Speaking as a person that converted a big shell script to Python a while back, I think both languages have their strengths. Writing something like:

    prog1 2> prog1.log | prog2 2> prog1.log | prog3

in Python is not nearly so succinct as in the shell (using only Python's standard library). And don't screw up waiting for processes or flushing buffers, things that the shell takes care of for you AFAIK.

On the other hand, things like string or date manipulation are easier in Python than in the shell.

It doesn't have to be Python--you can use pretty much any language you want, so just use your favorite one be it Ruby or Python or Haskell or whatever.

I personally only use Bash when the script is just a trivial translation of commands I enter.

I needed this guide to help me write my bash script that I use to build python and all its dependencies on all the machines I need to work on. That way I'm not at the mercy of whatever out of date python happens to be installed with the package manager by the admin.

Actually perl makes it way easier than python, because it supports more of bash features directly, from backticks to here-docs.

This guide is a great read even if all you do is short bash scripts.

Shell is Lingua Franca for system administrators.