debconf を readline で使う人は libterm-readline-gnu-perl を

私は debconf は Readline で使う人種です。このとき libterm-readline-gnu-perl をインストールしておくと、選択肢の既定値（現在の値）が入力済みで表示されるので便利です。locale の選択なんかは ちょっとげんなりするかもしれない…。

debconf(7) Frontends readline より（強調は私）

The most traditional frontend, this looks quite similar to how Debian configuration always has been: a series of questions, printed out at the console using plain text, and prompts done using the readline library. It even supports tab completion. The libterm-readline-gnu-perl package is strongly recommended if you chose to use this frontend; the default readline module does not support prompting with default values.  At the minimum, you'll need the perl-modules package installed to use this frontend.

This  frontend  has  some  special hotkeys. Pageup (or ctrl-u) will go back to the previous question (if that is supported by the package that is using debconf), and pagedown (or ctrl-v) will skip forward to the next question.

This is the best frontend for remote admin work over a slow connection, or for those who are comfortable with unix.