One of the sillier, but still fun, tools available on Linux is called “cowsay”. It’s used to display a phrase along with an ASCII art image of a cow.
The cowsay command allows you to create messages that are less likely to be overlooked and might come across as just a little friendlier than the other thousand or so messages most of us get every day. For example:
$ cowsay This is cowsay!
< This is cowsay! >
Once cowsay is installed on your system, you can create cute little messages – and you’re not limited to displaying a cow! In fact, if you wander over to the cowsay’s directory – /usr/share/cowsay/cows – you’ll see that there’s a fairly large collection of files available. Each includes a different image. You can choose from images as diverse as a snowman and a stegosaurus. If you want to greet your Australian friends using cowsay, you might try using the koala.
Source:: Network World – Linux