The Debian Installer consists of a number of special-purpose components to perform each installation task. Each component performs its task, asking the user questions as necessary to do its job. If there is no problem, the next component in the sequence takes over without any user interaction (other than various progress messages). When there is a problem, the user will see an error screen, and the installer menu may be shown in order to select some alternative action. If there are no problems, the user will never see the installer menu, but will simply answer questions for each component in turn.
The questions themselves are given priorities, and the priority of questions to be asked can be set. Thus if the installer knows what to do, and the user need not be aware of other choices which are available, then the installer will make the choice and not display the question. Serious error notifications are set to priority 'critical' so the user will always be notified.
Power users may be more comfortable with a menu-driven interface, where each step is controlled by the user rather than the installer performing each step automatically in sequence. To use the installer in a manual, menu-driven way, add the boot argument DEBCONF_PRIORITY=medium.
The normal installer display is character-based (as opposed to the now more familiar graphical interface). The mouse is not operational in this environment. Here are the keys you can use to navigate within the various dialogs. The right arrow or Tab key move `forward', and left arrow or Shift-Tab move `backward' between displayed buttons and selections. The up and down arrow select different items within a scrollable list, and also scroll the list itself. In addition, in long lists, you can type a letter to cause the list to scroll directly to the section with items starting with the letter you typed and use Pg-Up and Pg-Down to scroll the list in sections. The space bar selects an item such as a checkbox. Use Enter to activate choices.
Les messages d'erreur sont redirigés vers la troisième console (connue comme tty3). Vous pouvez y accéder en pressant Left Alt-F3 en gardant la touche Alt enfoncée pendant que vous appuyez sur la touche de fonction F3. Revenez en arrière sur avec Left Alt-F1.
Ces messages se retrouvent aussi dans /var/log/messages. Après l'installation, ce fichier-journal est copié dans /var/log/installer.log sur votre système. system. Other installation messages may be found in /target/var/log/debian-installer/ during the installation, and /var/log/debian-installer/ after the computer has been booted into the installed system.