Awesome

Selenium -- Gem wrapper for selenium server

$ gem install selenium

selenium install - installs selenium
selenium         -  runs the selenium server

If you are on OSX, you have better option with homebrew help:

brew install selenium-server-standalone

Standalone selenium server is implemented as launchd agent.

To have launchd start selenium-server-standalone at login, create soft link:

ln -sfv /usr/local/opt/selenium-server-standalone/*.plist ~/Library/LaunchAgents

Then load selenium-server-standalone agent:

launchctl load ~/Library/LaunchAgents/homebrew.mxcl.selenium-server-standalone.plist

It will run selenium server on port 4444.

If you don't want to use agent, use java directly:

java -jar /usr/local/opt/selenium-server-standalone/selenium-server-standalone-2.35.0.jar -p 4444