Ect. Router Fact

Command Help Facts

Help is available in all device modes. It is context sensitive, so the information you see depends on what you are doing. Cisco bases this on the mode you are in and the words or partial words you type with the ?.

To...	Use...
Show list of all commands available in the current mode	?
Show commands that begin with specific letter(s)	xx? (no space between the letter and ?)
Show keywords for a command	command ? (space between command and ?)
Get the full command from a partial command	partial command + <tab> (no space)

Note: Typing ? acts as a return, and repeats the last command you entered after the Help information displays. You do not need to retype the command after you ask for help on it.

When you use Help to display the possible keywords for a command, you will see the following types of items.

When you see...	Supply...
WORD (in caps)	Type a one-word response
LINE (in caps)	Type a multiple-word response
<0-4567>	Enter a number within the range in brackets
<0-FFFFFF>	Enter a hexadecimal number within the range in brackets
<cr>	The command is complete as typed, press Enter to execute the command
A.B.C.D	Enter an IP address

Editing Features Facts

The following lists summarize the advanced editing features of the CLI.

Use this ...	To ...
Ctrl + A	Move to the beginning of the line
Ctrl + E	Move to the end of the line
Ctrl + B Left arrow	Go back one character
Ctrl + F Right arrow	Go forward one character
Esc, then B (press and release Esc, before pressing B)	Go back one word
Esc, then F (press and release Esc, before pressing F)	Move forward one word
Ctrl + Z	Quit a configuration mode
terminal editing	Turn advanced editing on
terminal no editing	Turn advanced editing off

When you are in advanced editing mode, the $ indicator appears after the prompt. As you type, commands longer than the command line appear to scroll under the prompt.

Note: The editing feature uses the same keystrokes as UNIX emacs editing.

Command History Command List

By default, the IOS automatically saves the last 10 commands in the command history buffer. The command history is specific to the configuration mode you are in.

Use . . .	To . . .
Ctrl + P or Up arrow	Show the previous command
Ctrl + N or Down arrow	Show the next command
terminal history	Turn the command history on
terminal no history	Turn the command history off
terminal history size <0-256>	Set the size of the history buffer
show history	Show all the commands in the history buffer

Controlling Screen Output

As you work with the device at the console and make configuration changes, response messages are often displayed on the screen. The following table describes various ways to control the response messages shown.

Problem	Solution
When making configuration changes, the following message is constantly displayed (sometimes as you are typing): %SYS-5-CONFIG_1: Configured from console by console	Use: no logging console to turn these messages off.
When working with the device through a Telnet session, when you use a debug command, output will not be shown.	Use: terminal monitor to send debug output to the telnet session.
When viewing debug information, you want to review previous information, or debug information is shown too quickly for you to examine it.	Use: logging buffered to send logging information to RAM, then use: show log to view information one screen at a time.

Router Memory

Be sure you understand the difference between the following types of router storage.

Memory Type	Characteristics
ROM (Read-Only Memory)	Preprogrammed, non-writable memory containing the bootstrap startup program, an older, smaller-scale version of the operating system (IOS) software, and the Power-on Self-Test (POST) program
Flash	Non-volatile but programmable memory containing the proprietary Cisco operating system (IOS) images Note: Older routers don’t have flash memory
RAM (Random Access Memory)	Volatile memory containing the running operating system and current (unsaved) configuration information
NVRAM (Non-Volatile RAM)	Non-volatile but persistent memory that contains the backup copy of the startup configuration (startup-config) file and virtual configuration register Note: On some routers, NVRAM holds the IOS image

The contents of non-volatile memory (such as ROM, flash, and NVRAM) remain when the router is powered off. The contents of volatile memory (RAM) are lost when the router is powered down.

Copy Command List

The device can load a configuration file from:

NVRAM (startup-configuration file by default value 0x2102)
TFTP server

Changes to the configuration are stored in RAM in the running-config file. To save your configuration changes permanently, and to load different versions of the configuration files from various locations, use the copy command in privileged EXEC mode.

Use . . .	To . . .
Router#copy run start	Save the contents of the running-config file to NVRAM
Router#copy start run	Copy the startup-config file into RAM
Router#copy run tftp	Save the contents of the running-config file to a TFTP server
Router#copy start tftp	Save the contents of the startup-config file to a TFTP server
Router#copy tftp start	Copy a configuration file from the TFTP server into NVRAM
Router#copy tftp run	Copy a configuration file from the TFTP server into RAM
Router(config)#tftp-server flash <filename>	Configure a Cisco router as a TFTP server. When using this command, you must specific the location (flash or rom) of the IOS image file as well as the IOS image file name.

You can also use the erase command to delete the configuration files--but be very careful not to erase files you need!

Use . . .	To . . .
Router#erase flash	Delete the contents of Flash memory (deletes the IOS image)
Router#erase start	Erase the contents of the startup-config file
Router#erase nvram	Delete the contents of NVRAM (which also erases startup-config)
Router#reload	Restarts the router

You can also use the following commands to manage system files:

Use . . .	To . . .
show version	Display information about hardware and firmware including the configuration register value
configure memory or copy startup-config running-config	Copy configuration information from another source (like NVRAM)
configure terminal	Configure information into the RAM of a router