a foreign command if you use an asterisk
(*)when you define the foreign command.
An alternative to using a foreign command is to define new commands with
the Command Definition Utility. See the VMS Command Definition Utility
Manual for more information.

5-8

More on Expressions

An expression is a combination of values. A value is referred to as an
operand. Each value, or operand, is connected to another value by an
operator. For example:
$ BARK = 1 + 2 + 3

The symbol BARK is equated to an expression that adds three numbers. In
this case, the operands are 1, 2, and 3. The operator is the plus sign (+).
Expressions can evaluate to either character strings or integers. The following
sections describe the rules DCL uses to evaluate expressions.

6. 1

Character String Expressions
A character string expression can contain character strings, lexical functions
that evaluate to character strings, or symbols that have string values. It can
also contain string operands that are connected by operators. For example,
the following symbols are equated to character string expressions:
$ TEMP = 11 CAT 11
$ TOPIC = "THE" + TEMP
$ COUNT = F$STRING(65)
$ TOTAL = "NUMBER OF FILES = II + F$STRING(16)
$ SUBTOTAL = TOTAL

Some of these expressions contain a single value that is a character string,
another symbol, or a lexical function. However, some string expressions
contain character strings, symbols, and lexical functions that are connected
with string operators. For example, the symbol TOPIC contains a character
string ("THE ") and another symbol (TEMP):
$ TEMP = 11 CAT 11
$ TOPIC = "THE II + TEMP
$ SHOW SYMBOL TOPIC
TOPIC = "THE CAT"

For string operations to occur, both operands must have character string
values. When you use a character string in an expression, place quotation
marks around it. However, when you use a symbol in an expression, do not
use quotation marks.

6-1

More on Expressions
6.1 Character String Expressions

6.1.1

String Operations
.The result of a string operation is a character string value. Use the following
operators to perform string operations.
+

String concatentaion. The plus sign concatenates two character strings
to form a single character string.
String reduction. The minus sign subtracts one character string from
another.

Observe the following rules:
•

In order for string concatenation or reduction to occur, all operands must
be character string expressions. Otherwise, any string will be converted
to an integer and the result will be an integer.

•

If the string following the minus sign in a string reduction operation
occurs more than once in the preceding string, only the first occurrence is
removed.

Following are some examples of string operations:

6.1.2

Expression

Result

A = "MYFILE" + ".MEM"

"MYFILE.MEM"

8 = "FILENAME.MEM" - "FILE"

"NAME.MEM"

C = "LISTING.LIS" - "LIS"

"TING.LIS"

D ="MIS"+ C

"MISTING.LIS"

String Comparisons
The result of a string comparison is either true (1) or false (0). It is based on
the binary values of the ASCII characters in the string. (The ASCII characters
and their hexadecimal values are listed in Appendix B.) Use the following
operators in string comparisons:
.EQS.

Equal to

.GES.

Greater than or equal to

.GTS.

Greater than

.LES.

Less than or equal to

.LTS.

Less than

.NES.

Not equal to

Observe the following rules:

6-2

•

The comparison is on a character-by-character basis. The comparison
terminates as soon as two characters do not match.

•

If the result of a comparison is true, the expression is given a value of 1.
If the comparison is false, the expression is given a value of 0.

•

If one string is longer than the other, the shorter string is padded on the
right with nulls (an ASCII value of %XOO) before the comparison is made.
Null has a lower numeric value than any of the alphanumeric characters.

More on Expressions
6.1 Character String Expressions

•

Lowercase letters have higher numeric values than uppercase letters.

•

Operands in string comparisons are string expressions. If you specify
an integer value as an operand, it is converted to a string before the
comparison is performed. For information on how DCL converts integers
to strings, see Section 6.4.2.

•

If you do not enclose a character string in quotation marks, the command
interpreter assumes the string is a symbol name. If the symbol is not
defined, an error message is displayed.

Following are some examples of string comparisons:

6.1.3

Expression

Result

Explanation

"MAYBE" .LTS. "maybe"

1 (true)

The expression is true because
the ASCII value of "M" is less
than "m."

"ABCD" .LTS. "EFG"

1 (true)

The expression is true because
the ASCII value of "A" is less than
"E."

"YES" .GTS. "VESS"

0 (false)

The expression is false because
the ASCII value of a null character
is less than the ASCII value of
"S" .

.. AAB" .GTS. "AAA"

1 (true)

The expression is true because
the ASCII value of "B" is greater
than "A".

"TRUE" .EOS.1

0 (false)

DCL converts the integer 1 to the
string "1" before comparing the
ASCII value of "T' to the ASCII
value of "1 ".

"FALSE" .EOS.0

0 (false)

DCL converts the integer 0 to
the string "O" before making the
comparison.

"123" .EOS. 123

1 (true)

DCL converts the integer 123 to
the string "123" before making
the comparison.

Replacing Substrings
You can replace a part of a character string with another character string. The
assignment statement has the following format:
symbol-name[ offset,size] := replacement-string
or
symbol-name[ offset, size]:= replacement-string

6-3

More on Expressions
6.1 Character String Expressions

where:

•

offset is an integer that indicates the position of the replacement-string
relative to the first character in the original string. An offset of 0 means
the first character in the symbol, an offset of 1 means the second
character, and so on.

•

size is an integer that indicates the length of the replacement-string.

Observe the following rules:
•

The square brackets are required notation. No spaces are allowed
between the symbol name and the left bracket.

•

Integer values can be in the range of 0 through 768.

•

The replacement-string must be a character string.

For example:
$ A := PACKRAT
$ A[0,4] := MUSK

$ SHOW SYMBOL A

A = "MUSKRAT"

The first assignment statement gives the symbol A the value PACKRAT. The
second statement specifies that MUSK replace the first four characters in the
value of A. The result is that the value of A becomes MUSKRAT.
The symbol name you specify can be undefined initially. The assignment
statement creates the symbol name and, if necessary, provides leading or
trailing spaces in the symbol value. For example:
$ B[4,3] :=RAT

If the symbol B does not have a previous value, it is given a value of four
leading spaces followed by RAT. This format creates a blank line of any
length. The following example gives the symbol LINE a value of 80 blank
spaces:
$ LI NE [0 , 80] : = " "

Lining up records in columns makes a list easier to read and sort. You can
use this format to specify how you want data to be stored. For example:
$ DATA[0,15] := 'NAME'
$ DATA[17,1] := 'GRADE'

The first statement fills in the first 15 columns of DATA with whatever value
NAME has. The second statement fills in column 18 with whatever value
GRADE has. Columns 16 and 17 contain blanks. To see how this would be
useful, compare the following command procedures and their output. The
first command procedure does not use an assignment statement to format the
output.
$ !FIRST.COM
$ OPEN/WRITE RECORD LOG.DAT
$ LABEL:
$ INQUIRE NAME "Name"
$ INQUIRE GRADE "Grade"
$ WRITE RECORD NAME.GRADE
$ INQUIRE MORE "More (y/n)"
$ IF MORE THEN GOTO LABEL
$ CLOSE RECORD

6-4

More on Expressions
6.1 Character String Expressions

The output of FIRST.COM would look like the following:
BOBB
JOA
MEREDITHC
RALPHF

The second version uses the assignment statements discussed above to format
the output.
$ !SECOND.COM
$ OPEN/WRITE RECORD LOG.DAT
$ LABEL:
$ INQUIRE NAME "Name"
$ INQUIRE GRADE "Grade"

$ DATA[0,15] := 'NAME'
$ DATA[17,1] := 'GRADE'
$ WRITE RECORD DATA
$ INQUIRE MORE "More (y/n)"
$ IF MORE THEN GOTO LABEL
$ CLOSE RECORD

The output of SECOND.COM would look like the following:
BOB
JO
MEREDITH
RALPH

B
A
C
F

Figure 6-1 illustrates some applications of string substitutions using offsets.

6-5

More on Expressions
6.1 Character String Expressions

Figure 6-1

Replacing Character Strings in Assignment Statements

Interactive Assignment

Resulting Symbol Value

Comments

FILENAME:=MYFILE.DAT

MYFILE.DAT

The result is the initial value of symbol
FILENAME

FILENAMEC012J:=TR

TRF I LE. DAT

Two characters starting at offset Oare overlaid

FILENAMEC214J:=TESTING.LIS

TRTEST. bAT

When the string value is longer than the character count the value is truncated to the count

FILENAMEC1012J:=i1

TRTEST. DAT; 1

When the length of the string is equal to the
value of the offset, the string is appended to
the current value

COMMAND:=TYPE

TY PE

This is the initial value of the symbol command

COMMANDC5113J:='FILENAME

TYPE TRTEST. DAT; 1

Appends a space and the current value of
FILENAME to the TYPE command verb.
ZK-818-82

6.2

Numeric Expressions
A numeric expression can contain integers, lexical functions that evaluate
to integers, or symbols that have integer values. It can also contain integer
operands that are connected by arithmetic, logical, and comparison operators.
For example, the following symbols are equated to numeric expressions:
$ COUNT = 1
$ VALUE = %X1C
$ SUM = 1 + 7 - 4/3 + 10

6-6

More on Expressions
6.2 Numeric Expressions

6.2.1

Numeric Operations
The result of a numeric operation is an integer. Use the following operators:
+

Addition
Subtraction
Unary plus (indicates a positive number)

Unary negate (indicates a negative number)
Multiplication
/

Division (integer quotient)

Observe the following rules:
•

Operands in numeric operations are numeric expressions. If you specify a
string value as an operand, it is converted to an integer value before the
operation is performed. For information on how DCL converts a string to
an integer, see Section 6.4.1.

•

All nondecimal values (specified by radix operators) are converted to
integer values before the operation is performed.

•

All arithmetic is integer arithmetic. Fractional values are truncated. For
example, 5 divided by 2 equals 2.

Following are some examples of numeric operations:
Expression

6.2.2

Result

A=5+4

A=9

B = -5 + 4

B = -1

c = 6/3

C=2

D=6/4

D= 1

E = %X10 + 5

E = 21

Numeric Comparisons
The result of a numeric comparison is either true (1) or false (0). Use the
following operators in numeric comparisons:
.EO.

Equal to

.GE.

Greater than or equal to

.GT.

Greater than

.LE.

Less than or equal to

.LT.

Less than

.NE.

Not equal to

Observe the following rules:
•

If the result of a comparison is true, the expression is given a value of 1.
If the result of the comparison is false, the expression is given a value of
0.

6-7

More on Expressions
6.2 Numeric Expressions

•

Operands in numeric comparisons are numeric expressions. If you specify
a character string value as an operand, it is converted to an integer
value before the comparison is performed. For information on how DCL
converts a string to an integer, see Section 6.4.1.

Following are some examples of numeric comparisons:

6.2.3

Expression

Value of Expression

1.LE.2

1 (true)

1.GT.2

0 (false)

1 + 3 .EO. 2 + 5

0 (false)

"TRUE". EO. 1

1 (true)

"FALSE" .EO.O

1 (true)

"123".E0.123

1 (true)

Logical Operations
A logical operation affects all the bits in the number being acted upon. The
result of a logical operation is an integer. Operands for logical operations are
integer expressions. If you specify a character string value as an operand, it
is converted to an integer value before the operation is performed. Note the
following:
•

If the first character is T, t, Y, or y, a character string has a logical value

of true ( 1 ).
•

If the first character is not T, t, Y, or y, a character string has a logical

value of false (0).
•

If an integer is odd (the low-order bit is 1), it has a logical value of true
( 1 ).

•

If an integer is even (the low-order bit is 0), it has a logical value of false
( 0 ).

Use the following operators:
•

.NOT.-Reverses the bit configuration of a logical value. A true value
becomes false and a false value becomes true. In the following example,
the value of STATUS (-2) is even, or false:
$ SHOW SYMBOL STATUS
STATUS = 1 Hex = 00000001 Octal = 00000000001
$ STATUS = .NOT. STATUS
$ SHOW SYMBOL STATUS
STATUS = -2 HEX = FFFFFFFE Octal = 37777777776

•

6-8

.AND.-Combines two logical values as follows:

More on Expressions
6.2 Numeric Expressions

Bit Level

Entity Level

1 .AND. 1 = 1

true .AND. true =true

1 .AND. 0 = 0

true .AND. false= false

0 .AND. 1=0

false .AND. true= false

0 .AND. 0 = 0

false .AND. false= false

For example:
$ STAT1 = 11 TRUE 11
$ STAT2 = 11 FALSE 11
$ STATUS = STAT1 .AND. STAT2
$ SHOW SYMBOL STATUS

STATUS = 0

•

Hex = 00000000

Octal = 000000

. OR-Combines two logical values as follows:
Bit Level

Entity Level

1 .OR. 1 = 1

true .OR. true = true

1 .OR. 0 = 1

true .OR. false = true

0 .OR. 1 = 1

false .OR. true =true

0 .OR. 0 = 0

false .OR. false= false

For example:
$ STAT1 = 11 TRUE 11

$ STAT2 = 11 FALSE 11
$ STATUS= STAT1 .OR. STAT2
$ SHOW SYMBOL STATUS ~
STATUS = 1 Hex = 00000001

6.2.4

Octal = 000001

Numeric Overlays
A special format of the assignment statement can be used to perform binary
overlays of the current symbol value. This format is as follows:
$ symbol-name[bit-position,size] = replacement-expression
or

$ symbol-name[bit-position,size]

replacement-expression

where:

•

bit-position is an integer that indicates the location relative to bit 0 at
which the overlay is to occur.

•

size is an integer that indicates the number of bits to be overlaid.

Observe the following rules:
•

The square brackets are required notation. No spaces are allowed
between the symbol name and the left bracket.

•

Literal values are assumed to be decimal.

6-9

More on Expressions
6.2 Numeric Expressions

•

The maximum length for both bit-position and size is 32 bits.

•

The replacement-expression must be a numeric expression.

•

When symbol-name is either undefined or defined as a string, the result of
the overlay is a string. Otherwise the result is an integer.

The following example defines the symbol BELL as the value 7. The loworder byte of BELL has the binary value 00000111. By changing the 0 at
offset 5 to 1 (beginning with 0, count bits from right to left), you create the
binary value 00100111 (decimal value 39).
$ BELL = 7
$ BELL[5,1] = 1
$ SHOW SYMBOL BELL
BELL = 39
Hex = 00000027

6.3

Octal = 00000000047

Order of Operations
An expression can contain any number of operations and comparisons.
When an expression contains more than one operation, the operations are
performed in a certain order. Table 6-1 lists the operations you can use and
the order in which they are performed by DCL. Operators at the top of the
table are performed before operators at the bottom. Operators with the same
precedence are performed from left to right, as they appear in the command
line.

6-10

Table 6-1

Order of Operations

Operator

Precedence

Description

Indicates a positive number

Indicates a negative number

Multiplies two numbers

Divides two numbers

Adds two numbers or concatenates two character
strings

Subtracts two numbers or reduces two strings

.EOS.

Tests if two character strings are equal

.GES.

Tests if first string is greater than or equal to the
second

.GTS.

Tests if first string is greater than the second

.LES.

Tests if first string is less than or equal to the
second

.LTS.

Tests if first string is less than the second

.NES.

Tests if two strings are not equal

.EO.

Tests if two numbers are equal

.GE.

Tests if first number is greater than or equal to the
second

.GT.

Tests if first number is greater than the second

More on Expressions
6. 3 Order of Operations

Table 6-1 (Cont.)

Order of Operations

Operator

Precedence

Description

.LE.

Tests if first number is less than or equal to the
second

.LT.

Tests if first number is less than the second

.NE.

4
4

.NOT.

Logically negates a number

.AND.

Combines two numbers with a logical AND

.OR.

Tests if two numbers are not equal

Combines two numbers with a logical OR

Observe the following rules:
•

Begin and end logical and comparison operators with a period (. ).
Intervening blanks are not allowed.

•

You can type any number of blanks or tabs between operators and
operands. For example, the following expressions are equivalent:
A.EQS.B
A .EQS. B

•

Each operator (except .NOT. and the unary plus or minus signs) must
have an operand on each side. Note that the unary plus sign can be
the initial character in an assignment statement, but not in a WRITE
statement.

•

Use parentheses to override the order of operations. Items within
parentheses are calculated first.

Following are some examples:

6.4

Expression

Result

A=5+10/2

A= 10

8=5*3-4*6/2

8=3

c = 5 * (6 - 4) - s I (2 - 1)

C=2

Value Type Conversion
All the operands in an expression must be of the same value type (number or
character string) before DCL can evaluate the expression. When an expression
contains both number and string operands, DCL either converts all strings to
integers, or all integers to strings.
For example, if you include an integer in a string comparison, DCL converts
the integer to a string. In other expressions that contain both integer and
string values, DCL converts the strings to integers.
In addition, the following lexical functions let you determine or change the
value of an expression:
•

F$TYPE-Determines the current value type of a symbol
6-11

More on Expressions
6.4 Value Type Conversion

•

F$INTEGER-Converts a string expression to an integer value

•

F$STRING-Converts an integer expression to a string value

The following sections describe how DCL converts an integer to a string and
vice versa.

6.4.1

String to Integer Conversion
Character strings are converted to integers in the following ways:
•

Strings containing numbers are converted to their integer values. For
example, the string "45" is converted to the integer 45.

•

If a character string begins with T, t, Y, or y, it is converted to the integer
1.

•

If a string begins with any other letter, it is converted to the integer 0.

The following examples show how strings are converted to integer values:
String

Resulting Integer

"123"

->
->
->
->

123

"12XY"
"Test"
"hello"

6.4.2

0 (False)
1 (True)

0 (False)

Integer to String Conversion
When integers are converted to character strings, the resulting string contains
numbers that correspond to the integer value. The following examples show
how integers are converted to string values:
Integer

Resulting String

123

->
->
->

"123"

6.4.3

"1"
"O"

How DCL Evaluates an Expression
An expression has either an integer or a string value, depending on the types
of values and the operators used. Table 6-2 summarizes how DCL evaluates
expressions. The first column lists the different operands and operators that
an expression might contain. The second column tells, for each case, what
the entire expression is equated to. Within the table any value stands for a
string or an integer.

6-12

More on Expressions
6.4 Value Type Conversion

Table 6-2

Determining the Value of an Expression

Expression

Resulting
Value Type

Integer value

Integer

String value

String

Integer lexical function

Integer

String lexical function

String

Integer symbol

Integer

String symbol

String

+, -, or .NOT. any value

Integer

Any value .AND. or .OR. any value

Integer

String + or - string

String

Integer + or - any value

Integer

Any value + or - integer

Integer

Any value * or / any value

Integer

Any value (string comparison) any value

Integer

Any value (numeric comparison) any value

Integer

6-13

Symbol Substitution

The DCL command interpreter looks for certain cues that indicate when an
item in a command line is a symbol. When it finds an item that seems to be a
symbol, the command interpreter replaces the symbol with its current value.
Replacing a symbol with its current value is referred to as symbol substitution.
Symbol substitution happens automatically in certain situations. You can also
force DCL to recognize an item as a symbol with substitution operators. This
chapter describes how the command interpreter performs symbol substitution
in both cases.

7. 1

Automatic Symbol Substitution
The command interpreter assumes, in certain contexts, that a string beginning
with an alphabetic character is a symbol name or a lexical function. DCL
automatically tries to perform symbol substitution on character strings in the
following contexts:
•

On the right side of an= or== assignment statement. For example:
$ TOTAL = COUNT + 1

COUNT is automatically recognized and evaluated as a symbol.
•

In a lexical function. For example:
$ QUERY = "Haven't we met before?"
$ LEN = F$LENGTH(QUERY) + 5
$ SHOW SYMBOL LEN
LEN = 27
Hex = 0000001B Octal = 000033

In the second line, the symbol QUERY is automatically evaluated when it
is used with the F$LENGTH function. Also, the F$LENGTH function is
automatically evaluated because it is on the right side of an assignment
statement.

•

In a DEPOSIT, EXAMINE, or IF command. For example:
$ IF A .EQ. B THEN WRITE SYS$0UTPUT "DONE"

The IF command assumes that both A and B are symbol names and uses
their current values.
•

At the beginning of a line when the string is not followed by an equal
sign or a colon. For example:
$ PDEL = "DELETE SYS$PRINT/ENTRY="
$ PDEL 181

In the second line, the command interpreter automatically replaces PDEL
with its current value and executes the resulting command.
•

In the brackets on the left side of an assignment statement when you are
performing substring replacement or numeric overlays.

7-1

Symbol Substitution
7 .·1 Automatic Symbol Substitution

In any of these contexts, the command interpreter assumes that any character
string beginning with an alphabetic character is a symbol name and that any
string beginning with a number or with the radix operator ( % ) is a literal
numeric value.

7. 2

Substitution Operators
You can use a substitution operator to request symbol substitution in places
where DCL does not usually perform it. DCL accepts two substitution
operators:
•

Apostrophe (')

•

Ampersand ( & )

The difference between these two operators is the time when the substitution
occurs. Symbols preceded by apostrophes are substituted during the first
phase of command processing. Symbols preceded by ampersands are
substituted during the second phase of command processing. For more
information on the phases of command processing, see Section 7.3.

7.2.1

The A.postrophe ( ' )
The apostrophe is the normal substitution operator. Use it to request symbol
substitution when you use a symbol in place of a command parameter or
qualifier. For example:
$ LIT = "LIGHT.BILLS"
$ TYPE 'LIT'

The TYPE command expects a file specification. The apostrophes indicate
that LIT is a symbol that must be evaluated. If you had not used apostrophes,
DCL would have looked for a file called LIT.LIS (LIS is the default file type
for the TYPE command).
Use the apostrophe to request symbol substitution on the right side of a :=
(string assignment) statement. For example:
$NAME := REPORT
$FILE := 'NAME' .DAT
$ SHOW SYMBOL FILE
FILE= "REPORT.DAT"

The value for NAME is substituted so that FILE becomes REPORT.DAT.
When you use apostrophes to request symbol substitution, you cannot
continue the line (with the hyphen continuation character) in the middle of
the value that is being substituted.
7.2.1.1

Concatenation of Symbol Names
You can concatenate two or more symbol names. Place apostrophes around
each symbol name. For example:
$ NAME = "MYFILE"
$TYPE= ".DAT"
$ PRINT 'NAME' 'TYPE'

The PRINT command prints a copy of MYFILE.DAT.

7-2

Symbol Substitution
7.2 Substitution Operators

7.2.1.2

Substitution Within Character Strings
You can request symbol substitution within a quoted character string. Place
two apostrophes before the symbol name and one apostrophe after it. For
example:
$ MESSAGE = "Creating file ''NAME' . DAT"

If the current value of the symbol NAME is FRED, then MESSAGE has the

following value:
Creating file FRED.DAT

7.2.2

The Ampersand ( & }
The command interpreter also recognizes the ampersand as a substitution
operator. In many cases, the apostrophe and the ampersand are functionally
equivalent. For example:
$ TYPE 'NAME'
$ TYPE &NAME

In the first command, the command interpreter replaces the symbol NAME
with its current value during the first phase of command processing
(scanning). The second command replaces the symbol NAME with its current
value during the second phase of command processing (parsing). The result
is the same, even though the methods are different.
Ampersands are most effective as substitution operators when they are used
with apostrophes to affect the order in which substitution is performed. For
example:
$ P1 = "FRED.DAT"
$ COUNT = 1
$ TYPE &P'COUNT'

First, the command interpreter evaluates the symbol enclosed by apostrophes
(COUNT). The result is as follows:
TYPE &P1

Next, the command interpreter evaluates the symbol preceded by an
ampersand (Pl). The result is as follows:
TYPE FRED.DAT

Suppose you had used apostrophes with both P and COUNT, as in the
following example:
$TYPE 'P''COUNT'

Working left-to-right, the command interpreter attempts to evaluate P. P is
not a defined symbol, so DCL gives it a null value. Next, it evaluates the
symbol COUNT. The result is as follows:
PRINT 1

The action the command interpreter takes when a symbol is undefined
depends on the context of the command. For more information, see
Section 7.5.

7-3

Symbol Substitution
7.2 Substitution Operators

In the next example, A is equated to the current value of B:
$ B = "MYFILE.DAT"
$ A = "&B"
$ TYPE 'A'

The ampersand does not cause symbol substitution when it is used inside
quotation marks. Therefore, when the assignment is made, the value of B is
not substituted. However, the TYPE command displays MYFILE.DAT. This
occurs because the command interpreter first substitutes the value &B for A.
Next, it substitutes MYFILE.DAT for the symbol &B. If you were to redefine
B, the result of the TYPE command would change accordingly.
Observe the following rules:

7 .3

•

Place the ampersand before, but not after, the symbol name.

•

An ampersand must follow a delimiter (any blank or special character).

•

You cannot use ampersands to request substitution within character
strings enclosed in quotation marks.

•

You cannot use ampersands to concatenate two or more symbol names.

The Three Phases of Command Processing
The command interpreter performs symbol substitution in three phases, as
follows:

Command input scanning (also called the lexical input phase)
From left to right, the command interpreter evaluates symbols
preceded by apostrophes. Symbols that are preceded by single
apostrophes are translated iteratively, as described in Section 7.4.1.
Symbols preceded by double apostrophes are not translated
iteratively.

Command parsing
•

The command interpreter analyzes the command line. It checks the
first item on the line to see if it is a symbol. If it is, it is evaluated.

•

From left to right, the command interpreter evaluates symbols
preceded by ampersands.

Symbol substitution during this phase is not iterative.

Expression evaluation
•

The command interpreter evaluates symbols that are preceded by the
DEPOSIT, EXAMINE, IF, and WRITE commands.

•

The command interpreter evaluates symbols within lexical functions.

Symbol substitution during this phase is not iterative.

Note: The command interpreter does not scan any lines that are read as input
data by commands or programs executed within a command procedure.
Therefore, the command interpreter does not perform symbol substitution
within these data lines. For example:

7-4

Symbol Substitution
7.3 The Three Phases of Command Processing

$ RUN AVERAGE
55
57

9999

The program AVERAGE reads 55, 57, and 9999 from SYS$1NPUT (the
command input stream). These data lines are never read by the command
interpreter. If you enter symbol names as input, they are not evaluated.

7 .4

Repetitive and Iterative Substitution
Symbol substitution can be repetitive or iterative:
•

Repetitive substitution results when more than one type of substitution
occurs in a single command line.

•

Iterative substitution occurs when the command interpreter examines
a substituted value to see if the value itself is a symbol. Iterative
substitution occurs only when symbols preceded by apostrophes are
translated during the first phase of command processing.

The following sections describe iterative substitution.

7.4.1

First Phase
When you use an apostrophe to request symbol substitution, the command
interpreter performs iterative substitution during the first phase of command
processing.
Substitution using apostrophes is not iterative, however, when a symbol is
included in a quoted character string. For example:
$ MAC = "5"
$A= "'MAC'"
$ B = 'A'
$ SHOW SYMBOL B
B = 11511

After the statement B = 'A' the resulting value of the symbol B is 5. The
explanation follows:
1

The symbol name A is enclosed in apostrophes, so it is replaced with its
current value ('MAC').

Because this value ('MAC') is also enclosed in apostrophes, the command
interpreter replaces MAC with its current value ( 5 ).

Because this value ( 5 ) has no apostrophes, the first phase of command
processing is complete. No further substitution is required during the
second or third phases. Therefore, 5 is the final value given to the
symbol name B.

Note, however, what happens when you include A in a quoted character
string:
$ B = 11 ' 'A' 11
$ SHOW SYMBOL B

B = II 'MAC' II

7-5

Symbol Substitution
7.4 Repetitive and Iterative Substitution

In this case, B has the value 'MAC'. The symbol name A is replaced only
once, because substitution is not iterative within quoted character strings.

7.4.2

Second Phase
The command interpreter performs iterative substitution automatically only
when an apostrophe is in the command line. In some cases, you may want to
nest command synonym definitions, as follows:
$ MAC = "TYPE A.B"
$EXEC= "'MAC'"
$ EXEC

In this example, when EXEC is processed, the command interpreter performs
substitution only once. The result is the string 'MAC'. The command
interpreter displays an error message because it does not recognize MAC
as a command.
This error occurs because, during the first phase of command processing, no
substitution is performed (the string EXEC is not delimited by apostrophes).
During the second phase, the string 'MAC' is substituted for EXEC because
EXEC is the first value on the command line. This substitution is not iterative.
Therefore, even though 'MAC' is delimited by apostrophes, no additional
substitution is performed.
To use the command synonym EXEC correctly, enclose it in apostrophes, as
shown below:
$ 'EXEC'

In this case, the symbol EXEC is evaluated during the first phase of command
processing. Because this substitution is iterative, ('MAC') is also evaluated
and the string TYPE A. B is substituted.

7.4.3

Third Phase
When the command interpreter analyzes an expression in a command,
any symbols specified in the expression are replaced only once. You can,
however, force iterative substitution by using an apostrophe or an ampersand
in the expression. When you force iteration in this way, you must remember
the following:
•

The command interpreter performs all substitutions requested by
apostrophes and ampersands before the command string is executed.

•

Commands that automatically perform symbol substitution do so after the
first and second phases of command processing.

The following example shows iterative substitution in an IF command.
$ P1 = "FRED.DAT"
$ COUNT = 1

$ IF P'COUNT' .EQS. "" THEN GOTO END

When the command interpreter scans this line, it replaces the symbol COUNT
with its current value. The result is as follows:
IF P1 . EQS. '"' THEN GOTO END

7-6

Symbol Substitution
7 .4 Repetitive and Iterative Substitution ,

Because this string has no apostrophes, the command interpreter does not
perform any more substitution. However, when the IF command executes, it
automatically evaluates the symbol name Pl and replaces it with its current
value.
Note, however, that if substitution does not result in a valid symbol name,
the command fails. For example:
$ FILENAME = 11 A.B 11
$ IF 'FILENAME' . NES.

1111

THEN TYPE 'FILENAME'

The command interpreter replaces the symbol FILENAME with its current
value (A.B). The result is as follows:
IF A.B .NES.

1111

THEN TYPE A.B

When the IF command executes the command line, A.B is not a valid symbol
and an error occurs. For this IF command to be processed correctly, omit the
apostrophes, as follows:
$ IF FILENAME .NES.

7. 5

1111

THEN TYPE 'FILENAME'

Undefined Symbols
If a symbol is not defined when it is used in a command line, the command
interpreter either displays an error message or replaces the symbol with a null
string, depending on the context. The rules are as follows:

•

During the first and second phases of command processing, the
command interpreter replaces all undefined symbols that are preceded by
apostrophes or ampersands with null strings.

•

During the third phase of command processing, if the command
interpreter finds an undefined symbol, it displays a warning message
and does not finish processing.

The following example shows how the command interpreter processes an
undefined symbol that is preceded by an apostrophe:
$ FILE := MYFILE'FILE_TYPE'
$ SHOW SYMBOL FILE

FILE = "MYFILE"
$ PRINT 'FILE'

When the symbol FILE is created, the symbol FILE_TYPE is replaced with
its current value. If FILE_TYPE is not defined, the command interpreter
replaces FILE_TYPE with a null string. The absence of a file type in the file
specification causes the PRINT command to use the default file type of LIS.
Thus, the file specification is interpreted as MYFILE.LIS.
In the following example, the expression is evaluated during the third phase
of command processing:
$ A=1
$ C=A+ B
%DCL-W-UNDSYM, undefined symbol - check validity and spelling

The symbol Bis undefined so the command interpreter cannot evaluate the
expression.

7-7

Protection

Devices, volumes, logical name tables, files, directories, mailboxes, common
event flag clusters, global sections, and queues are some of the things you
work with in the VMS operating system. In general, these are referred to as
system objects. The operating system provides two mechanisms to control the
access that users have to system objects:
•

VIC-based protection-Every user has a user identification code (VIC)
stored in the user authorization file (UAF). Each system object also has
a VIC (the VIC of its owner) and a protection code that defines who is
allowed what type of access. The relationship between your VIC and the
object's UIC controls whether or not you have access to it.

•

ACL-based protection-A system object can have an access control list
(ACL) that specifies the access that a particular user or group of users
are allowed. You can specify ACL-based protection for files, directories,
devices, logical name tables, and global sections.

When determining whether or not you have access to a particular object,
the system first checks to see if the object has an ACL. If there is not an
ACL, or if the ACL does not explicitly allow or refuse access, the system uses
UIC-based protection to determine access. (Even if the ACL denies access,
the system may still grant access based on the SYSTEM and OWNER fields of
the VIC-based protection. You can also use BYPASS, GRPPRV, READALL,
or SYSPRV privilege to override ACL- and VIC-based protection.)
This chapter describes UIC-based protection. For more information on
ACL-based protection, see the Guide to VMS System Security.

8.1

What is UIC-Based Protection?
Each user of the system has a VIC defined in the system UAF. Each system
object also has a VIC (the VIC of its owner) and a protection code. The
system compares your VIC to the VIC of a system object. This comparison
reveals the relationship between you and the object. It tells what type of user
you are in relationship to that object (for example, are you its owner). Next,
the system checks the protection code of the object. The protection code
specifies what type of access certain types of users have.

8.1.1

User Identification Code (UIC)
The system manager uses the AUTHORIZE utility to assign a VIC to
each user. The VIC tells what group you belong to followed by your
unique identification within that group. A VIC can be in either numeric
or alphanumeric format.
The numeric format of a VIC is as follows:
[group,member]

8-1

Protection
8.1 What is UIC-Based Protection?

where:

•

group is the number of the group you belong to. It is an octal number in
the range of 0 through 37776.

•

member is your unique member number, an octal number in the range of
0 through 177776.

You can omit leading zeros when you specify group and member numbers in
numeric format. The brackets are required.
The alphanumeric format of a VIC is as follows:
[member]
[group,member]

where:

•

group is the name of the group you belong to. The group name is
optional.

•

member is your unique name within the group.

Group and member names in alphanumeric format can contain 1 to 31
alphanumeric characters and must contain at least one alphabetic character.
The names can also include the dollar sign ( $) and underscore ( _ ). The
brackets are required.

8.1.2

UIC Translation and Storage
Regardless of the format of the UIC, the system translates it to a 32-bit value
that represents a group number and a member number; the high-order 16
bits contain the group number and the low-order 16 bits contain the member
number. When translating an alphanumeric UIC, VMS equates the member
part of the alphanumeric VIC to both the group and member parts of a
numeric VIC. The resulting 32-bit numeric VIC is kept in the system rights
database (a file that contains information about access rights).
This method of storing alphanumeric UICs dictates that member names must
be unique and that no member can participate in more than one group.
That is, each member name must be unique for each user on the system.
For example, you could not have the two VICs [GROUPl,JONES] and
[GROUP2,JONES] on the same system. The member JONES can have only
one numeric UIC.
Every UIC has a group name associated with it. When the system translates
an alphanumeric UIC that includes both a group and a member name, the
system obtains the longword integer associated with the member. It then
checks the group name against the member.
Because an alphanumeric UIC is equated to a numeric UIC in the system
rights database, you can generally specify either format to refer to a user.
For example, the following VIC specifications could all be valid for the user
JONES:

8-2

Protection
8.1 What is UIC-Based Protection?

[360 ,031]
[JONES]
[GROUP1, JONES]

Note: You can use either numeric or alphanumeric format in a DCL command
that requires a UIC specification.

8.1.3

How the System Determines Access
When you attempt to access a system object, your UIC is compared to the
owner UIC of the object. Once the two UICs are compared, you are put into
one or more of the following user categories:
SYSTEM
•

All users who have the system privilege (SYSPRV).

•

Users with low group numbers, usually from 1 through 10
(octal). However, the exact range of system group numbers
is determined by the system manager (with the SYSGEN
parameter MAXSYSGROUP) when the system is generated,
and may range as high as 37776 (octal). These group numbers
are generally for system managers, security managers, system
programmers, and operators.

•

Users with the user privilege GRPPRV whose UIC group
matches the group of the object's owner.

•

For files on disk volumes, users whose UIC matches the owner
UIC of the volume on which the file is located.

OWNER

The user with the same UIC as the user who created (and therefore
owns) the object.

GROUP

All users, including the owner, who have the same group number in
their UICs as the object's owner.

WORLD

All users, including those in the first three categories.

Figure 8-1 illustrates the relationships of these categories to each other.

8-3

Protection
8.1 What is UIC-Based Protection?

Figure 8-1

Illustrating User Categories with a UIC of [100, 100]

WORLD
(All UICs)

g = Group Number
m = Member Number

NOTE: THE SYSTEM MANAGER CAN EXTEND THE SYSTEM GROUP NUMBER LIMIT TO 377768
ZK-778-82

The protection code determines what type of access each user category has.
With DIC-based protection you can specify any of the following types of
access:
•

READ

•

WRITE

•

EXECUTE

•

DELETE

CONTROL access is a fifth type of access that grants the user all the privileges
of the object's actual owner. For example, if you have CONTROL access, you
can change the protection and file characteristics, just as the owner could.
CONTROL access is automatically granted to users in the system or owner
categories. Users in the group or world categories never receive control
access. Although you cannot specify CONTROL access in the standard
DIC-based protection code, you can include it in an ACL.
The actual abilities conveyed by READ, WRITE, EXECUTE, DELETE, and
CONTROL vary depending on the situation where they apply. For example,
EXECUTE access permits very different operations depending on whether it is
granted for file, directory, or volume access.

8-4

Protection
8.1 What is UIC-Based Protection?

8.1.4

The Protection Code
The protection code lists each user category followed by the type of access
that it has. For example:
$ SET PROTECTION=(SYSTEM:RWED,OWNER:RWED,GROUP:RE,WORLD:RE) SURVEY.DIR

This protection code specifies that anyone in the SYSTEM and OWNER
categories has READ, WRITE, EXECUTE, and DELETE access to the file
SURVEY.DIR. Anyone in the GROUP and WORLD categories has READ and
EXECUTE access.
The following syntax rules apply to protection codes:
•

When you specify a protection code, abbreviate access types to one
character (R, W, E, or D). User categories can be entered in full or
truncated to any number of characters. Separate each user category
from its access types with a colon or an equal sign. If you specify more
than one user category, separate the categories with commas and enclose
the entire code in parentheses.

•

You can specify the user categories and access types in any order. If you
omit an access type for a user category, that category of user is denied
that type of access. If you want to deny all access to a user category,
specify the user category but omit the colon and do not list any access
types. The following example denies all access to those in the WORLD
category:
$ SET PROTECTION=(SYSTEM:RWED,OWNER:RWED,GROUP:R,WORLD) HIRE.DAT

8.1.5

•

When you omit a user category from a protection code applied to one or
more files, or from a code specified for the default protection, the current
access allowed for that category remains unchanged.

•

When you omit a user category from a protection code applied to an
entire volume, that category is denied all types of access. However,
SYSTEM and OWNER always have access on magnetic tape volumes,
regardless of the protection specified.

How the System Interprets a Protection Code
To determine access to an object, the system uses the object's protection code
for each user category. The system checks user categories from outermost to
innermost, in the following sequence:
1

WORLD

GROUP

OWNER

SYSTEM

You can access an object as soon as the system finds a user category that you
fit into that gives you the access you have requested.
To deny access to a user category, be sure to deny access to all outer
categories. For example, the following protection code denies DELETE
access to a file's owner:

8-5

Protection
8.1 What is UIC-Based Protection?

SYSTEM:RWED, OWNER:RW, GROUP:RW, WORLD:RWED

However, the owner can still delete the file because the owner is also a
member of the WORLD category, which has DELETE access.

8.1.6

How Privileges Affect Protection
There are four system privileges that affect the access a user actually receives.
They are as follows:
SYSPRV

A user with SYSPRV receives the access accorded to
users in the SYSTEM category.

GRPPRV

A user with GRPPRV, whose UIC group matches the
group of the owner of the object, receives the same
access accorded to users in the SYSTEM category. Thus,
the user with GRPPRV is able to manage a group's files.

BYPASS

A user with BYPASS receives all types of access to the
object, regardless of its protection.

READALL

A user with READALL receives READ and CONTROL
access to the object, even if that access is denied by
the ACL- or UIC-based protection. In addition, the user
may receive any other access that is granted through the
protection code.

If a user holds any of these privileges, the outcome of the protection check
may be quite different from your expectations. For example, a user with
BYPASS privilege can delete any file on the system, despite the protection
any file might have.

8.2

Establishing and Changing UIC-Based Protection
This section describes how to establish or change the UIC-based protection
for devices, queues, volumes, directories, logical name tables, global sections,
and files.

8.2.1

Devices
UIC-based protection on record-oriented devices must be reestablished
every time the system is booted. Set device protection with the following
command:
SET PROTECTION=(code)/DEVICE device-name[:]

When applied to devices, access types have the following meanings:

8-6

READ

The right to issue read requests to the device.

WRITE

The right to issue write requests to the device.

CONTROL

The right to change the device ACL.

Protection
8.2 Establishing and Changing UIC-Based Protection

8.2.2

Queues
UIC-based protection lets you restrict the types of jobs and users for a
particular queue. Set queue protection with any of the following commands:
INITIALIZE/QUEUE/PROTECTION=( code)
START /QUEUE/PROTECTION=( code)
SET QUEUE/PROTECTION=(code)
When applied to queues, access types have the following meanings:

READ
WRITE
EXECUTE
DELETE

8.2.3

The right to display the attributes of a job.
The right to submit jobs to the queue.
The right to act as operator for the queue, the ability to affect any
jobs in the queue.
The right to delete a job.

Volumes
Volume protection is coded into the home block of the disk or tape when it
is mounted. It can be specified or defaulted from the device protection code.
Set volume protection with any of the following commands:
INITIALIZE
MOUNT
SET VOLUME
For disk volumes, the system provides protection at the file, directory, and
volume levels. For tape volumes, the system provides protection only at
the volume level. The protection applied to a magnetic tape volume applies
equally to all files on the volume.
When applied to volumes, access types have the following meanings:

READ
WRITE
EXECUTE
DELETE
CONTROL

The right to examine, print, or copy files on a volume.
The right to modify or to write existing files on a volume.
The right to create files on the volume and write into them.
The right to delete files on the volume.
The right to change the protection and ownership of the volume.

If you do not specify the protection when a volume is initialized, all users
have READ and WRITE access. Moreover, system users and the owner are
always given both READ and WRITE access, regardless of what you specify
in a protection code. Granting a user category WRITE access automatically
permits READ access.

Keep the following points in mind when setting the protection for a magnetic
tape volume:
•

EXECUTE and DELETE access are not valid for magnetic tapes.

•

For magnetic tapes mounted with the /FOREIGN qualifier, system users
and the owner are always given logical and physical I/O access in
addition to READ and WRITE access, regardless of what you specify in
the protection code.

8-7

Protection
8.2 Establishing and Changing UIC-Based Protection

•

8.2.4

File protection on a given magnetic tape can be changed only if the tape
is reinitialized.

Directories
Each directory file has a protection associated with it. Directory protection
can be specified or defaulted from the directory level above it. Set directory
protection with either of the following commands:
CREATE/DIRECTORY /PROTECTION=( code)
SET PROTECTION=(code)
When applied to directories, access types have the following meanings:
READ

The right to examine or list the directory file.

WRITE

The right to modify or write to the directory file

EXECUTE

The right to look up files in the directory if you specify the file name

DELETE

The right to delete the directory file

READ access lets you display the contents of the directory file with the
DIRECTORY command. You can use wildcards (explicitly or implicitly). In
addition, you can access any file cataloged in the directory unless the file's
protection denies you access. However, if a directory denies you READ
access, you cannot look up or access even those files that permit access to
users in your group. (It is possible to access files without using the directory
in which they are listed through suitable programming techniques. To
guarantee protection, therefore, individual files should also be protected.)
WRITE access lets you write to the directory file. You must have both READ
and WRITE access to a directory to create files in it, rename files, or perform
any file operation that involves changes to the directory file.
EXECUTE access has a special meaning when it is applied to directories.
EXECUTE access lets you use the DIRECTORY command to look up files that
you can identify by name. In addition, if you do not perform an operation
that modifies the directory file, you can access files that are not protected
against users in your category. However, you cannot list all the entries in the
directory by using wildcards. Therefore, EXECUTE access provides some, but
not all of the operations that READ provides.
DELETE access lets you delete a directory file. Before you delete a directory
file, do the following:
1

Remove all the files that are in it.

Use the SET PROTECTION command to assign DELETE access to the
OWNER category of the directory file.

Directory protection can override the protection of individual files in the
directory. Make sure your files are adequately protected at both the directory
and file level.

8-8

Protection
8.2 Establishing and Changing UIC-Based Protection

8.2.5

Files
Each file on a disk has its own protection code. You can specify a protection
code when you create a file or change the protection for an existing file. Set
file protection with either of the following commands:
COPY /PROTECTION=( code)
SET PROTECTION=(code)
If you do not define a protection code for a file when you create it, the system
applies a default protection. If a version of the file already exists, protection

is taken from the previous version of the file. For a new file, the protection is
determined in one of two ways:
•

If the directory where the file is to be cataloged has an associated access

control list that specifies the DEFAULT_PROTECTION entry, then the
specified protection is used.
•

If the directory does not have an associated access control list, then the

default process protection is used. (The default process protection is
established with the SET PROTECTION/DEFAULT command, or by
default when you log in.)
Use the following DCL commands to change or display file protection:
SHOW PROTECTION

Displays the current default protection.

SET PROTECTION/DEFAULT

Changes the default protection applied to files
that you create during a terminal session.

DIRECTORY /PROTECTION

Displays the current protection associated
with a specific file or group of files.

When applied to files, access types have the following meanings:
READ

The right to examine, print, or copy the file.

WRITE

The right to modify or write to the file.

EXECUTE

The right to execute a file that contains an executable program
image or DCL command procedure.

DELETE

The right to delete the file.

CONTROL

The right to change the protection and file characteristics of the file.

Note the following:
•

READ access also implies EXECUTE access.

•

To open a file for a write operation, you must have both READ and
WRITE access. This is because the VMS operating system does not
support write-only files.

•

To delete a file you must have DELETE access to both the file and the
directory that contains the file.

8-9

Protection
8.2 Establishing and Changing UIC-Based Protection

8.2.6

Global Sections
UIC-based protection on global sections, except those backed by disk files,
must be reestablished every time the system is booted. If the global section
is backed by a disk file, the section protection is derived from the disk file.
Changing the file protection changes the section protection.
For PFN and page file global sections, you set the protection in the $CRMPSC
system service call that creates the section. You cannot change the protection
after the section is created.
When applied to global sections, access types have the following meanings:

8.2.7

READ

The right to map the section for read access.

WRITE

The right to map the section for write access.

EXECUTE

The right to map the section for execute access (available only to
privileged software).

CONTROL

The right to change the access control list (applies only to PFN and
page file global sections).

Logical Name Tables
UIC-based protection on logical name tables must be reestablished every
time the system is booted. Set logical name table protection by applying
the protection argument to the $CRELNT system service call or with the
following command:
CREATE/NAME_TABLE /PROTECTION=( code) table-name
You cannot change the protection on an existing logical name table.
When applied to logical name tables, access types have the following
meanings:

8-10

READ

The right to look up logical names in the table.

WRITE

The right to create and delete logical names in the table.

DELETE

The right to delete the table.

CONTROL

The right to change the logical name table ACL.

ENABLE

The right to create a shareable logical name table.

VMS Process Privileges and Resource Quotas

Tables A-1 and A-2 summarize the full set of process privileges and resource
quotas. The system manager sets each user's privileges and resource quotas
in the user authorization file (UAF). If you need special quotas or privileges
to use DCL commands, the command descriptions in the VMS DCL Dictionary
note these restrictions.
Table A-1

Process Privileges

Privilege

Operations Permitted

ACNT

Create a process or subprocess with accounting disabled (RUN
command and SYS$CREPRC system service)

ALLS POOL

Allocate a spooled device (ALLOCATE command and SYS$ALLOC
system service)

ALTPRI

Increase base priority and create processes with higher priorities
(SYS$SETPRI and SYS$CREPRC system services)

BUGCHK

Make BUGCHK error log entries

BYPASS

Access all objects bypassing protection

CM EXEC

Change mode to executive (SYS$CMEXEC system service)

CMKRNL

Change mode to kernel (SYS$CMKRNL system service)

DETACH

Create a detached process (SYS$CREPRC system service) with
arbitrary UIC

DIAGNOSE

Run online diagnostic programs and read messages written to the
error log file

EXOUOTA

Exceed disk quotas

GROUP

Affect other processes in the same group (SET QUEUE,
DELETE/ENTRY, STOP/ENTRY, and SET PROCESS commands;
SYS$SUSPND, SYS$RESUME, SYS$DELPRC, SYS$SETPRI,
SYS$VVAKE, SYS$SCHDVVK, SYS$CANVVAK,SYS$FORCEX, and
SYS$GET JPI system services)

GRPNAM

Create and delete group logical names (DEFINE, DEASSIGN, and
MOUNT commands; SYS$CRELNM and SYS$DELLNM system
services)

GRPPRV

Access protected files and other objects within the same group
as a system user, and change the protection on files and other
objects within the same group

LOG_IO

Perform logical 1/0 operations (SYS$010 system service)

MOUNT

Perform the mount volume 1/0 function (SYS$010 system service)

NETMBX

Perform DECnet operations

OPER

Set devices spooled, control queues, control public volumes,
broadcast messages, and perform other system-wide operations

PFNMAP

Map to physical memory and 1/0 registers

A-1

VMS Process Privileges and Resource Quotas

Table A-1 (Cont.)

A-2

Process Privileges

Privilege

Operations Permitted

PHY_IO

Perform physical 1/0 operations (SYS$010 system service)

PRMCEB

Create and delete permanent common event flag clusters
(SYS$ASCEFC and SYS$DLCEFC system services)

PRMGBL

Create global sections (SYS$CRMPSC system service) and install
global sections (also requires CMKRNL and SYSGBL privileges)

PRMMBX

Create and delete permanent mailboxes (SYS$CREMBX and
SYS$DELMBX system services)

PSWAPM

Disable and enable swapping (RUN command; SYS$CREPRC and
SYS$SETSWM system services)

READ ALL

Allow read and control access to all objects

SECURITY

Perform security-related activities such as enabling or disabling
security audits and setting the system password

SETPRV

Grants a process any privilege

Assign a channel to a device even if the channel is allocated to
another device

SHMEM

Create global sections and mailboxes in multiport memory (also
requires the appropriate PRMGBL, PRMMBX, SYSGBL, and
TMPMBX privileges)

SYSGBL

Create system global sections (SYS$CRMPSC) and install known
images (also requires CMKRNL and PRMGBL privileges)

SYSLCK

Lock system-wide resources (SYS$ENO system service)

SYSNAM

Create and delete system logical names (DEFINE, DEASSIGN, and
MOUNT commands; SYS$CRELNM and SYS$DELLNM system
services)

SYSPRV

Access protected files and other objects as a system user and
change the protection on files and other objects

TM PM BX

Create temporary mailboxes (SYS$CREMBX system service)

VO LP RO

Initialize a volume with a different UIC, override an expiration date,
mount a volume foreign, and override volume protection (affecting
system volumes also requires SYSNAM privilege)

WORLD

Affect all other processes (SET QUEUE, DELETE/ENTRY,
STOP/ENTRY, and SET PROCESS commands; SYS$SUSPND,
SYS$RESUME, SYS$DELPRC, SYS$SETPRI, SYS$WAKE,
SYS$SCHDWK, SYS$CANW AK, SYS$FORCEX, and SYS$GETJPI
system services)

VMS Process Privileges and Resource Quotas

Table A-2

Resource Quotas

Name

Quota

ASTLM

AST (asynchronous system trap) limit

BIOLM

Buffered 1/0 limit

BYTLM

Buffered 1/0 byte count (buffer space) quota

CPUTIME

CPU time limit

DIOLM

Direct 1/0 limit

ENQLM

Enqueue limit

FILLM

Open file quota

JTQUOTA

Initial byte quota for job logical name table

MAXACCTJOBS

Maximum active processes for an account

MAXDETACH

Maximum detached processes for a user name

MAXJOBS

Maximum active processes for a user name

PGFLQUOTA

Paging file quota

PRCLM

Subprocess quota

SHRFILLM

Maximum number of open shared files

TQELM

Timer queue entry ql;Jota

WSDEFAULT

Default working set size

WSEXTENT

Working set extent quota

WSQUOTA

Working set size quota

A-3

DEC Multinational Character Set

Figure B-1

DEC Multinational Character Set and Hexadecimal
Values

HEX
Code

ASCII
Char.

HEX
Code

ASCII
Char.

HEX
Code

00
01
02
03
04
OS
06
07
08
09
DA
OB

NUL
SOH
STX
ETX
EOT
ENQ
ACK
BEL
BS
HT
LF
VT
FF
CR

20
21
22
23
24
2S
26
27
28
29
2A
2B
2C
2D
2E
2F
30
31
32
33
34
JS
36
37
38
39
3A
3B
JC
3D
3E
3F

40
41
42
43
44
4S
46
47
48
49
4A
4B
4C
4D
4E
4F

DC
OD
OE
OF
10
11
12
13

14
lS
16
17
18
19
lA
lB

lC
lD
lE
lF

SI
DLE
DCl
DC2
DC3
DC4
NAK
SYN
ETB
CAN
EM
SUB
ESC
FS
GS
RS

!
II

#
$
%
&
I

(
)

*
,

0
1
2
3
4

6
7
8
9
:
;

<
=

>
?

ASCII
Char.

HEX
Code

ASCII
Char.

60
61
62
63
64
6S
66
67
68
69
6A
6B
6C
6D
6E
6F
70
71
72
73
74
7S
76
77
78
79
7A
7B
7C
7D
7E
7F

'
a

A
B

D
E
F
G
H

I
J

K
L
M
N
0
p

Sl
S2
S3
S4
SS
S6
S7
S8
S9
SA
SB
SC
SD
SE
SF

Q
R

w
x
y

z
[

]

c
d

e
f
g
h
i
j
k

1
m
n
0

p
q
r

s
t
u

v
w
x
y

z
{

I
}
"v

DEL
ZK-820-82

B-1

DCLCharacterSet

Table C-1

DCL Character Set

Symbol Name

Meaning

At sign

Places the contents of a command procedure file in the
command input stream.

Colon

Device name delimiter in a file specification. A double
colon (::) is a node name delimiter. A colon also acts as
a qualifier delimiter. It separates a qualifier name from its
value.

Slash

Qualifier prefix.

Plus sign

Parameter separator. With some commands it acts as a
parameter concatenator. The plus sign is also recognized
as a string concatenation operator, a unary plus sign, and
an addition operator in a numeric expression.

Comma

List element separator for parameters or argument lists.

Hyphen

Continuation character. The hyphen is also recognized
as a string reduction operator, a unary minus sign, a
subtraction operator in a numeric expression, and a
directory-searching wildcard character.

()

Parentheses

List delimiters for argument list. Parentheses are also
used to indicate the order of operations in a numeric
expression.

[]

Square
brackets

Directory name delimiters in a file specification. Equivalent
to angle brackets.

Angle
brackets

Directory name delimiters in a file specification. Equivalent
to square brackets.

Question
mark

Help character.

Ampersand

Execution-time substitution operator. Otherwise, a
reserved special character.

Backslash

Reserved special character.

Equal sign

Qualifier value delimiter. It separates a qualifier name from
its argument.

Circumflex

Reserved special character.

Pound sign

Reserved special character.

Asterisk

Wildcard character in a file specification. The asterisk
is also used as a multiplication operator in a numeric
expression and as an abbreviation delimiter in a symbol
definition.

Apostrophe

Substitution operator.

C-1

DCL Character Set

Table C-1 (Cont.)

DCL Character Set

Symbol Name

Meaning

Period

C-2

File type and version number delimiter in a file
specification. Also used as a subdirectory delimiter.

Semicolon

V(3rsion number delimiter in a file specification.

Percent sign

Wildcard character in a file specification. Also used as a
radix operator.

Exclamation
point

Indicates a comment.

Quotation
mark

Literal string delimiter.

Index
.AND.

A
Abbreviation
in command procedures• 1-6
of commands• 1-5
of keywords• 1-12
of qualifiers• 1-12
Absolute time
combined with delta time• 1-16
default values for date and time fields• 1-14
examples• 1-15
rules for entering • 1-14
syntax• 1-14
Access control string
definition• 3-2
example• 3-3
format in a node name• 3-3
in a logical node name• 4-21 to 4-23
rules for entering • 3-3
Access mode
and the DEFINE command• 1-8, 4-14
for a logical name• 4-14
for a logical name table• 4-17
using qualifiers to specify• 1-8, 4-14, 4-17
Access types
See also CONTROL access
See also DELETE access
See also EXECUTE access
See also READ access
See also WRITE access
defined for a device• 8-6
defined for a directory• 8-8
defined for a file• 8-9
defined for a global section• 8-10
defined for a logical name table• 8-10
defined for a queue• 8-7
defined for a volume• 8-7
list of• 8-4
ACL-based protection
definition • 8-1
ALLOCATE command • 3-6
Allocation class field
definition• 3-6
Ampersand (&)
as a substitution operator• 7-3 to 7-4

in a logical operation• 6-8
ANSI-labeled magnetic tape volume
file specification format• 3-16
Apostrophe (')
as a substitution operator• 7-2
Arrow keys
to move the cursor• 2-5
to recall commands• 2-6
ASCII "a" character set• 3-16
ASCII character set• B-1
ASSIGN command
See also DEFINE command
function• 4-2
how it handles a colon in a logical name• 4-2
Assignment statement
creating a blank line• 6-4
creating a global symbol• 5-3
creating a local symbol• 5-3
formating output records• 6-4
including an asterisk• 5-4
including a symbol as part of a character string•
5-7
syntax• 5-2
syntax for numeric overlay• 6-9
syntax for string overlay• 6-3
Asterisk (*) Wildcard
in directory specifications• 3-18
in input file specifications• 3-18
in output directory specifications• 3-20
in output file specification• 3-19
in UIC format directory specifications• 3-18
rules for using• 3-18
used to rename files• 3-19

B
BACKSPACEkey•2-5
Bit operation
examples• 6-8 to 6-9
rules• 6-8 to 6-9
Built-in command
definition• 1-1
interrupting and canceling• 2-2
table of DCL built-in commands• 1-2
BYPASS privilege• 8-6

lndex-1

Index

c
Character string
See String
Cluster device name
allocation class field• 3-6
cluster node field • 3-6
format for dual pathed device• 3-6
format in a file specification• 3-6
Cluster node field
definition • 3-6
Combination time
examples• 1-17
rules for entering• 1-1 6
syntax• 1-16
Command
See also Foreign command
abbreviating• 1-5
cancelling• 1-4, 2-1
DCL syntax line• 1-3
executing• 2-1
interrupting• 2-1 to 2-3
rules for entering• 1-3
types• 1-1
Command image
definition• 1-1, 2-1
privileged and nonprivileged • 2-1
Command input scanning
definition• 7-4
Command line
See also Editing the command line
continuation over multiple lines• 1-4
indicating a comment• 1-5
parts of• 1-3
recalling• 2-6 to 2-7
rules for entering parameters• 1-6
rules for entering qualifiers• 1-7
terminators• 2-1
Command parsing
definition• 7-4
Command procedure
passing parameters• 5-1
position of a label in a command line• 1-3
symbol substitution• 7-4
use of dollar sign prompt• 1-3
Command processing
first phase• 7-4
parsing a foreign command• 5-8
second phase • 7-4

lndex-2

Command processing (cont'd.)
third phase• 7-4
Command qualifier
definition• 1-7
Command values
date and time formats• 1-13
Comment
in a command line• 1-5
Concatenation
See String
of character strings• 5-5
of symbol names• 7-2
Concealed device name
definition • 4-13
CONTINUE command
to resume command execution• 2-2
used to resume command execution• 2-3
Continuing the command line• 1-4
CONTROL access
for a device • 8-6
for a file • 8-9
for a global section• 8-10
for a logical name table• 8-10
for a volume• 8-7
in UIC-based protection • 8-4
Controller designation field
default value• 3-6
definition • 3-4
COPY command• 3-5, 3-19, 8-9
to rename files• 3-19
CREATE/DIRECTORY command• 3-12, 8-8
CREATE/NAME_TABLE command• 4-15, 8-10
CTRL/8•2-7
to recall commands• 2-6
CTRL/C
See also CTRL/Y
to interrupt or cancel DCL commands• 2-1
used to interrupt or cancel DCL commands•
2-7
CTRL/T
to interrupt DCL commands• 2-1, 2-8
CTRL/U • 2-5, 2-6, 2-8
CTRL/Y
See also CTRL/C
to interrupt or cancel DCL commands• 2-1,
2-8
CTRL/Z • 2-1, 2-8
CTRL keys•2-5 to 2-6, 2-7 to 2-8

Index

Device field (cont'd.)

D
Date
specifying absolute and delta combinations•
1-16
specifying absolute time• 1-14
specifying delta time• 1-1 5
DBG$1NPUT • 4-7
DBG$0UTPUT•4-7
DCL command prompt
in command procedures• 1-3
DEASSIGN command• 4-4
default logical name table• 4-5
to delete a logical name table• 4-16
Default file types
table of•3-14
Default values in file specifications• 3-22
DEFINE command
See also ASSIGN command
default logical name table• 4-5
example with access mode qualifier• 4-14
function• 4-2
how it handles a colon in a logical name• 4-2
specifying the access mode• 1-8, 4-14
DELETE access
for a directory• 8-8
for a file• 8-9
for a logical name table• 8-10
for a queue• 8-7
for a volume• 8-7
DELETE command• 3-12
DELETE key• 2-5
DELETE/SYMBOL command• 5-4
Delta time
combined with absolute time• 1-16
default values• 1-·15
examples• 1-16
rules for entering• 1-1 5
syntax for• 1-15
DEPOSIT command• 7-1 , 7-4
Device
See also Logical name
mass storage• 3-4
record oriented • 3-4
unit record• 3-4
Device code field
definition • 3-4
in a cluster device name• 3-6
Device field
default value• 3-22

definition • 3-1
Device name
See also Cluster device name
See also Device field
See also Physical device name
generic • 3-6
rules for entering• 3-4
using a logical name• 3-6
Device protection
access types • 8-6
commands for setting• 8-6
DIRECTORY command • 3-12
Directory field
default value• 3-22
definition• 3-1
rules for using an asterisk wildcard • 3-18,
3-20
rules for using an ellipsis wildcard • 3-20
rules for using a percent sign wildcard • 3-19
Directory file
defintion • 3-7
how to delete • 3-1 2, 8-8
Directory hierarchy
definition• 3-7
example• 3-7
Directory name
See also Directory field
named format in a file specification• 3-9
translating UIC format to named format• 3-10
UIC format in a file specification• 3-9
using the ellipsis (... ) wildcard • 3-10
using the hyphen (-) wildcard • 3-12
Directory protection
access types• 8-8
commands for setting• 8-8
DIRECTORY /PROTECTION command• 8-9
Directory structure
default directory• 3-7
duplicating with wildcards • 3-20
hierarchy• 3-7
master file directory• 3-7
subdirectory• 3-7
top-level directory• 3-7
user file directory• 3-7
Disk volume
See Volume
Down arrow key• 2-8
to recall commands• 2-6
Dual pathed device specification • 3-6

lndex-3

Index

E
Editing the command line
enabling line editing• 2-4
insert mode• 2-4
line editing keys• 2-5
overstrike mode• 2-4
Ellipsis (... ) wildcard
in a directory name• 3-10
in output directory specifications• 3-20
.EQ.
in a numeric comparison• 6-7
.EQS.
in a string comparison• 6-2
Equivalence name
definition• 4-2
EXAMINE command• 7-1, 7-4
EXECUTE access
for a directory• 8-8
for a file• 8-9
for a global section• 8-10
for a queue• 8-7
for a volume• 8-7
Executive mode
See access mode
Expression
See also Numeric expression
See also Operand
See also Operator
See also String expression
definition • 5-7
iterative substitution• 7-6
logical operators• 6-8
numeric comparison operators• 6-7
numeric operators• 6-7
rules for determining the value• 6-12
string comparison operators• 6-2
string operators• 6-2
summary of operators• 6-10
Expression evaluation
definition• 7-4

F
F$1NTEGER • 6-11
F$STRING • 6-11
F$TYPE • 6-1 1

lndex-4

F10 key•2-8
F6 .. F 14 keys• 2-5 to 2-6
F6key•2-7
File access
on a disk volume set• 3-5
on a tape volume set• 3-5
File name
See also File name field
rules for entering• 3-13
valid characters• 3-13
File name field
default value• 3-22
definition • 3-1
rules for using an asterisk wildcard • 3-18,
3-19
rules for using a percent sign wildcard • 3-19
with a null value• 3-16
File protection
access types • 8-9
changing the default protection• 8-9
commands for setting• 8-9
displaying the default protection• 8-9
displaying the protection for a specific file• 8-9
how default protection is determined • 8-9
File specification
See also Device
See also Directory name
See also File name field
See also File type field
See also File version number field
See also Node field
See also Wildcards
alternate form for magnetic tapes• 3-16
as a parameter value• 1-6
as a qualifier value• 1-10
See also Output file specifications for
qualifiers
as a search list• 4-20
as multiple search lists• 4-21
default values• 3-22
default values created by logical name
translation• 4-13 to 4-14
example• 3-1
file name• 3-13
file type• 3-14
file version number• 3-15
format • 3-1 , 3-1 3
list of included fields• 3-1
node name• 3-2
rules for entering• 3-1 to 3-2

Index

File type
definition• 3-14
rules for entering• 3-14
File type field
default values• 3-14, 3-22
default values created by logical name
translation• 4-13
definition• 3-1
rules for using an asterisk wildcard • 3-18,
3-19
rules for using a percent sign wildcard • 3-19
with a null value• 3-16
File version number
format in a file specification• 3-15
File version number field
default value• 3-22
definition • 3-1
rules for using an asterisk wildcard • 3-18,
3-19
Foreign command • 5-1
definition • 5-8
parsing in a command line • 5-8
syntax• 5-8
Foreign file specification
on a network• 3-3
Function keys• 2-5 to 2-6, 2-7 to 2-8

G
.GE.
in a numeric comparison• 6- 7
Generic device name
definition• 3-6
.GES.
in a string comparison• 6-2
Global section protection
access types • 8-10
how to set• 8-10
Global symbol table
DCL reserved symbols• 5-2
definition• 5-2
in the search order• 5-3
GROUP category
definition• 8-3
Group logical name table
definition• 4-6
logical name for• 4-6
GRPPRV privilege• 8-6
.GT.
in a numeric comparison• 6-7

.GTS.
in a string comparison• 6-2

H
Hexadecimal value• 8-1
Hierarchy
See Directory hierarchy
Hyphen
and command line continuation • 1-4
Hyphen (-) wildcard
in a directory name• 3-12

I
IF command•7-1, 7-4, 7-6
Image
See Command image
INITIALIZE command• 8-7
INITIALIZE/QUEUE command• 8-7
Input file
temporary defaults in a parameter list• 3-16
Input stream
definition• 4-5
INQUIRE command• 5-1, 5-4
Insert mode
definition• 2-4
Integer
See Number
Interactive command
definition • 1-1
Interactive mode
definition • 1-1
Interrupting a DCL command• 2-1 to 2-3
Iterative substitution
definition• 7-5
during the three phases of command processing
•7-4
in an expression• 7-6
using apostrophes• 7-5
using command synonyms• 7-6
Iterative translation
See also Logical name translation
definition• 4-3, 4-12

lndex-5

Index

J
Job logical name
definition• 4-6
function in a job tree• 4-6
Job logical name table
default contents• 4-6
limiting its size• 4-1 7
logical name for• 4-6
Job tree
definition • 4-5

K
Kernel mode
See access mode
Key definition
defineable keys• 2-9
description• 2-9
Keyword
abbreviating• 1-12
definition• 1-3

L
Label
DCL syntax line• 1-3
Language compilers
effects of qualifiers on output files•
1-10 to 1-11
.LE.
in a numeric comparison• 6-7
Left arrow key• 2-5
.LES.
in a string comparison• 6-2
Lexical function
definition• 5-6
syntax• 5-6
Lexical input phase
See Command input scanning
Line editing
See Editing the command line
LINEFEED key• 2-6
Line terminators• 2-1
LINK command• 4-13
LNM$DCL_LQGICAL • 4-10

lndex-6

LNM$DIRECTORIES • 4-10
LNM$FILE_DEV • 4-10
to redefine the search order• 4-16
LNM$GROUP • 4-6, 4-9, 4-10
LNM$JOB • 4-6, 4-9, 4-10
LNM$PERMANENT_MAILBOX• 4-10
LNM$PROCESS • 4-5, 4-9
LNM$PROCESS_DIRECTORY • 4-8, 4-9
LNM$PROCESS_TABLE•4-9
LNM$SYSTEM • 4-7 4-11
LNM$SYSTEM _DIRECTORY • 4-8, 4-11
LNM$SYSTEM_TABLE• 4-11
LNM$TEMPORARY_MAILBOX• 4-11
Local symbol table
definition • 5-1
in the search order• 5-3
P1 .. PS•5-1
Logical name
See also Job logical name
I

See also Logical name table
See also Process logical name
access modes• 4-14
concealed device name• 4-13
creating• 4-2
defined as a search list• 4-18
for a mounted disk or tape• 4-6
for a node specification• 4-21 to 4-23
for a temporary mailbox• 4-6
in an input file list• 4-13
in the device field of a file specification• 3-6
overview• 4-1
placing in a user-defined table• 4-16
rules for creating• 4-2
translation in file specifications• 1-6
use of the colon• 4-2
Logical name directory table
definition • 4-1, 4-8
process • 4-8
system•4-9
Logical name table
See also Group logical name table
See also Job logical name table
See also Process logical name table
See also System logical name table
A CL-based protection• 4-18
defining the access mode• 4-17
definition• 4-1, 4-4
including a user-defined table in the search
order• 4-16
limiting its size• 4-1 6

Index

Logical name table (cont'd.)
list of those provided by the system• 4-1
process-private• 4-1 5
rules for creating• 4-15
search order• 4-11
shareable• 4-15
shareable tables• 4-6
UIC-based protection• 4-18
Logical name table protection
access types• 8-10
how to set• 8-10
Logical name translation
default search order• 4-11
default values• 4-13
in file specifications• 4-13 to 4-14
iterative• 4-12
preventing iterative translation• 4-13
when the file specification contains a wildcard •

4-19
.LT.
in a numeric comparison• 6-7
.LTS.
in a string comparison• 6-2

M
Magnetic tape volume
See Tape volume
Mass storage device
definition• 3-4
Master file directory
definition• 3-7
MFD
See Master file directory
MOUNT command• 3-6, 8-7
Multiple file specifications
in a parameter list• 3-16

N
Named directory specification
definition • 3-9
format in a file specification• 3-9
rules for entering• 3-9
.NE.
in a numeric comparison• 6- 7
.NES.
in a string comparison• 6-2

Network file specification
conventional format• 3-3
foreign file format• 3-3
task specification string • 3-3
Network node
See also Access control string
See also Node name
accessing a local node• 3-2
accessing a remote node• 3-2
accessing a remote node with an access control
string• 3-2
Node field
default value• 3-22
definition• 3-1
Node name
See also Access control string
See also Node field
format in a file specification• 3-2
rules for entering• 3-2
using a logical name• 4-21 to 4-23
Noninteractive mode
definition• 1-1
Nonprivileged command image
interrupting and canceling• 2-2
.NOT.
in a logical operation• 6-8
Null value
for file name• 3-16
for file type• 3-16
Number
converting to a string value• 6-12
integer values recognized by DCL • 5-5
Numeric expression
comparison operators• 6-7
definition• 6-6
examples• 6-1 , 6-7, 6-8

0
Object
See System object
Octal numbers
in a numeric UIC • 8-2
in a UIC dire('.tory specification• 3-9
Offset
definition • 6-3
Operand
See also Expression
See also Operator

lndex-7

Index

Operand (cont'd.)

Parameter qualifier

definition • 5-7, 6- l
example • 6-1
Operator

definition• 1-7
Percent sign (%) wildcard
in input file specifications• 3-19
rules for using• 3-19
Physical device name
controlller designation field• 3-4
device code field • 3-4
format in a file specification• 3-4
unit number field• 3-4
Positional qualifier
definition• 1-7
Privileged command image
interrupting and executing• 2-3
Process directory logical name table
default contents• 4-8
Process logical name
function in a job tree• 4-5
Process logical name table
default contents • 4-5
definition• 4-5
logical name for• 4-5
Process permanent files
default logical names• 4-23
Prompt
in a command line• 1-4
Protection
See ACL-based protection

See also Expression
See also Operand
definition • 5-7, 6-1
example• 6-1
logical • 6-8
numeric• 6-7
numeric comparison• 6-7
order of evaluation• 6-10
string• 6-1
string comparison• 6-2
string concatenation• 6-2
string reduction• 6-2

.OR.
in a logical operation• 6-9
Output file specifications for qualifiers
/EXE CUT ABLE• 1-10
file naming conventions• 1-10 to 1-11
/LIST• 1-10
/OBJECT• 1-10
Output stream
definition • 4-5
Overlay
in a string assignment• 6-3
numeric• 6-9
Overstrike mode
definition• 2-4
OWNER category
definition• 8-3

p
P1 .. PS•5-1
Parameter
DCL syntax line• 1-3
definition• 1-3
logical names in file specification values• 1-6
passing parameters to a command procedure•

5-1
syntax• 1-6
using a file specification as a value• 1-6
Parameter list
defaults for multiplie file specifications• 3-16
multiple file specifications• 3-16 to 3-17
syntax• 1-6

lndex-8

See UIC-based protection
effect of privileges• 8-6
Protection code
definition • 8-5
rules for entering• 8-5
syntax• 8-5

a
Qualifier
abbreviating• 1-12
commonly used qualifiers• 1-12 to 1-13
DCL syntax line• 1-3
definition• 1-3
rules for entering• 1-7
Qualifier format
for position/ negative qua Iifiers • 1- 7
for qualifiers that override other qualifiers• 1-8
for qualifiers that require values• 1-8
Qualifier types
modifying a command• 1- 7

Index

Qualifier types (cont'd.)
modifying a parameter• 1-7
positional• 1-7
Qualifier values
See also Output file specifications for qualifiers
abbreviating• 1-10, 1-12
date and time formats• 1-1 3
default values• 1-7
output file specifications• 1-10
rules for entering• 1-9
syntax• 1-9
types• 1-9
Queue protection
access types• 8-7
commands for setting• 8- 7

R
READ access
for a device• 8-6
for a directory• 8-8
for a file• 8-9
for a global section• 8-10
for a logical name table• 8-10
for a queue • 8-7
for a volume• 8-7
READALL privilege• 8-6
READ command• 5-1, 5-4
Recall buffer• 2-6
RECALL command• 2-6
Recalling commands• 2-6 to 2-7
Record oriented device
definition• 3-4
used as an output file specification• 3-5
Redirecting output• 3-5
Reduction
See String
Renaming files
with the COPY command and the asterisk (*)
wildcard • 3-19
Repetitive substitution
definition• 7-5
$REST ART• 5-2
RETURN key• 2-1, 2-8
Right arrow key• 2-5

s
Search list
and the SET DEFAULT command• 4-20
definition• 4-18
example• 4-18
in a file specification• 4-20
multiple search lists• 4-21
nested search lists• 4-21
Search order
for logical name translation• 4-11
SET ACL command• 4-18
SET DEFAULT command• 3-12
and a logical name search list• 4-20
SET DIRECTORY command• 3-12
SET PROTECTION command• 8-6, 8-8, 8-9
SET PROTECTION/DEFAULT command• 8-9
SET QUEUE command • 8-7
SET SYMBOL/SCOPE command• 5-4
SET TERMINAL command• 2-4
SET VOLUME command • 8-7
$SEVERITY• 5-2
Shareable tables
definition• 4-6
group logical name table• 4-6
job logical name table• 4-6
system logical name table• 4-7
user-defined • 4-1 5
SHOW DEFAULT command• 3-12
SHOW LOGICAL command
See also SHOW TRANSLATION command
default search order• 4-3
including a wildcard • 4-4
to display all logical name tables• 4-3
to display a particular logical name table• 4-4
to display the access mode of a logical name•
4-14
to display the logical name table structure• 4-8
SHOW PROTECTION command• 8-9
SHOW SYMBOL command • 5-4
SHOW TERMINAL command• 2-4
SHOW TRANSLATION command• 4-3
See also SHOW LOGICAL command
SPAWN command
to create a subprocess• 2-3
ST ART /QUEUE command• 8-7
$STATUS•5-2
STOP command
to terminate command execution• 2-2
used to terminate command execution• 2-3

lndex-9

Index

String
concatenation• 5-5, 6-1, 6-2
continuation over multiple lines• 5-5
converting to an integer value• 6-12
definition• 5-5, 6-1
multiple string values in an expression• 6-1
reduction• 6-2
rules for creating• 5-5
String expression
comparison operators• 6-2
examples• 6-2, 6-3
rules for creating• 6-1
Subdirectory
definition • 3-7
rules for creating • 3-7
Subprocess
creating one with the SPAWN command• 2-3
Substitution
See Symbol substitution
Substitution operator
definition• 7-2
order of evaluation• 7-3, 7-4
Substitution operator> ampersand (&) • 7-3
Substitution operator> apostrophe (') • 7-2
Supervisor mode
See access mode
Suspending terminal display• 2-7, 2-8
Symbol
concatenation• 7-2
defined as a lexical function• 5-6
defined as an expression• 5-7
defined as another symbol• 5-7
definition• 5-1
forcing symbol substitution with an apostrophe•
5-7
global• 5-1
indicating a numeric value• 5-3, 5-5
iterative substitution• 7-5
local• 5-1
repetitive substitution • 7-5
rules for abbreviating• 5-4
rules for creating • 5-2
search order• 5-3
two ways to indicate a character string value•
5-3,5-5
undefined• 7-7
uses• 5-1
Symbol substitution
See also Iterative substitution
See also Repetitive substitution
See also Substitution operator

lndex-10

Symbol substitution (cont'd.)
automatic evaluation • 7-1
definition • 7-1
in a command procedure • 7-4
in a lexical function• 7-1
performed by command interpreter• 7-4
rules for• 7-1
using an ampersand • 7-3
using an apostrophe• 7-2
within a quoted character string• 7-3, 7-4,
7-5
Symbol table
See also Global symbol table
See also Local symbol table
search order• 5-3
Syntax
cluster device specification • 3-6
DCL command line• 1-3
device specification • 3-4
directory specification• 3-9
file specification• 3-1 , 3-13
file specification on a tape volume• 3-16
for date and time values• 1-14 to 1-17
foreign command• 5-8
lexical function• 5-6
logical name definition• 4-2
node specification• 3-2, 3-3
parameter specification• 1-6
qualifier value• 1-9
symbol definition• 5-2
UIC specification• 8-1
SYS$COMMAND • 4-5, 4-23
redefining• 4-26
SYS$COMMON • 4-7
SYS$DISK • 4-5
SYS$ERROR•4-5,4-23
redefining• 4-25
SYS$ERRORLOG • 4-7
SYS$EXAMPLES • 4-7
SYS$HELP • 4-7
SYS$1NPUT•4-5, 4-23
redefining• 4-24
SYS$1NSTRUCTION • 4-7
SYS$LIBRARY•4-7
SYS$LOGIN • 4-6
SYS$LOGIN_DEVICE • 4-6
SYS$MAINTENANCE • 4-7
SYS$MANAGER • 4-7
SYS$MESSAGE • 4-7
SYS$NET • 4-5
SYS$NODE•4-7

Index

SYS$0UTPUT•4-5,4-23
redefining• 4-24
SYS$REM_ID • 4-6
SYS$REM_NODE • 4-6
SYS$SCRATCH•4-6
SYS$SHARE•4-7
SYS$SPECIFIC • 4-7
SYS$SYSDEVICE • 4-7
SYS$SYSROOT•4-7
SYS$SYSTEM•4-8,5-8
SYS$TEST • 4-8
SYS$UPDATE•4-8
SYSPRV privilege• 8-6
SYSTEM category
definition• 8-3
System directory logical name table
default contents• 4-9
System logical name table
default contents• 4-7
definition• 4-7
logical name for• 4-7
System object
definition • 8-1
System rights database
definition• 8-2

T
TAB key•2-6
Tape volume
file specification • 3-16
See also Volume• 3-16
Task specification string
on a network• 3-3
Temporary defaults in an input file list• 3-16
Terminal display
stopping and starting• 2-7
Time
specifying absolute and delta combinations•
1-16
specifying absolute time• 1-14
specifying delta time• 1-1 5
Top-level directory
See also User file directory
definition• 3-7
TT•4-5

u
UFD
See User file directory
UIC
See User identification code
UIC-based protection
See also Access types
See also Protection code
See also User category
definition• 8-1
user categories• 8-3
UIC directory specification
definition• 3-9
format in a file specification• 3-9
rules for entering• 3-9
translating to named format• 3-10
wildcards • 3-21
Undefined symbol• 7-7
Unit number field
default value• 3-6
definition• 3-4
Unit record device
definition • 3-4
Up arrow key• 2-7
to recall commands• 2-6
User category
definition• 8-3
group•8-3
owner•8-3
system•8-3
world•8-3
User file directory
See also Top-level directory
definition• 3-7
User identification code
alphanumeric format• 8-2
examples• 8-2
in a directory name• 3-9
numeric format• 8-1
User mode
See access mode

v
Value
DCL syntax line• 1-3

lndex-11

Index

Value (cont'd.)
definition• 1-3
Version number
See File version number• 3-1 5
Volume
definition • 3-5
Volume protection
access types • 8-7
commands for setting• 8-7
for a disk volume• 8-7
for a tape volume• 8-7
when initializing a volume• 8-7
Volume set
definition • 3-5
disk•3-5
tape•3-5

w
Wildcards
asterisk (*) • 3-17, 3-19 to 3-20
ellipsis (... ) • 3-10, 3-10 to 3-11
hyphen (-) • 3-10, 3-12
in a file specification that contains logical names
• 4-19
in input file specifications• 3- 17
in output directory specifications• 3-20, 3-21
in output file specifications• 3-19
in UIC format output directory specifications•
3-21
percent sign (%) • 3-17
to display logical names• 4-4
WORLD category
definition• 8-3
WRITE access
for a device • 8-6
for a directory • 8-8
for a file• 8-9
for a global section• 8-10
for a logical name table• 8-10
for a queue• 8-7
for a volume• 8-7
WRITE command• 5-1, 7-4

lndex-12

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