I bought this book several years ago, when I was
just getting into UNIX, and I was disappointed,
because nothing in it seemed meaningful or
relevant. I recently picked it up again, hoping
to find an answer to some networking problems I'd
run into, and I was amazed - everything I needed
was there, concisely explained. The book had
always been perfect; it was just waiting for the
reader to be able to appreciate it. Since then,
it's become one of my favorite O'Reilly books.