Advice on Unix Internals

[Pledger]

An excellent book on UNIX internals was written by Maurice Bach, called
"The Design of the Unix Operating System".  It provides a very detailed
coverage on the internal structures and algorithms used for AT&T's SYS5.
However it does not address any shells.  Another pretty good beginning 
book on OS's is "Operating Systems, Design and Implementation" by 
Tanenbaum.  This book (and Dietel's) gives an introductory background
on OS design.  Tanenbaum uses an OS called MINIX (mini-unix) that he
developed himself.  He uses this as a working example throughout his
book.  I bought these books a couple of years ago while taking two
operating system classes at George Mason U. (GMU) in Fairfax, Va.
If you want to know BSD internals, there is another book out there
called something like "The Design of the BSD Unix Operating System".
I recently saw it on the bookself, but did not get the author.  

I hope this helps you out.  Any response is gotta be good response.