Command Line Interface
This chapter describes the Cisco IOS Command Line Interface (CLI), how to use it to configure your switch module, and includes the following topics:
Understanding Command Modes
The Cisco IOS user interface is divided into many different modes. The commands available 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 module, 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 (shows the current configuration status), and clear commands (clears counters or interfaces). The user EXEC commands are not saved when the switch module 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 module 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 hostname Switch.
Table 2-1 Command Mode Summary
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|
|
|
|
User EXEC |
Start a session with the switch module |
|
Enter logout or quit |
- Changes terminal settings
- Performs basic tests
- Displays system information
|
Privileged EXEC |
While in user EXEC mode, enter the enable command |
|
Enter disable to exit |
Verifies 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 |
|
To exit to privileged EXEC mode, enter exit or end, or press Ctrl-Z |
Configures parameters that apply to the entire switch module |
VLAN configuration |
While in global configuration mode, enter the vlan vlan-id command. |
|
To exit to global configuration mode, enter the exit command. To return to privileged EXEC mode, press Ctrl-Z or enter end. |
Configures VLAN parameters |
Interface configuration |
While in global configuration mode, enter the interface command (with a specific interface) |
|
To exit to global configuration mode, enter exit. To return to privileged EXEC mode, press Ctrl-Z or enter end. |
Configures parameters for the Ethernet ports. For information about defining interfaces, see the “Using Interface Configuration Mode” section. 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 |
|
To exit to global configuration mode, enter exit. To return to privileged EXEC mode, press Ctrl-Z or enter end. |
Configures parameters for the terminal line |
Understanding the CLI Help System
To display a list of commands available for each command mode, enter a question mark (?) at the system prompt. You can also obtain a list of associated keywords and arguments for any command, as shown in Table 2-2 .
Table 2-2 CLI Help Summary
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|
help |
Brief description of the help system in any command mode |
abbreviated-command-entry ? |
List of commands that begin with a particular character string. For example:
|
abbreviated-command-entry < Tab > |
Complete a partial command name. For example:
Switch#
show configuration
|
? |
List all commands available for a particular command mode. For example:
|
command ? |
List the associated keywords for a command. For example:
|
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
|
Understanding Abbreviated Commands
You need to enter only enough characters for the switch module to recognize the command as unique. This example shows how to enter the show configuration privileged EXEC command in an abbreviated form:
Understanding 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 Error Messages
Table 2-3 lists some error messages that you might encounter while using the CLI to configure your switch module.
Table 2-3 Common CLI Error Messages
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% Ambiguous command: "show con"
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You did not enter enough characters for your switch module 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 display. |
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You did not enter all the keywords or values required by this command |
% Invalid input detected at ‘^’ marker
|
You entered the command incorrectly - he caret (^) marks the point of the error |
Using Command History
The software provides a history or record of commands that you have entered. The command history feature is particularly useful for recalling long or complex commands or entries, including access lists. You can customize this feature to suit your needs as described in these sections:
Changing the Command History Buffer Size
By default, the switch module records ten command lines in its history buffer. You can alter this number for a current terminal session or for all sessions on a particular line. These procedures are optional.
Beginning in privileged EXEC mode, enter this command to change the number of command lines that the switch module records during the current terminal session (range is from 0 to 256):
Switch#
terminal history
[
size
number-of-lines
]
Beginning in line configuration mode, enter this command to configure the number of command lines the switch module records for all sessions on a particular line (range is from 0 to 256):
Switch#
terminal history
[
size
number-of-lines
]
Recalling Commands
To recall commands from the history buffer, perform one of the optional actions listed in Table 2-4 .
Table 2-4 Recalling Commands
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|
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 appear is controlled by the setting of the terminal history global configuration command and the history line configuration command. |
Disabling the Command History Feature
The command history feature is automatically enabled. You can disable it for the current terminal session or for the command line. These procedures are optional.
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.
Enabling and Disabling Editing Features
Although enhanced editing mode is automatically enabled, you can disable it, re-enable it, or configure a specific line to have enhanced editing. These procedures are optional.
To globally disable enhanced editing mode, enter this command in line configuration mode:
The arrow keys function only on ANSI-compatible terminals such as VT100s.Switch (config-line)#
no editing
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:
Switch(config-line)#
editing
Editing Commands Through Keystrokes
Table 2-5 shows the keystrokes that you need to edit command lines. These keystrokes are optional.
Table 2-5 Editing Commands through Keystrokes
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|
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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 |
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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 module 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 Delete or Backspace |
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 |
Designate a particular keystroke as an executable command, perhaps as a shortcut |
Press 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 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 Return |
Scroll down one line |
|
Press the Space bar |
Scroll down one screen |
Redisplay the current command line if the switch module suddenly sends a message to your screen. |
Press Ctrl-L or Ctrl-R |
Redisplay the current command line |
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. The keystroke actions are optional.
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 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. Using these commands is optional.
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 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