Technical data

Using Cisco IOS Software

This chapter provides helpful tips for understanding and conﬁguring Cisco IOS software using the

command-line interface (CLI).

• Getting Help

• Understanding Command Modes

• Using the No and Default Forms of Commands

• Saving Conﬁguration Changes

For an overview of Cisco IOS software conﬁguration, refer to the Conﬁguration Fundamentals

Conﬁguration Guide.

For information on the conventions used in the Cisco IOS documentation set, refer to the “About this

Guide” chapter at the beginning of this book.

Getting Help

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, use one of the

following commands:

Command Purpose

help Obtain a brief description of the help system in any command

mode.

abbreviated-command-entry? Obtain a list of commands that begin with a particular character

string. (No space between command and question mark.)

abbreviated-command-entry<Tab> Complete a partial command name.

? List all commands available for a particular command mode.

command ? List a command’s associated keywords. (Space between command

and question mark.)

command keyword ? List a keyword’s associated arguments. (Space between the

keyword and question mark.)