If ever there was a testimonial to "one-size-DOESNT-fit-all", it's Linux - if you take the average distro and install a reasonable number of apps and system components, you'll find that between them just about all the major scripting languages have been used.
Your background is with the more "English-like" languages, so you might try Python or Tcl. I work in more of a C++ environment, so I tend to use Perl or even Java.
And while Rexx isn't all that common under Linux, if you like Rexx, why not build on it:
http://users.comlab.ox.ac.uk/ian.collier/Rexx/ ?
Besides, *IBM* likes Rexx, and IBM likes Linux. Colishaw has been doing some interesting things in the last few years that take the Rexx core concepts to places that most people wouldn't have even considered.
Of course the "ultimate" scripting language is shell scripting if you want to become pompous and obese in the ways of Unix guruhood. All joking aside, the batch language of DOS is pretty feeble compared to a system where you can find who's eating up your disk space with:
du -ak | grep '.java$' | sort -n | tail -n 15
That lists the 15 biggest files in your directories that end in '.java' displayed in kilobytes. And that's not even a script!
So live dangerously! Try them all. You're sure to find 2 or 3 that you like!