pkill can’t kill processes with parent process id 1

I want to kill the following processes using

pkill "run_tcp_sender.sh"

or
pkill -SIGKILL  "run_tcp_sender.sh"


    root     14320     1  0  2012 ?        00:00:00 bash run_tcp_sender.sh 138.96.116.22
    root     14323     1  0  2012 ?        00:00:00 bash run_tcp_sender.sh 138.96.116.22
    root     14325     1  0  2012 ?        00:00:00 bash run_tcp_sender.sh 138.96.116.22
    root     14327     1  0  2012 ?        00:00:00 bash run_tcp_sender.sh 138.96.116.22
    root     14328     1  0  2012 ?        00:00:00 bash run_tcp_sender.sh 138.96.116.22
    root     14330     1  0  2012 ?        00:00:00 bash run_tcp_sender.sh 138.96.116.22

but it is useless
the processes remain there
what is wrong with my command?

BTW:
I can use the following command to achieve what I want

kill -9 $(ps -ef|grep "run_tcp"|grep -v "grep"|awk '{print $2}')

Answers:

Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

pkill by default sends the SIGTERM signal to processes to stop. Here’s a list of the signals you can send a process. You can send them by name or number typically:

$ kill -l
 1) SIGHUP       2) SIGINT       3) SIGQUIT      4) SIGILL       5) SIGTRAP
 6) SIGABRT      7) SIGBUS       8) SIGFPE       9) SIGKILL     10) SIGUSR1
11) SIGSEGV     12) SIGUSR2     13) SIGPIPE     14) SIGALRM     15) SIGTERM
16) SIGSTKFLT   17) SIGCHLD     18) SIGCONT     19) SIGSTOP     20) SIGTSTP
21) SIGTTIN     22) SIGTTOU     23) SIGURG      24) SIGXCPU     25) SIGXFSZ
26) SIGVTALRM   27) SIGPROF     28) SIGWINCH    29) SIGIO       30) SIGPWR
31) SIGSYS      34) SIGRTMIN    35) SIGRTMIN+1  36) SIGRTMIN+2  37) SIGRTMIN+3
38) SIGRTMIN+4  39) SIGRTMIN+5  40) SIGRTMIN+6  41) SIGRTMIN+7  42) SIGRTMIN+8
43) SIGRTMIN+9  44) SIGRTMIN+10 45) SIGRTMIN+11 46) SIGRTMIN+12 47) SIGRTMIN+13
48) SIGRTMIN+14 49) SIGRTMIN+15 50) SIGRTMAX-14 51) SIGRTMAX-13 52) SIGRTMAX-12
53) SIGRTMAX-11 54) SIGRTMAX-10 55) SIGRTMAX-9  56) SIGRTMAX-8  57) SIGRTMAX-7
58) SIGRTMAX-6  59) SIGRTMAX-5  60) SIGRTMAX-4  61) SIGRTMAX-3  62) SIGRTMAX-2
63) SIGRTMAX-1  64) SIGRTMAX

So you’re sending signal # 15. If the processes are not responding to this signal then you may need to use signal #9, pkill -SIGKILL.

From the man page of pkill:

-signal

  Defines the signal to send to each matched process.  Either the
  numeric  or  the symbolic signal name can be used.  (pkill only.)

Issues with pkill

The OP mentioned that he was unsuccessful in getting pkill -SIGKILL "run_tcp" to work. We initially thought that the issue had to do with pkill potentially killing itself before it had finished killing all the “run_tcp” processes.

But that was hard to accept given a foot note in the pkill man page:

The running pgrep or pkill process will never report itself as a match.

In addition to that, @Gilles left a comment basically saying the same thing, that pkill just does not kill itself. Then he gave us a pretty big clue as to what was actually going on.

Here’s an example that demonstrates what the OP and myself were missing:

step 1 – make a sleepy.bash script

#!/bin/bash

sleep 10000

step 2 – load up some fake sleep tasks
$ for i in `seq 1 5`;do bash sleepy.bash & done
[1] 12703
[2] 12704
[3] 12705
[4] 12706
[5] 12707

step 3 – check the running tasks
$ ps -eaf|egrep "sleep 10000|sleepy"
saml     12703 29636  0 21:48 pts/16   00:00:00 bash sleepy.bash
saml     12704 29636  0 21:48 pts/16   00:00:00 bash sleepy.bash
saml     12705 29636  0 21:48 pts/16   00:00:00 bash sleepy.bash
saml     12706 29636  0 21:48 pts/16   00:00:00 bash sleepy.bash
saml     12707 29636  0 21:48 pts/16   00:00:00 bash sleepy.bash
saml     12708 12704  0 21:48 pts/16   00:00:00 sleep 10000
saml     12709 12707  0 21:48 pts/16   00:00:00 sleep 10000
saml     12710 12705  0 21:48 pts/16   00:00:00 sleep 10000
saml     12711 12703  0 21:48 pts/16   00:00:00 sleep 10000
saml     12712 12706  0 21:48 pts/16   00:00:00 sleep 10000

step 4 – try using my pkill
$ pkill -SIGTERM sleepy.bash

step 5 – what happened?

Doing the ps command from above, we see that none of the processes were killed, just like the OPs issue. What’s going on?

Turns out this is an issue in how we were attempting to make use of pkill. The command:

pkill -SIGTERM "sleepy.bash"

was looking for a process by the name of “sleepy.bash”. Well there aren’t any processes by that name. There’s processes that are named “bash sleepy.bash” though. So pkill was looking for processes to kill and not finding any and then exiting.

So if we slightly adjust the pkill we’re using to this:

$ pkill -SIGTERM -f "sleepy.bash"
[1]   Terminated              bash sleepy.bash
[2]   Terminated              bash sleepy.bash
[3]   Terminated              bash sleepy.bash
[4]-  Terminated              bash sleepy.bash
[5]+  Terminated              bash sleepy.bash

Now we get the effect we were looking for. What the difference? We made use of the -f switch to pkill which makes pkill use the entire command line path when matching vs. just the process name.

from pkill man page

-f      The pattern is normally only matched against the process name.  
        When  -f  is  set, the full command line is used.

Alternative methods

kill, ps

This method is pretty verbose but does the job as well:

kill -9 $(ps -ef|grep "run_tcp"|grep -v "grep"|awk '{print $2}')

pgrep w/ pkill & killall

You can use either pgrep to feed a list of PIDs to pkill or make use of killall instead.

Examples

# pgrep solution
$ pgrep "run_tcp" | pkill -SIGKILL

# killall
killall -SIGKILL -r run_tcp

References

Method 2

This is unrelated to the parent process ID. The problem is simply that you are killing all the processes running run_tcp_sender.sh, but you have no such processes — the processes you’re interested in are running bash.

You can instruct pkill to match on the whole command line:

pkill -f '^bash run_tcp_sender.sh'

Another approach would be to kill all the processes that have the script open. That could make collateral damage, e.g. to an editor that was just opening the script.
fuser -k /path/to/run_tcp_sender.sh

As long as you aren’t editing the script as root, killing only root’s processes would solve that issue:
kill $(lsof -uroot /path/to/run_tcp_sender.sh)

Method 3

Below command is easy and worked perfect for me! The above suggestions didn’t work or not efficient (too complicated).

kill -9 $(pgrep -f somepattern)

I recommend to see which processes match before running kill command
pgrep -af somepattern

Method 4

Try to kill process with “signal 9” , i mean use

kill -9 PID

normally signal 9 is not recommended for killing databases engine

if process remains in memory, some i/o lost or process is waiting for i/o completion


All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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