If you want kill a running process called main.py, you could do
$ ps | grep main | grep py $ kill -9 <pid>
but that's a hassle. To do it in one step, you can do
$ kill -9 `ps | grep main | grep py | cut -f 1 -d" "`
If you have many python scripts with 'matterhorn' in the path (visible by doing "ps auxwww") then you can do
$ ps auxwww | grep python | grep matterhorn | awk '{print $2}' | xargs kill -9
What this does is: