apt-cudf: 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/apt-cudf - from package: apt-cudf

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

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