Starting with the macOS Catalina beta, your Mac will use zsh as the default shell in Terminal, replacing Bash.
Bash and Z Shell
Bash, otherwise known as the Bourne Again Shell, started in 1989 to replace the older Bourne shell. It’s been the default shell in macOS starting with OS X Jaguar released in 2002. However, people have always been able to change what shell they want, and Z shell is a popular alternative. Z shell extends Bash with a bunch of improvements.
Changing Your Default Shell From Users & Groups
- Choose Apple menu > System Preferences, then click Users & Groups.
- Click the lock icon, then enter your account name and password.
- Control-click your user name in the list of users on the left, then choose Advanced Options.
- Choose a shell from the ”Login shell” menu, then click OK to save the changes.
Changing Your Default Shell From Terminal
Open Terminal and enter the following command:
$ chsh -s path
Where path is one of shell paths listed in /etc/shells, such as /bin/zsh, /bin/bash, /bin/csh, /bin/dash, /bin/ksh, /bin/sh, or /bin/tcsh.