cdfeke: 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/cdfeke - from package: cdftools

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

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