Technical data

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Understanding Command Modes
Understanding Command Modes
The Cisco IOS user interface is divided into many different modes. The commands available to you
at any given time depend on which mode you are currently in. Entering a question mark (?) at the
system prompt allows you to obtain a list of commands available for each command mode.
When you start a session on the router, you begin in user mode, often called EXEC mode. Only a
limited subset of the commands are available in EXEC mode. In order to have access to all
commands, you must enter privileged EXEC mode. Normally, you must enter a password to enter
privileged EXEC mode. From privileged mode, you can enter any EXEC command or enter global
configuration mode. Most of the EXEC commands are one-time commands, such as show
commands, which show the current status of something, and clear commands, which clear counters
or interfaces. The EXEC commands are not saved across reboots of the router.
The configuration modes allow you to make changes to the running configuration. If you later save
the configuration, these commands are stored across router reboots. In order to get to the various
configuration modes, you must start at global configuration mode. From global configuration mode,
you can enter interface configuration mode, subinterface configuration mode, and a variety of
protocol-specific modes.
ROM monitor mode is a separate mode used when the router cannot boot properly. If your router or
access server does not find a valid system image when it is booting, or if its configuration file is
corrupted at startup, the system might enter read-only memory (ROM) monitor mode.
Summary of Command Modes
The following table summarizes some of the main command modes of the Cisco IOS software.
Table 2 Summary of Main Command Modes
Command
Mode Access Method Prompt Exit Method
User EXEC Log in.
Router>
Use the logout command.
Privileged
EXEC
From user EXEC mode, use
the enable EXEC command.
Router#
To exit back to user EXEC mode, use the disable command.
To enter global configuration mode, use the configure
terminal privileged EXEC command.
Global
configuration
From privileged EXEC
mode, use the configure
terminal privileged EXEC
command.
Router(config)#
To exit to privileged EXEC mode, use the exit or end
command or press Ctrl-Z.
To enter interface configuration mode, enter an interface
configuration command.
Interface
configuration
From global configuration
mode, enter by specifying an
interface with an interface
command.
Router(config-if)#
To exit to global configuration mode, use the exit command.
To exit to privileged EXEC mode, use the exit command or
press Ctrl-Z.
To enter subinterface configuration mode, specify a
subinterface with the interface command.
Subinterface
configuration
From interface configuration
mode, specify a subinterface
with an interface command.
Router(config-subif)#
To exit to global configuration mode, use the exit command.
To enter privileged EXEC mode, use the end command or
press Ctrl-Z.