ubuntu - rails TCPServer Error: Address already in use

When you try to start the rails server with the following command

rails s

and if webrick doesn't start and throws "Address already in use" error, following are the directions on ubuntu to kill all ready running

Type the following from terminal

lsof|grep 3000

This gives a list of running processses that are using 3000 port.  Find a line that starts with ruby, and note the process id

ruby  12345 ....

Type the following command at terminal

kill -9 12345

And your webrick server should start fine now