I consider this the best practical guide for a Unix system administrator I've yet found. It's valid for most major platforms; Solaris, AIX, HP-UX and Linux (to a slighly less extent. It addresses the most common practical problems you might experience; backing up, boot problems, managing filesystems, security, etc., etc. I'm only giving up this copy because I had a book and each worksite and ended up with an extra.
Very good book for the new System Administrator.
