SDN/SDDC Retreat in Miami, Florida (November 4th-6th)
Separate SDN hype from real life!

IOS doesn't have Unix-style pipes

Recently one of my readers asked an interesting question:

“It looks like the second pipe character (¦) in an output filter is interpreted as an OR, not as yet another filter. How can I thus implement a filter that will match string_a AND string_b?

As explained in my IP Corner article Enhance the IOS user interface, the output filters are extensions of the show command. The first ¦ character starts the filter specification and anything after the first keyword is part of a regular expression (where ¦ means or).

To match a combination of two strings, you could either write a small Tcl script or use a more convoluted regular expression where you combine both strings into a single expression (inserting .* between them to match any intermediate set of characters). For example, to find all static host routes in your router configuration, you could use the following filter:

show running | include ip route.*255\.255\.255\.255

Note: The \. matches the dot character, whereas the . matches anything.


  1. Static default route will be missed with this regexp

  2. Well, the filter is supposed to match static host routes (those with the mask


You don't have to log in to post a comment, but please do provide your real name/URL. Anonymous comments might get deleted.