So, it uses the fact that bash allows functions with non-alphanumeric names, in this case it defines a function called :. If we rename that to, for example bomb it becomes a little clearer:
bomb(){ bomb | bomb& };bomb
This defines a function that calls itself piped into a version of itself in a separate, background, process (that’s what the & does) and then calls that function. Calling itself means the function never ends (it’s essentially a recursive version of an infinite loop) and the extra background process that is created each time it’s called means that it just keeps exponentially creating new processes that don’t exit and each of which infinitely forks off more processes until the OS runs out of resources (unless you use ulimit to set per-session/per-user process limits - this may even be done by default on some distros these days, it’s been a while since I looked)
Thank you, this is the first time I’ve ever actually seen the fork bomb described in a way that makes sense. I knew what it did but I didn’t understand how the input string caused it, it was effectively just a magic rune of crashing to me. This is a great explanation.
People do it as a stress test of their system. A goodly OS should be able to stop it before it crashes the system, otherwise it won’t cause much damage (depends on what else you’re doing when it crashes)
All my computer is for is drawing pictures, making noise and occasionally doing internet stuff that’s too obnoxious to do from my phone. I don’t game or code or torrent. Really mostly just Blender and PrusaSlicer.
In easier terms: it’s a script function, which when executed starts itself twice (recursion), leading to an infinite loop that takes up resources, and - in the worst case - causes a freeze or crash. Due to its cryptic code, an unknowing user might not know what they get themselves into when they run it.
Can you explain for us casuals?
So, it uses the fact that bash allows functions with non-alphanumeric names, in this case it defines a function called
:. If we rename that to, for examplebombit becomes a little clearer:bomb(){ bomb | bomb& };bombThis defines a function that calls itself piped into a version of itself in a separate, background, process (that’s what the
&does) and then calls that function. Calling itself means the function never ends (it’s essentially a recursive version of an infinite loop) and the extra background process that is created each time it’s called means that it just keeps exponentially creating new processes that don’t exit and each of which infinitely forks off more processes until the OS runs out of resources (unless you useulimitto set per-session/per-user process limits - this may even be done by default on some distros these days, it’s been a while since I looked)Thank you, this is the first time I’ve ever actually seen the fork bomb described in a way that makes sense. I knew what it did but I didn’t understand how the input string caused it, it was effectively just a magic rune of crashing to me. This is a great explanation.
So does it actually hurt anything?
It might freeze up your computer.
Worse case you just gotta reboot your PC.
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Sounds awful. Since I switched to Mint my computer has only crashed when I got out of hand with Blender, I can’t see myself doing it on purpose.
People do it as a stress test of their system. A goodly OS should be able to stop it before it crashes the system, otherwise it won’t cause much damage (depends on what else you’re doing when it crashes)
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All my computer is for is drawing pictures, making noise and occasionally doing internet stuff that’s too obnoxious to do from my phone. I don’t game or code or torrent. Really mostly just Blender and PrusaSlicer.
In easier terms: it’s a script function, which when executed starts itself twice (recursion), leading to an infinite loop that takes up resources, and - in the worst case - causes a freeze or crash. Due to its cryptic code, an unknowing user might not know what they get themselves into when they run it.