Your question is not clear, you talk about a daemon in the title, but in the body only talk about a generic process.
For a daemon there are specific means to stop it, for example in Debian you have
service daemon-name stop
or
/etc/init.d/daemon-name stop
Similar syntaxes exist for other initscript standards used in other distributions/OS.
To kill a non-daemon process, supposing it is in some way out of control, you can safely use killall or pkill, given that they use by default the SIGTERM (15) signal, and any decently written application should catch and gracefully exit on receiving this signal. Take into account that these utilities could kill more that one process, if there are many with the same name.
If that do not work, you can try SIGINT (2), then SIGHUP (1), and as a last resort SIGKILL (9). This last signal cannot be catched by the application, so that it cannot perform any clean-up. For this reason it should be avoided every time you can.
Both pkill and killall accept a signal parameter in the form -NAME, as in
pkill -INT process-name
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}'`
Best Answer
If you need to match the full command line (command + parameters) as you reported in your example you will have to use the
-foption:accordingly to the man page: