Cisco 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 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.
Mode
|
Access Method
|
Prompt
|
Exit Method
|
About This Mode
|
|---|---|---|---|---|
User EXEC
|
Begin a session with your switch.
| Switch> |
Enter logoutor quit.
|
Use this mode to
•
 Change terminal settings.
•
Perform basic tests.
•
Display system information. |
Privileged EXEC
|
While in user EXEC mode, enter the enablecommand.
| Switch# |
Enter disable to 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-idcommand.
| Switch(config-vlan)# |
To exit to global configuration mode, enter the exitcommand.
To return to privileged EXEC mode, press Ctrl-Zor enter end.
|
Use this mode to configure VLAN parameters. When VTP mode is transparent, you can create extended-range VLANs (VLAN IDs greater than 1005) and save configurations in the switch startup configuration file.
|
VLAN configuration
|
While in privileged EXEC mode, enter thevlan databasecommand.
| Switch(vlan)# |
To exit to privileged EXEC mode, enter exit.
|
Use this mode to configure VLAN parameters for VLANs 1 to 1005 in the VLAN database.
|
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-Zor enter end.
|
Use this mode to configure parameters for the switch and LRE CPE Ethernet interfaces.
To configure multiple interfaces with the same parameters, see the "Configuring a Range of Interfaces" section.
|
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-Zor 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.
Specifying Ports in Interface Configuration Mode
To configure a port, you need to specify the interface type, slot, and port number by using the interface configuration command. For example, to configure port 4 on a switch, you enter:
switch(config)# interface fa 0/4
•Interface type—Each switch platform supports different types of interfaces. To display a complete list of the interface types supported on your switch, enter the interface ? global configuration command.
Interface type—Each switch platform supports different types of interfaces. To display a complete list of the interface types supported on your switch, enter the interface ? global configuration command.
•Slot number—The slot number on the switch. On the modular Catalyst 2900 XL switches, the slot number is 1 or 2. On Catalyst 2950 or Catalyst 2955 switches, the slot number is 0.
Slot number—The slot number on the switch. On the modular Catalyst 2900 XL switches, the slot number is 1 or 2. On Catalyst 2950 or Catalyst 2955 switches, the slot number is 0.
•Port number—The number of the physical port on the switch. Refer to your switch for the port numbers.
Port number—The number of the physical port on the switch. Refer to your switch for the port numbers.Abbreviating Commands
You have to enter only enough characters for the switch to recognize the command as unique. This example shows how to enter the show configurationprivileged EXEC 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 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 2-3 lists some error messages that you might encounter while using the CLI to configure your switch.
Using Command History
The Cisco 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 switch 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 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:
Action 1
|
Result
|
|---|---|
Press Ctrl-Por 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-Nor 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 appear is determined by the setting of the terminal history global configuration command and history line configuration command.
|
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 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
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 privileged 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.
Capability
|
Keystroke1
|
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 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.
|
Press theDelete orBackspacekey.
|
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-Uor 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.
| |
Designate a particular keystroke as an executable command, perhaps as a shortcut.
|
Press Ctrl-Vor Esc Q.
| |
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, includingshow command output. You can use the Return and Spacebar keystrokes whenever you see the More prompt. |
Press theReturn key.
|
Scroll down one line.
|
Press theSpace bar.
|
Scroll down one screen.
| |
Redisplay the current command line if the switch suddenly sends a message to your screen.
|
Press Ctrl-Lor 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.
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 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)# $108.2.5 255.255.255.0 131.108.1.20 255.255.255.0 eq 45
After you complete the entry, press Ctrl-A to check the complete syntax before pressing the Return key to execute the command. The dollar sign ($) 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 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 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 are not displayed, but the lines that contain Outputappear.
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
Before you can access the CLI, you need to connect a terminal or PC to the switch console port and power on the switch as described in the hardware installation guide that shipped with your switch. Then, to understand the boot process and the options available for assigning IP information, see"Assigning the Switch IP Address and Default Gateway."
If your switch is already configured, you can access the CLI through a local console connection or through a remote Telnet session, but your switch must first be configured for this type of access. For more information, see the "Setting a Telnet Password for a Terminal Line" section.
You can 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.
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.
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 that 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.
Start one of the supported browsers.
Step 2 In the URL field, enter the IP address of the command switch.
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.
When the Cisco Systems Access page appears, click Telnet to start a Telnet session.
Step 4 Enter the switch password.
Enter the switch password.
The user EXEC prompt appears on the management station.
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