How to change your UNIX login shell from the default assigned Bourne (BASH) shell
Step-by-step guide
Open Terminal:
Check and note your current login shell
echo $SHELL /bin/bash
To change your shell, create a ~/.bash_profile in the root of your home directory with the following lines or if you already have a .bash_profile append it with the below entries. This example is for zsh.
export SHELL=/bin/zsh exec zsh
List of other shell on macOS
/bin/bash /bin/csh /bin/ksh /bin/sh /bin/tcsh /bin/zsh
Check and note your new login shell by opening another terminal window and do another "echo $SHELL" this time you should get zsh instead.
echo $SHELL /bin/zsh