Bash – How to kill a process after detaching it from bash

There is a standard method, if the programs cooperate. Run kill -- -42 where 42 is the pid of the parent process. This sends a signal to all the processes in the process group lead by process 42 (the minus sign before the pid means process group).

Normally, if you run your python script from a shell prompt and it simply forks gnuchess, the two processes should remain in the same process group. But this doesn't seem to be the case, since Ctrl+C sends SIGINT to the whole foreground process group.

Gnuchess might be in its own process group because it made itself a session leader (but I don't know why it would do this), or because you've double-forked it (python forks a shell which forks gnuchess). A double fork is probably avoidable, but I can't tell you how without seeing your code.

A reasonably reliable and POSIX-compliant way of finding the pid of the gnuchess process is

gnuchess_pids=$(ps -A -o pid= -o cmd= | awk '$2 ~ /(^|\/)gnuchess$/ {print $1}')

Specific unix variants may have better ways of achieving this, such as pgrep.

Try to use pkill selenium if neither this, nor one of the others work you can keep using your method with another pipe sequence such as

kill `ps -ef|grep -i selenium| grep -v grep| awk '{print $2}'`