cdfnorth_unfold: 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/cdfnorth_unfold - from package: cdftools

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

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