Here's a few helping me now become a better LINUX administrator. In high school I used to punch IBM cards to get things going. They were my punch cards held together with a rubber band, now that's security. Where are those punch cards?
Administering your Linux system at http://alien.slackbook.org/dokuwiki/doku.php?id=linux:admin
An A-Z Index of the Bash command line for Linux at http://www.ss64.com/bash/
Useful introduction to Linux Command at http://linuxcommand.org/index.php