xmpi: 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/xmpi - from package: xmpi

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

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