/usr/bin/kdekillall is in kdesdk-scripts 4:17.12.3-0ubuntu1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28  | #! /bin/sh
case $1 in
    -*) signal=$1; shift;;
esac
if [ $# = 0 ]; then
    echo "Usage: $0 [-<signal>] <process>"
    echo 'Kills the process "kdeinit4: <process> with signal <signal>"'
	echo "if <signal> is not specified, it defaults to SIGTERM,"
	echo "see kill -l for a list of possible signals"
else
    list=$(ps auwx | grep $USER | awk "/[k]deinit[4|]: $1/ {print \$2}")
    if test -z "$list"; then
        # on newer Linux kernels (>= 2.6.10) KDE is able to use 
        # prctl(PR_SET_NAME) to change the process name...
        list=$(ps auwx | grep $USER | awk "/\[kdeinit[4|]\] $1/ {print \$2}")
    fi
    if test -z "$list"; then
        # with KDE 3.4 we changed the view again...
        list=$(ps auwx | grep $USER | awk "/$1 \[kdeinit[4|]\]/ {print \$2}")
    fi
    if test -n "$list"; then 
        kill $signal $list
    else
        echo 'No process killed'
        exit 1
    fi
fi
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