Cisco Systems 2950 Using the Command-Line Interface

CHAPTER
2-1
Catalyst2950 Desktop Switch Software Configuration Guide
78-11380-05
2
Using the Command-Line Interface
This chapter describes the IOS command-line interface (CLI ) th at you ca n u se to con figure your
switches. It contains these sections:
•IOS Command Modes, page 2-1
•Getting Help, page 2-3
•Abbreviating Commands, page 2-3
•Using no and default Forms of Commands, page 2-4
•Understanding CLI Messages, page 2-4
•Using Command History, page 2-5
•Using Editing Features, page 2-6
•Searching and Filtering Output of show and more Commands, page 2-9
•Accessing the CLI, page 2-9
IOS Command Modes
The Cisco IOS user interface is divided into many different modes. The commands available to you
depend on which mode you are currently in. Enter a question mark (?) at the system prompt to obtain a
list of commands available for each command mode.
When you start a session on the switch, you begin in user mode, often cal le d user EXE C m ode . On ly a
limited subset of the commands are available in user EXEC mode. For exam ple, most of the user EXEC
commands are one-time commands, such as show commands, which show the current configuration
status, and clear commands, which clear counters or inte rfaces. The user EXEC commands are not saved
when the switch reboots.
To have access to all commands, you must enter privileged EXEC mode. Normally, you must enter a
password to enter privileged EXEC mode. From this mode, you can enter any privileged E XEC
command or enter global configuration mode.
Using the configuration modes (global, interface, and line), y ou can ma ke cha ng es t o the ru nning
configuration. If you save the configuration, these commands are stored and used when the switch
reboots. To access the various configuration modes, you must start at global configuration mode. From
global configuration mode, you can enter interface configuration mode and line configuration mode .
Table 2 -1 describes the main command modes, how to access each one, the prompt you see in that mode, and
how to exit the mode. The examples in the table use the host name Switch.