Introduction

Many of you already know about the cat(1) command. Maybe you have already used it or even wrote scripts that used it. It's the kind of command that's small with a small number of options, yet popular and powerful at the same time. So don't expect a lengthy article here, but expect one about a powerful command that will save you from a lot of situations when you're at the command line. As usual, you should know that this is in no way a manual page substitute, so if you haven't installed the documentation already, do so now. cat(1) is part of the coreutils package, which is already installed 99.9% of the times, unless you have a really weird/geeky setup.

Basic usage and options

As with all Unix commands, cat also has a short but meaningful name. In our case, the originating word is concatenate. Merriam-Webster defines the word (the verb) as "to link together in a series or chain". The origin is the Latin word catena, which means "chain", and con, meaning "together". Now that we got etymology out of the way, let's see how the command works. It takes one or more files as arguments (and options, of course), and prints the result to standard output. The result being the two or more files' content together, one after the other, so the order of the arguments is important. If there's only one file, it simply prints the contents to stdout. So if I want to see my user's Vim config file page by page, I use cat, a pipe and less:

 $ cat ~/.vimrc | less