These shortcuts can be used to speed up operating with the CLI:
| Ctrl+B or Left | Move the cursor one character to the left |
| Ctrl+F or Right | Move the cursor one character to the right |
| Esc, B | Move the cursor one word to the left |
| Esc, F | Move the cursor one word to the right |
| Ctrl+A | Move cursor to the beginning of the line |
| Ctrl+E | Move cursor to the end of the line |
| Ctrl+P or Up | Retrieve last command from history |
| Ctrl+N or Down | Retrieve next command from history |
| Ctrl+T | Swap the current character with the one before it |
| Ctrl+W | Erase one word |
| Ctrl+U | Erase the entire line |
| Ctrl+L | Reprint the line |
| Ctrl+C | Exit configuration mode |
| Ctrl+Z | Apply the current command and exit configuration mode |
Most show commands support filtering with the pipe (|) character, allowing a user to display only the information he's looking for.
Switch# show interface status | include notconnect
Gi1/0/7 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/9 notconnect 1 auto auto 10/100/1000BaseTX
Gi1/0/22 notconnect 1 auto auto 10/100/1000BaseTX
Filter options are include, exclude, and begin. The remaining characters after one of these filter types is processed as a regular expression, which could be a simple string (as in the example above) or something a bit more complex. The example below demonstrates filtering for interface numbers and any assigned IP addresses.
Switch# show run | inc ^interface|ip address
interface FastEthernet0
ip address 192.168.0.1 255.255.255.0
interface FastEthernet1
interface FastEthernet2
ip address 192.168.1.1 255.255.255.0
ip address 192.168.2.1 255.255.255.0 secondary
interface FastEthernet3
You can also filter by section. Thanks to Carl Baccus to reminding me to include this.
R1# show run | section bgp
router bgp 100
no synchronization
redistribute connected
neighbor 172.16.0.2 remote-as 200
neighbor 172.16.0.9 remote-as 300
no auto-summary
You can begin viewing a configuration with the begin filter:
Router# show run | begin interface
interface FastEthernet0/0
no ip address
shutdown
...
You can also skip forward to a certain line once you've already begun viewing the configuration by hitting / at the --More-- prompt, followed by the string you want to match:
Router# sh run
Building configuration...
Current configuration : 601 bytes
!
version 12.4
...
!
!
/interface
filtering...
interface FastEthernet0/0
no ip address
shutdown
...
Exec commands can be issued from within configuration mode via the do command. This can be handy for double-checking the current configuration before applying any changes.
Switch(config-if)# do show run int f0
Building configuration...
Current configuration : 31 bytes
!
interface FastEthernet0
description Internal LAN
ip address 172.16.0.1 255.255.0.0
end
You can insert question marks into literal strings (such as interface descriptions) by typing CTRL+V immediately before the question mark. This acts as an escape character and prevents the command line from summoning the help menu.
Switch(config-if)# description Where does this go[ctrl+v]?
The interface description will appear as "Where does this go?"
Don't you hate it when this happens?
Switch# shrun
Translating "shrun"...domain server (255.255.255.255)
% Unknown command or computer name, or unable to find computer address
You can disable automatic DNS lookups with no ip domain-lookup, which will remove the delay before returning a new console prompt. However, this will also prevent you from referencing remote hosts by name, for example when telneting.
Switch(config)# no ip domain-lookup
...
Switch#shrun
Translating "shrun"
% Unknown command or computer name, or unable to find computer address
When logging to the console is enabled, a Cisco device will often dump messages directly to the screen. This can become irritating when it interrupts you in the midst of typing a command. (FYI, you can continue typing normally and the command will still take, but this still throws some people off.)
Synchronous logging can be enabled to "clean up" the CLI when this happens, outputting a fresh prompt below the message, along with any partially completed command.
Switch(config)# line con 0
Switch(config-line)# logging synchronous
Switch(config-line)# line vty 0 15
Switch(config-line)# logging synchronous
The default command, called from global configuration, can be used to revert any part of a configuration to its default value (which is often nothing). For example, it can be used to remove all configuration from a particular interface:
Switch(config)# default g1/0/5
Interface GigabitEthernet1/0/5 set to default configuration
Switch(config)# ^Z
Switch# show run int g1/0/5
Building configuration...
Current configuration : 38 bytes
!
interface GigabitEthernet1/0/5
end
For reasons unknown to me, IOS doesn't include a command to view what interfaces have ACLs applied. The closest we can get is drudging through the entire output of show ip interface. But, with a little ingenuity and the help of regular expressions, we can summon an efficient view of where our ACLs are applied.
Switch# sh ip int | inc line protocol|access list is [^ ]+$
FastEthernet0 is up, line protocol is down
FastEthernet1 is up, line protocol is up
Inbound access list is prohibit-web
FastEthernet2 is up, line protocol is up
Inbound access list is 42
FastEthernet3 is up, line protocol is down
FastEthernet4 is up, line protocol is up
For those curious, the regex above matches a line which either a) contains the string "line protocol", or b) contains the string "access list is " followed by a single word. This matches an ACL number or name (which can't contain spaces) but not "not set".
When the show running-config command is issued, the output has to be assembled from numerous values in memory into the human-friendly display you see on the CLI. Unfortunately, the longer your configuration is, the more time this takes. IOS 12.3T introduced a feature to cache the running configuration text for quicker output:
Router(config)# parser config cache interface
Hat tip to Jeremy Cioara for blogging this!