Cisco IOS Modes of Operation EXEC | Privileged | Global configuration mode

Cisco IOS Modes of Operation EXEC | Privileged | Global configuration mode

This article is about the Cisco IOS Modes of Operation that are EXEC mode, Privileged mode and Global configuration mode. You will learn a brief introduction of all these Cisco IOS configuration modes & Cisco IOS bakup restore. Following are the main command modes are:

1. User EXEC Mode (>) 
2. EXEC Mode with privileges (#) 
3. Global configuration mode (config#)

The User Execution Mode  is useful in case of some basic operations that have to do with monitoring or consultation, but does not allow the execution of any command that can change the configuration of the device. For its part, the  privileged Execution Mode allows you to enter the global configuration mode and the highest configuration modes.

NAVIGATION BETWEEN IOS MODES

Once you understand the execution modes (which are only two), the navigation between the modes is also done through commands and these are the first commands you should learn:

With the enable command, you can  enter EXEC mode with privileges.
With the exit command, you can exit the previous command mode in the hierarchy.

You can review the above figure for clear understanding of switching different Cisco IOS Modes of Operation.

COMMAND MODE SETTINGS

The image above shows new ways that you should know and are very simple:

• To configure the device, the user must enter the global configuration mode, using the configure terminal command
• The global configuration mode is identified by an input request that ends with (config) # after the device name, such as Switch (config) #
• Subconfiguration modes can be accessed from the EXEC mode with privileges.
• Some examples: switch (config-line) # and switch (config-if) #

THE IOS COMMAND STRUCTURE
Let's see the basic structure of IOS commands:

• The general syntax for a command is the command followed by the corresponding keywords and arguments.
• Keyword : a specific parameter defined in the operating system
• Argument : not predefined; is a user-defined value or variable

Cisco IOS SUPPORT FEATURE

The IOS has two forms of help available if you do not remember any command: contextual help and the command syntax checker. Let's look at practical examples to use when we forget the commands.

CONTEXTUAL HELP

• Command options ( "characters" + "?" ): A list of commands or keywords that begin with those "characters" is displayed.

Switch # cl?
clear clock

• Command explanation ( "keyword" + "?" ): It shows what arguments or variables of the command can be written and provides an explanation of each.

Switch # clock set?
 hh: mm: ss Current Time

Switch # clock set 14:09:00?
 <1-31> Day of the month
 MONTH Month of the year

COMMAND SYNTAX VERSIFIER

• Incomplete command : It returns a help message indicating that the necessary keywords or arguments were omitted from the end of the command.

Switch # clock set
% Incomplete command

• Ambiguous Command : Returns a help message indicating that not enough characters were entered for the command interpreter to recognize.

Switch # d
% Ambiguous command: "d"

• Invalid argument : IOS returns a “^” to indicate which part of the command interpreter cannot be decrypted.

Switch # clock set 19:50:10 28 8
                             ^
% Invalid input detected at '^' marker.

SHORTCUT AND SHORTCUT KEYS

Commands and keywords can be shortened to the minimum number of characters that identifies a unique selection. For example, the configure command can be shortened to conf , since configure is the only command that starts with conf .

Cisco IOS Hotkeys  

Key	Description
Tabulation	Complete partial command name entry
Recoil	Delete the character to the left of the cursor
Ctrl + D	Delete the character after the cursor
Ctrl + K	Delete all characters from the cursor
Esc + D	Delete all characters from the cursor to the end of the word
Ctrl + U / X	Delete all characters
Ctrl + W	Delete the word to the left of the cursor
Ctrl + A	Move the cursor to the beginning of the line
Ctrl + E	Move the cursor to the end of the line / td>
Down arrow	It allows to move forward through the previous commands.
Up arrow	It allows you to scroll back through the previous commands.
Ctrl + Shift + 6	It allows the user to interrupt an IOS process, such as ping or traceroute.
Ctrl + Z	When in any configuration mode, finish the configuration mode and return to privileged EXEC mode