Catalyst 2950 Desktop Switch Software Configuration Guide, 12.1(9)EA1
Using the Command-Line Interface
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Using the Command-Line Interface

Table Of Contents

Using the Command-Line Interface

IOS Command Modes

Getting Help

Abbreviating Commands

Using no and default Forms of Commands

Understanding CLI Messages

Using Command History

Changing the Command History Buffer Size

Recalling Commands

Disabling the Command History Feature

Using Editing Features

Enabling and Disabling Editing Features

Editing Commands through Keystrokes

Editing Command Lines that Wrap

Searching and Filtering Output of show and more Commands

Accessing the CLI

Accessing the CLI from a Browser

Saving Configuration Changes

Where to Go Next


Using the Command-Line Interface


This chapter describes the IOS command-line interface (CLI) that you can use to configure your switches. It contains these sections:

IOS Command Modes

Getting Help

Abbreviating Commands

Using no and default Forms of Commands

Understanding CLI Messages

Using Command History

Using Editing Features

Searching and Filtering Output of show and more Commands

Accessing the CLI

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 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 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 EXEC command or enter 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 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.

Table 2-1 Command Mode Summary 

Mode
Access Method
Prompt
Exit Method
About This Mode

User EXEC

Begin a session with your switch.

Switch>

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.

Switch#

Enter disable or exit.

Use this mode to verify commands that you have entered. Use a password to protect access to this mode.

Global configuration

While in privileged EXEC mode, enter the configure command.

Switch(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 switch.

Config-vlan

While in global configuration mode, enter the vlan vlan-id command.

Switch(config-vlan)#

To exit to global configuration mode, enter the exit command. To return to privileged EXEC mode, press Ctrl-Z or enter end.

Use this mode to configure VLAN-specific parameters. When VTP mode is transparent, you can create extended-range VLANs (VLAN IDs greater than 1005) and save the configurations in the switch startup configuration file.

VLAN configuration

While in privileged EXEC mode, enter the vlan database command.

Switch(vlan)#

To exit to privileged EXEC mode, enter exit.

Use this mode to configure VLAN-specific parameters in the VLAN database. Valid only for normal-range VLANs (1 to 1005).

Interface configuration

While in global configuration mode, enter the interface command (with a specific interface).

Switch(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 interfaces.

Line configuration

While in global configuration mode, specify a line with the line vty or line console command.

Switch(config-line)#

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 terminal line.


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 2-2.

Table 2-2 Help Summary 

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.

For example:

Switch# di?
dir  disable  disconnect 

abbreviated-command-entry<Tab>

Complete a partial command name.

For example:

Switch# sh conf<tab>
Switch# show configuration

?

List all commands available for a particular command mode.

For example:

Switch> ?

command ?

List the associated keywords for a command.

For example:

Switch> show ?

command keyword ?

List the associated arguments for a keyword.

For example:

Switch(config)# cdp holdtime ?
  <10-255>  Length of time (in sec) that receiver must keep this packet 

Abbreviating Commands

You only have to enter enough characters for the switch to recognize the command as unique. This example shows how to enter the show configuration command:

Switch# show conf

Using no and default Forms of Commands

Almost every configuration command also has 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 command no shutdown 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 2-3 lists some error messages that you might encounter while using the CLI to configure your switch.

Table 2-3 Common CLI Error Messages 

Error Message
Meaning
How to Get Help
% Ambiguous command: 
"show con"

You did not enter enough characters for your switch 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 appear.

% Incomplete command.

You did not enter all of 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 appear.

% 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 of the commands that are available in this command mode.

The possible keywords that you can enter with the command appear.


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 control lists (ACLs). You can customize the command history feature to suit your needs as described in these sections:

Changing the Command History Buffer Size

Recalling Commands

Disabling the Command History Feature

Changing the Command History Buffer Size

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

Switch> terminal history [size number-of-lines]

The range is from 0 to 256.

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

Switch(config-line)# history [size number-of-lines]

The range is from 0 to 256.

Recalling Commands

To recall commands from the history buffer, perform one of the actions listed in Table 2-4:

Table 2-4 Recalling Commands 

Action 1
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 user EXEC mode, list the last several commands that you just entered.

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


Disabling the Command History Feature

The command history feature is automatically enabled.

To disable the feature during the current terminal session, enter the terminal no history user 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

Editing Commands through Keystrokes

Editing Command Lines that Wrap

Enabling and Disabling Editing Features

Although enhanced editing mode is automatically enabled, you can disable it.

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

Switch> terminal editing

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

Switch(config-line)# editing

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

Switch(config-line)# no editing

Editing Commands through Keystrokes

Table 2-5 shows the keystrokes that you need to edit command lines.

Table 2-5 Editing Commands through Keystrokes 

Capability
Keystroke 1
Purpose

Move around the command line to make changes or corrections.

Press Ctrl-B, or press the left arrow key.

Move the cursor back one character.

 

Press Ctrl-F, or press the right arrow key.

Move the cursor forward one character.

Press Ctrl-A.

Move the cursor to the beginning of the command line.

Press Ctrl-E.

Move the cursor to the end of the command line.

Press Esc B.

Move the cursor back one word.

Press Esc F.

Move the cursor forward one word.

Press 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 switch provides a buffer with the last ten items that you deleted.)

Press Ctrl-Y.

Recall the most recent entry in the buffer.

 

Press Esc Y.

Recall the next buffer entry.

The buffer contains only the last ten 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.

Press the Delete or Backspace key.

Erase the character to the left of the cursor.

 

Press Ctrl-D.

Delete the character at the cursor.

Press Ctrl-K.

Delete all characters from the cursor to the end of the command line.

Press Ctrl-U or Ctrl-X.

Delete all characters from the cursor to the beginning of the command line.

Press Ctrl-W.

Delete the word to the left of the cursor.

Press Esc D.

Delete from the cursor to the end of the word.

Capitalize or lowercase words or capitalize a set of letters.

Press Esc C.

Capitalize at the cursor.

 

Press Esc L.

Change the word at the cursor to lowercase.

Press Esc U.

Capitalize letters from the cursor to the end of the word.

Scroll down a line or screen on displays that are longer than the terminal screen can display.

Note The More prompt is used for any 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.

Press the Return key.

Scroll down one line.

 

Press the Space bar.

Scroll down one screen.

Redisplay the current command line if the switch suddenly sends a message to your screen.

Press Ctrl-L or Ctrl-R.

Redisplay the current command line.

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


Editing Command Lines that Wrap

You can use a wraparound 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 scroll back and check the syntax at the beginning of the command.

To scroll 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 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 scrolled to the left. Each time the cursor reaches the end of the line, the line is again shifted ten spaces to the left.

Switch(config)# access-list 101 permit tcp 131.108.2.5 255.255.255.0 131.108.1
Switch(config)# $ 101 permit tcp 131.108.2.5 255.255.255.0 131.108.1.20 255.25
Switch(config)# $t tcp 131.108.2.5 255.255.255.0 131.108.1.20 255.255.255.0 eq
Switch(config)# $108.2.5 255.255.255.0 131.108.1.20 255.255.255.0 eq 45 

When you have completed the entry, press Ctrl-A to check 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 scrolled to the right:

Switch(config)# access-list 101 permit tcp 131.108.2.5 255.255.255.0 131.108.1$

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 user 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 through 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:

command | {begin | include | exclude} regular-expression

Expressions are case-sensitive. For example, if you enter | exclude output the lines that contain output do not appear, but the lines that contain Output appear.

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

Switch# show interfaces | include protocol
Vlan1 is up, line protocol is up
Vlan10 is up, line protocol is down
GigabitEthernet0/1 is up, line protocol is down
GigabitEthernet0/2 is up, line protocol is up 

Accessing the CLI

This procedure assumes you have already assigned IP information and password to the switch or command switch. For information about assigning IP information to the switch, see the "Assigning Switch Information" section.

To access the CLI, follow these steps:


Step 1 Start the emulation software (such as ProComm, HyperTerminal, tip, or minicom) on the management station.

Step 2 If necessary, reconfigure the terminal-emulation software to match the switch console port settings (default settings are 9600 baud, no parity, 8 data bits, and 1 stop bit).

Step 3 Establish a connection with the switch by either

Connecting the switch console port to a management station or dial-up modem. For information about connecting to the console port, refer to the switch hardware installation guide.

Using any Telnet TCP/IP or encrypted Secure Shell (SSH) package from a remote management station. The switch must have network connectivity with the Telnet or SSH client, and the switch must have an enable secret password configured.

For information about configuring the switch for Telnet access, see the "Setting a Telnet Password for a Terminal Line" section. The switch supports up to 16 simultaneous Telnet sessions. Changes made by one Telnet user are reflected in all other Telnet sessions.

For information about configuring the switch for SSH, see the "Configuring the Switch for Secure Shell" section. The switch supports up to five simultaneous secure SSH sessions.


After you connect through the console port, through a Telnet session, or through an SSH session, the user EXEC prompt appears on the management station.

Accessing the CLI from a Browser

This procedure assumes you have met the software requirements (including browser and Java plug-in configurations) and have assigned IP information and a Telnet password to the switch or command switch, as described in the release notes.

To access the CLI from a web browser, follow these steps:


Step 1 Start one of the supported browsers.

Step 2 In the URL field, enter the IP address of the command switch.

Step 3 When the Cisco Systems Access page appears, click Telnet to start a Telnet session.

You can also access the CLI by clicking Monitor the router- HTML access to the command line interface from the Cisco Systems Access page. For information about the Cisco Systems Access page, see the "Accessing CMS" section in the release notes.

Step 4 Enter the switch password.

The user EXEC prompt appears on the management station.



Note Copies of the CMS pages that you display are saved in your browser memory cache until you exit the browser session. A password is not required to redisplay these pages, including the Cisco Systems Access page. You can access the CLI by clicking Web Console - HTML access to the command line interface from a cached copy of the Cisco Systems Access page. To prevent unauthorized access to CMS and the CLI, exit your browser to end the browser session.


Saving Configuration Changes

The show command always displays the running configuration of the switch. When you make a configuration change to a switch or switch cluster, the change becomes part of the running configuration. The change does not automatically become part of the config.text file in Flash memory, which is the startup configuration used each time the switch restarts. If you do not save your changes to Flash memory, they are lost when the switch restarts.

To save all configuration changes to Flash memory, you must enter the write memory command in privileged EXEC mode.


Note The write memory privileged EXEC command does not apply to the Catalyst 1900 and Catalyst 2820 switches, which automatically save configuration changes to Flash memory as they occur.



Tip As you make cluster configuration changes, make sure that you periodically save the configuration. The configuration is saved on the command and member switches.


Where to Go Next

The rest of this guide provides descriptions of the software features and general switch administration. Refer to the Catalyst 2950 Desktop Switch Command Reference for complete descriptions of the switch commands.


Note For information about the standard IOS Release 12.1 commands, refer to the IOS documentation set available from the Cisco.com home page at Service and Support > Technical Documents. On the Cisco Product Documentation home page, select Release 12.1 from the Cisco IOS Software drop-down list.