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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.
Example of Context Sensitive Help
The following example illustrates how the context-sensitive help feature creates an access list from the configuration
mode.
Enter the letters “co” at the system prompt followed by a question mark (?). Do not leave a space between the last
letter and the question mark (?). The system provides the commands that begin with
co
.
Router#
co?
configure Enter configuration mode
copy Copy from one file to another
Router# co
Enter the
configure
command followed by a space and a question mark (?) to list the command’s keyword(s) and a
brief explanation:
Router#
configure ?
