hpiwdt: 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 CentOS possible default full paths are:

/usr/bin/hpiwdt - from package: openhpi32
/usr/bin/hpiwdt - from package: openhpi

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/hpiwdt - from package: openhpi-clients

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

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