Using the Command-Line Interface

This chapter describes the IOS command-line interface (CLI), which you can use to configure your access point. This chapter contains these sections:

Cisco IOS Command Modes

The Cisco IOS user interface is divided into many different modes. The commands available to you depend on the mode you are currently using. Enter a question mark (?) at the system prompt to obtain a list of commands available for each command mode. Refer to the Cisco IOS Command Reference for Cisco Aironet Access Points and Bridges for a list of the supported Cisco IOS commands.

When you start a session on the access point, you begin in user mode, often called user EXEC mode. Only a limited subset of the commands are available in user EXEC mode. For example, 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 interfaces. The user EXEC commands are not saved when the access point reboots.

To have access to all commands, you must enter privileged EXEC mode. Normally, you must enter a password to enter privileged EXEC mode. You must enter privileged EXEC mode before you can enter the global configuration mode.

Using the configuration modes (global, interface, and line), you can make changes to the running configuration. If you save the configuration, these commands are stored and used when the access point reboots. To access the various configuration modes, you must start at global configuration mode.

Table 5-1 describes the main command modes, how to access each one, the prompt you see in that mode, how to exit the mode, and how to use the mode. The examples in the table use the host name ap.

Table 5-1 Command Mode Summary
Mode	Access Method	Prompt	Exit Method	Using This Mode
User EXEC	Begin a session with your access point.	`ap>`	Enter logout or quit.	Use this mode to: •Change terminal settings •Perform basic tests •Display system information
Privileged EXEC	While in user EXEC mode, enter the enable command.	`ap#`	Enter disable to exit.	Use this mode to verify commands. Use a password to protect access to this mode.
Global configuration	While in privileged EXEC mode, enter the configure command.	`ap(config)#`	To exit to privileged EXEC mode, enter exit or end, or press Ctrl-Z.	Use this mode to configure parameters that apply to the entire access point.
Interface configuration	While in global configuration mode, enter the interface command (with a specific interface).	`ap(config-if)#`	To exit to global configuration mode, enter exit. To return to privileged EXEC mode, press Ctrl-Z or enter end.	Use this mode to configure parameters for the Ethernet and radio interfaces. The 2.4-GHz radio is radio 0, and the 5-GHz radio is radio 1.

Getting Help

You can enter a question mark (?) at the system prompt to display a list of commands available for each command mode. You can also obtain a list of associated keywords and arguments for any command, as shown in Table 5-2.

Table 5-2 Help Summary
Command	Purpose
help	Obtains a brief description of the help system in any command mode.
abbreviated-command-entry?	Obtains a list of commands that begin with a particular character string. For example: `ap# di?` `dir disable disconnect`
abbreviated-command-entry<Tab>	Completes a partial command name. For example: `ap# sh conf<tab>` `ap# show configuration`
?	Lists all commands available for a particular command mode. For example: `ap> ?`
command ?	Lists the associated keywords for a command. For example: `ap> show ?`
command keyword ?	Lists the associated arguments for a keyword. For example: `ap(config)# cdp holdtime ?` `<10-255> Length of time (in sec) that receiver must keep this packet`

Abbreviating Commands

You have to enter only enough characters for the access point to recognize the command as unique. If you do not enter enough characters, the access point indicate an error (% Unknown command). This example shows how to enter the show configuration privileged EXEC command:

Using no and default Forms of Commands

Most configuration commands also have a no form. In general, use the no form to disable a feature or function or reverse the action of a command. For example, the no shutdown interface configuration command reverses the shutdown of an interface. Use the command without the keyword no to re-enable a disabled feature or to enable a feature that is disabled by default.

Configuration commands can also have a default form. The default form of a command returns the command setting to its default. Most commands are disabled by default, so the default form is the same as the no form. However, some commands are enabled by default and have variables set to certain default values. In these cases, the default command enables the command and sets variables to their default values.

Understanding CLI Messages

Table 5-3 lists some error messages that you might encounter while using the CLI to configure your access point.

Table 5-3 Common CLI Error Messages
Error Message	Meaning	How to Get Help
`% Ambiguous command: "show con"`	You did not enter enough characters for your access point to recognize the command.	Re-enter the command followed by a question mark (?) with a space between the command and the question mark. The possible keywords that you can enter with the command are displayed.
`% Incomplete command.`	You did not enter all the keywords or values required by this command.	Re-enter the command followed by a question mark (?) with a space between the command and the question mark. The possible keywords that you can enter with the command are displayed.
% Invalid input detected at `^' marker.	You entered the command incorrectly. The caret (^) marks the point of the error.	Enter a question mark (?) to display all the commands that are available in this command mode. The possible keywords that you can enter with the command are displayed.

Using Command History

The IOS provides a history or record of commands that you have entered. This feature is particularly useful for recalling long or complex commands or entries, including access lists. You can customize the command history feature to suit your needs as described in these sections:

Changing the Command History Buffer Size

By default, the access point records ten command lines in its history buffer. Beginning in privileged EXEC mode, enter this command to change the number of command lines that the access point records during the current terminal session:

Beginning in line configuration mode, enter this command to configure the number of command lines the access point records for all sessions on a particular line:

Recalling Commands

To recall commands from the history buffer, perform one of the actions listed in Table 5-4:

Table 5-4 Recalling Commands
Action¹	Result
Press Ctrl-P or the up arrow key.	Recall commands in the history buffer, beginning with the most recent command. Repeat the key sequence to recall successively older commands.
Press Ctrl-N or the down arrow key.	Return to more recent commands in the history buffer after recalling commands with Ctrl-P or the up arrow key. Repeat the key sequence to recall successively more recent commands.
show history	While in privileged EXEC mode, list the last several commands that you just entered. The number of commands that are displayed is determined by the setting of the terminal history global configuration command and history line configuration command.

¹The arrow keys function only on ANSI-compatible terminals such as VT100s.

Disabling the Command History Feature

To disable the feature during the current terminal session, enter the terminal no history privileged EXEC command.

To disable command history for the line, enter the no history line configuration command.

Using Editing Features

This section describes the editing features that can help you manipulate the command line. It contains these sections:

Enabling and Disabling Editing Features

To re-enable the enhanced editing mode for the current terminal session, enter this command in privileged EXEC mode:

To reconfigure a specific line to have enhanced editing mode, enter this command in line configuration mode:

To globally disable enhanced editing mode, enter this command in line configuration mode:

Editing Commands with Keystrokes

Table 5-5 Editing Commands with Keystrokes
Capability	Keystroke¹	Purpose
Move around the command line to make changes or corrections.	Ctrl-B or the left arrow key	Move the cursor back one character.
	Ctrl-F or the right arrow key	Move the cursor forward one character.
	Ctrl-A	Move the cursor to the beginning of the command line.
	Ctrl-E	Move the cursor to the end of the command line.
	Esc-B	Move the cursor back one word.
	Esc-F	Move the cursor forward one word.
	Ctrl-T	Transpose the character to the left of the cursor with the character located at the cursor.
Recall commands from the buffer and paste them in the command line. The access point provides a buffer with the last ten items that you deleted.	Ctrl-Y	Recall the most recent entry in the buffer.
	Esc-Y	Recall the next buffer entry. The buffer contains only the last 10 items that you have deleted or cut. If you press Esc Y more than ten times, you cycle to the first buffer entry.
Delete entries if you make a mistake or change your mind.	Delete or Backspace	Erase the character to the left of the cursor.
	Ctrl-D	Delete the character at the cursor.
	Ctrl-K	Delete all characters from the cursor to the end of the command line.
	Ctrl-U or Ctrl-X	Delete all characters from the cursor to the beginning of the command line.
	Ctrl-W	Delete the word to the left of the cursor.
	Esc-D	Delete from the cursor to the end of the word.
Capitalize or lowercase words or capitalize a set of letters.	Esc-C	Capitalize at the cursor.
	Esc-L	Change the word at the cursor to lowercase.
	Esc-U	Capitalize letters from the cursor to the end of the word.
Designate a particular keystroke as an executable command, perhaps as a shortcut.	Ctrl-V or Esc Q
Scroll down a line or screen on displays that are longer than the terminal screen can display. Note The More prompt appears for output that has more lines than can be displayed on the terminal screen, including show command output. You can use the Return and Space bar keystrokes whenever you see the More prompt.	Return	Scroll down one line.
	Space	Scroll down one screen.
Redisplay the current command line if the access point suddenly sends a message to your screen.	Ctrl-L or Ctrl-R	Redisplay the current command line.

¹The arrow keys function only on ANSI-compatible terminals such as VT100s.

Editing Command Lines That Wrap

You can use a wrap-around feature for commands that extend beyond a single line on the screen. When the cursor reaches the right margin, the command line shifts ten spaces to the left. You cannot see the first ten characters of the line, but you can move back to verify the syntax at the beginning of the command.

To move back to the beginning of the command entry, press Ctrl-B or the left arrow key repeatedly. You can also press Ctrl-A to immediately move to the beginning of the line.

Note The arrow keys function only on ANSI-compatible terminals such as VT100s.

In this example, the access-list global configuration command entry extends beyond one line. When the cursor first reaches the end of the line, the line is shifted ten spaces to the left and redisplayed. The dollar sign ($) shows that the line has been moved to the left. Each time the cursor reaches the end of the line, the line is again shifted ten spaces to the left.

After you complete the entry, press Ctrl-A to verify the complete syntax before pressing the Return key to execute the command. The dollar sign ($) appears at the end of the line to show that the line has been shifted to the right:

The software assumes you have a terminal screen that is 80 columns wide. If you have a width other than that, use the terminal width privileged EXEC command to set the width of your terminal.

Use line wrapping with the command history feature to recall and modify previous complex command entries. For information about recalling previous command entries, see the "Editing Commands with Keystrokes" section.

Searching and Filtering Output of show and more Commands

You can search and filter the output for show and more commands. This is useful when you need to sort through large amounts of output or if you want to exclude output that you do not need to see.

To use this functionality, enter a show or more command followed by the pipe character (|), one of the keywords begin, include, or exclude, and an expression that you want to search for or filter out:

Expressions are case sensitive. For example, if you enter | exclude protocol the lines that contain protocol are not displayed, but the lines that contain Protocol are displayed.

This example shows how to include in the output display only lines where the expression protocol appears:

Accessing the CLI

Opening the CLI with Telnet

Follow these steps to open the CLI with Telnet. These steps are for a PC running Microsoft Windows with a Telnet terminal application. Check your PC operating instructions for detailed instructions for your operating system.

If Telnet is not listed in your Accessories menu, choose Start > Run, type Telnet in the entry field, and press Enter.

Step 2

When the Telnet window appears, click Connect and choose Remote System.

Note

In Windows 2000, the Telnet window does not contain drop-down menus. To start the Telnet session in Windows 2000, type open followed by the access point's IP address.

Step 3

In the Host Name field, type the access point's IP address and click Connect.

Step 4

At the username and password prompts, enter your administrator username and password. The default username is Cisco, and the default password is Cisco. The default enable password is also Cisco. Usernames and passwords are case-sensitive.

Opening the CLI with Secure Shell

Secure Shell Protocol provides a secure, remote connection to networking devices set up to use it. Secure Shell (SSH) is a software package that provides secure login sessions by encrypting the entire session. SSH features strong cryptographic authentication, strong encryption, and integrity protection. For detailed information on SSH, visit the homepage of SSH Communications Security, Ltd. at this URL: http://www.ssh.com/

SSH provides more security for remote connections than Telnet by providing strong encryption when a device is authenticated. See the Cisco IOS Software Configuration Guide for Cisco Aironet Access Points for detailed instructions on setting up the access point for SSH access.

Table Of Contents