<p>I currently do my textfile manipulation through a bunch of badly remembered AWK, sed, Bash and a tiny bit of Perl.</p>

<p>I've seen mentioned a few places that python is good for this kind of thing. How can I use Python to replace shell scripting, AWK, sed and friends?</p>

I suggest the awesome online book
Dive Into Python
.  It's how I learned the language originally.
Beyond teaching you the basic structure of the language, and a whole lot of useful data structures, it has a good chapter on
file handling
and subsequent chapters on
regular expressions
and more.