Red Hat EL 4 apt-get, yum, up2date
If you are new to red-hat EL here is a small cheat sheet link list.
up2date how to: http://www.cyberciti.biz/faq/howto-use-up2date-command/
apt-get, yum how to: http://digg.com/linux_unix/Finally_a_good_how_to_FAQ_about_rpm
