5.2. Khả năng truy cập

Some users may need specific support because of e.g. some visual impairment. Most accessibility features have to be enabled manually. Some boot parameters can be appended to enable accessibility features. Note that on most architectures the boot loader interprets your keyboard as a QWERTY keyboard.

5.2.1. Installer front-end

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 Phần 5.3.2, “Tham số trình cài đặt Debian”.

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.

5.2.2. Thiết bị bảng

Một số thiết bị khả năng truy cập nào đó là bảng thật được cắm vào bên trong máy tính, mà đọc văn bản một cách trực tiếp từ vùng nhớ ảnh động. Để hiệu lực thiết bị kiểu này, bạn cần phải tắt hỗ trợ cho vùng đệm khung bằng cách sử dụng tham số khởi động fb=false. Tuy nhiên, việc này cũng giảm số các ngôn ngữ sẵn sàng.

5.2.3. Sắc thái cao tương phản

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.

5.2.4. Zoom

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.

5.2.5. Expert install, rescue mode, automated install

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 Phụ lục B, Tự động hoá việc cài đặt bằng chèn sẵn.

5.2.6. Accessibility of the installed system

Documentation on accessibility of the installed system is available on the Debian Accessibility wiki page.