By default, your Mac uses either zsh or bash as the command-line interpreter for the login shell and interactive shell:
- zsh (Z shell) is the default shell for all newly created user accounts, starting with the macOS Catalina beta, currently available only to members of the Apple Developer Program.
- bash is the default shell in macOS Mojave and earlier.
zsh is highly compatible with the Bourne shell (sh) and mostly compatible with bash, with some differences. For more about zsh and its comprehensive command-line completion system, enter
man zsh in Terminal.
How to change your default shell
Whether your user account is configured to use zsh (recommended), bash, or another shell, you can change the default shell from Users & Groups preferences or the command line.
From Users & Groups preferences
- Choose Apple menu > System Preferences, then click Users & Groups.
- Click the lock , 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.
From the command line
In Terminal, enter
$ chsh -s path, where path is one of the shell paths listed in /etc/shells, such as /bin/zsh, /bin/bash, /bin/csh, /bin/dash, /bin/ksh, /bin/sh, or /bin/tcsh.
How to use a different shell without changing the default
If you don't want Terminal to use the default login shell in new Terminal windows and tabs:
- Open Terminal, then choose Terminal > Preferences.
- From the General pane, select ”Command (complete path).”
- In the field provided, enter one of the shell paths listed in /etc/shells, such as /bin/zsh, /bin/bash, /bin/csh, /bin/dash, /bin/ksh, /bin/sh, or /bin/tcsh.
If you invoke the bash shell while macOS Catalina is configured to use a different shell, you'll see a message that the default interactive shell is now zsh. To silence this warning, you can add this command to ~/.bash_profile or ~/.profile:
How to switch to a zsh profile and prompt
If you're using a bash profile, such as to set environment variables, aliases, or path variables, you should switch to using a zsh equivalent. For example:
- .zprofile is equivalent to .bash_profile and runs at login, including over SSH
- .zshrc is equivalent to .bashrc and runs for each new Terminal session
If you're using .profile (a POSIX-compliant profile), you can make zsh automatically read its settings by adding this command to .zprofile:
[[ -e ~/.profile ]] && emulate sh -c 'source ~/.profile'
You can also move some settings from a bash profile to a zsh profile without modification. For example, to set environment variables:
zsh recognizes a different set of prompt specifiers than bash and has a cleaner syntax for specifying colorized output, eliminating the need to use complex ANSI escape sequences. For example, here's the syntax for a default bash prompt from .bash_profile:
export PS1="\[\e[92;40m\]\h\[\e[m\]:\[\e[93m\]\W\[\e[m\] \\$ "
To convert that bash prompt to a zsh prompt when using .zprofile or .zshrc:
export PS1="%10F%m%f:%11F%1~%f \$ "
See the zsh man page for more details.
How to test your shell scripts
To test script compatibility with Bourne-compatible shells in macOS Catalina, you can change /var/select/sh to /bin/bash, /bin/dash, or /bin/zsh. If you change /var/select/sh to a shell other than bash, be aware that scripts that make use of bashisms may not work properly.
zsh can be made to emulate sh by executing the command
zsh --emulate sh.