Using the Command-Line Interface
The Cisco IOS command-line interface (CLI) is the primary user interface used for configuring, monitoring, and maintaining Cisco devices. This user interface allows you to directly and simply execute Cisco IOS commands, whether using a router console or terminal, or using remote access methods. This chapter describes the basic features of the Cisco IOS CLI andhow to use them. Topics covered include an introduction to Cisco IOS command modes, navigation and editing features, help features, and command history features. Additional user interfaces include Setup mode (used for first-time startup), the Cisco Web Browser, and user menus configured by a system administrator. For information about Setup mode, see the “Using AutoInstall and Setup” chapter of thisbook. For information on issuing commands using the Cisco Web Browser, see the “Using the Cisco Web Browser User Interface” chapter of this book. For information on user menus, see the “Managing Connections, Menus, and System Banners” chapter of this book. For a complete description of the user interface commands in this chapter, refer to the “Basic Command-Line Interface Commands” chapter of theRelease 12.2 Cisco IOS Configuration Fundamentals Command Reference. To locate documentation of other commands that appear in this chapter, use the Cisco IOS Command Reference Master Index or search online. This chapter contains the following sections:
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Cisco IOS CLI Command Modes Overview Cisco IOS CLI Task List Using the Cisco IOS CLI Examples
Cisco IOS CLI Command Modes OverviewTo aid in the configuration of Cisco devices, the Cisco IOS command-line interface is divided into different command modes. Each command mode has its own set of commands available for the configuration, maintenance, and monitoring of router and network operations. The commands available to you at any given time depend on the mode you are in. Entering a question mark (?) at the system prompt (routerprompt) allows you to obtain a list of commands available for each command mode. The use of specific commands allows you to navigate from one command mode to another. The standard order that a user would access the modes is as follows: user EXEC mode; privileged EXEC mode; global configuration mode; specific configuration modes; configuration submodes; and configuration subsubmodes.
Cisco IOSConfiguration Fundamentals Configuration Guide
Using the Command-Line Interface Cisco IOS CLI Command Modes Overview
When you start a session on a router, you generally begin in user EXEC mode, which is one of two access levels of the EXEC mode. For security purposes, only a limited subset of EXEC commands are available in user EXEC mode. This level of access is reserved for tasksthat do not change the configuration of the router, such as determining the router status. In order to have access to all commands, you must enter privileged EXEC mode, which is the second level of access for the EXEC mode. Normally, you must enter a password to enter privileged EXEC mode. In privileged EXEC mode, you can enter any EXEC command, as the privileged EXEC mode is a superset of the userEXEC mode commands. Most EXEC mode commands are one-time commands, such as show or more commands, which show the current configuration status, and clear commands, which clear counters or interfaces. EXEC mode commands are not saved across reboots of the router. From privileged EXEC mode, you can enter global configuration mode. In this mode, you can enter commands that configure general systemcharacteristics. You also can use global configuration mode to enter specific configuration modes. Configuration modes, including global configuration mode, allow you to make changes to the running configuration. If you later save the configuration, these commands are stored across router reboots. From global configuration mode you can enter a variety of protocol-specific or feature-specific...
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