mhf_server: 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/mhf_server - from package: pvm-examples

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

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