How to redirect output of a running program to /dev/null

I know that in order to suppress the output of a program I can redirect it to /dev/null, for example to hide all error and warning messages from chromium I can start the program like this

chromium-browser 2> /dev/null &

However, if I happen to forget about the error messages and type

chromium-browser &

(which is quite annoying when they appear in the middle of a command) I don’t know what to do except for stopping the application and starting it again properly.

Can I somehow redirect error output without restarting the application?

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Answers:

Method 1

Method 2

Method 3

Answers:

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Method 1

This was answered here : here by vladr.
The answer is (quoting) :

attach to the process in question using gdb, and run:
p dup2(open(“/dev/null”, 0), 1) (for stdout redirection)
p dup2(open(“/dev/null”, 0), 2) (for stderr redirection)
detach
quit

I tried it on the following script :
[edition after first comment :]

sleep 10 # so I can have the time to attach to the process
if [ "$sonorfather" == "father" ] # avoid infinite recursion 
then 
   sonorfather=son ./test & 
fi 

while true 
do 
   echo "stdout $sonorfather" 
   echo "stderr $sonorfather" >&2 
   sleep 1 
done

I disabled the stderr output before the son process was created, here is the output :

stdout father 
stdout son 
stdout father 
stdout son 
[and so on...].

I hope this answer your question : the son process stderr was redirected too.

Method 2

You can also launch the browser with nohup and then close the terminal window with the following:

nohup chromium-browser &

This way, the browser will launch and detach from the console, that can then be closed quietly.

Method 3

You could also setup an alias for chromium-browser to instead run chromium-browser 2> /dev/null

e.g. if you are using bash, edit /home/username/.bashrc and add line:

chromium-browser='chromium-browser 2> /dev/null'

or better yet

chrome='chromium-browser 2> /dev/null'

and save some keystrokes.

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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