How to kill a zombie (process)

How to kill a zombie in one row. Execute the below command as root.

# kill -HUP `ps -A -ostat,ppid | grep -e '^[Zz]' | awk '{print $2}'`

Other good-to-know commands:

Who is a zombie?
# ps aux | awk '{ print $8 " " $2 }' | grep -w Z

Kill the zombie.
# kill -9 PID

Kill the zombie's parent (process).
# ps ef

Find the zombie.

# ps aux | grep 'Z'

or

# ps aux | grep 'defunct'

which gives

USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND

backuppc 12397 0.0 0.0 0 0 ? Z Apr16 1:33 [BackupPC_dump] <defunct>

backuppc 12749 0.0 0.0 0 0 ? Z Apr13 6:44 [BackupPC_dump] <defunct>

backuppc 16986 0.0 0.0 0 0 ? Z Apr16 2:28 [BackupPC_dump] <defunct>

root 19409 0.0 0.0 103308 860 pts/1 S+ 07:59 0:00 grep Z

root@mach217 ~/ [0]#

# pstree -H 12397 -p

which gives eg

init(1)---cnid_metad(1311)---cnid_dbd(5145)

Kill immediately with

# kill -9 5145

For the other kind of zombies

Smash, cut off, shoot, bash, or whatever, its head.
Fire may work as well in some scenarios in order immobilize them.