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: http://www.stsci.edu/ftp/documents/system-docs/vms-guide/html/VUG_12.html
Дата изменения: Wed Nov 1 17:38:22 1995 Дата индексирования: Sun Dec 23 18:29:48 2007 Кодировка: Поисковые слова: южная атлантическая аномалия |
HELP command. Typing HELP invokes the system's help facility. Help is available for most DCL commands, although you don't have to know the name of the command in order to get help. It is possible to navigate through the help libraries by letting the system tell you what information is available at any given level. Figure 1.4 shows how the system responds to a simple HELP command.
When you type a
You can quickly get information about the parameters or qualifiers used by a command by specifying them on the command line when you invoke the help facility. Keep in mind that parameters are used to provide additional information to the command and are specified with a space between the name of the command and the parameter value. Qualifiers modify the behavior of the command and are specified with a slash (
The last piece of information that the help facility provides is a list of the additional help libraries that are available (sometimes you'll have to press
To access an additional help library, you must precede its name with an at character (@). For example, to use the SITEHELP library, you would type:
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Figure 1.4: Menu-Driven VMS Help Facility
To get information about a specific command, type the name of the command on the command line right after the HELP command (with a space in between). For example, you could type HELP DIRECTORY, HELP SET, or even HELP HELP. HELP command, the help facility will briefly describe the command and its parameters, and will often ask you to supply the name of a subtopic on which you want additional information. The help facility tells you what subtopics it knows about under the heading "Additional information available." Any help topic can be redisplayed by typing a question mark (?). /) between the command and the qualifier name. When issuing a help command to get information about a parameter or a qualifier, you must specify the space or slash just as you would when entering the command itself. For example:
$ HELP SHOW USERS
$ HELP DIRECTORY/DATE
If you know that a command has several levels of help for subtopics, parameters, and qualifiers, you can specify to the help facility that it is to display all information on every level. This is done by typing three periods immediately following the topic. For example, the SHOW command can be used to display information on everything from device status to the names of all users currently logged on the system. To see information about every permutation of the SHOW command, you would type:
$ HELP SHOW...
You can specify topics using characters and wildcards (similar to specifying file names). For example, to get information about every command that begins with "PA," you would type one of the following commands:
$ HELP PA
or
$ HELP PA*
If you want information about every command that begins with "PA," and you want information about every parameter, qualifier, and subtopic of those commands, you could type the following command:
$ HELP PA...
Additional Help Libraries:
In addition to the standard help library, users can define their own help libraries that will be searched whenever you issue a HELP command. These libraries are set up by defining the logical names HLP$LIBRARY, HLP$LIBRARY_1, HLP$LIBRARY_2, and so on, in the process, group, or system logical name tables (for more information, see "Logical Names" on page 25). 
a few times to see the library names). Some of these include libraries established for everyone on the system, as well as those established for group members and individual users.
$ HELP @SITEHELP
You can also specify the name of the additional library in response to the Topic? prompt--don't forget to precede the name with an "@" character!