how to check zombie process in ubuntu

Find the zombie

$ ps aux | grep 'Z'

What you get is Zombies and anything else with a Z in it, so you will also get the grep:

USER       PID     %CPU %MEM  VSZ    RSS TTY      STAT START   TIME COMMAND
usera      13572   0.0  0.0   7628   992 pts/2    S+   19:40   0:00 grep --color=auto Z
usera      93572   0.0  0.0   0      0   ??       Z    19:40   0:00 something

Find the zombie’s parent:

$ pstree -p -s 93572

Will give you:

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

kill process ubuntu

sudo kill -9 process_id

$ sudo kill -1 7667

$ sudo kill -9 1317

Kill all processes you can kill.

 $ sudo  kill -9 -1

working your way up to -9