How to kill only if process is running?

Question

Currently, I use a line like this in my sh script file:

kill $(ps aux | grep -F 'myServer' | grep -v -F 'grep' | awk '{ print $2 }')

But I wonder how to call it only if process (myServer here) is running?

it's impossible to call `kill` only when the process is running, because there is a race condition between the test and the invocation of `kill` (it's possible the process stopped for another reason in that short time). You should use `pkill` or `killall` which do exactly the same as what you try to do, but with less to type (and probably some other advantages too). — JanC, May 10 '16 at 12:26
Related: [How to let 'kill' ignore processes that are not alive](https://superuser.com/a/155915/500826). Also, you can avoid ps+grep x2 with `pgrep` — Pablo Bianchi, Jul 05 '22 at 07:22

score 32 · Answer 1 · answered Oct 03 '14 at 13:17

32

I usually just use pgrep and pkill

if pgrep myServer; then pkill myServer; fi

answered Oct 03 '14 at 13:17

boutch55555

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Why not `pkill myServer` or `killall -q myServer`? There's no downside to attempting to kill inexistent processes. – David Foerster Oct 03 '14 at 15:57
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It will not exit 0 if there is no process to kill, so it could break scripts. – boutch55555 Oct 06 '14 at 15:00
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Append `|| true` then. – David Foerster Oct 06 '14 at 15:01
True, but you won't have the flexibility to add a else to inform you the process was already dead. – boutch55555 Oct 06 '14 at 16:57
What about `if ! killall -q myServer; then echo ERROR; fi`? – David Foerster Oct 06 '14 at 17:07
@DavidFoerster: the `|| true` top is excellent, thanks! – WoJ Aug 12 '21 at 10:32

score 10 · Answer 2 · answered Jan 31 '12 at 13:05

10

You could kill processes by name using pkill or killall, check their man pages.

answered Jan 31 '12 at 13:05

enzotib

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yes, unlike `kill`, this kills only if process is running. For example `pkill -u myuser -f myprocess\.[0-9]+` – Chase T. Jun 26 '17 at 18:50

score 9 · Answer 3 · edited Jun 27 '17 at 15:51

9

A bit of a different approach would be something like this:

killall PROCESS || echo "Process was not running."

This will avoid the 1 Error-Code returned from the killall command, if the process did not exist. The echo part will only come into action, if killall returns 1, while itself will return 0 (success).

edited Jun 27 '17 at 15:51

Anwar

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answered Mar 27 '17 at 07:03

codepleb

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Using `killall -q` is better – Anwar Jun 27 '17 at 15:51
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Warning, `killall -q` isn't supported on all unix flavors, macOS Catalina still doesn't have it. – tresf Oct 04 '19 at 14:36
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@tresf my ubuntu distribution doesn't have it either – FooBar Sep 25 '20 at 22:00

score 1 · Answer 4 · answered May 10 '16 at 11:42

1

Check if the process exist with pidof. If it does, kill it:

(! pidof process_name) || sudo kill -9 $(pidof process_name)

Exit code is always 0 after executing the above command.

answered May 10 '16 at 11:42

Juuso Ohtonen

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score 0 · Answer 5 · answered Mar 06 '20 at 19:19

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Use pkill with option -f

pkill -f myServer

Option -f is the pattern that is normally matched against the process name.

answered Mar 06 '20 at 19:19

Chase T.

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score 0 · Answer 6 · edited Jul 05 '22 at 07:14

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pkill -9 -f jboss || true

or

pkill -9 -f tomcat || true

edited Jul 05 '22 at 07:14

Pablo Bianchi

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answered Sep 13 '21 at 17:07

vinitha s

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score 0 · Answer 7 · edited Jul 05 '22 at 07:17

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Small Script I have created with R&D. I hope you will like it

#!/bin/bash

echo "Enter the process name:"
read $proc_name
if pgrep $proc_name; then
  echo "$proc_name running "
  pkill $proc_name
  echo "$proc_name got killed"
else
  echo "$proc_name is not running/stopped "
fi

save it with some name like script.sh then

chmod +x script.sh
./script.sh

Then give your process name.

Note: I have tried many times with this and its fine.

edited Jul 05 '22 at 07:17

Pablo Bianchi

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answered Oct 03 '14 at 14:01

Raja G

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May I know whats wrong with this script and -ve vote needs an explanation please. – Raja G Oct 05 '14 at 05:33
Nothing wrong with this script... +1 – WinEunuuchs2Unix Nov 13 '16 at 01:26

score -1 · Answer 8 · answered Jan 31 '12 at 12:41

-1

try using:

sudo kill `pidof process_name`

where process_name is the name of the process you want to kill. What's great about this is that pidof will list the pid's of all processes matching the given name. Since kill accepts multiple pid's, it will kill of all of them in a single whim.

Let me know if this helps.

answered Jan 31 '12 at 12:41

amandion

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What if list is empty? (my main point was not to call kill at all if possible) – myWallJSON Jan 31 '12 at 12:44
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If the list is empty, kill will return an error code 1 and not kill anything. It would be the equivalent as trying to call kill with no arguments. You could add an if statement that first checks if pidof returns an empty list. If it does not return an empty list, call ``kill `pidof process_name``. If it does return an empty list, skip the kill call. – amandion Jan 31 '12 at 12:59

score -1 · Answer 9 · answered Jan 31 '12 at 13:18

-1

I would use:

ps x --no-header -o pid,cmd | awk '!/awk/&&/myServer/{print $1}' | xargs -r kill

The xargs -r tells to run kill only if there is input. The ps --no-header -eo pid,cmd gets the output into a better format for parsing.

answered Jan 31 '12 at 13:18

Arcege

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How to kill only if process is running?

9 Answers9