cdfconvert: 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/cdfconvert - from package: cdftools

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

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