A shell, also called "the command line", provides the traditional user interface for the Unix operating system and for Unix-like systems. Users direct the operation of the computer by entering command input as text for a shell to execute.
Note : A normal user can only change their own login shell, whereas the super user can change the login shell for any user account.
The syntax is :
So If I am a superuser and I want the login shell for user account 'staz' to be sh then I would type:
Keep in mind a normal user can only change their login shell to one that is listed in /etc/shells.
This file contains the full pathname of valid login shells. An Example of its contents is shown below.
/bin/csh /bin/sh /usr/bin/es /usr/bin/ksh /bin/ksh /usr/bin/rc /usr/bin/tcsh /bin/tcsh /usr/bin/esh /bin/dash /usr/bin/screen /bin/bash /bin/rbash