Understanding the Command-Line Interface

Information About the CLI Prompt

Once you have successfully accessed the device, the CLI prompt displays in the terminal window of your console port or remote workstation as shown in the following example: 


User Access Verification 
login: admin
Password:<password> 
Cisco Nexus Operating System (NX-OS) Software 
TAC support: http://www.cisco.com/tac 
Copyright (c) 2002-2009, Cisco Systems, Inc. All rights reserved. 
The copyrights to certain works contained in this software are 
owned by other third parties and used and distributed under 
license. Certain components of this software are licensed under 
the GNU General Public License (GPL) version 2.0 or the GNU 
Lesser General Public License (LGPL) Version 2.1. A copy of each 
such license is available at 
http://www.opensource.org/licenses/gpl-2.0.php and 
http://www.opensource.org/licenses/lgpl-2.1.php 
switch#

You can change the default device hostname.

From the CLI prompt, you can do the following:

  • Use CLI commands for configuring features

  • Access the command history

  • Use command parsing functions


Note

In normal operation, usernames are case sensitive. However, when you are connected to the device through its console port, you can enter a login username in all uppercase letters regardless of how the username was defined. As long as you provide the correct password, the device logs you in.

Command Modes

This section describes command modes in the Cisco NX-OS CLI.

Special Characters

This table lists the characters that have special meaning in Cisco NX-OS text strings and should be used only in regular expressions or other special contexts.

Table 1. Special Characters

Character

Description
%

Percent

#

Pound, hash, or number

...

Ellipsis
|

Vertical bar

< >

Less than or greater than

[ ]

Brackets

{ }

Braces

Keystroke Shortcuts

This table lists command key combinations that can be used in both EXEC and configuration modes.

Table 2. Keystroke Shortcuts

Keystokes

Description

Ctrl-A

Moves the cursor to the beginning of the line.

Ctrl-B

Moves the cursor one character to the left. When you enter a command that extends beyond a single line, you can press the Left Arrow or Ctrl-B keys repeatedly to scroll back toward the system prompt and verify the beginning of the command entry, or you can press the Ctrl-A key combination.

Ctrl-C

Cancels the command and returns to the command prompt.

Ctrl-D

Deletes the character at the cursor.

Ctrl-E

Moves the cursor to the end of the line.

Ctrl-F

Moves the cursor one character to the right.

Ctrl-G

Exits to the previous command mode without removing the command string.

Ctrl-K

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

Ctrl-L

Redisplays the current command line.

Ctrl-N

Displays the next command in the command history.

Ctrl-O

Clears the terminal screen.

Ctrl-P

Displays the previous command in the command history.

Ctrl-R

Redisplays the current command line.

Ctrl-T

Transposes the character under the cursor with the character located to the right of the cursor. The cursor is then moved one character to the right.

Ctrl-U

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

Ctrl-V

Removes any special meaning for the following keystroke. For example, press Ctrl-V before entering a question mark (?) in a regular expression.

Ctrl-W

Deletes the word to the left of the cursor.

Ctrl-X, H

Lists the history of commands you have entered.

When using this key combination, press and release the Ctrl and X keys together before pressing H.

Ctrl-Y

Recalls the most recent entry in the buffer (press keys simultaneously).

Ctrl-Z

Ends a configuration session, and returns you to EXEC mode.

When used at the end of a command line in which a valid command has been typed, the resulting configuration is first added to the running configuration file.

Up arrow key

Displays the previous command in the command history.

Down arrow key

Displays the next command in the command history.

Right arrow key

Left arrow key

Moves your cursor through the command string, either forward or backward, allowing you to edit the current command.

?

Displays a list of available commands.

Tab

Completes the word for you after you enter the first characters of the word and then press the Tab key. All options that match are presented.

Use tabs to complete the following items:

  • Command names

  • Scheme names in the file system

  • Server names in the file system

  • Filenames in the file system

Example: 


switch(config)# xm<Tab>
switch(config)# xml<Tab>
switch(config)# xml server

Example: 


switch(config)# c<Tab>
callhome  class-map  clock  cts
cdp       cli        control-plane
switch(config)# cl<Tab>
class-map   cli         clock 
switch(config)# cla<Tab> 
switch(config)# class-map

Example: 


switch# cd bootflash:<Tab>
bootflash:             bootflash://sup-1/ 
bootflash:///          bootflash://sup-2/ 
bootflash://module-5/  bootflash://sup-active/ 
bootflash://module-6/  bootflash://sup-local/

Example: 


switch# cd bootflash://mo<Tab> 
bootflash://module-5/  bootflash://module-6/cv
switch# cd bootflash://module-

Abbreviating Commands

You can abbreviate commands and keywords by entering the first few characters of a command. The abbreviation must include sufficient characters to make it unique from other commands or keywords. If you are having trouble entering a command, check the system prompt and enter the question mark (?) for a list of available commands. You might be in the wrong command mode or using incorrect syntax.

This table lists examples of command abbreviations.

Table 3. Examples of Command Abbreviations

Command

Abbreviation

configure terminal

conf t

copy running-config startup-config

copy run start

interface ethernet 1/2

int e 1/2

show running-config

sh run

Completing a Partial Command Name

If you cannot remember a complete command name, or if you want to reduce the amount of typing you have to perform, enter the first few letters of the command, and then press the Tab key. The command line parser will complete the command if the string entered is unique to the command mode. If your keyboard does not have a Tab key, press Ctrl-I instead.

The CLI recognizes a command once you have entered enough characters to make the command unique. For example, if you enter conf in EXEC mode, the CLI will be able to associate your entry with the configure command, because only the configure command begins with conf .

In the following example, the CLI recognizes the unique string for conf in EXEC mode when you press the Tab key: 

switch# conf<Tab>
switch# configure

When you use the command completion feature the CLI displays the full command name. The CLI does not execute the command until you press the Return or Enter key. This feature allows you to modify the command if the full command was not what you intended by the abbreviation. If you enter a set of characters that could indicate more than one command, a list of matching commands displays.

For example, entering co<Tab> lists all commands available in EXEC mode beginning with co : 

switch# co<Tab>
configure   copy
switch# co

Note that the characters you entered appear at the prompt again to allow you to complete the command entry.

Identifying Your Location in the Command Hierarchy

Some features have a configuration submode hierarchy nested more than one level. In these cases, you can display information about your present working context (PWC).

SUMMARY STEPS

  1. where detail

DETAILED STEPS

Command or Action Purpose

where detail

Example:


switch# configure terminal
switch(config)# interface mgmt0
switch(config-if)# where detail
mode:                conf
                         interface mgmt0
  username:            admin

Displays the PWC.

Using the no Form of a Command

Almost every configuration command has a no form that can be used to disable a feature, revert to a default value, or remove a configuration. The Cisco NX-OS command reference publications describe the function of the no form of the command whenever a no form is available.

This example shows how to disable a feature:

switch# configure terminal 
switch(config)# feature tacacs+
switch(config)# no feature tacacs+

This example shows how to revert to the default value for a feature:

switch# configure terminal 
switch(config)# banner motd #Welcome to the switch# 
switch(config)# show banner motd
Welcome to the switch 

switch(config)# no banner motd
switch(config)# show banner motd
User Access Verification

This example shows how to remove the configuration for a feature:

switch# configure terminal
switch(config)# radius-server host 10.10.2.2
switch(config)# show radius-server
retransmission count:0 
timeout value:1 
deadtime value:1 
total number of servers:1 

following RADIUS servers are configured:
        10.10.1.1:
                available for authentication on port:1812
                available for accounting on port:1813
        10.10.2.2:
                available for authentication on port:1812
                available for accounting on port:1813
 
switch(config)# no radius-server host 10.10.2.2
switch(config)# show radius-server
retransmission count:0 
timeout value:1 
deadtime value:1 
total number of servers:1 

following RADIUS servers are configured:
        10.10.1.1:
                available for authentication on port:1812
                available for accounting on port:1813

This example shows how to use the no form of a command in EXEC mode: 

switch# cli var name testinterface ethernet1/2 
switch# show cli variables
SWITCHNAME="switch"
TIMESTAMP="2009-05-12-13.43.13"
testinterface="ethernet1/2"

switch# cli no var name testinterface
switch# show cli variables
SWITCHNAME="switch"
TIMESTAMP="2009-05-12-13.43.13"

Configuring CLI Variables

This section describes CLI variables in the Cisco NX-OS CLI.

Command Aliases

This section provides information about command aliases.

Command Scripts

This section describes how you can create scripts of commands to perform multiple tasks.

Context-Sensitive Help

The Cisco NX-OS software provides context-sensitive help in the CLI. You can use a question mark (?) at any point in a command to list the valid input options.

CLI uses the caret (^) symbol to isolate input errors. The ^ symbol appears at the point in the command string where you have entered an incorrect command, keyword, or argument.

This table shows example outputs of context sensitive help.

Table 4. Context-Sensitive Help Example

Example Outputs

Description

 

switch# clock ?
  set  HH:MM:SS Current Time 
switch# clock

Displays the command syntax for the clock command in EXEC mode.

The switch output shows that the set keyword is required for using the clock command. 

switch# clock set ?
  WORD  HH:MM:SS Current Time 
switch# clock set

Displays the command syntax for setting the time.

The help output shows that the current time is required for setting the clock and how to format the time.

 
switch# clock set 13:32:00<CR> 
% Incomplete command 
switch#

Adds the current time.

The CLI indicates the command is incomplete.

 
switch# <Ctrl-P>
switch# clock set 13:32:00

Displays the previous command that you entered. 

switch# clock set 13:32:00 ?
  <1-31>     Day of the month
switch# clock set 13:32:00

Displays the additional arguments for the clock set command. 


switch# clock set 13:32:00 18 ?
  April      Month of the year
  August     Month of the year
  December   Month of the year
  February   Month of the year
  January    Month of the year
  July       Month of the year
  June       Month of the year
  March      Month of the year
  May        Month of the year
  November   Month of the year
  October    Month of the year
  September  Month of the year 
switch# clock set 13:32:00 18

Displays the additional arguments for the clock set command. 


switch# clock set 13:32:00 18 April 08<CR>
% Invalid input detected at '^' marker.

Adds the date to the clock setting.

The CLI indicates an error with the caret symbol (^) at 08.

 

switch# clock set 13:32:00 18 April ?
  <2000-2030>  Enter the year (no abbreviation) 
switch# clock set 13:32:00 18 April

Displays the correct arguments for the year.

 

switch# clock set 13:32:00 18 April 2008<CR>
switch#

Enters the correct syntax for the clock set command.

Understanding Regular Expressions

The Cisco NX-OS software supports regular expressions for searching and filtering in CLI output, such as the show commands. Regular expressions are case sensitive and allow for complex matching requirements.

Searching and Filtering show Command Output

Often, the output from show commands can be lengthy and cumbersome. The Cisco NX-OS software provides the means to search and filter the output so that you can easily locate information. The searching and filtering options follow a pipe character (| ) at the end of the show command. You can display the options using the CLI context-sensitive help facility: 

switch# show running-config | ? 
  cut      Print selected parts of lines.
  diff     Show difference between current and previous invocation (creates temp files:
           remove them with 'diff-clean' command and don't use it on commands with big
           outputs, like 'show tech'!)
  egrep    Egrep - print lines matching a pattern
  grep     Grep - print lines matching a pattern
  head     Display first lines
  human    Output in human format
  last     Display last lines
  less     Filter for paging
  no-more  Turn-off pagination for command output
  perl     Use perl script to filter output
  section  Show lines that include the pattern as well as the subsequent lines that are
           more indented than matching line
  sed      Stream Editor
  sort     Stream Sorter
  sscp     Stream SCP (secure copy)
  tr       Translate, squeeze, and/or delete characters
  uniq     Discard all but one of successive identical lines
  vsh      The shell that understands cli command
  wc       Count words, lines, characters
  xml      Output in xml format (according to .xsd definitions)
  begin    Begin with the line that matches
  count    Count number of lines
  end      End with the line that matches
  exclude  Exclude lines that match
  include  Include lines that match

Searching and Filtering from the --More-- Prompt

You can search and filter output from --More–- prompts in the show command output.

This table describes the --More-- prompt commands.

Table 5. --More-- Prompt Commands

Commands

Description

[lines]<space>

Displays output lines for either the specified number of lines or the current screen size.

[lines]z

Displays output lines for either the specified number of lines or the current screen size. If you use the lines argument, that value becomes the new default screen size.

[lines]<return>

Displays output lines for either the specified number of lines or the current default number of lines. The initial default is 1 line. If you use the optional lines argument, that value becomes the new default number of lines to display for this command.

[lines]d or [lines]Ctrl+shift+D

Scrolls through output lines for either the specified number of lines or the current default number of lines. The initial default is 11 lines. If you use the optional lines argument, that value becomes the new default number of lines to display for this command.

q or Q or Ctrl-C

Exits the --More-- prompt.

[lines]s

Skips forward in the output for either the specified number of lines or the current default number of lines and displays a screen of lines. The default is 1 line.

[lines]f

Skips forward in the output for either the specified number of screens or the current default number of screens and displays a screen of lines. The default is 1 screen.

=

Displays the current line number.

[count]/expression

Skips to the line that matches the regular expression and displays a screen of output lines. Use the optional count argument to search for lines with multiple occurrences of the expression. This command sets the current regular expression that you can use in other commands.

[count]n

Skips to the next line that matches the current regular expression and displays a screen of output lines. Use the optional count argument to skip past matches.

{! | :![shell-cmd]}

Executes the command specified in the shell-cmd argument in a subshell.

.

Repeats the previous command.

Using the Command History

The Cisco NX-OS software CLI allows you to access the command history for the current user session. You can recall and reissue commands, with or without modification. You can also clear the command history.

Enabling or Disabling the CLI Confirmation Prompts

For many features, the Cisco NX-OS software displays prompts on the CLI that ask for confirmation before continuing. You can enable or disable these prompts. The default is enabled.

SUMMARY STEPS

  1. [no] terminal dont-ask [persist]

DETAILED STEPS

Command or Action Purpose

[no] terminal dont-ask [persist]

Example:

switch# terminal dont-ask

Disables the CLI confirmation prompt. The persist keyword makes the setting persistent across sessions for the current username. The default is enabled.

Use the no form of the command to enable the CLI confirmation prompts.

Setting CLI Display Colors

You can change the CLI colors to display as follows:

  • The prompt displays in green if the previous command succeeded.
  • The prompt displays in red of the previous command failed.
  • The user input displays in blue.
  • The command output displays in the default color.

The default colors are those set by the terminal emulator software.

SUMMARY STEPS

  1. terminal color [evening] [persist]

DETAILED STEPS

Command or Action Purpose

terminal color [evening] [persist]

Example:

switch# terminal color

Sets the CLI display colors for the terminal session. The evening keyword is not supported. The persist keyword makes the setting persistent across sessions for the current username. The default setting is not persistent.

Sending Commands to Modules

You can send commands directly to modules from the supervisor module session using the slot command.

The slot has the following syntax:

slot slot-number [quoted] command-string

By default, the keyword and arguments in the command-string argument are separated by a space. To send more than one command to a module, separate the commands with a space character, a semicolon character (;), and a space character.

The quoted keyword indicates that the command string begins and ends with double quotation marks ("). Use this keyword when you want to redirect the module command output to a filtering utility, such as diff, that is supported only on the supervisor module session.

The following example shows how to display and filter module information: 


switch# slot 1 show version | grep lc

This example shows how to filter module information on the supervisor module session: 


switch# slot 1 quoted "show version" | diff
switch# slot 4 quoted "show version" | diff -c
*** /volatile/vsh_diff_1_root_8430_slot__quoted_show_version.old        Wed Apr 29 20:10:41 2009
--- -   Wed Apr 29 20:10:41 2009
***************
*** 1,5 ****
! RAM 1036860 kB
! lc2
  Software
    BIOS:      version 1.10.6
    system:    version 4.2(1) [build 4.2(0.202)]
--- 1,5 ----
! RAM 516692 kB
! lc4
  Software
    BIOS:      version 1.10.6
    system:    version 4.2(1) [build 4.2(0.202)]
***************
*** 12,16 ****
  Hardware
      bootflash: 0 blocks (block size 512b)
 
!    uptime is 0 days 1 hours 45 minute(s) 34 second(s)
 
--- 12,16 ----
  Hardware
      bootflash: 0 blocks (block size 512b)
 
!    uptime is 0 days 1 hours 45 minute(s) 42 second(s)

BIOS Loader Prompt

When the supervisor modules power up, a specialized BIOS image automatically loads and tries to locate a valid kickstart image for booting the system. If a valid kickstart image is not found, the following BIOS loader prompt displays: 


loader>

For information on how to load the Cisco NX-OS software from the <loader> prompt, see the Cisco Nexus troubleshooting guide for your device.

Examples Using the CLI

This section includes examples of using the CLI.

Additional References for the CLI

This section includes additional information related to the CLI.