whirlpool-hash: 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/whirlpool-hash - from package: rhash

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

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