Selenium: Invalid “already running” error when starting server

Question

I am trying to get the Selenium server up and running. However, when I type:

java -jar selenium-server-standalone-2.0b3.jar

I get an Exception

Answer 1

In OSX if you follow the command from @HaloWebMaster (lsof -i -n -P | grep 4444) the next step is to take the PID (usually a 4 - 5 digit number indicating the process ID) and run the following command:

kill -9

You shouldn't need sudo unless the process was started by another user or root.