Kill processes that cannot be killed

In two cases, kill is not allowed:

First, the process has become a zombie process. When its parent process recycles it or kill its parent process, it will be invisible to the PS output;

Second, the process is in the kernel state, and the Linux process runs in the kernel andUserWhen the process enters the Kernel Status, all signals, including sigkil, are blocked. Therefore, kill-9 becomes invalid at this time.

Check whether the process is dead (use the "Ps" command to return the "defunct" process)


If you do not kill it, it is normal that it does not occupy system resources.


In addition, the process is in the "kernel mode" (core State) and is waiting for unattainable resources. Processes in the core state ignore all signal processing, so these processes that have been in the core state can only be implemented by restarting the system. Processes in Unix/Linux are in two states: user and core. Only processes in the user State can be terminated with the "kill" command.