System information as of Fri Mar  9 19:40:01 KST 2012

  System load:    0.59               Processes:           167
  Usage of /home: 23.0% of 11.00GB   Users logged in:     1
  Swap usage:     0%                 IP address for eth1:

  => There is 1 zombie process.

  Graph this data and manage this system at https://landscape.canonical.com/

10 packages can be updated.
4 updates are security updates.

Last login: Fri Mar  9 10:23:48 2012
a@SERVER:~$ ps auxwww | grep 'Z'
usera     13572  0.0  0.0   7628   992 pts/2    S+   19:40   0:00 grep --color=auto Z

How to find that zombie process?

  • why dont you open the system monitor and search for the zombie process?
    – dlin
    Jul 6, 2012 at 8:00
  • 9
    How to do that on a headless no-X server?
    – SabreWolfy
    Feb 27, 2013 at 10:01
  • 2
    Surprising that no answer below actually says that there's no zombie process in the system based on the above output. If there really was one, the ps auxwww | grep 'Z' command should have shown a process in a Z state. The "system information" saying => There is 1 zombie process. seems to be a bug. Either that, or there's missing information in the question.
    – arielf
    Jun 6, 2018 at 22:44

9 Answers 9


To kill a zombie (process) you have to kill its parent process (just like real zombies!), but the question was how to find it.

Find the zombie (The question answered this part):

a@SERVER:~$ ps aux | grep 'Z'

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

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:

a@SERVER:~$ pstree -p -s 93572

Will give you:


In this case you do not want to kill that parent process and you should be quite happy with one zombie, but killing the immediate parent process 5145 should get rid of it.

Additional resources on askubuntu:

  • 3
    The result you show in your answer is the the grep command itself, not the zombie process. It is the same mis-interpratation as Pablo made in his answer. The answer by Rinzwind below does actually look for the zombie process and list them. Another option could be to grep for "defunct"
    – FvD
    Jul 23, 2013 at 23:24
  • 1
    pstree -H your_desired_pid -p Apr 9, 2014 at 16:45
  • 1
    This is a great answer! It is still valid today! I was able to find my zombie process and kill its parent process without any problems. Thank you!
    – Terrance
    Oct 29, 2015 at 5:30
  • 2
    if you do not have pstree installed, ps wauxf does the same thing
    – JDS
    Mar 18, 2016 at 14:10
  • 2
    I'd add the -w flag. As in grep -w Z to only match the word Z and avoid clutter.
    – Karl Pokus
    Jan 7, 2020 at 10:09

Even though this question is old I thought everyone deserved a more reliable answer:

ps axo pid=,stat=

This will emit two whitespace-delimited columns, the first of which is a PID and the second of which is its state.

I don't think even GNU ps provides a way to filter by state directly, but you can reliably do this with awk

ps axo pid=,stat= | awk '$2~/^Z/ { print }'

You now have a list of PIDs which are zombies. Since you know the state it's no longer necessary to display it, so that can be filtered out.

ps axo pid=,stat= | awk '$2~/^Z/ { print $1 }'

Giving a newline-delimited list of zombie PIDs.

You can now operate on this list with a simple shell loop

for pid in $(ps axo pid=,stat= | awk '$2~/^Z/ { print $1 }') ; do
    echo "$pid" # do something interesting here

ps is a powerful tool and you don't need to do anything complicated to get process information out of it.

(Meaning of different process states here - https://unix.stackexchange.com/a/18477/121634)

  • 2
    awk is also a powerful tool which doesn't just split text but can also match it. +1 ... the others used grep where it's unnecessary and imprecise. May 26, 2014 at 12:28
  • so now that i have list of zombie processes. how do i kill them?
    – chovy
    Dec 21, 2015 at 4:58
  • @chovy: It will depend, but generally involves killing or signalling the parent. Other answers here go in to that. From within the loop shown above you can find the parent pid like this: ps -p "$pid" -opid=,ppid=
    – Sorpigal
    Dec 22, 2015 at 14:50
  • if i will the parent won't it kill all its child processes? I just want to kill the one zombie process. I know the ppid.
    – chovy
    Dec 23, 2015 at 1:32
  • 1
    I do suggest to add ppid= to the options list, so no need to use a separate command to obtain ppid. Apr 4, 2019 at 6:26

Less is more though:

ps afuwwx | less +u -p'^(\S+\s+){7}Z.*'

That's like, give me a forest (tree) of all users' processes in a user oriented format with unlimited width on any tty and show it to me at half a screen above where it matches the case that the 8th column contains a Z, and why not highlight the whole line.

User oriented format seems to mean: USER, PID, %CPU, %MEM, VSZ, RSS, TTY, STAT, START, TIME, COMMAND so the Zombie status will show up in the 8th column.

You can throw in an N before the p if you want line numbers, and a J if you want an asterisk at the match. Sadly if you use G to not highlight the line that asterisk will not show, though J creates space for it.

You end up getting something that looks like:

  root      2919  0.0  0.0  61432  5852 ?      Ss Jan24 0:00 /usr/sbin/sshd -D
  root     12984  0.0  0.1 154796 15708 ?      Ss 20:20 0:00  \_ sshd: lamblin [priv]
  lamblin  13084  0.0  0.0 154796  9764 ?      S  20:20 0:00      \_ sshd: lamblin@pts/0
* lamblin  13086  0.0  0.0  13080  5056 pts/0  Z  20:20 0:00          \_ -bash <defunct>
  lamblin  13085  0.0  0.0  13080  5056 pts/0  Ss 20:20 0:00          \_ -bash
  root     13159  0.0  0.0 111740  6276 pts/0  S  20:20 0:00              \_ su - nilbmal
  nilbmal  13161  0.2  0.0  13156  5004 pts/0  S  20:20 0:00                  \_ -su
  nilbmal  13271  0.0  0.0  28152  3332 pts/0  R+ 20:20 0:00                      \_ ps afuwwx
  nilbmal  13275  0.0  0.0   8404   848 pts/0  S+ 20:20 0:00                      \_ less +u -Jp^(\S+\s+){7}Z.*

You could follow this up with (and it'll detect if your terminal likes -U Unicode or -A Ascii):

pstree -psS <PID LIST>

OR just, you know, use the up-arrow in less to follow that tree/forest through the hierarchy; which is what I was recommending with the "Less is more" approach.

  • 1
    I like how the first command also selects the found process. Thank you!
    – ilyazub
    Oct 20, 2020 at 17:22
  • @IlyaZub If only I could show how that looks without needing to use a screenshot.
    – dlamblin
    Oct 20, 2020 at 17:55
  • Wow, thanks for this little known less fu .. 😏
    – eMPee584
    Aug 1, 2023 at 20:23

I usually find them on my server with

ps aux | grep 'defunct'

ps aux | awk '{ print $8 " " $2 }' | grep -w Z

From: http://www.cyberciti.biz/tips/killing-zombie-process.html

From the comments an improved one:

for p in $(ps jauxww | grep Z | grep -v PID | awk '{print $3}'); do
    for every in $(ps auxw | grep $p | grep cron | awk '{print $2}'); do
        kill -9 $every;

Careful though: this one also kills the proces.

  • still returns nothing. I think my way also wasn't wrong.
    – Pablo
    Mar 9, 2012 at 10:51
  • The 2nd example is hellishly unreliable and the former is needlessly verbose (try ps axo pid=,stat= | awk '$2~/Z/ {print $1}' instead).
    – Sorpigal
    Apr 7, 2019 at 11:52

While both dlambin's and Sorpigal's answers are excellent and accomplish the job nicely, I just wanted to document my finding of how to use awk to find the STAT column when changing between ps output formats, instead of hard-coding it:

ps au | awk '{
    if (NR==1) {
        for (i=1; i<=NF; i++) {
            if ($i=="STAT")
    } else if ($stat~/^Z/)

This will list all processes in ps's "user-oriented format" and pipe into awk. On the header line (NR=record number == 1) it will walk all fields (up to NF=number of fields) and store the field number where the string "STAT" matches in the variable stat, then proceeding to print the line. For all other records (lines), it will check that column for a regex match of starting with a capital Z, only then printing the line.

Condensed version:

ps au|awk '{if(NR==1){for(i=1;i<=NF;i++){if($i=="STAT")stat=i};print}else if($stat~/^Z/)print}'

I suggest you this command:

ps aux | awk '"[Zz]" ~ $8 { printf("%s, PID = %d\n", $8, $2); }'
  • 2
    Using aux and munging strings out of it is needlessly unreliable when you can use -o and request exactly what you want. Use ps ax -o pid=,stat= | awk '$2 ~ "[Zz]" { printf("%s, PID = %d\n", $2, $1); }' instead.
    – Sorpigal
    Feb 23, 2018 at 20:16

To list process zombies, try this command:

ps j | awk '$7 ~ "Z"'

You may need to change $7 depending on your operating system.

This also will return the list of their parent process ids (PPID).

To try to kill the zombies (after testing the above command), try:

kill -9 $(ps j | awk 'NR>1 && $7 ~ "Z" {print $2}')

To identify their parents, try with pstree, like:

$ ps j | awk 'NR>1 && $7 ~ "T" {print $2}' | xargs -L1 pstree -sg
  • Resorting to stripping one column out of the j format for this is needlessly complicated. Use -o to select what you want instead.
    – Sorpigal
    Feb 23, 2018 at 20:09
  • 3
    ps j doesn't print all processes in the system. It only lists the current user procs (in BSD jobs style) so it may miss zombie processes.
    – arielf
    Jun 6, 2018 at 22:34

why we're not telling "ps" what info we want to get provided? let's have a try:

read zSTAT zPPID zPID zSTAT zCMD <<< $(ps -xao stat,ppid,pid,cmd|awk '$1=="Z" {print $1" "$2" "$3" "$4}')
[[ ! -z ${zPPID} ]] && echo "Zombie found! PID: "${zPID}" ("${zCMD}"), Parent to kill: "${zPPID}

this way is pretty quick and works fine. but careful! The system is marking a lot of processes for short time as zombie, some ms later they are reaped and gone... so make sure to count up a variable and only react on zombies which are not reaped after the third detection in a row... then i have to kill the parent process because the cpu is heating up by running on highest frequency, consuming a lot of electrical power for a parent process that is no longer working as expected...

checking if the zombie is reaped or not can be quicker if we only check one parameter:

zombie=$(ps -xao pid|awk '$1=="'${zPID}'" {print $1}')
[[ ! -z ${zombie} ]] && sudo kill -KILL ${zPPID}

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