pbwtest: 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/pbwtest - from package: pvm-examples

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

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