Some users may need specific support because of e.g. some visual impairment. USB braille displays are detected automatically (not serial displays connected via a serial-to-USB converter), but most other accessibility features have to be enabled manually. On machines that support it, the boot menu emits beeps when it is ready to receive keystrokes. It beeps once on BIOS systems, and beeps twice on UEFI systems. Some boot parameters can then be appended to enable accessibility features (see also Avsnitt 5.1.5, ”Uppstartsskärmen”). Note that on most architectures the boot loader interprets your keyboard as a QWERTY keyboard.
The Debian installer supports several front-ends for asking questions, with varying convenience for accessibility: notably, text
uses plain text while newt
uses text-based dialog boxes. The choice can be made at the boot prompt, see the documentation for DEBIAN_FRONTEND
in Avsnitt 5.3.2, ”Parametrar för Debian Installer”.
With the newt
front-end (used mostly with braille), one mostly just selects answers with arrow keys and presses Enter to validate the choice. Pressing Tab or Shift - Tab allows to switch between dialog elements, and notably to access the Go Back
button, which brings back again to previous questions. Some dialogs contain check boxes, which can be ticked on and off by pressing Space.
With the text
front-end (used mostly with speech), one mostly selects answers either by typing their number followed by pressing Enter, or by selecting an answer with arrow keys, and pressing Enter to validate the choice. One can also not type anything and just press Enter to simply accept the default value. Typing <
and pressing Enter brings back again to previous questions. When a selection of choices has to be made (e.g. during task selection), one can type !
to express an empty selection.
Punktskriftsskärmar för USB ska identifieras automatiskt. En textversion av installationsprogrammet kommer sedan att väljas automatiskt och stöd för punktskriftsskärmen kommer att installeras automatiskt på målsystemet. Du kan därför bara trycka på Enter vid uppstartsmenyn. När brltty
har startats så kan du välja en punktskriftstabell genom att gå in i inställningsmenyn. Dokumentation för tangentbindingar för punktskriftsskärmar finns tillgänglig på webbsidan för brltty
.
Serial braille displays cannot safely be automatically detected (since that may damage some of them). You thus need to append the brltty=
boot parameter to tell driver
,port
brltty
which driver and port it should use. driver
should be replaced by the two-letter driver code for your terminal (see the BRLTTY manual). port
should be replaced by the name of the serial port the display is connected to, ttyS0
is the default, ttyUSB0
can be typically used when using a serial-to-USB converter. A third parameter can be provided, to choose the name of the braille table to be used (see the BRLTTY manual); the English table is the default. Note that the table can be changed later by entering the preference menu. A fourth parameter can be provided to pass parameters to the braille driver, such as protocol=foo
which is needed for some rare models. Documentation on key bindings for braille devices is available on the brltty
website.
Support for software speech synthesis is available on all installer images which have the graphical installer, i.e. all netinst, CD and DVD images, and the netboot gtk variant. It can be activated by selecting it in the boot menu by typing s
Enter. The textual version of the installer will then be automatically selected, and support for software speech synthesis will be automatically installed on the target system.
Om flera ljudkort upptäcks uppmanas du att trycka på Enter när du hör tal från önskat ljudkort.
Den första frågan (språket) talas på engelska, och resten av installationen talas på det valda språket (om tillgängligt i espeak
).
The default speech rate is quite slow. To make it faster, press CapsLock+6. To make it slower, press CapsLock+5. The default volume should be medium. To make it louder, press CapsLock+2. To make it quieter, press CapsLock+1. To get more details on the browsing shortcuts, see the Speakup guide. To just accept the default answer for a question, simply press Enter at the prompt. To provide an empty answer for a question, type !
at the prompt. To get back to the previous question, type <
at the prompt.
Support for hardware speech synthesis devices is available on all installer images which have the graphical installer, i.e. all netinst, CD and DVD images, and the netboot gtk variant. You thus need to select a ”Graphical install” entry in the boot menu.
Talsyntesenheter (maskinvara) kan inte identifieras automatiskt. Du behöver därför lägga till uppstartsparametern speakup.synth=
för att berätta för drivrutin
speakup
vilken drivrutin som den ska använda. drivrutin
ska ersättas med koden för drivrutinen för din enhet (se kodlista för drivrutiner). Textversionen av installationsprogrammet kommer sedan att väljas automatiskt och stöd för talsynteser kommer automatiskt att installeras på målsystemet.
Vissa hjälpmedelsenheter är faktiska kort som ansluts inne i datorn och som läser test direkt från grafikminnet. För att få dem att fungera så måste stöd för framebuffer inaktiveras genom att använda uppstartsparametern vga=normal
.fb=false
Detta kommer dock att minska antalet tillgängliga språk.
If desired a textual version of the bootloader can be activated before adding the boot parameter by typing h
Enter.
For users with low vision, the installer can use a high-contrast color theme that makes it more readable. To enable it, you can use the ”Accessible high contrast” entry from the boot screen with the d
shortcut, or append the theme=dark
boot parameter.
For users with low vision, the graphical installer has a very basic zoom support: the Control++ and Control+- shortcuts increase and decrease the font size.
Expert, Rescue, and Automated installation choices are also available with accessibility support. To access them, one has to first enter the ”Advanced options” submenu from the boot menu by typing a
. When using a BIOS system (the boot menu will have beeped only once), this has to be followed by Enter ; for UEFI systems (the boot menu will have beeped twice) that must not be done. Then, to enable speech synthesis, s
can optionally be pressed (followed again by Enter on BIOS systems but not on UEFI systems). From there, various shortcuts can be used: x
for expert installation, r
for rescue mode, or a
for automated installation. Again these need to be followed by Enter when using a BIOS system.
The automated install choice allows to install Debian completely automatically by using preseeding, whose source can be entered after accessibility features get started. Preseeding itself is documented in Appendix B, Automatiserad installation med förinställningar.
Dokumentation om tillgänglighet för det installerade systemet finns på Debian tillgänglighet wikisidan.