Yes, at least on linux, the os sends a signal (namely SIGSEGV) to the process, which the process may or may not handle. But kill also sends signals (including S

Yes, at least on linux, the os sends a signal (namely SIGSEGV) to the process, which the process may or may not handle. But kill also sends signals (including SIGSEGV if you specify), so the answer to your question is that it's not really either/or but both. (edit to add: note that it isn't trivial to handle seg fault in particular because unless you do some trickery you return to the same instruction that caused the segfault, and just get another segfault see e.g.: https://stackoverflow.com/questions/2663456/how-to-write-a-signal-handler-to-catch-sigsegv https://stackoverflow.com/questions/2663456/how-to-write-a-s... )