It’s awfull when you don’t have a response from a running program. You’re waiting and wasting your time and nothing happens. To terminate a linux program on the quick and dirty way i use the simple shell script. The script takes a as argument the programm name. Just place it in a directory inside your working path (i have a local directory bin with all my scripts inside my home directory) and make it executable (chmod 755 killit). After that just type : $ killit firefox. Enjoy.
#!/bin/bash
function killit () {
ps aux | grep "$1" | awk '{print $2}' | xargs kill
}
if [ $# -lt 1 ]; then
echo "Usage: `basename $0 ` <programname> "
exit
fi
killit "$1"
exit