While hunting for good study material for the LPIC-2 certificate (linux professional institute certification) I came across a very good online book that’s up to date and very structured at the time of writing. It’s from a dutch site dedicated to linux/unix:
http://www.snow.nl/dist/xhtmlc
Kudos to the snow.nl team! The material is really useful, even for general linux knowledge and familiarization.
David Vassallo's Blog 