Kill Processes – Best Way to Kill Processes Created by Bash Script

killlinuxprocessshell-script

I have a script running in a server and it will create many sub-processes( around 800 ). I want to kill them all in one stretch. Below is the ps information.

root     26363  0.0  0.0 119216  1464 ?        Ss   Mar02   0:00 SCREEN -S website_status
root     26365  0.0  0.0 108472  1844 pts/12   Ss   Mar02   0:00  \_ /bin/bash
root      4910  0.0  0.0 161684  1956 pts/12   S    Mar02   0:00      \_ su webmon
webmon    4939  0.0  0.0 108472  1924 pts/12   S+   Mar02   0:00          \_ bash
webmon    1094  3.4  0.0 107256  2432 pts/12   S    05:37   2:26              \_ sh /home/webmon/scripts/for_html/website/website_status.sh
webmon    5159  0.0  0.0 100956  1288 pts/12   S    05:37   0:00                  \_ mysql -vvv -h 192.168.12.38 -uwebmon -px xxxxxxxxxxxxx -e show processlist;
webmon    5160  0.0  0.0 103252   816 pts/12   S    05:37   0:00                  \_ grep in set
webmon    5161  0.0  0.0 105952   900 pts/12   S    05:37   0:00                  \_ awk {print $1}
webmon   12094  0.0  0.0 100956  1288 pts/12   S    05:37   0:00                  \_ mysql -vvv -h 192.168.12.38 -uwebmon -px xxxxxxxxxxxxx -e show processlist;
webmon   12095  0.0  0.0 103252   820 pts/12   S    05:37   0:00                  \_ grep Sleep -c
webmon   15044  0.0  0.0  60240  3004 pts/12   S    05:37   0:00                  \_ ssh -q 192.168.12.38 uptime | grep -o load.* | cut -f2 -d:
webmon   15166  0.0  0.0 100956  1292 pts/12   S    05:37   0:00                  \_ mysql -vvv -h 192.168.12.38 -uwebmon -px xxxxxxxxxxxxx -e show processlist;
webmon   15167  0.0  0.0 103252   816 pts/12   S    05:37   0:00                  \_ grep in set
webmon   15168  0.0  0.0 105952   900 pts/12   S    05:37   0:00                  \_ awk {print $1}
webmon   18484  0.0  0.0 100956  1288 pts/12   S    05:38   0:00                  \_ mysql -vvv -h 192.168.12.38 -uwebmon -px xxxxxxxxxxxxx -e show processlist;
webmon   18485  0.0  0.0 103252   816 pts/12   S    05:38   0:00                  \_ grep in set
webmon   18486  0.0  0.0 105952   900 pts/12   S    05:38   0:00                  \_ awk {print $1}
webmon   25110  0.0  0.0  60240  3008 pts/12   S    05:38   0:00                  \_ ssh -q 192.168.12.38 uptime | grep -o load.* | cut -f2 -d:
webmon    2598  0.0  0.0 100956  1292 pts/12   S    05:38   0:00                  \_ mysql -vvv -h 192.168.12.38 -uwebmon -px xxxxxxxxxxxxx -e show processlist;
webmon    2599  0.0  0.0 103252   816 pts/12   S    05:38   0:00                  \_ grep in set
webmon    2600  0.0  0.0 105952   900 pts/12   S    05:38   0:00                  \_ awk {print $1}

Killing of script only didn't work out, what is the best and fastest way if I have many sub-process here?

Best Answer

Have you tried pkill -signal -P ppid?

From the pkill manual:

pkill - look up or signal processes based on name and other attributes

-signal Defines the signal to send to each matched process

-P ppid Only match processes whose parent process ID is listed

If you wanted to kill 2432, and all its children, you should first try pkill -15 -P 2432, and if that doesn't work and you're willing to use the nuclear option: pkill -9 -P 2432.

Related Solutions

Shell – How to kill two or more processes with one kill command

First of all, check out pkill. You can kill off any number of process given their name:

pkill java

You can even use the full command with arguments as part of the search

pkill -f some_string_in_arguemnts

Secondly, your construct with xargs will work just fine for multiple PID's as long as they are piped in as either space or newline separated numbers.

Process – Why pkill Can’t Kill Processes with Parent Process ID 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