When is sigkill generated

You definitely could argue that some P0 activity is in process context, but your user mode code cannot do anything about it. A kernel-only process a zombie for example cannot receive a signal, because it does not poll for them. Maybe this is the source of confusion. The kernel "part" does stuff, the user land part does not do "stuff" — jim mcnamara. It has to be able to access the cpu. True for all signals. Community Bot 1 1 1 silver badge. Victor Burenkov Victor Burenkov 7 7 bronze badges.

Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Podcast The first ten years of our programming lives. Upcoming Events. Featured on Meta. Now live: A fully responsive profile. For example, if the program creates temporary files, it should handle the other termination requests by deleting the temporary files.

It cannot be handled or ignored, and is therefore always fatal. It is also not possible to block this signal.

This signal is usually generated only by explicit request. The system will generate SIGKILL for a process itself under some unusual conditions where the program cannot possibly continue to run even to run a signal handler. I realized that having a consolidated book which explains these terms clearly is better than searching loads of webpages.

I did the later since i had kept my unix os book away from my reach. To my disappointment, there was no single link that listed out all differences in an orderly fashion.

Hence, in this post, i wish to delineate these terms by consolidating my findings from stackoverflow, wikipedia and other unix internals websites. The "kill -9" command in linux generates the same signal. However, this signal can be handled, ignored or caught in code. If the signal is not caught by a process, the process is killed. Also, this is used for graceful termination of a process.

The default action is to terminate gracefully. It can be handled, ignored or caught in code. This too, can be handled, ignored or blocked. A process has to explicitly handle this signal for it to work.