mpb-split: 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-split - from package: mpb

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

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