Have background in Solaris, HP-UX, and AIX. What is best reference book for taking that knowledge and transitioning it into RHEL?

Google it! You will get many Notes.
There is no such single book which covers all RHEL.

Most of the basic ie non-admin cmds are the same or enhanced if using the GNU version (default on Linux).
http://linux.die.net/man/

As per differences at admin level between those *nix, Linux is different again ...
Try eg http://www.linuxtopia.org/online_boo...ion/index.html & more generally www.linuxtopia.org, especially the System/Network Admin section.

This is a good Linux (RHEL oriented) tutorial http://rute.2038bug.com/index.html.gz

Such an answer is very far from the quality level we are trying to build and maintain here at LinuxQuestions! Not to mention you've taken an unanswered thread out of the Zero Reply List for nothing. Man warned...

Hi, I know a few books very cool:

Basic books: --> slackware book ( http://www.slackbook.org/html/book.html )
--> redhat unleashed
--> red hat fedora for dummies
, all starting from zero.

Advanced books: --> linux bible 2008 Edition Boot Up to Ubuntu, Fedora, Knoppix, Debian, openSUSE and 11 other distributions
--> unix and linux system administration handbook

Advanced books is perfect to read after the basic books then this knowledge about linux become solid.

My website with examples of commands (I put a new command every day) starting from zero too.

http://www.pgio.com.br/paginas/linux.html[COLOR="Silver"]

---------- Post added 06-08-12 at 07:22 AM ----------

The Linux Comman Line.. William E. Schotts.

I'm new to Linux as well and through my job I have access to books24x7. I often find myself referring back to Introduction to Linux/Unix by Christopher Diaz, Linux Command Line and Shell Scripting Bible, Second Edition by Richard Blum and Christine Bresnahan and another one was listed above by GioBarr linux bible 2008 (although this is now into 2011 and soon to be 2012 version). I don't remember the name, but RH releases a book just for RH and I think the book for RH6 is coming out soon. I've enjoyed RH5 version.

But I think beyond books what's helped me the most in learning is deciding what I want to do and then trying to figure out how to do it. Whether it be referencing books or doing a google search having a goal to reach or something to accomplish really helped me faster then just reading.

There's a tremendous amount of stuff at The Linux Documentation Project.

I can recommend this commercially available book. I don't know whether it has been updated to RHEL 6 yet, but it's the first thing I've read that explained vi in a way that I found concise, clear, and usable.

Amazon has "Red Hat Linux Bible" and "Red Hat Administrators' Handbook", both with good reviews.