It should be noted that this tutorial deals primarily with the HP-UX version of UNIX. This flavour of Unix falls into the System-V camp and if one is using a BSD style Unix then some of the command syntax will differ. From a user's perspective it makes no difference whether you are using version 9.x or 10.x of HP-UX; this FAQ is equally applicable to both versions. Where there are differences between the two versions of the OS, the specific variations of command syntax, file structure and such will be provided explicitly. For different flavours (such as SunOS or Solaris) the specific syntax of some of the commands may be different but the basic concepts remain the same.
The most easily accessible source of UNIX information are the online manual pages. Although sometimes cryptic they are very useful.
Naturally, books are a good place to start when inquiring about a new subject. Anything published by O'Reilly &Associates is of very high quality but some of their titles may not be appropriate for novice users. The O'Reilly title Using csh and tcsh is a pretty good introduction to the two most popular UNIX interfaces. As well, the O'Reilly title UNIX in a nutshell: System V Edition is an excellent quick reference; this book is however a poor choice for novice users.
There is a fair bit of UNIX information available on the Internet (the information footpath) ranging from novice end user material to literature for system administrators and developers. A few good sites I have found are (caveat emptor - I haven't checked these links for a long time):
What are the man pages and how do I read them?
When asking for UNIX help, you may have heard the expression RTFM; this means Read The Friendly Manual (the word friendly is often replaced with the abbreviation for firetruck). Some of the man pages are quite readable while some seem to be written in Swahili! The man pages accesses information from the on-line version of the Unix reference manual. The man pages can be used to display documentation for various UNIX commands and facilities. For example, to access the man page for the chmod command, one would type man chmod. In fact, there are a set of man pages for the man command; read them, live them, love them!