1.1 Mac OS X Shells
Mac OS X comes with the Bourne-again shell ( bash ) as the default user shell, and also includes the TENEX C shell ( tcsh ) and the Z shell ( zsh ). Both bash and zsh are sh -compatible. When tcsh is invoked through the csh link, it behaves much like csh . Similarly, /bin/sh is a hard link to bash , which also reverts to traditional behavior when invoked through this link (see the bash manpage ).
If you install additional shells, you should add them to /etc/shells . To change the Terminal's default shell, see Section 1.4, later in this chapter. To change a user's default shell (used for both the Terminal and remote and console logins), see Section 3.7.5 in Chapter 3.