zombie process | ps aux -> Z | kill -s SIGCHLD

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How do I see if there are zombie processes on a system?

Run “ps aux” and look for a Z in the STAT column.
How do I remove zombie processes from a system?
Well, first you can wait. It’s possible that the parent process is intentionally leaving the process in a zombie state to ensure that future children that it may create will not receive the same pid. Or perhaps the parent is occupied, and will reap the child process momentarily.
Secondly, you can send a SIGCHLD signal to the parent (“kill -s SIGCHLD <ppid>“). This will cause well-behaving parents to reap their zombie children.

Finally, you can kill the parent process of the zombie. At that point, all of the parent’s children will be adopted by the init process (pid 1), which periodically runs wait() to reap any zombie children.
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kernel may not be able to successfully kill the process in some situations. If the process is waiting for network or disk I/O, the kernel won’t be able to stop it. Zombie processes and processes caught in an uninterruptible sleep cannot be stopped by the kernel, either. A reboot is required to clear those processes from the system.


You can clean up a zombie process by killing its parent process with the following command:

kill -HUP $(ps -A -ostat,ppid | grep -e '[zZ]'| awk '{ print $2 }')

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