dangerous script

[jody]

Hi

Recently i saw a post with the following script:

:() { :|: & } ; :

Out of curiosity i ran it on my machine - and it completely froze:
i even couldn't connect via ssh. I had to do a cold start...

Can anybody explain what exactly this script does?
I have no idea what those brackets and colons mean.

Thank You
Jody

[Irithori]

It´s a fork bomb.
It forks children and waits for their completion, but the childs also fork childs and wait....
That grows exponentially.

So the machines´ load explodes and it will run out of memory eventually.

You can prevent that by setting limits.
Which might be a good idea in a multi-user environment

[jody]

Thank you for your reply

I'd like to understand the details:
Could you explain in more detail the different parts?
Like which is the command for forking, what is the
meaning of the curly brackets and their content, and
what do the colons mean?

Or perhaps you can give a ointer where i can read about this?
(I tried googling these things, but googling for colons or brackets doesn't work.)

Thank You
Jody

[gerard4143]

The : are equal to true and the others...well they may actually depend on context so I'm not sure...but you can try here

Advanced Bash-Scripting Guide

If I had to guess

:() { :|: & } ; :

:() is a function declaration
{}this is the body of the function
:|:& is the contents of the function
and finally : is caling the function..Like I said guess

[scathefire]

Understanding Bash fork() bomb ~ ){ :& };:

[elija]

Hi

Recently i saw a post with the following script:

:() { :|: & } ; :

Out of curiosity i ran it on my machine - and it completely froze:
i even couldn't connect via ssh. I had to do a cold start...

Can anybody explain what exactly this script does?
I have no idea what those brackets and colons mean.

Thank You
Jody

function fork() {
  fork | fork &
}
fork()

is equivalent. It works by starting new processes in the background, each of which starts new processes. Eventually the computer can't keep up with the number of processes being started.

By coincidence, I am wearing a t-shirt with

:() { :|: & } ; :

on it