a fork bomb is a denial-of-service (DoS) attack wherein a process continually replicates itself to deplete available system resources, slowing down or crashing the system due to resource starvation.
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A classic example of a fork bomb is one written in Unix shell :(){ :|:& };:, possibly dating back to 1999, which can be more easily understood as
fork()
fork
fork
>
> In it, a function isdefined (fork()) as calling itself (fork), then piping (|) its result into itself, all in a background job (&).
>
> The code using a colon `:` as the function name isnot valid in a shell as defined by POSIX, which only permits alphanumeric characters and underscores in function names. However, its usage is allowed in GNU Bash as an extension.
[Wikipedia](https://en.wikipedia.org/wiki/Fork_bomb)
I don’t know what that is, but it feels to me like it might be a fork bomb.
Edit: Yep, fork bomb.
Because I didn’t know what a fork bomb was:
[…]
fork() fork fork
> > In it, a function is defined (fork()) as calling itself (fork), then piping (|) its result into itself, all in a background job (&). > > The code using a colon `:` as the function name is not valid in a shell as defined by POSIX, which only permits alphanumeric characters and underscores in function names. However, its usage is allowed in GNU Bash as an extension. [Wikipedia](https://en.wikipedia.org/wiki/Fork_bomb)