An administrator is troubleshooting to determine why backups are failing on a particular server. The administrator runs the ps command and analyzes the following output. The administrator runs kill…

kill -9 --force is not a valid option for the kill command; additionally, SIGKILL is already the most forceful signal and cannot be caught or ignored, yet it still has no effect on zombie processes.

A zombie process appears in ps output with state 'Z' (defunct) - it has completed execution but its exit status has not been collected by the parent process via wait(). Because the process itself is no longer alive, sending any signal including SIGKILL does nothing; the process entry persists until the parent reaps it or the system is rebooted, which causes init/systemd to reparent and clean up orphaned zombies.

An out-of-memory condition would manifest as the OOM killer terminating processes, not as a process that ignores SIGKILL; memory pressure does not cause a process to become un-killable.

renice changes the scheduling priority of a running process to reduce CPU usage, but it does not address a zombie process that is already dead and consuming no CPU or memory resources.