I am a big believe in BASH. It's still my go to tool for most scripting in UNIX. It is everywhere, which makes a big difference. People used to use Perl because it was so ubiquitous. But on current systems it is Python that I see more commonly. Node.js, Ruby and Go are out there a lot too. The one thing that you can almost always count on is BASH. It's simple, it's standard and it is really fast to do simple things.