This gives you suggestions for how to look up Unix commands, find online Unix books, and link to support sites and information about paper Unix books.
Commands lists popular beginner's commands.
Books lists a selection of paper books and CDs about Unix. In composing a Unix command at the shell prompt, you might make use of one or more of these special symbols. On the command manual page, you'll see the command name followed by a cryptic number in partenthesis. This table explains those numbers. This is a list that I could come up with, with links to companies.