He also doesn't set -eu or -o pipefail.

I always recommend people use zsh for scripting instead of bash--it gets word splitting right. Most of my sysadminny scripts start with #!/bin/zsh these days. It would be really nice if Linux distros came with zsh installed automatically!

For some reason the shell quoting behavior never seems to get brought up when comparing zsh and bash. It is, IMO, the most important distinction between the two shells.

That's the tricky thing about 'sysadminny' scripts is that they generally need to be written for the least common denominator, which usually ends up being a very old version of $(software). I frequently have to use Python 2.4 to reach many of the RHEL-ish 5 machines in our environment.

As someone who's never used zsh - you don't need to quote stuff in zsh?

By default, no. Word splitting only happens when you request it: ${=words}. It reminds me of ,@list in Lisp, which is a warm and fuzzy feeling.

It depends on options set. There is one that causes word splitting only to happen when explicitly asked for.

Actually the first rule of bash programming should be: Don't use bash.

If your script is longer than 10 lines then you should probably write it in a less error prone language.