Most Useful Scripting Language To Learn?

Bash has to be the most useful in day to day admin work.

Of course that doesn't make it the best for more complex projects.

I know complaining about lack of options is frowned upon, but I think the bash option should be replaced with Bourne shell (sh). The Bourne shell syntax is supported by sh, ksh, and bash. Bash, on the other hand, is a "new" shell with special features not available in the other shells.

I get frustrated when kids write shell scripts that use bash-special features. There's a reason to write it in basic Bourne shell syntax.

Okay, time for everyone to get off my lawn...

Sorry, but MATLAB is the industry standard. As big of a pain as it is, we have a huge repository of functions already written in it. There's just too much momentum to change. Believe me, I tried!

And it is often a bad choice to use bash in your script. Using sh gives you much more portability, you do not need to worry about which version of bash you are running on: there is only one sh. sh is installed on all unixes. And sh interpretors are faster and lighter than bash interpretors.

Why write complex scripts in bash if you can write them in sh?

Lua is not an acronym. From the Lua web page:
"Lua" (pronounced LOO-ah) means "Moon" in Portuguese. As such, it is neither an acronym nor an abbreviation, but a noun.

LuaJIT [luajit.org] is probably the fastest scripting language in existence. I have found for math-heavy algorithms it's as fast as optimized compiled C code. Plus it's FFI interface is stunningly fast, allowing easy fast access to native libraries.

Yes, there is. Scripting languages replace what an operator can execute as a series of commands. Java doesn't do that - it has no provisions for it.

bash and perl are scripting languages. python? Hardly.

Come back with your java once you can do something like

perl -pi.bak -e 's/#include "stdio.h"/#include <stdio.h>/' *.c

or

ssh othermachine "grep 'sh$' /etc/passwd" | awk -F: '{print $5}' | sort -u

or

vmrun list | grep '^/' | sed 's/^/vmrun suspend "/;s/$/"/' | sh

Scripting languages exist because they're useful - you can do things very quickly.

Bad idea. Abort, abort.
Use csh (or better, tcsh) as a shell if you like, but don't use it [grymoire.com] for scripting [faqs.org].