How to Use Predict Commands

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# How to Use Predict Commands

This document covers the following topics:

- Where to Enter Commands

- Repeating Command Execution

- Truncating Commands

- Syntax of Predict Commands

- Taking Parameter Values from the Command Context

- Specifying Commands in Keyword or Positional Form

- Delimiting Parameters in Predict Commands

- Metasyntax

## Where to Enter Commands

Predict commands can be entered:

- On any Predict screen containing the Command ===> prompt. The line containing this prompt is referred to throughout the Predict documentation as the command line.

- After the Natural `NEXT` prompt, preceded by CMD and separated by blank.

- In batch jobs: Retrieval, active retrieval, generation, incorporation and comparison commands are also available in batch mode, but most maintenance commands are not.

## Repeating Command Execution

The command `LAST` returns to the Predict Main Menu and displays the Predict command that was executed last. The command can then be modified or reexecuted.

## Truncating Commands

Commands can be truncated provided that the input remains unambiguous. For example, the command `GENERATE` can be entered as G since no other command begins with G. However, the command `LOGON` must be entered in full, since truncations (LOGO, LOG etc.) could be confused with the `LOGOFF` command.

If the truncated command is ambiguous, the Predict command processor checks whether any accompanying object type is unambiguous. If so, it checks what commands can be applied to this object type.

## Syntax of Predict Commands

General and standard Predict commands have the following syntax:

    <command> <parameters>

Type-dependent commands have the following syntax:

    <command><object-type><object-ID><parameters>

or

    <command><object-type><association-type><object-ID><parameters>

Meaning
<command> | The command used to call a specific function, for example `ADD`, `COPY`, `DISPLAY`, `RETRIEVE`. Commands are written in upper case throughout the documentation.
<object-type> | Type of object to be processed, for example system or file.
<association-type> | Type of association to be processed, for example the association type for the command `LINK`.
<object-ID> | ID of the object to be processed.
<parameters> | Additional information needed to carry out the function.

## Taking Parameter Values from the Command Context

Wherever possible, Predict takes parameter values that are omitted from the context in which a command is entered:

- If an object type is omitted, the object type of the current menu is taken. If for example the command `MAINTAIN` is entered in the File Retrieval menu, the File Maintenance menu is displayed.

- Other parameter values are taken from the hot object table as far as possible. See Specifying Parameter Values in the section Predict User Interface in the Introduction to Predict documentation.

## Specifying Commands in Keyword or Positional Form

Commands can be specified in keyword form, positional form or a mixture of both. Throughout the documentations the command syntax is described in keyword form. The positional form is obtained by omitting the keywords and the Natural assign character (=). The assign character can be changed in Natural.

### Keyword Form

    COMMAND KEY1=value1, KEY2=value2, KEY3=value3

or, if parameter 2 is omitted:

    COMMAND KEY1=value1, KEY3=value3, KEY4=value4

### Positional Form

    COMMAND value1, value2, value3

or, if parameter 2 is omitted:

    COMMAND value1,, value3, value4

In the positional form, the omitted parameter is represented by an empty parameter only if followed by other parameters.

### Mixing Keyword and Positional Form

The keyword and positional form of specifying command parameters can be mixed.

    COMMAND KEY5=value5, value6,, value8

## Delimiting Parameters in Predict Commands

The individual parameters in Predict commands are delimited by the character that is specified as the delimiter character in Natural. Throughout the following descriptions a comma (,) is used as the delimiter character. The delimiter character can be changed in Natural.

## Metasyntax

The following notations are used in the command descriptions:

[ ] | Square brackets indicate optional parts of a command that can be omitted.
<> | Parameter values are enclosed in angle brackets. Angle brackets must not be typed. Replace text in lower case with an appropriate value. Parentheses can be omitted only when the text they enclose is omitted.
KEYWORD | Keywords are shown in upper case and can be truncated provided that the input is unambiguous.

### On this page

- Where to Enter Commands
- Repeating Command Execution
- Truncating Commands
- Syntax of Predict Commands
- Taking Parameter Values from the Command Context
- Specifying Commands in Keyword or Positional Form
- Delimiting Parameters in Predict Commands
- Metasyntax