The Silo Chronicles
The not so exciting adventures of a Network Engineer

Ask any experienced Cisco Engineer and they will tell you one of the basic commands they can’t live without is the output modifiers. While they aren’t required to get the job done they do make things easier at times. As you would expect output modifiers modify the output. If you are a linux/unix/bsd person you are most likely familiar with grep. This of the output modifiers as the grep for Cisco.

This is the first of a series of posts about output modifiers. To start with I am going to cover four basic output modifiers; include, exclude, begin and section. In future posts I will cover the other modifiers and some advanced patterning. As with most Cisco features and commands not all modifiers will be available on all platforms and versions.

include

This modifier only returns lines that match the pattern given. This is useful for requiring quick pieces of information from the configuration and other output heavy commands. Some of the modifier variations I use often are:

I would recommend you play around with this modifier as I am sure you can come up with some great variations of this.

exclude

As you have probably gathered this is the absolute opposite of the include modifier. I don’t use this modifier nearly as much as include but one of the great uses is to look at your processes and how much cpu they are consuming. If you have ever looked you will find a very large number of processes of which most are using no resources. Using the following command will only show you processes that actually use resources.

If you compare the two outputs you will notice the exclude modifier greatly reduces the output. I would recommend making an alias in your device for this command as it is quite long to type and if your device is truly suffering a cpu resource issue the last thing you want to do is type a long command.

begin

If you want to jump to a section of configuration without having to smash the space bar a bunch of times you can just use the begin modifier. If you are looking at a high density switch such as a 3750, 4500 or 6500 this can be useful to jump to the various switches/blades. For example:

There isn’t much more to be said about this modifier. It is fairly straight forward.

section

This is very handy for getting sections of configuration. How many times do you want to look at a section of code such as an interface, controller, route-map or dial-peer without seeing the rest of the configuration. This modifier makes this very simple. For example:

You will notice that this modifier is actually a superset of include as it will return any lines that matches the pattern but if that line is a section title it also includes the other lines in the section.

This entry was posted on Monday, April 21st, 2008 at 10:24 pm and is filed under Tips and Tricks. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.