linux - The Bash command :(){ :|:& };: will spawn processes to kernel death. Can you explain the syntax?

Question

I looked at this page and can't understand how this works.

This command "exponentially spawns subprocesses until your box locks up".

But why? What I understand less are the colons.

user@host$ :(){ :|:& };:

question from:https://stackoverflow.com/questions/515844/the-bash-command-will-spawn-processes-to-kernel-death-can-you-exp

Answer 1

That defines a function called : which calls itself twice (Code: : | :). It does that in the background (&). After the ; the function definition is done and the function : gets started.

So every instance of : starts two new : and so on... Like a binary tree of processes...

Written in plain C that is:

fork();
fork();