cdfsig0: 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/cdfsig0 - from package: cdftools

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

Error in other languages:
cdfsig0: bevel nie gevind nie
cdfsig0: comandă negăsită
cdfsig0: comando não encontrado
cdfsig0: commande introuvable
cdfsig0: command not found
cdfsig0: käsku ei ole
cdfsig0: không tìm thấy lệnh
cdfsig0: komanda nerasta
cdfsig0: Kommando nicht gefunden.
cdfsig0: kommandot finns inte
cdfsig0: komut yok
cdfsig0: nie znaleziono polecenia
cdfsig0: níor aimsíodh an t-ordú
cdfsig0: no se encontró la orden
cdfsig0: no s'ha trobat l'ordre
cdfsig0: opdracht niet gevonden
cdfsig0: parancs nem található
cdfsig0: perintah tidak ditemukan
cdfsig0: príkaz nenájdený
cdfsig0: příkaz nenalezen
cdfsig0: команда не найдена
cdfsig0: командата не е открита
cdfsig0: 命令找不到
cdfsig0: コマンドが見つかりません