Using the no and default Forms of Commands
Almost every configuration command has a
no
form. In general, use the
no
form to disable a function. Use
the command without the
no
keyword to re-enable a disabled function or to enable a function that is disabled
by default. For example, IP routing is enabled by default. To disable IP routing, use the
no ip routing
command;
to re-enable IP routing, use the
ip routing
command. The Cisco IOS software command reference publications
provide the complete syntax for the configuration commands and describe what the
no
form of a command
does.
Many CLI commands also have a
default
form. By issuing the command
default command-name
, you can
configure the command to its default setting. The Cisco IOS software command reference publications describe
the function of the
default
form of the command when the
default
form performs a different function than
the plain and
no
forms of the command. To see what default commands are available on your system, enter
default ?
in the appropriate command mode.
Saving Configuration Changes
Use the
copy running-config startup-config
command to save your configuration changes to the startup
configuration so that the changes will not be lost if the software reloads or a power outage occurs. For example:
Router#
copy running-config startup-config
Building configuration...
It might take a minute or two to save the configuration. After the configuration has been saved, the following
output appears:
[OK]
Router#
On most platforms, this task saves the configuration to NVRAM. On the Class A Flash file system platforms,
this task saves the configuration to the location specified by the CONFIG_FILE environment variable. The
CONFIG_FILE variable defaults to NVRAM.
Filtering the Output of the show and more Commands
You can search and filter the output of
show
and
more
commands. This functionality is useful if you need to
sort through large amounts of output or if you want to exclude output that you need not see.
To use this functionality, enter a
show
or
more
command followed by the
“
pipe
”
character ( | ); one of the
keywords
begin
,
include
, or
exclude
; and a regular expression on which you want to search or filter (the
expression is case sensitive):
show command
| {
begin
|
include
|
exclude
}
regular-expression
The output matches certain lines of information in the configuration file. The following example illustrates
how to use output modifiers with the
show interface
command when you want the output to include only
lines in which the expression
“
protocol
”
appears:
Router#
show interface | include protocol
FastEthernet0/0 is up, line protocol is up
Serial4/0 is up, line protocol is up
Serial4/1 is up, line protocol is up
Serial4/2 is administratively down, line protocol is down
Serial4/3 is administratively down, line protocol is down
Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide, Cisco IOS
XE Everest 16.5
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Using Cisco IOS XE Software
Using the no and default Forms of Commands