How to shield the kill output [duplicate]

Answer 1

The message isn't coming from either kill or the background command, it's coming from bash when it discovers that one of its background jobs has been killed. To avoid the message, use disown to remove it from bash's job control:

sleep 20 &
PID=$!
disown $PID
kill -9 $PID

Answer 2

I was able to accomplish this by redirecting the output of the command that I am running in the background. In your case it would look like:

sleep 20 >>${LOG_FILE} 2>&1 &

... or if you do not want a log file:

sleep 20 &> /dev/null &

Then, when you want to kill that background process' PID, it will not show on standard out.

Answer 3

Another way to disable job notifications is to put your command to be backgrounded in a sh -c 'cmd &' construct.

#!/bin/bash

# ...

sh -c '
sleep 20 &
PID=$!
kill -9 $PID # >/dev/null 2>&1
'

# ...

Answer 4

This can be done using 'wait' + redirection of wait to /dev/null :

sleep 2 &
PID=$!
kill -9 $PID
wait $PID 2>/dev/null
sleep 2
sleep 2
sleep 2

This script will not give the "killed" message:

-bash-4.1$ ./test
-bash-4.1$ 

While, if you try to use something like:

sleep 2 &
PID=$!
kill -9 $PID 2>/dev/null
sleep 2
sleep 2
sleep 2

It will output the message:

-bash-4.1$ ./test
./test: line 4:  5520 Killed                  sleep 2
-bash-4.1$

I like this solution much more than using 'disown' which may have other implications.

Idea source: https://stackoverflow.com/a/5722850/1208218