A lot of IOS commands give you a lot of information. Most of the time, though, it’s way too much information, and it sure would be nice to do some grep-like stuff on the output, right? Well, just like on Linux, you can use the pipe (|) to do such. That’s not a butt cheek, by the way.
The most useful function is the include directive. This is the equivalent of just plain grep on Linux, and will show you only lines that match a string that you give it. Say that you want to find what ports on your switch are down, but don’t want to grind through all the lines of a show ip interface brief. If you just pipe it to the include command followed by the word “down”, you’ll see something like this.