kill -SIGINT pid does not work, I get error saying "SIGINT unknown signal". then I typed kill -l to see list of options. Among several options were INT and TERM.
kill -TERM PID killed the process and so did kill -9 pid. But kill -2 pid and kill -INT pid fail. kill -HUP pid also works.
It maybe that all the kill options are not active on my system? Thanks for your response.