core.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"

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