cdfmkmask: command not found

Have You tried accessing the binary with the full path?

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/cdfmkmask - from package: cdftools

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