mdm-sync: 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/mdm-sync - from package: mdm

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

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