deb-preconf-drbl: 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/share/drbl/sbin/deb-preconf-drbl - from package: drbl

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

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