Slightly related question: It seems zsh is gaining in popularity. What is the learning curve like coming from bash? Is it a "superset" of bash or completely different?
basically depends on how much of bash you've been using. i'd say it's a strict superset of 99% of what 99% of bash users do. the prompt language is about the only thing i can think of at the moment that most people ever touch at all that's significantly different. (if you're into writing custom completion modules or something, that's part's completely different.)
zsh is pretty much a superset of bash, I'd expect most bash scripts to work with zsh with no modification whatsoever, even using most of bash's more advanced features.
