mdf2iso: 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/mdf2iso - from package: mdf2iso

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

Error in other languages:
mdf2iso: bevel nie gevind nie
mdf2iso: comandă negăsită
mdf2iso: comando não encontrado
mdf2iso: commande introuvable
mdf2iso: command not found
mdf2iso: käsku ei ole
mdf2iso: không tìm thấy lệnh
mdf2iso: komanda nerasta
mdf2iso: Kommando nicht gefunden.
mdf2iso: kommandot finns inte
mdf2iso: komut yok
mdf2iso: nie znaleziono polecenia
mdf2iso: níor aimsíodh an t-ordú
mdf2iso: no se encontró la orden
mdf2iso: no s'ha trobat l'ordre
mdf2iso: opdracht niet gevonden
mdf2iso: parancs nem található
mdf2iso: perintah tidak ditemukan
mdf2iso: príkaz nenájdený
mdf2iso: příkaz nenalezen
mdf2iso: команда не найдена
mdf2iso: командата не е открита
mdf2iso: 命令找不到
mdf2iso: コマンドが見つかりません