mdf2c: 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 CentOS possible default full paths are:

/usr/lib64/dx/bin/mdf2c - from package: dx

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/lib/dx/bin/mdf2c - from package: dx

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

Error in other languages:
mdf2c: bevel nie gevind nie
mdf2c: comandă negăsită
mdf2c: comando não encontrado
mdf2c: commande introuvable
mdf2c: command not found
mdf2c: käsku ei ole
mdf2c: không tìm thấy lệnh
mdf2c: komanda nerasta
mdf2c: Kommando nicht gefunden.
mdf2c: kommandot finns inte
mdf2c: komut yok
mdf2c: nie znaleziono polecenia
mdf2c: níor aimsíodh an t-ordú
mdf2c: no se encontró la orden
mdf2c: no s'ha trobat l'ordre
mdf2c: opdracht niet gevonden
mdf2c: parancs nem található
mdf2c: perintah tidak ditemukan
mdf2c: príkaz nenájdený
mdf2c: příkaz nenalezen
mdf2c: команда не найдена
mdf2c: командата не е открита
mdf2c: 命令找不到
mdf2c: コマンドが見つかりません