mpb: 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/mpb - from package: mpb

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

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