- Using the Command-Line Interface
- Information About Using the Command-Line Interface
- Command Modes
- Using the Help System
- Understanding Abbreviated Commands
- No and Default Forms of Commands
- CLI Error Messages
- Configuration Logging
- How to Use the CLI to Configure Features
- Configuring the Command History
- Changing the Command History Buffer Size
- Recalling Commands
- Disabling the Command History Feature
- 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 Through a Console Connection or Through Telnet
Using the Command-Line Interface
Information About Using the Command-Line Interface
- Command Modes
- Using the Help System
- Understanding Abbreviated Commands
- No and Default Forms of Commands
- CLI Error Messages
- Configuration Logging
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.
You can start a CLI session through a console connection, through Telnet, a SSH, or by using the browser.
When you start a session, 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.
This table describes the main command modes, how to access each one, the prompt you see in that mode, and how to exit the mode.
Mode |
Access Method |
Prompt |
Exit Method |
About This Mode |
---|---|---|---|---|
User EXEC |
Begin a session using Telnet, SSH, or console. |
Switch>
|
Enter logout or quit. |
Use this mode to |
Privileged EXEC |
While in user EXEC mode, enter the enable command. |
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. |
VLAN configuration |
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 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. |
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 ports. |
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. |
Using the Help System
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.
1.
help
2.
abbreviated-command-entry
?
3.
abbreviated-command-entry <Tab>
4.
?
5.
command
?
6.
command keyword ?
DETAILED STEPS
Understanding Abbreviated Commands
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:
Switch# show conf
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 reenable 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.
CLI Error Messages
This table lists some error messages that you might encounter while using the CLI to configure your switch.
Error Message |
Meaning |
How to Get Help |
---|---|---|
% Ambiguous command: "show con" |
You did not enter enough characters for your switch to recognize the command. |
Reenter the command followed by a question mark (?) without any 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. |
Reenter 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. |
Configuration Logging
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. |
How to Use the CLI to Configure Features
Configuring the 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.
Changing the Command History Buffer Size
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. This procedure is optional.
1.
terminal history [size number-of-lines]
DETAILED STEPS
Command or Action | Purpose |
---|
Recalling Commands
To recall commands from the history buffer, perform one of the actions listed in this table. These actions are optional.
Note | The arrow keys function only on ANSI-compatible terminals such as VT100s. |
1.
Ctrl-P or use the up arrow key
2.
Ctrl-N or use the down arrow key
3.
show history
DETAILED STEPS
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. This procedure is optional.
1.
terminal
no history
DETAILED STEPS
Command or Action | Purpose |
---|
Enabling and Disabling Editing Features
Although enhanced editing mode is automatically enabled, you can disable it and reenable it.
1.
terminal editing
2.
terminal no editing
DETAILED STEPS
Editing Commands Through Keystrokes
The keystrokes help you to edit the command lines. These keystrokes are optional.
Note | The arrow keys function only on ANSI-compatible terminals such as VT100s. |
Editing Commands |
Description |
||
Ctrl-B or use the left arrow key | Moves the cursor back one character. |
||
Ctrl-F or use the right arrow key | Moves the cursor forward one character. |
||
Ctrl-A | Moves the cursor to the beginning of the command line. |
||
Ctrl-E | Moves the cursor to the end of the command line. |
||
Esc B | Moves the cursor back one word. |
||
Esc F | Moves the cursor forward one word. |
||
Ctrl-T | Transposes the character to the left of the cursor with the character located at the cursor. |
||
Delete or Backspace key | Erases the character to the left of the cursor. |
||
Ctrl-D | Deletes the character at the cursor. |
||
Ctrl-K | Deletes all characters from the cursor to the end of the command line. |
||
Ctrl-U or Ctrl-X | Deletes all characters from the cursor to the beginning of the command line. |
||
Ctrl-W | Deletes the word to the left of the cursor. |
||
Esc D | Deletes from the cursor to the end of the word. |
||
Esc C | Capitalizes at the cursor. |
||
Esc L | Changes the word at the cursor to lowercase. |
||
Esc U | Capitalizes letters from the cursor to the end of the word. |
||
Ctrl-V or Esc Q | Designates a particular keystroke as an executable command, perhaps as a shortcut. |
||
Return key | Scrolls down a line or screen on displays that are longer than the terminal screen can display.
|
||
Space bar | Scrolls down one screen. |
||
Ctrl-L or Ctrl-R | Redisplays the current command line if the switch suddenly sends a message to your screen. |
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. |
The following example shows how to wrap a command line that extends beyond a single line on the screen.
1.
access-list
2.
Ctrl-A
3.
Return key
DETAILED STEPS
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.
1.
{show | more} command | {begin | include | exclude}
regular-expression
DETAILED STEPS
Accessing the CLI on a Switch Stack
You can access the CLI through a console connection, through Telnet, a SSH, 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 on the stack master. Commands that 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.
Accessing the CLI Through a Console Connection or Through Telnet
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:
Connect the switch console port to a management station or dial-up modem, or connect the Ethernet management port to a PC. For information about connecting to the console or Ethernet management port, see the switch hardware installation guide.
Use 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.
- The switch supports up to 16 simultaneous Telnet sessions. Changes made by one Telnet user are reflected in all other Telnet sessions.
- The switch supports up to five simultaneous secure SSH sessions.
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.