It greatly depends on the environment in which your data processing and glue scripts runs: if it's homogenous enough to go for an installer runtime like python or ruby, then so be it.
As a matter of fact, Perl is often available, and the CPAN is a trove of readily available solutions.
This kind of scripts is typically what I'm doing on frequent occasion, and I've always found that portable shell scripting has always trumped any other solution as long as your environment is unix driven - and then for this rare cases where Windows is the platform of choice, I package a few cygwin exes and dlls with the script. I'm working on a very controlled environment though, and expecting to have access to CPAN, much less to Python or Ruby runtimes is a recipe for a great deception.
Shell scripts I say: it's a default on so many plaforms that it's worth keeping it fresh.
As for the next step, I'd say Perl because of its pervasiveness - and the fact that it's a still alive and mightily kicking language - then Python as it's quite common on Linux distributions now.
A closing word: don't dismiss a language because it feels old. If C is a bit overkill for glue and data manipulation code, shell scripting is not going away soon. IMO, the important part of doing our type of job is to know to use the pertinent tool to get a result quickly enough without compromising maintainability too much.