I'm trying to kill a background process 'sleep 600'. For that I got the following script which is working fine.
ps -ef | grep "sleep 600" | grep -v grep | awk '{print $2}' | xargs -I{} kill {}
I would like to know what does 'grep -v grep' do?
Could you please go through following.
ps -ef | ##Running ps -ef command to get all running pids information on server, passing its Output to next command as an Input.
grep "sleep 600" | ##Looking for lines which have sleep 600 in it and sending its output as input to next line.
grep -v grep | ##grep -v basically omits lines which have string grep in them, since grep command also creates a process to get string in above command so basically it is there to avoid that command's pid.
awk '{print $2}' | ##Getting 2nd field of the process and sending it to next command as an Input.
xargs -I{} kill {} ##Killing pid which was passed from previous command to this one.
From man grep:
-v, --invert-match Invert the sense of matching, to select non-matching lines. (-v is specified by POSIX.)
Suggestion for OP's command improvement: You could remove multiple usage of grep and awk and could do this in a single awk like:
ps -ef | awk '/sleep 600/ && !/awk/{print $2}' | xargs -I{} kill {}
OR make use of pkill option: Please make sure you test it before running in PROD/LIVE environments. Also while providing patterns make sure you are giving correct pattern which catches right process else it may kill other PIDs too, so just a fair warning here.
pkill -f 'sleep 60'