- Zombie processes take up room in your process list. Ubuntu Linux will eventually purge these processes from the list, but they add additional complexity to your process queries through the extra space they take. Additionally, an extremely active system may run out of available process handles if these processes are not purged.
- Zombies can be identified by opening a new terminal window and typing "ps -el | grep 'Z'" (without the quotation marks). All processes in a "zombie" status will be displayed. Zombie processes will have the text <defunct> in the label, clearly identifying them. Additionally, the PPID, or Parent Process ID, of the application that spawned the zombie process is displayed.
- Ubuntu Linux routinely purges zombie processes from the system automatically and no action is required. You can purge zombie processes manually by sending a SIGCHILD command to the parent of the zombie. To do this, type "kill -s SIGCHLD <pid>" (without the quotation marks). Replace <pid> with the ID number of the zombie's parent process, which is displayed in the list that identifies the process as a zombie.
- A zombie can be orphaned when its parent process dies suddenly and it has not been reaped by the system. The system will reap this process automatically, but you can quickly regain control of the situation and reap the process by restarting the application or process that originally spawned it.
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