Understanding Fork Bombs in 5 Minutes or Less 

Warning: Don't run this on your own system. If you want to test it, create a VM like I did.

Short version: it creates a function called : that calls itself infinitely Also it calls 2 functions for each function which run at the same time so each step the number of functions is doubled

I know this classic for over a decade now, but this was such a great video explaining it in detail! Thats the content i love this channel for. No BS straight to the point. ❤

Great explanation! The expanded version really made it go from black magic to "oh it's that simple"

I love videos like these. Straight to the point, clearly explained with concise examples and demonstrations

That's why I love your content EM. Learning so much from you. Keep them coming :)

Wow that's interesting! Love the breakdown of how that code actually worked

dude idk how i havent came across your content yet but i dig it.

Great video, great explanation! Thank you for putting in the effort each time!

Fantastic explanation, quality video

The colon being a valid function name was what blew my mind. :D

Wow!! this guy actually explained it very well.. I like it

I've seen it a number of times recently. Used to be kind of common, then it seemed to get old and I didn't see it so much, now it seems to be common again.

Great education. Appreciated.

I love this new series

I actually did this in my phone, good thing I did some buttons and it restarted. I was so scared but I was relieved when it restarted successfully.

great video. concise and informative

" this is the initial call to fork me" How did you say that with a straight face.. Cuz I am rolling 😂 😂

Pipe is not the real issue here that causes program to explode. When you running a function, shell executes whatever command you gave it (and forks itself to execute external programs), but ampersand makes shell not to wait for a job to complete and then return but instead put that job in a background and let user to cleanup it with a wait command manualy. What is a job? Job is basically a group of processes with the same Process group ID (read manpage 7 credentials to learn more). Shell, when you launch several command with a pipe between them, first calls fork, then in a child assigns the same PGID as it's PID to itself, then it calls more forks which will inherit the same PGID (despite having new PIDs) with their stdins and stdouts connected one to another, and then each of that child executes whatever command you gave it to execute. Why PGID needed? To call kill command on the whole group of processes with the same PGID instead of calling kill to each one of them, or even lose control when initial child died and replaced itself with a new process with new PID. Since PGID is inherited by the child, and if child does not changes it explicitly by calling setpgid, you can just `kill -- -${child_pid}` (notice the minus before the process id and double-minus to make kill take that negative pid not as another option but as a pid value). This is how shell kills the whole pipe sequence at once. And yes, if child changes its PGID, its becoming immune to group kill (the game was rigged from the start), which does makes sence, but its hard to work around this if you really want to end all child and grandchildren processes, if at all possible. Try to write cron yourself, you will spend on it at least a hour or two of experimenting with what works and what not if you start from scratch knowing nothing about jobs, PGID, SID, what kill and wait calls allow you to do and what permissions you have to play with for changing processes credentials.

keep it up brother, have a nice day everyone

Great explanation!

Very clear, thank you again

Excellent video

great explanation!

Cool! I've created a jpeg bomb of 530 bytes that renders 4 billion pixels to the screen when opened. It freezes my laptop.. lol. I achieved this neat trick in Notepad ++ by accident when editing the Hex values in the dimensions sector of the code....

Great explanation

great video! Brings back memories of crashing uni sun-ray clients ;)

You can do the same on Windows, but normally the system does not outright crash and you can recover from that (with taskmanager).

Great video

You have to love it!

i understood the fork bomb at 1:00 great title

Cant you do the same thing without the pipe? It feels like f(){f&}; f should do the same job. If you want to increase the forks exponentially, just have each function run two other ones like so: f(){f&; f&}; f

so it's basically how all my recursion functions go? :))))

Pipe bomb would've been a great name for this

thanks, it was interesting!

Thanks. But the most interesting part with pipe and fork itself were not covered:( You said pipe is what actually creates a fork bomb, but why?

Noice 👌 Thanks for sharing 👍

I kinda accidentally let it loose on the uni network and it crashed the network for a few days and I got failed :(

It's tempting

Time to run it on my system

Awesomeness 🎉

Delightful

The only reason I was confused when I first saw this was that I didn't know you could use a colon as a function name. It makes much more sense as f(){f|f&};f It seems many modern 'nux systems default to limiting the number of forks a process can start now.

My roommate will love this prank

How did you replace semicolons with text?

Awesome 👍

type the command 'gnome-terminal' (or any other command that opens a bash shell) in the end of the .bashrc file and save it and then see the magic when you open a terminal.😂 You might to do it in the .zshrc file depending on the type of shell you are using (bash or zsh = Bourne Again Shell or Z shell).

Great!

are you able to pipe it multiple times inside the same command to make it crash the system faster?

when you use fish shell for several good reasons and the "expert professionals" roll their eyes at you.

This isn't a fork bomb it's a picture of a cat.

Nice didn't know you could limit number of processes for a user

Spoon Nuke next plz

Oh THAT's why you don't want everything to be run by the root user

I wonder how this does on WSL

do you need the &?

forbidden emojis are teh most powahful

hey guys i want to know what other pranks have u done like this?

fyi: i have tested this code on my android phone and it works 😂

what do you mean by "friends on linux"?

Could you please show your hotkeys for the editor?

what if i write this in my bashrc ?

Fork me, that was a good video! ;-)

you won a subscriber

shouldn't proliferating dummy processes just hang the system forever? why would it crash the system anyway?

if you set the video playing speed fast enough you can almost hear "fork me" to another very similar term

What about :(){:&;:&);: Also exponential or linear?

Ran this on production server for fun, bos didn't seem really enjoy it

i was sad when browsers started detecting and halting infinite javascript recursions

Does not :(){:&;:&} do the same thing (without pipe) ?

I remember my first attempt at a fork bomb, it was perhaps 15 years ago in high school and I wrote it in C, it didn't really work too well, I probably had some more advanced scheduler than I thought and while it slowed down my computer I was able to still kill the process. But I added a small malloc (about 4k if I remember correctly) in the loop ant it totally freezed my computer in seconds. Fun times Edit: If I had known more when I was young I'd probably done a mix of forking and daemonizing to try to hit it harder

Oh no I'm wrong, your right eyebrow is still always higher than the other one

So i got trolled in a stackoverflow question...

ah yes, for(;;){fork();} good times...

Reminds me of the prankster batch files for cmd.exe I used to make during my windows years. The simplest I managed to create (DO NOT RUN THIS) %0 >> %0 %0 With an empty line after,

Hilarious 🎉

I made a batch bomb in the 90s.

So you watched Dave's Garage and made your own fork bomb video. K.

I prefer the spoon bomb

Fork me, this is interesting!(:

"Fork me". That's what she said.

What happens if instead of piping, you start 2 background processes each time? like :(){:&:&};:

stress testing without a stop 🛑 button 😅

You can fix a lot of problems in Linux by running sudo dd if=/dev/null of=/dev/sda

Can you please tecah us these skills. Please 🙏🙏🙏

the VM setup is questional, you said you had to restart your system and the VM. sounds like you gave it too much pc resources or using some vm i never heard about before which doesnt asign a limited number of resources in order to run it.

hi :)

Systemd solution this.... Límite del 30% de procesos máximos del sistema.

It is Not exponential. it is just times 2.

Cat :3

%0|%0 is the windows version it is fun

Is your name a Daniel?

How is your eyebrow straight again

fork bombs are for dorks

"There is ways" There are.

Being an old fart, I have to point out that the fork bomb existed prior to linux, albeit with the same shell syntax you describe. en.wikipedia.org/wiki/Fork_bomb

What if i run it on an instance 🥸