cdfets: 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/cdfets - from package: cdftools

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

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