apt-moo

Print a cow easter egg

$ apt moo

apt-get moo

The apt-moo command is a classic Easter egg included in the APT (Advanced Package Tool) package management system commonly found on Debian-based Linux distributions like Ubuntu. It's a harmless, whimsical command that, when executed, displays an ASCII art cow that says 'Moo!'.

It serves no functional purpose in package management or system administration. Its sole intention is to amuse users who discover it. The existence of apt-moo demonstrates a sense of humor within the software development community.

Technically, it's implemented as a conditional branch within the APT source code that is triggered by the specific command. The developers chose a cow as the Easter egg subject for no obvious reason, although cows tend to be a meme in the Linux community. It's a tiny piece of code that adds a lighthearted touch to an otherwise serious tool.

The apt-moo command will only work when called with "apt-get moo". Other variants like "apt moo" or "sudo apt moo" may result in other errors or be interpreted as attempts to install a non-existent package.

New users often stumble upon apt-moo by accident or through online searches for Linux Easter eggs. It's a common suggestion for beginners to try, adding to its mystique. There is no other use for apt-moo except to display the ascii art cow.

The inclusion of the apt-moo Easter egg dates back to the early development of APT. It has persisted through various versions of APT and Debian releases, becoming a well-known and beloved quirk of the package manager.
It is not known for certain the exact purpose or original design intent but it has gained popularity over the years among the Linux userbase and become a mainstay for new Debian users to experience upon first use.

apt-get(8), apt(8)