debconf: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/debconf - from package: debconf

You may install the required package with command apt-get install {package}

Error in other languages:
debconf: bevel nie gevind nie
debconf: comandă negăsită
debconf: comando não encontrado
debconf: commande introuvable
debconf: command not found
debconf: käsku ei ole
debconf: không tìm thấy lệnh
debconf: komanda nerasta
debconf: Kommando nicht gefunden.
debconf: kommandot finns inte
debconf: komut yok
debconf: nie znaleziono polecenia
debconf: níor aimsíodh an t-ordú
debconf: no se encontró la orden
debconf: no s'ha trobat l'ordre
debconf: opdracht niet gevonden
debconf: parancs nem található
debconf: perintah tidak ditemukan
debconf: príkaz nenájdený
debconf: příkaz nenalezen
debconf: команда не найдена
debconf: командата не е открита
debconf: 命令找不到
debconf: コマンドが見つかりません