Help

MPW


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MPW Command Reference

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Help

Built-in

SYNTAX

Help [subject1] [subject2]… [-f helpFile]

DESCRIPTION

The Help command briefly summarizes one or more subjects. Normally Help assumes that you want information from the file MPW.Help, found in your {ShellDirectory}. This file contains entries on a variety of subjects, including the individual MPW commands and other MPW items such as variables. You can also specify another help file by using the -f option.

MPW.Help uses a compact system of syntax notation that differs slightly from the one adopted in this manual. Its syntax elements and their meanings are shown below. Notice particularly the symbols designating input and output.

Syntax	Explanation
[optional]	Brackets; indicates that the enclosed elements are optional.
repeated…	Ellipses; allows you to repeat the preceding element one or more times.
a \| b	A vertical bar; lets you choose either a or b but not both.
(grouping)	Parentheses; groups elements that can be used together. This is useful in conjunction with the \| and … notation.
< input	Input symbol; designates the input. If input is not specified, the command reads standard input.
> output	Output symbol; writes to standard output.
≥ progress	Diagnostic output symbol; designates that progress information is written to diagnostic output if you specify -p on a command line.

INPUT

None

OUTPUT

Standard output. Help writes a brief summary of the requested subjects to standard output. If you omit the subject parameter, Help writes information about itself to standard output.

STATUS

Help can return the following status codes:

0	subject found
1	syntax error
2	subject not found
3	help file could not be opened

PARAMETERS

subject1 [subject2]…

Specifies one or more subjects to be summarized. The subjects covered by MPW Help include the individual MPW commands, expressions, patterns, and selections. For a complete list of subjects use the Help command without any parameter or option.

Note that if you specify a different help file, the list of possible subjects is determined by its entries (-f).

OPTIONS

-f helpFile

Uses a different MPW text file as the help file. Normally Help assumes you want the help file MPW.Help; however, you can specify a different file as long as it meets certain criteria: first, the help file must contain a set of entries, each separated by a blank line beginning with one hyphen. Second, you must place each entry's keyword (that is, its subject) at the beginning of the first line. See the Examples for a sample entry.

EXAMPLES

The command

Help FileDiv

searches for the FileDiv entry in the MPW.Help file and produces the following output:

FileDiv       # divide a file into several smaller files
FileDiv [option…] file [prefix] ≥ progress
-b            # input is a byte stream instead of lines
-f            # split file at formfeed character
-n splitPoint # split file after splitPoint lines or bytes (-b)
-p            # write progress information to diagnostics
-s n          # set -b input buffer to n * 512 bytes

Using a custom help file called MyHelpFile, the command line

Help -f MyHelpFile MyCommand

displays information about MyCommand.

According to the rules governing the structure of help files (see -f), the file MyHelpFile from the previous example might contain this entry:

-
MyCommand      # Deletes comments from the specified files.
MyCommand [option…] [file…] >
   -l length   # only comments length characters or longer
   -t type     # only files of this type
-

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Last Updated July 2000