Using The No And Default Forms Of Commands - Cisco ASR 1000 Configuration Manual

Using the no and default Forms of Commands

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 Output from 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
Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide
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Chapter 1 Using Cisco IOS XE Software
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