If there is no automatic login, the first screen presented is the login screen. The basic purpose of this screen is to authenticate the account name and password. Some distros may provide a list of available accounts. In this case, you just need to select the account, and enter the password. To discourage attempts to break a system, there is a limit to the number of failed passwords, before the login screen blocks any attempts to login into that account for a specified period of time. Both of these values are part of the system configuration.
In addition to normal user accounts, the login screen may allow you to login into the guest or root accounts. The root account never appears on the list of available accounts, while the guest account may appear in the list. For improved security, some systems may block any attempts to login into the root account. These systems require you to login as a normal user, before being able to access the root account. If you don't remember your account password, you can login as root, and change the password for the user account. The Users and Groups chapter discusses how to change the password. If you do not know the password to the root account, Booting Linux chapter discusses another alternative.
The login screen established the identity of the user for this session. Any changes to the account, such as adding a new group, are not reflected until the next login.
Beyond account authentication, the login screen may provide other options. The following table lists these options for the distros covered in this course:
|Fedora||The top menu bar provides Accessibility, Speaker, Power, and Shutdown options.|
|Linux Mint||After the Accessibility, Power, and Time icons, the rightmost icon provides various options, including a Shutdown option. The Shutdown option option opens a menu that provides for Restart and Power Off.|
|Lubuntu||While the menu bar provides for desktop selection, the options for KDE and Gnome do not apply. The OpenBox Session icon defaults back to the LXDE desktop.|
|openSUSE||There are two icons in the login box. The leftmost icon allows you to select different desktops. IceWM and TWM are supported as alternates, but are not supported in this course. The next options provides various login options, including recovery, console, and shutdown. The shutdown option brings up another menu with different options including restarting the system. The console option starts a text based session.|
|Ubuntu||The Ubuntu options are the same as those for Linux Mint.|
|Xubuntu||The Xubuntu login screen provides an option to choose between the Xfce desktop and the Xubuntudesktop. The Xfce desktop is the standard Xfce desktop, whereas the Xubuntu desktop is an enhanced desktop provided by the Xubuntu community. The rightmost icon on the menu bar provides options the Restart and Shutdown.|
|text only||Simply prompts for account name and then the password.|
There are three ways to terminate a session:
- Logging out returns you to the login screen.
- Rebooting the system, often called Restart, forces a logout.
- Shutting down the system forces a logout.
The following table describes how to perform these action in each of the above distributions:
If you click your full name icon in the right corner of the menu bar, you will find options for Log Off and Suspend. To restart or power down the system, you must log off, and click on the rightmost icon in the menu bar.
If you click your full name icon in the left corner of the menu bar, you find options for Log Off and Shut Down. The Shut down options opens a complete menu of options, including Restart and Power Off.
The Logout option under the Application Launcher and the rightmost icon on the menu bar open the same menu. This menu provides for the options for Logout, Shutdown, and Reboot.
Open the Application Launcher and move the mouse over the Leave menu, then select the desired option.
The rightmost icon on the menu bar provides the Log Out and Shut Down options. The Shut Down option opens another menu that provides the Restart and Power Off options.
The Logout option under the Application Launcher menu (the left most icon) opens a menu that contains the Log Out, Restart, and Shut Down options. The same options are available by clicking the account name on the rightmost side of the menu bar to open its submenu.
To logout, you can either enter the exit command, or press <CTRL>D keys. The reboot, or shutdown -r now commands cause the system to reboot. The halt, poweroff, or shutdown -n now commands power down the system.
The following sections discuss each of the desktops in more detail.