-d-useradd command is used to add the user in the system. by default it creates the users home directory in /home if you want to specify the users home directory in different location use the -d and name of directory with path. example: useradd -d /var/user1 user1 useradd -s /bin/sh user1 : sets the sh shell as default shell to user user1 after adding the user use the usermod command to change the users home directory, login shell, account lock, account unlock etc.