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This chapter describes the Cisco IOS command-line interface (CLI) and how to use it to configure your standalone switch or a switch stack, referred to as the switch. It contains these sections:
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 1-1 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.
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 1-2 .
You need to enter only enough characters for the switch to recognize the command as unique.
This example shows how to enter the show configuration privileged EXEC command in an abbreviated form:
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.
Table 1-3 lists some error messages that you might encounter while using the CLI to configure your switch.
You can log and view changes to the switch configuration. You can use the Configuration Change Logging and Notification feature to track changes on a per-session and per-user basis. The logger tracks each configuration command that is applied, the user who entered the command, the time that the command was entered, and the parser return code for the command. This feature includes a mechanism for asynchronous notification to registered applications whenever the configuration changes. You can choose to have the notifications sent to the syslog.
Note Only CLI or HTTP changes are logged.
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:
By default, the switch 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 records during the current terminal session:
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:
To recall commands from the history buffer, perform one of the actions listed in Table 1-4 . These actions are optional.
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Recall commands in the history buffer, beginning with the most recent command. Repeat the key sequence to recall successively older commands. |
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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. |
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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. |
1.The arrow keys function only on ANSI-compatible terminals such as VT100s. |
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.
This section describes the editing features that can help you manipulate the command line. It contains these sections:
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:
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:
Table 1-5 shows the keystrokes that you need to edit command lines. These keystrokes are optional.
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Move around the command line to make changes or corrections. |
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Transpose the character to the left of the cursor with the character located at the cursor. |
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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. |
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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. |
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Delete all characters from the cursor to the end of the command line. |
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Delete all characters from the cursor to the beginning of the command line. |
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Capitalize or lowercase words or capitalize a set of letters. |
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Designate a particular keystroke as an executable command, perhaps as a shortcut. |
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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. |
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Redisplay the current command line if the switch suddenly sends a message to your screen. |
2.The arrow keys function only on ANSI-compatible terminals such as VT100s. |
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 ($) shows that the line has been scrolled to the left. Each time the cursor reaches the end of the line, the line is again shifted ten spaces to the left.
After you complete the entry, press Ctrl-A to check the complete syntax before pressing the Return key to execute the command. The dollar sign ($) appears at the end of the line to show that the line has been scrolled to the right:
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.
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:
You can access the CLI through a console connection, through Telnet, or by using the browser.
You manage the switch stack and the stack member interfaces through the stack master. You cannot manage stack members on an individual switch basis. You can connect to the stack master through the console port or the Ethernet management port of one or more stack members. Be careful with using multiple CLI sessions to the stack master. Commands you enter in one session are not displayed in the other sessions. Therefore, it is possible to lose track of the session from which you entered commands.
Note We recommend using one CLI session when managing the switch stack.
If you want to configure a specific stack member port, you must include the stack member number in the CLI command interface notation.
To debug a specific stack member, you can access it from the stack master by using the session stack-member-number privileged EXEC command. The stack member number is appended to the system prompt. For example, Switch-2#
is the prompt in privileged EXEC mode for stack member 2, and where the system prompt for the stack master is Switch
. Only the show and debug commands are available in a CLI session to a specific stack member.
Before you can access the CLI, you must connect a terminal or a PC to the switch console or connect a PC to the Ethernet management port and then power on the switch, as described in the hardware installation guide that shipped with your switch.
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.
You can use one of these methods to establish a connection with the switch:
After you connect through the console port, through the Ethernet management port, through a Telnet session or through an SSH session, the user EXEC prompt appears on the management station.