douf00: 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/douf00 - from package: douf00

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

Error in other languages:
douf00: bevel nie gevind nie
douf00: comandă negăsită
douf00: comando não encontrado
douf00: commande introuvable
douf00: command not found
douf00: käsku ei ole
douf00: không tìm thấy lệnh
douf00: komanda nerasta
douf00: Kommando nicht gefunden.
douf00: kommandot finns inte
douf00: komut yok
douf00: nie znaleziono polecenia
douf00: níor aimsíodh an t-ordú
douf00: no se encontró la orden
douf00: no s'ha trobat l'ordre
douf00: opdracht niet gevonden
douf00: parancs nem található
douf00: perintah tidak ditemukan
douf00: príkaz nenájdený
douf00: příkaz nenalezen
douf00: команда не найдена
douf00: командата не е открита
douf00: 命令找不到
douf00: コマンドが見つかりません