Choosing a Shell - northwood-labs/macos-for-development GitHub Wiki

See Determining your shell first.

Z-Shell

Z-Shell is the default shell for new setups as of macOS 10.15 “Catalina” (October 2019). This is a popular, modern shell that can also emulate Bash. It has some popular extensions in the form of Oh My Zsh, Powerlevel10k, and Starship.

This shell is pre-installed.

Bash 3.2

Bash was the default shell for all new setups from Mac OS X 10.3 “Panther” (October 2003) through macOS 10.14 “Mojave” (September 2018). Unfortunately, Bash 4.0 changed their license from GPL 2.0 to GPL 3.0, which is largely incompatible with most corporations. As a result, Apple was unable to legally upgrade Bash beyond version 3.2.57.

Any shell script that begins with #!/bin/bash is executed with this version of Bash.

This shell is pre-installed.

Bash 5

Bash can be upgraded to a modern version by installing from Homebrew . This is a version of Bash that is licensed as GPL 3.0. Apple cannot agree to this license, but you can. A more complete tutorial can be found at Configuring modern Bash as the default shell for macOS.

This shell is NOT pre-installed, but you can install it via Homebrew.

brew install bash
sudo bash -c "echo $(brew --prefix bash)/bin/bash >> /etc/shells"
chsh -s $(brew --prefix bash)/bin/bash

You can use this modern Bash by defining #!/usr/bin/env bash at the top of a shell script.

Others

Most other shells are pretty uncommon on macOS. There's nothing inherently wrong with them, they're just far less common.