A. This is a bash function. It gets called recursively (recursive function). This is most horrible code for any Unix / Linux box. It is often used by sys admin to test user processes limitations (Linux process limits can be configured via /etc/security/limits.conf and PAM).
Once a successful fork bomb has been activated in a system it may not be possible to resume normal operation without rebooting, as the only solution to a fork bomb is to destroy all instances of it.
WARNING! These examples may crash your computer if executed.
Understanding :{ :|:& };: fork() bomb code
: - It is a function name. It accepts no arguments at all. Generally, bash function is defined as follows:
foo(){
arg1=
echo ''
#do_something on $arg argument
}
fork() bomb is defined as follows:
:{
:|:&
};:
:|: - Next it call itself using programming technique called recursion and pipes the output to another call of the function ':'. The worst part is function get called two times to bomb your system.
& - Puts the function call in the background so child cannot die at all and start eating system resources.
; - Terminate the function definition
: - Call (run) the function aka set the fork() bomb.
Here is more human readable code:
bomb() {
bomb | bomb &
}; bomb
Properly configured Linux / UNIX box should not go down when fork() bomb sets off.
