NPpvm: 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/NPpvm - from package: netpipe-pvm

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

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