Kill a process tree

kill_tree.sh

#!/bin/bash -eu

#From http://stackoverflow.com/questions/392022/best-way-to-kill-all-child-processes?lq=1
#See that URL for alternative methods which don't require pstree

function kill_tree() {
    #$1 is the name of the process, i.e. the file that was executed
    readonly gpid=$(pgrep -o $1)
    #Now $gpid is the group id of all the sub processes
    if [[ ! -z $gpid ]]
    then
        #So this is nasty, but the only sane way I have found to do this so far
        #Take a look at what pstree produces as output and this mayhem will make sense
        #Basically we're getting all the recursive child processes and then passing them
        #To kill
        kill -${2} $(pstree -p ${gpid} | sed 's/(/\n(/g' | grep '(' | sed 's/(\(.*\)).*/\1/' | tr "\n" " ")
    else
	echo "No process matching $1 found"
    fi
}

# e.g kill_tree run-docker.sh -9

kill_tree $1 ${2:-9}

Also see http://stackoverflow.com/questions/392022/best-way-to-kill-all-child-processes?lq=1