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3.4 Advanced Features Supported within the Command Mode
Entering a question mark (?) at the system prompt displays a list of commands available for each command
mode. You can also get a list of any command's associated keywords and arguments with the context-
sensitive help feature.
To get help specific to a command mode, a command, a keyword, or an argument, perform one of the
following commands:
Command Purpose
help
Obtain a brief description of the help system in any
command mode.
?
List all commands available for a particular
command mode.
When using context-sensitive help, the space (or lack of a space) before the question mark (?) is significant.
To obtain a list of commands that begin with a particular character sequence, type in those characters
followed immediately by the question mark (?). Do not include a space. This form of help is called word help,
because it completes a word for you.
To list keywords or arguments, enter a question mark (?) in place of a keyword or argument. Include a space
before the question mark (?). This form of help is called command syntax help, because it reminds you
which keywords or arguments are applicable based on the command, keywords, and arguments you already
have entered.
You can abbreviate commands and keywords to the number of characters that allow a unique abbreviation.
For example, you can abbreviate the configure terminal command to config term, or even con t. Because
the shortened form of the command is unique, the router will accept the shorted form and execute the
command.
Enter the help command (which is available in any command mode) for a brief description of the help
system:
Router# help
CLI/VTY provides advanced help feature. When you need help,
anytime at the command line please press '?'.
If nothing matches, the help list will be empty and you must backup until
entering a '?' shows the available options.
Two styles of help are provided:
1. Full help is available when you are ready to enter a command argument (e.g.
'show ?') and describes each possible argument.
2. Partial help is provided when an abbreviated argument is entered and you
want to know what arguments match the input (e.g. 'show cl?'.)
Router# show cl?
clock Display the system clock
Router# show cl
As described in the help command output, you can enter a partial command name and a question mark (?)
to obtain a list of commands beginning with a particular character set.