cowsay is a program that generates ASCII art pictures of a cow with a message.

[2] It can also generate pictures using pre-made images of other animals, such as Tux the Penguin, the Linux mascot.

.cow files for cowsay exist which are able to produce different variants of cows, with different kinds of eyes, and so forth.

[3] It is sometimes used on IRC, desktop screenshots, and in software documentation.

[4] The Unix command fortune can also be piped into the cowsay command: Using the parameter -f followed by tux, one can replace the cow with other beings, such as Tux, the Linux mascot: Using the parameter -l shows all available cow files: